JPL D-7938, Volume 6 22 November 1995 Radio Science Handbook Galileo Redshift Observations / USO Tests Galileo Solar Wind Scintillation Experiment Galileo Jupiter Occultation Experiment Prepared by: Radio Science Support Team Edited by: S. W. Asmar, R. G. Herrera, and T. Priest ------------------------------------------------------------------------------ Distribution: DSN S. Abbate 507-215 M. Andrews 507-120 J. Conley 507-120 A. Devereaux 161-241 D. Recce 507-120 S. Rockwell 507-215 B. Yetter 507-120 Radio Science J. Anderson 301-230 J. Armstrong 238-737 S. Asmar 161-260 M. Bird Germany J. Caetta 264-325 J. Campbell 301-125L D. Chong 264-325 M. Connally 264-325 P. Edenhoffer Germany P. Eshe 264-325 F. Estabrook 169-327 M. Flasar Goddard R. Herrera 264-325 D. Hinson Stanford U. T. Horton 264-325 T. Howard Stanford U./Chaparral Comm. A. Kliore 161-260 T. Krisher 301-150 T. Priest 264-325 W. Rafferty 161-260 T. Rebold 161-241 M. Tinto 161-241 W. Weber 238-540 R. Woo 238-737 J. Yuen 238-428 Galileo N. Ausman, Jr. 264-419 P. Beyer 303-404 K. Buxbaum 264-765 J. Erickson 264-419 J. Gleason 264-580 J. McKinney 264-419 R. Mitchell 264-419 J. Nash 264-580 W. O'Neil 264-419 W. Sible 264-419 G. Stuffelbeam 264-419 J. Taylor 264-832 Vellum File TMS managers wishing to send copies to DSCC 10, 40, 60, and NOCC Ops Chief can request extra copies from the editors. ------------------------------------------------------------------------------ Table of Contents 1.0 Introduction 2.0 Science Description 3.0 Instrument Description and Configuration 4.0 Team Organization and Responsibilities 5.0 Operations 6.0 Data Products Appendix A DSN Radio Science Open-Loop System Appendix B Abbreviations and Acronyms Appendix C The Radio Science Directory ------------------------------------------------------------------------------ Section 1 Introduction 1.0 The Radio Science Handbook 1.1 The Radio Science Master Schedule 1.2 The Radio Science Library 1.0 Introduction The Radio Science Handbook is an internal reference document prepared and used by the Radio Science Support Team (RSST) for planning, preparation, operations, and analysis of the activities listed on the cover page. It contains information, plans, strategies, and procedures to guide and assist the team members to achieve the goals identified for the activities being supported. It also contains descriptions of the various functions and roles, capabilities and facilities of the Radio Science Support Team. This Handbook does not replace Flight Project or DSN documents and procedures. The Project Sequence of Events (and associated redlines) and the DSN's Network Operations Plan and Keyword File are intended to be the controlling documents for Radio Science activities. Since the Voyager Neptune encounter operations plan, the following volumes of Radio Science Handbooks have been published by the RSST: 625-460 on February 1, 1990: Radio Science Operations Plan for the Ultrastable Oscillatory/Redshift Observations and Venus Range Fix Experiment Volume 1 on 15 November 1990: Galileo Earth 1 Flyby/Mass Determination Ulysses First Opposition Test Galileo Redshift Observations/USO Tests Volume 2 on 14 June 1991: Ulysses Solar Corona Experiment Galileo Redshift Observations/USO Tests Volume 3 on 10 January 1992: Galileo Radio Scintillation Experiment Galileo Redshift Observations/USO Tests Ulysses Jupiter Encounter/IPTO Experiment Ulysses Gravitational Wave Experiment Volume 4 on 22 January 1993: GLL/ULS/MO Joint Gravitational Wave Experiment Galileo Redshift Observations/USO Tests Mars Observer Cruise Tests Volume 5 on 21 October 1994 Galileo Redshift Observations/USO Tests Galileo Solar Wind Scintillation Experiment Ulysses Solar Corona Experiment Galileo Gravitational Wave Experiment Volume 6 on 22 November 1995 Galileo Redshift Observations/USO Tests Galileo Solar Wind Scintillation Experiment Galileo Jupiter Occultation Experiment Experiments not addressed above will be included in future volumes of the Handbook. 1.1 Radio Science Master Schedule The Radio Science Master Schedule, shown in Figures 1-1 and 1-2, is a schedule of the major Radio Science observation opportunities spanning the period from 1994 through 2009, and including Galileo, Ulysses, Mars Global Surveyor, and Cassini opportunities. The Master Schedule is used for reference during planning of future Radio Science activities and resource allocation within the support team. Also included are major events in development of the Deep Space Network (DSN) relevant to Radio Science. 1.2 The Radio Science Library The following documents contain information relevant to the Radio Science activities of interest. These documents may be found in the Radio Science Library (264-325). 1.2.1 Project and DSN Interface Documents Deep Space Network Operations Plan, Project Galileo, Document 870-7, Rev. C, August 15, 1990. Deep Space Network/Flight Project Interface Design Handbook, Document 810-5, Rev. D, July 15 1988. Deep Space Network Systems Requirements Detailed Interface Design, Document 820- 13, Rev. A. Radio Science Software and SPA Radio Science Software Specification Document, SSD1-DMO-5542-OP, Rev. B, Section 2, September 28, 1994. DSS Subsystem Requirements, DSCC Radio Science Subsystem, Document 824-18, Rev. D, Section 2 DSN 34m Beam Waveguide Antenna Station System-Level Design Description Document, Document 831-7, July 1, 1994. Galileo Science Requirements Document, PD 625-50, Rev D, Jan. 18, 1989. Galileo Detailed Mission Requirements, Document 870-256, February 15, 1994. Supersedes Galileo SIRD, PD 625-501, Rev. A, May 1988. Galileo Mission Operations System Functional Requirements, Radio Science System, No MOS-GLL-4-233A, Change 3, November 1, 1990. Galileo Orbiter Functional Requirements Document, Telecommunications System, Document 625-205 GLL 3-300B May 9, 1989. Ulysses Radio Science Requirements Document, ISPM-PI-2138, Issue 4, Updated for 1990 launch. Ulysses SIRD, Document 628-6, Rev. A, June 12, 1990. 1.2.2 Recent Publications Relevant to the Science Experiments Anderson, J. D., J. W. Armstrong, J.K. Campbell, F.B. Estabrook, T.P. Krisher, and E.L. Lau. "Gravitation and Celestial Mechanics Investigations with Galileo", Space Science Reviews, Vol. 60, pp. 591-610, May 1992. Armstrong, J. W. "Spacecraft Gravitational Wave Experiments," Gravitational Wave Data Analysis, B. F. Schutz, ed., pp. 153-172, 1989. Asmar, S. W., P. Eshe, D. Morabito. "Evaluation of Radio Science Instrument: A Preliminary Report on the USO Performance", JPL IOM 3394-90-061, August 10, 1990. Asmar, S. W. and N. A. Renzetti. The Deep Space Network as an Instrument for Radio Science Research, JPL Publication 80-93, Rev. 1, April 15, 1993. Bertotti, B., R. Ambrosini, S. W. Asmar, J. P. Brenkle, G. Comoretto, G. Giampieri, L. Iess, A. Messeri, H. D. Wahlquist. "The Gravitational Wave Experiment," Astronomy and Astrophysics, Suppl. Ser. 1, January 1992. Berotti, B., "The Search for Gravitational Waves with ISPM," in The International Solar Polar Mission - Its Scientific Investigation, K. P. Wenzel, R. G. Mardsen and B. Battrick, eds., ESA SP-1050, 1983. Bird, M.K., S. W. Asmar, J.P. Brenkle, P. Edenhofer, O. Funke, M. Patzold, and H. Volland. "Ulysses Radio Occultation Observations of the Io Plasma Torus During the Jupiter Encounter", Science, Vol. 257, pp. 1531-1535, September 11, 1992. Bird, M. K., S. W. Asmar, J. P. Brenkle, P. Edenhofer, M. Patzold, and H. Volland. "The Coronal-Sounding Experiment," Astronomy and Astrophyiscs, Suppl. Ser. 1, January 1992. Howard, H.T., V.R. Eshleman, D.P. Hinson, A.J. Kliore, G.F. Lindal, R. Woo, M.K. Bird, H. Volland, P. Edenhofer, M. Patzold, and H. Porsche. "Galileo Radio Science Investigations", Space Science Review, Vol. 60, pp. 565-590, May 1992. Krisher, T. P., J. D. Anderson, J. K. Campbell. "Test of the Gravitational Redshift Effects at Saturn", Physical Review Letters, Vol. 64 No. 12, March 19, 1990. Krisher, Timothy P., David D. Morabito, John D. Anderson. "The Galileo Solar Redshift Experiment", Physical Review Letters , 1993. Thorne, K. S. "Gravitational Radiation," in Three Hundred Years of Gravitation, S. W. Hawking and W. Israel, eds., Cambridge University Press, 1987. Tyler, G. Leonard, Georges Balmino, David P. Hinson, William L. Sjogren, David E. Smith, Richard Woo, Sami W. Asmar, Michael J. Connally, Carole L. Hamilton, and Richard A. Simpson. "Radio Science Investigations with Mars Observer", Journal of Geophysical Research, Vol. 97, No. E5, pp. 7759-7779, May 25, 1992. Woo, R. "A Synoptic Study of Doppler Scintillation Transients in the Solar Wind," Journal of Geophysical Research, Vol. 93, No. A5, pp. 3919-3926, May 1, 1988. ------------------------------------------------------------------------------ Section 2 Observation Description 2.0 Introduction 2.1 Galileo Redshift Observations & USO Tests 2.2 Galileo Solar Wind Scintillation Experiment 2.3 Galileo Jupiter Occultation Experiment (J0) 2.0 Introduction Radio Science investigators examine small changes in the phase, amplitude, and/or polarization of the radio signal propagating from a spacecraft to an Earth receiving station in order to study the atmospheric and ionospheric structure of planets and satellites, planetary gravitational fields, shapes, and masses, planetary rings, ephemerides of planets, solar plasma and magnetic fields, and aspects of the theory of general relativity like gravitational waves, gravitational redshift, etc. Section 1.0 includes a list of recent journal publications relevant to these experiments. The Radio Science experiments described below have been implemented, are in progress, or are planned for the near future for the Galileo project. Mars Global Surveyor and Cassini Radio Science experiments will be described in future volumes of this document. Section 4.0 list investigators involved in these experiments. 2.1 Galileo Redshift Observations & USO Tests The Redshift Observations are performed to measure the frequency shift caused by the motion of the spacecraft as it moves in and out of the solar (or planetary) gravitational field. One of the four predicted effects of Einstein's Theory of General Relativity is the change of a clock rate (an oscillator frequency) in a varying gravitational potential. The Galileo Ultra Stable Oscillator (USO) is the signal source for these observations and has sufficient inherent stability to allow detection of this phenomenon. The Galileo VEEGA trajectory provides a unique opportunity to detect the USO frequency shift as it flies through the changing solar and planetary gravitational fields. The objectives of the Redshift Observations and USO tests are: 1. Make a direct scientific measurement of the redshift phenomenon described above. 2. Make engineering measurements of the USO frequency and frequency stability for calibration of the Radio Science instrument. 3. Exercise the operational aspects of the Radio Science system in the Project and at the Deep Space Network. 4. Train the Project (including the Radio Science Support Team) and the DSN in the operations required in preparation for the Jupiter Encounter. 5. Exercise the Radio Science software and analysis tools. Prior to the observations, the orbiter will be commanded to use the USO as the frequency reference for the downlink radio signal for a period of about two hours. The frequency and frequency stability of the carrier will be estimated. When the data are received by the RSST, in the form of tracking ATDFs and, for some passes, open-loop ODRs, they will then be processed to produce frequency residuals. From these, phase noise and frequency stability (Allan variance) can be determined. 2.2 Galileo Solar Wind Scintillation Experiment Although the most interesting region of the solar wind is that surrounding the Sun, it has not yet been observed directly by spacecraft measurements. Until missions such as Solar Probe are flown, we must rely on remote sensing techniques with planetary spacecraft such as Galileo to probe the inner heliosphere. Radio scintillation and scattering measurements conducted during the Galileo superior conjunctions represent a powerful and essentially only tool for studying the complicated solar wind structure near the Sun. The Galileo solar wind radio scintillation experiment is based on observations of radio scattering phenomena that arise from the propagation of radio waves through the turbulent plasma of the solar wind. These consist of Doppler and amplitude scintillations (fluctuations), as well as broadening of Galileo's monochromatic S-band signal (spectral broadening). Characteristics of these phenomena and the deduced solar wind structure are obtained from the processing of narrowband DSP recordings of the Galileo radio signal. Successful DSP recordings are, therefore, important to the scintillation experiment. Interplanetary disturbances, which are manifested as transients in the scintillation and spectral broadening measurements, are of particular interest in the Galileo experiment. Correlations with events observed on the Sun (e.g., flares) and at spacecraft located near 1 AU (e.g., Pioneer Venus) will be made. These correlative studies are clearly most effective if continuous radio scintillation data are available. For this reason, prolonged periods of near-continuous tracking of Galileo have been arranged. During the approximately +1 month period surrounding superior conjunction, the Galileo radio signal will be probing the solar within about 0.3 AU of the Sun. 2.3 Galileo Jupiter Occultation Experiment (J0) On December 7, 1995, the Galileo Probe will descend into the atmosphere of Jupiter transmitting 75 minutes of atmospheric and magnetospheric data back to the Orbiter high above the cloud tops of the planet. Approximately, ten hours later, the Radio Science Jupiter Occultation Experiment will begin. The Jupiter Occultation Experiment is actually a series of observations during which the spacecraft travels behind Jupiter from the Earth's point of view. The occultation on December 8 is the first and best Earth occultation of the two-year Galileo tour of Jupiter. As the radio signal passes through the Jovian atmosphere, it is bent by the atmosphere much like light is bent by a lens. The bending is observed as a phase delay on the ground and, since the position of the spacecraft is known, the amount of refraction can be deduced from the data. A refractivity profile (refraction vs. atmospheric depth) is constructed and combined with a model of the composition of the atmosphere which takes into account the types of gases present and their behavior. The result of this analysis is a number density profile. From this number density profile, pressure and temperature profiles can be developed for the atmosphere of Jupiter along the ingress and egress raypaths. At ingress, the spacecraft will be 859,000 km from Jupiter and the radio signal will cut across at -25.8 degrees latitude. At egress, the spacecraft will be 1.03 million km from Jupiter and will exit from behind the planet at -44.9 degrees latitude. This is the closest that the spacecraft will ever be to the planet during an occultation of the Earth. Thus, the resolution for this experiment is the best that we will see for the tour. Before ingress, the signal will be recorded starting at 25,000 km above the 1-bar pressure level at Jupiter, and the signal will be recorded out to a 25,000-km altitude after egress. This will provide a baseline before the signal begins changing due to the atmosphere. The observation will conducted in one-way configuration (TWNC ON) with the carrier almost completely unsuppressed (20 degree modulation index). The carrier needs to be as strong as possible so that the ground stations can see it for as long as possible through Jupiter's atmosphere. The Radio Science instrument is used to make the measurements for this investigation. There are two parts to the instrument: the spacecraft and the DSN. For many Radio Science experiments, the stability requirements are such that the downlink is referenced to the uplink which is directly referenced to the maser at the ground station. However, during an occultation the uplink may be disrupted as it moves through the atmosphere, so an ultra-stable oscillator (USO) was installed on Galileo to provide the necessary stability to detect the small changes in the signal as it travels through the Jovian atmosphere. The DSN records the signal using specialized equipment developed for Radio Science experiments. In July 1995, new software and hardware was delivered to the DSN called the Radio Science Signal Digitization Assembly (RSSD). The Radio Science instrument is described in more detail in Section 3. ------------------------------------------------------------------------------ Section 3 Instrument Description and Configuration 3.0 Introduction 3.1 The Spacecraft 3.2 The Ground Data System 3.3 NOCC and Other Facilities 3.0 Introduction This section describes the instrumentation used in support of the Radio Science activities. The Radio Science instrument is distributed between the spacecraft and the Ground Data System (GDS). The latter includes several subsystems at the Deep Space Communication Complexes (DSCCs) as well as several facilities at JPL used for Radio Science communications and data monitoring. 3.1 The Spacecraft 3.1.1 The Galileo Spacecraft The Galileo spacecraft is shown in Figure 3-1. The Galileo telecommunications subsystem is shown in Figure 3-2. It handles three types of data: command, telemetry, and radiometric. The latter provides the capability to navigate the orbiter as well as to perform Radio Science observations. The subsystem is equipped with two redundant transponders with dual frequency (S- and X- bands) uplink and downlink capabilities. This means that the spacecraft can have the following combinations of uplink/downlink: S/S, X/X, S/X&S. The subsystem may be operated in the coherent mode (i.e., the downlink signal is referenced to the uplink signal) or the non-coherent mode (i.e., an ultrastable oscillator (USO) onboard the spacecraft provides the downlink signal reference). In the absence of an uplink signal, the subsystem will switch to the one-way mode automatically. The spacecraft can also be commanded to a specific mode (TWNC ON or OFF) and/or to one of the following states: spacecraft modulated telemetry alone, ranging alone, spacecraft telemetry and ranging, or carrier alone. During periods when no ground station coverage is available a tape recorder onboard the spacecraft will store data for playback at a later time. The HGA is aligned with the spin axis of the spacecraft and is pointed at the Earth by the attitude control system. Low Gain Antenna 1 (LGA-1) is located at the end of the HGA feed and is thus aligned with the spin axis. Low Gain antenna 2 (LGA-2) is located at the end of a boom as shown in Figure 3-1. When the signal is transmitted through LGA-2, a sinusoidal signature in the received Doppler is induced since the spacecraft is spinning with the antenna being located 3.58 meters off the spin axis. S- band on the HGA is linearly polarized whereas X-band is RCP; both LGA's transmit RCP. The spacecraft was launched (10/89) with the HGA in the stowed position. The planned deployment date was April 1991; it was unsuccessful at that time and the Project has attempted various maneuvers to open the antenna. In the spring of 1993, the Project announced the implementation of a new mission designed for the lower data rates available through LGA-1. In spring of 1996, after the Relay/JOI data have been transmitted back to earth, the Project will once again attempt to free the HGA. The USO onboard the spacecraft provides the downlink signal reference. Approximately, one hundred twenty-five USO tests have been performed since launch (1989), dating to the end of 1994. A plot of the USO frequencies for each of these tests is shown in Figure 3-3a. The plot shows a positive logarithmic USO frequency increase (from 89/341 to 91/154) due to the liberation of contamination on the crystal formed during its dormant state of non-operation from 1986 to 1989. The next six USO tests occurred after the USO was turned off (91/217) and back on (91/228) in support of efforts to unstick the ribs of the HGA. In 1992, there were four more warming and/or cooling turns to support the HGA deployment effort. The USO tests frequency points for this time period (92/070 to 92/302) reflect this activity. USO tests from 93/022 to 94/298 (when the USO was not turned off) show the expected linear aging of the USO frequency. Figure 3-3b shows USO frequencies for 1993 and 1994 USO tests only, and was used to approximate the USO frequency of 2294997651 Hz for the upcoming Jupiter Encounter on Dec. 7, 1995. 3.2 The Ground Data System 3.2.1 The Deep Space Network The Deep Space Communication Complexes (DSCCs) are an integral part of the Radio Science instrument, along with the other receiving stations and the spacecraft's Radio Frequency Subsystem. Their system performance directly determines the degree of success of the Radio Science investigations and their system calibration determines the degree of accuracy in the results of the experiments. The following paragraphs describe those functions performed by the individual subsystems of a DSCC. Figures 3-4 through 3-8 show the various systems relevant to the Radio Science activities. 3.2.1.1 DSCC Monitor and Control Subsystem The DSCC Monitor and Control Subsystem (DMC) is part of the Monitor and Control System (MON) which also includes the ground communications Central Communications Terminal and the Network Operations Control Center (NOCC) Monitor and Control Subsystem. The DMC is the center of activity at a DSCC. The DMC receives and archives most of the information from the NOCC needed by the various DSCC subsystems during their operation. Control of most of the DSCC subsystems as well as the handling and displaying of any responses to control directives and configuration and status information received from each of the subsystems is done through the DMC. The effect of this is to centralize the control, display and archiving functions necessary to operate a DSCC. Communication between the various subsystems is done using a Local Area Network (LAN) hooked up to each subsystem via a Network Interface Unit (NIU). The DMC operations are divided into two separate areas: the Complex Monitor and Control (CMC) and the Link Monitor and Control (LMC). The primary purpose of the CMC processor for Radio Science support is to receive and store all predict sets transmitted from NOCC such as Radio Science, antenna pointing, tracking, receiver, and uplink predict sets and then, at a later time, distribute them to the appropriate subsystems via the LAN. Those predict sets can be stored in the CMC for a maximum period of three days under normal conditions. The CMC also receives, processes and displays event/alarm messages and maintains an operator log and produces tape labels for the DSP. Assignment and configuration of the LMCs is done through the CMC and to a limited degree the CMC can perform some of the functions performed by a LMC. There is one on-line CMC, one backup CMC, and three LMCs at each DSCC. The backup CMC can function as an additional LMC if necessary. The LMC processor provides the operator interface for monitor and control of a link which is a group of equipment required for support of a spacecraft pass. For Radio Science, a link might include the DSCC Spectrum Processing Subsystem (DSP) (which, in turn, can control the Radio Science Communications Processor), or the Tracking Subsystem. The LMC also maintains an operator log which includes the operator directives and subsystem responses. One important Radio Science specific function which the LMC performs is receipt and transmission of the system temperature and signal level data for display at the LMC console as well as placing this information in the Monitor 5-9 blocks. These blocks are recorded on magnetic tape as well as displayed in the MCCC displays. The LMC is required to operate without interruption for the duration of the Radio Science data acquisition period. The Station Communication Processor (SCP), which is part of the Digital Communications Subsystem, controls all data communication between the stations and JPL. The SCP receives all required data and status messages from the LMC/CMC and can record them to tape as well as transmit them to JPL via the data lines. The SCP also receives predicts and other data from JPL and passes them on to the CMC. 3.2.1.2 DSCC Antenna Mechanical Subsystem Multi-mission Radio Science activities require support from the 70-m, the 34-m HEF, the 34-m STD, or (soon) from the 34-m BWG antenna subnets. The antenna at each DSCC will function as a large aperture collector which, by double reflection, causes the incoming RF energy to enter the feed horns. The large collecting surface of the antenna focuses the incoming energy onto a subreflector, which is adjustable in the axial and angular positions. These adjustments are made to optimize the channeling of energy from the primary reflector to the subreflector and then to the feedhorns. The 70-m and 34-m HEF antennas have "shaped" primary and secondary reflectors, whose forms are that of a modified paraboloid. This customization allows more uniform illumination of one reflector by the other. Conversely, the 34-m STD primary reflectors are classical paraboloids, while the subreflectors are similarly standard hyperboloids. On the 70-m and 34-m STD antennas, the subreflector reflects the received energy from the antenna onto the dichroic plate, a device which reflects S-band energy to the S-band feedhorn and passes X-band energy through to the X-band feedhorn. In the 34-m HEF, there is one "common aperture feed", which accepts both frequencies, and therefore no plate. RF energy to be transmitted into space by the horns is focused by reflectors into narrow cylindrical beams, pointed with high precision (either to the dichroic plate or directly to the subreflector) by a series of drive motors and gear trains that can rotate the movable components and their support structures. The different antennas can be pointed by several common means. Two pointing modes commonly used during a tracking pass are 1) CONSCAN on, or 2) CONSCAN off (blind pointing). With CONSCAN on, once the closed-loop receiver has acquired a signal from the spacecraft to provide feedback, the radio source is tracked by conically scanning around it. Pointing angle adjustments are computed from signal strength information supplied by the receiver. In this mode, the Antenna Pointing Assembly (APA) generates a circular scan pattern which is sent to the Antenna Control Subsystem (ACS). The ACS adds the scan pattern to the corrected pointing angle predicts. Software in the receiver- exciter controller computes the received signal level and sends it to the APA. The correlation of the scan position of the antenna with the received signal level variations allows the APA to compute offset changes which are sent to the ACS. Thus, within the capability of the closed-loop control system, the scan center is pointed precisely at the apparent direction of the spacecraft signal. An additional function of the APA is to provide antenna position angles and residuals, antenna control mode/status information and predict-correction parameters to the Station Communication Processor (SCP) via the LAN, which then sends this information to JPL via the GCF for antenna status monitoring. During periods when excessive signal level dynamics or low received signal levels are expected (e.g., in an occultation experiment), CONSCAN cannot be used. Under these conditions, blind pointing (CONSCAN off) is used, and pointing angle adjustments rely on a predetermined Systematic Error Correction (SEC) model. Independent of the CONSCAN state, subreflector motion in at least the z-axis may introduce phase variations in the received Radio Science data. For that reason,during certain experiments, the subreflector in the 70-m and 34-m HEFs may be frozen in the z-axis at an elevation angle selected to minimize the phase change and signal degradation. This can be done via operator OCIs from the LMC to the Subreflector Controller (SRC) which resides in the alidade room of the antennas.The SRC passes the commands to motors that drive the subreflector to the desired position. Unlike the two antennas mentioned above, the 34-m STD is not an Az-El pointed antenna, but a HA-DEC antenna. The same positioning of the subreflector of the 34-m STD does not create the same effect as for the 70-m and 34-m HEF. Pointing angles for all three antenna types are computed by the NSS from an ephemeris provided by the Project and converted into antenna pointing predicts for each station. These predicts are received and archived by the CMC. Before each track, they are transferred to the APA, which transforms the direction cosines of the predicts into Az-El coordinates for the 70-m and 34-m HEF, and into HA-DEC coordinates for the 34-m STD. The LMC operator then downloads the antenna Az-El or HA-DEC (respectively) predict points to the antenna-mounted ACS computer along with a selected pointing SEC model. The pointing predicts consist of time-tagged Az-El or HA-DEC points at selected time intervals, and also include polynomial coefficients for interpolation between the points. The ACS automatically interpolates the predict points, corrects the pointing predicts for refraction and subreflector position, and adds the proper systematic error correction and any manually entered antenna offsets. The ACS then sends angular position commands for each axis at the rate of once per second. In the 70-m and 34-m HEF, rate commands are generated from the position commands at the servo controller and are subsequently used to steer the antenna. In the 34-m STD, motors, not servos, are used to steer the antenna, so there is no feedback once the antenna has been told where to point. When not using binary predicts (the routine mode for spacecraft tracking), the antennas can be pointed using planetary mode, a simpler mode which uses right ascension (RA) and declination (DEC) values. These change very slowly with respect to the celestial frame. Values are provided to the station in text form for manual entry. The ACS quadratically interpolates between three RA and DEC points which are on one-day centers. Other than predict and planetary, a third mode, sidereal, is available and is usually used to track radio sources fixed with respect to the celestial frame as in radio astronomy applications. Regardless of the mode being used to track a spacecraft, a 70-m antenna has a special, high-accuracy pointing capability called Precision mode. A pointing control loop derives the main Az-El pointing servo drive error signals from a two-axis autocollimator mounted on the Intermediate Reference Structure. The autocollimator projects a light beam to a precision mirror mounted on the Master Equatorial drive system, a much smaller structure, independent of the main antenna, which is exactly positioned in HA and DEC with shaft encoders. The autocollimator detects elevation/cross-elevation errors between the two reference surfaces by measuring the angular displacement of the reflected light beam. This error is compensated in the antenna servo by moving the antenna in the appropriate (Az-El) direction. If not using the optical link Precision mode, a less accurate computer mode can be used where the servo utilizes the Az-El axis encoder readout for positioning, as done in the 34-m HEF. From 1994 to 1996, four new 34-meter beam waveguide (BWG) antennas will be implemented in the DSN. These 34-meter beam waveguide antennas will use beam waveguides to channel the RF energy collected by the reflector dish to the feedhorn located in the pedestal of the antenna. Figures 3-8a and 3-8b show the 34-m BWG block diagram and station respectively. The components of the BWG structure are located in the pedestal room, and are therefore more accessible than those of non-beam waveguide antennas which are mounted inside the antenna dish. The BWG antenna also incorporates a new mechanism for subreflector positioning which uses a two-axis servomotor that allows movement in both horizontal and vertical directions. The RS software currently in use cannot generate DSS 24 data blocks, however, the RS equipment is capable of receiving and recording BWG IF channels (S- and X-band only) if the receiver is manually connected to the BWG channels via the IF Distribution Assembly, and a suitable front end alias is provided to the software. 3.2.1.3 DSCC Antenna Microwave Subsystem 3.2.1.3.1 70-m Antennas Each 70-m station has three feed cones installed on a structure at the center of the main reflector. The feeds are positioned 120 degrees apart on a circle. Selection of the feed is made by rotation of the subreflector. A dichroic mirror assembly, half on the S-band cone and half on the X-band cone, permit simultaneous use of the S- and X-band frequencies. The third cone is devoted to R&D and more specialized work. The Antenna Microwave Subsystem (AMS) accepts the received S- and X- band signals at the feedhorn and transmits them through the polarizer plates to the orthomode transducer. The polarizer plates are adjusted so that the signals are directed to either of a set of redundant amplifiers for each frequency. For X-band, these amplifiers are Block IIA X-band Traveling Wave Masers (TWMs), and for S-band there are two Block IVA S-band TWMs. 3.2.1.3.2 34-m STD Antennas These antennas have two feed horns, for S- and X-band energy, respectively. These horns are mounted on a cone which is fixed in relation to the subreflector. A dichroic plate mounted above the horns directs energy from the subreflector into the proper horn. The AMS directs the received S- and X-band signals through the polarizer plates and on to amplification. There are two Block III S-band TWMs and two Block I X-band TWMs. During the Galileo Tour, several antennas will be arrayed at DSCC 40 including the 34-m STD (DSS 42) in order to enhance the telemetry capability. No other 34-m STD is expected to be used. It is not expected that the 34-m STD antennas will be used during the remainder of the Galileo Mission. 3.2.1.3.3 34-m HEF Antennas Unlike the other antennas, the 34-m HEF uses a single feed horn for both X- and S- band. Simultaneous S- and X-band receive, as well as X-band transmit, is possible however, due to the presence of an S/X "combiner", which acts as a diplexer. As in the general case, the next component in the AMS on the X- band path is a polarizer, and then the orthomode transducer; for S-band, RCP or LCP is user selected through a switch, and not simultaneous, so neither device (polarizer and transducer) is present. X-band amplification can be selected from one of two Block II X-band TWMs or from a single X-band HEMT Low Noise Amplifier (LNA). S-band amplification is provided by one FET LNA. It is not expected that the 34-m HEF antennas will be used during the remainder of the Galileo Mission. 3.2.1.3.4 34-m Beam Waveguide Antennas The Antenna Microwave Subsystem (UWV) feedhorns transform free-space waves to guided waves and vice versa. The primary downlink function of the UWV provides low noise amplification via the TWM or cryogenically cooled HEMT at X-band and cryohemt at S-band. Each band has one output to the Block V Downconverter Assembly. For the S-band uplink, the amplified RF energy from the Exciter- Transmitter Subsystem (ETX) is coupled into the UWV via a diplexer. The signal is then routed through the S-band feedhorn to the antenna. During the Tour, several antennas will be arrayed at DSCC 40 including the 34- m BWG (DSS 24) in order to enhance the telemetry capability. No other 34-m BWG is expected to be used. 3.2.1.4 DSCC Receiver-Exciter Subsystem The Receiver-Exciter Subsystem is composed of three groups of equipment: the closed-loop receiver group, the open-loop receiver group, and the RF monitor group. This subsystem is controlled by the Receiver-Exciter Controller (REC) which communicates directly with the DMC for predicts and OCI reception and status reporting. The exciter generates the S-band signal, (or X-band signal for 34-m HEF only), which is provided to the Transmitter Subsystem for the spacecraft uplink signal. It is tunable under the command of the Digitally Controlled Oscillator (DCO) which receives predicts from the Metric Data Assembly (MDA). The diplexer in the signal paths between the transmitters and the feed horns for all three antennas (used for simultaneous transmission and reception) may be configured such that it is out of the received signal path (in listen-only or bypass mode) in order to improve the signal-to-noise ratio in the receiver system. 3.2.1.4.1 Closed-Loop Receivers The Block IV receiver-exciter at the 70-m stations allows for two receiver channels, each capable of L-band, S-band or X-band reception, and an S-band exciter for generation of uplink signals through the low-power or high-power transmitter. The Block III receiver-exciter at the 34-m STD stations allows for two receiver channels, each capable of S-band or X-band reception and an exciter used to generate an uplink signal through the low-power transmitter. The receiver-exciter at the 34-m HEF stations allows for one channel only. The closed-loop receivers provide the capability for rapid acquisition of a spacecraft signal and telemetry lockup. In order to accomplish acquisition within a short time, the receivers are predict driven to automatically search for, acquire, and track the downlink. Rapid acquisition precludes manual tuning even though the latter remains as a backup capability. The subsystem utilizes FFT analyzers for rapid acquisition. The predicts are NSS generated, transmitted to the CMC which sends them to the Receiver-Exciter Subsystem where two sets can be stored. The receiver starts acquisition at uplink time plus one round-trip-light-time or at operator specified times. In addition, the receivers can be operated from the LMC without a local operator attending them. The receivers send performance and status data, displays, and event messages to the LMC. Either the exciter synthesizer signal or the SIM synthesizer signal is used as the reference for the Doppler extractor, depending on the spacecraft being tracked (and Project guidelines). The SIM synthesizer is not ramped; instead, it uses one constant frequency, the Track Synthesizer Frequency (TSF), which is an average frequency for the entire pass. The closed-loop receiver AGC loop can be configured to one of three settings; narrow, medium or wide. It will be configured such that the expected amplitude changes are accommodated with minimum distortion. The loop bandwidth (2BLo) will be configured such that the expected phase changes can be accommodated while maintaining the best possible loop SNR. The initial Block V implementation at Goldstone has two channels (S- and X- band) for carrier processing. Future expansion of the Block V will allow support of additional frequencies (Ka-band) at BWG stations and support for additional antennas of the BWG cluster. Large scale modifications of the Block V Receiver electronics will allow Radio Science and VLBI signal reception and processing within the Block V Receiver without additional RS or VLBI specific external equipment. The BVR was fully implemented for GLL by the end of October 1995. 3.2.1.4.2 Radio Science Open-Loop Receiver The Radio Science Open-Loop Receiver (OLR) is a dedicated four channel, narrow- band receiver which provides amplified and downconverted video band signals to the DSCC Spectrum Processing Subsystem (DSP). The Radio Science open-loop receiving system and RIV are shown in figures 2a, 2b and 3 of appendix B. The OLR utilizes a fixed first Local Oscillator (LO) frequency and a tunable second LO frequency to minimize phase noise and improve frequency stability. The OLR consists of an RF-to-IF downconverter located in the antenna, an IF selection switch (IVC), and a Radio Science IF-VF downconverter (RIV) located in the SPC. The RF-IF in the 70- m antenna are equipped for four IF channels: XRCP, SRCP, XLCP, and SLCP. The 34-m HEF stations are equipped with a two- channel RF-IF: S-band and X-band. The IVC switches between IF sources, that is, between the 70-m and 34-m HEF stations. The RIV contains the tunable second LO, a set of video bandpass filters, IF attenuators, and a controller (RIC). The LO tuning is done via DSP control of the POCA/PLO combination based on a predict set. The POCA is a Programmable Oscillator Control Assembly and the PLO is a Programmable Local Oscillator (commonly called the DANA synthesizer). The bandpass filters are selectable via the DSP. The RIC provides an interface between the DSP and the RIV. It is controlled from the LMC via the DSP. The RIC selects the filter and attenuator settings and provides monitor data to the DSP. The RIC could also be manually controlled from the front panel in case the electronic interface to the DSP is lost. Figures 2a and 2b in appendix B show block diagrams of the open-loop receiver. Calibrations will be performed on the OLR and the DSP RSSD using estimates of the peak signal levels expected during the experiments as described in section 3.2.2. 3.2.1.4.3 RF Monitor: RSCP The RF monitor group of the Receiver-Exciter Subsystem provides spectral measurements, measurements of the received channel system temperature, and spacecraft signal level using the Radio Science Communications Processor (RSCP). The RSCP provides a local display of the received signal spectrum at a dedicated terminal at the DSCC and routes these same data to the DSP which routes them to NOCC for remote display at JPL for real-time monitoring and RIV/DSP configuration verification. These displays are used to validate Radio Science System data at the DSS, NOCC, and Radio Science Mission Support Areas. The RSCP configuration is controlled by the DSP. During real-time operations, the RSCP data also serve as a quick look science data type for the Radio Science experiments. System noise temperatures (SNT) are measured using a Noise Adding Radiometer (NAR) and downlink signal levels are measured using the Signal Level Estimator (SLE). The RSCP accepts its input from the closed-loop receiver. SNT is measured by injecting known amounts of noise power into the signal path and comparing the total power with the noise injection "on" against the total power with the noise injection "off". That operation is based on the fact that receiver noise power is directly proportional to temperature, and thus measuring the relative increase in noise power due to the presence of a calibrated thermal noise source allows direct calculation of SNT. Signal level is measured by calculating an FFT to estimate the SNR between the signal level and the receiver noise floor whose power is known from the SNT measurements. 3.2.1.5 DSCC Transmitter Subsystem The Transmitter Subsystem accepts the S-band frequency exciter signal from the Block III, Block IV, or Block V Receiver-Exciter Subsystem exciter and amplifies it to the required transmitted output level. The amplified signal is routed via the diplexer through the feedhorn to the antenna and then focused and beamed to the spacecraft. The Transmitter Subsystem power capabilities range from 18 kW to 400 kW. Power levels above 18 kW are available only at 70-m stations. 3.2.1.6 DSCC Tracking Subsystem The Tracking Subsystem's primary functions are to acquire and maintain the communications link with the spacecraft and to generate and format radiometric data containing Doppler and range. A block diagram of the DSN tracking system appears in Figures 3-6 and 3-7. The DSCC Tracking Subsystem (DTK) receives the carrier signals and ranging spectra from the Receiver-Exciter Subsystem. The Doppler cycle counts are counted, formatted, and transmitted to JPL in real-time. Ranging data are also transmitted to JPL in real-time. Also contained in these blocks is the AGC information from the Receiver-Exciter Subsystem. The Radio Metric Data Conditioning Team (RMDCT) at JPL produces an ATDF tape which contains Doppler and ranging data. In addition, the Tracking Subsystem receives from the CMC frequency predicts (used to compute frequency residuals and noise estimates), receiver tuning predicts (used to tune the closed-loop receivers), and uplink tuning predicts (used to tune the exciter). From the LMC, it receives configuration and control directives as well as configuration and status information on the transmitter, microwave and frequency and timing subsystems. The Metric Data Assembly (MDA) controls all of the DTK functions supporting the uplink and downlink activities. The MDA receives uplink predicts and controls the uplink tuning by commanding the DCO. The MDA also controls the SRA. It formats the Doppler and range measurements and provides them to the GCF for transmission to NOCC. The Sequential Ranging Assembly (SRA) measures the round trip light time (RTLT) of a radio signal traveling from a ground tracking station to a spacecraft and back. From the RTLT, phase, and Doppler data, the spacecraft range is measured. A coded signal is modulated on an S-band carrier and transmitted to the spacecraft where it is detected and transponded back to the station. As a result, the signal received at the tracking station is delayed by its round trip through space and shifted in frequency by the Doppler effect due to the relative motion between the spacecraft and the tracking station on Earth. 3.2.1.7 DSCC Spectrum Processing Subsystem (DSP) The DSCC Spectrum Processing Subsystem (DSP) located at the SPC digitizes and records on magnetic tapes the narrowband output data from the RIV. It consists of a DSP-R Signal Digitizer Assembly (RSSD) containing four Analog- to-Digital Converters (ADCs), a ModComp CLASSIC computer processor called the Spectrum Processing Assembly (SPA) and two to six magnetic tape drives. The block diagram for the SPA-R hardware is shown in Figure 3-5. The DSP is operated through the LMC. Using the SPA-R software, the DSP allows for real-time frequency and time offsets (while in RUN mode) and, if necessary, snap tuning between the two frequency ranges transmitted by the spacecraft: coherent and noncoherent. The DSP receives Radio Science frequency predicts from the CMC, allows for multiple predict set archival (up to 60 sets) at the SPA and allows for manual predict generation and editing. It accepts configuration and control data from the LMC, provides display data to the LMC and transmits the signal spectra from the RSCP as well as status information to NOCC and the Project Mission Support Area (MSA) via the GCF data lines. The DSP records the digitized narrowband samples and the supporting header information (i.e., time tags, POCA frequencies, etc.) on 8mm magnetic tapes as described in module RSC 11-13 of DSN document 820-13. The data format on the tape (called Original Data Record, ODR) is defined in document 820-13 module RSC-11-10A. The Radio Science IF Switch (RIS) provides the DSP with the ability to select Prime, Cross, or Faraday Rotation configuration for the 34-meter and 70-mater antennas. In Prime mode, X-RCP, S-RCP, X-LCP, and S-LCP from the 70-meter antenna are selected as input signals to the RIV. In Cross mode, X-RCP and S- RCP from the 34-meter and X-LCP and S-LCP from the 70-meter antenna are selected as the input to the RIV. Faraday Rotation configurations the same as Prime configuration. The RIC provides the DSP with the ability to control the IF to Video selection. The RIC can select the signal with the desired frequency (S-band or X-band) and polarization (Left or Right Circular). The signal is then directed to the RSSD for analog signal processing. The S-band and X-band signals from the spacecraft are mixed with the RF local oscillator frequency in the receiver to produce a Video Frequency (VF) signal. The VF signal is digitized by the RSSD. The digitized data are recorded on 8mm tape and transmitted to SFOC. The RSSD performs a Fast Fourier Transform (FFT) on the IF signal so that a signal power spectrum can be displayed. Through the DSP-RIC interface, the DSP controls the RIV's filter selection and attenuation levels. It also receives RIV performance monitoring via the RIC. In case of failure of the DSP-RIC interface, the RIV can be controlled manually from the front panel. All the RIV and DSP control parameters and configuration directives are stored in the SPA in a macro-like file called an "experiment directive" table. A number of default directives exist in the DSP for the major Radio Science experiments. Operators can create their own table entries. The items controlled by the directive are shown in Section 3.2.2. Items such as verification of the configuration of the prime open-loop recording subsystem, the selection of the required predict sets, and proper system performance prior to the recording periods will be checked in real- time at JPL via the NOCC displays. Transmission of the DSP/RSCP monitor information is enabled prior to the start of recording. The specific run time and tape recording times will be identified in the SOE. The DSP can be used to duplicate ODRs. It also has the capability to play back a certain section of the recorded data after the conclusion of the recording periods. 3.2.1.8 DSCC Frequency and Timing Subsystem The Frequency and Timing Subsystem (FTS) provides all frequency and timing references required by the other DSCC subsystems. It contain four frequency standards of which one is prime and the other three are backups. Selection of the prime standard is done via the CMC. Of these four standards, there are two Hydrogen masers followed by clean-up loops (CUL) and two Cesium standards. These four standards all feed the Coherent Reference Generator (CRG) which provides the frequency references used by the rest of the complex. It also provides the frequency reference to the Master Clock Assembly (MCA) which in turn provides time to the Time Insertion and Distribution assembly (TID) which provides UTC and SIM-time to the complex. The ability to monitor the DSCC FTS at JPL is limited to the MDA calculated Doppler pseudo-residuals, the Doppler noise, the RSCP, and via the GPS. The GPS receivers receive a one-pulse-per-second pulse from the station's (Hydrogen maser referenced) FTS and a pulse from a GPS satellite at scheduled times. After compensating for the satellite signal delay, the timing offset is reported to JPL where a database is kept. The clock offsets reported in the JPL database between the clocks at the three DSN sites are given in microseconds, where each reading is a mean reading of measurements from several GPS satellites and the time tag associated with it is a mean time of the measurements. The clock offsets provided include those of SPC 10 relative to UTC (NIST), SPC 40 relative to SPC 10,...,etc. 3.2.2 DSS Calibration and Configuration 3.2.2.1 Open-Loop Receiver Attenuation Calibration The open-loop receiver attenuator calibrations are performed to establish the output of the open-loop receivers at a level that will not saturate the input signal to the analog-to- digital converters. To achieve this goal, the calibration is done using a test signal generated by the exciter/translator that is set to the peak predicted signal level for the upcoming pass. Then the output level of the receiver's video band spectrum envelope is adjusted to the level determined by the third equation below (to 5 sigma). Note that the SNR in the second equation is in dB, and the SNR in the third equation is not. Use the fourth equation to compute changes in RMS voltage levels. (1) PN = -198.6 + 10 log (SNT) +10 log (Filter BW x 1.2) (2) SNR = PS - PN (3) Output Voltage (Vrms) = sqrt(SNR+1)/(1+0.283*sqrt(SNR)) (4) V2 = V1*sqrt((1+SNR2 )/(1+SNR1 )) 3.2.2.2 Station Configuration The station configuration during the Radio Science activities is governed by Volume 2 of the Deep Space Network Operations Plan (NOP). Table 5-1 shows the recommended configuration of the DSCC Spectrum Processing Assembly (DSP) and open-loop system for reference by the Radio Science Support Team. For specific DSS station parameters see Section 5. 3.2.2.2.1 Galileo USO Configuration The Doppler sample rate will be ten samples per second. The required frequency and timing reference is the Hydrogen maser. The DSP will not be utilized for this experiment. DSP configurations are shown in Table 5.1. 3.2.2.2.2 Galileo Solar Wind Scintillation Experiment Configuration The Doppler sample rate will be one per second. The required frequency and timing reference is the Hydrogen maser. During the experiment, Galileo will use the 70-m subnet (S-band). The DSP will not be utilized for this experiment. DSP configurations are showned in Table 5.1. 3.2.2.2.3 Jupiter Occultation Experiment Configuration The sample rate will be 5k samples per second. The required frequency and timing reference is the Hydrogen maser. The DSP should be configured as shown in Table 5-2. 3.3 NOCC and Other Facilities 3.3.1 GROUND COMMUNICATIONS FACILITY (GCF) The Ground Communications Facility (GCF) provides the communication networks needed to support the communication requirements of the Radio Science System. These facilities exist at the DSCC and JPL and are briefly described in the following paragraphs. 3.3.1.1 GCF Data Subsystem Presently, monitoring information from the DSN complexes is transported over Ground Communication Facility (GCF) data lines. A copy of the data (TRK, RSC, and MON) is sent via an ethernet line to RODAN and the Radio Science Real-time Monitoring System (RMS). A X.25 serial line is used as a backup data line if problems occur with the primary ethernet line. See Section 5 for a discussion of the normal configuration of these lines. The GCF data lines transmit Radio Science open-loop tuning predicts from the NOCC to the DSS (and CTA-21) and send Radio Science, Tracking, and Monitor and Control Subsystems status and configuration data from the DSCC to the NOCC in real-time. 3.3.1.2 GCF Data Records Subsystem The GCF Data Records Generator (DRG) formats the incoming closed-loop data from the DSCC and provides them to the RMDCT team which converts the Doppler and range data into computer-compatible tapes called Archival Tracking Data Files (ATDF). 3.3.13 Voice Net Communications The Ground Communications Facility voice nets provide both the means of controlling worldwide spacecraft tracking operations and for relaying information required to verify proper operation of the various ground and spacecraft subsystems. Section 5.2.1 contains a description of the voice nets as it is planned for Radio Science activities. 3.3.1.4 RODAN Interface Data lines from GCF to RODAN allow the RSST to capture and display Radio Science data from the GCF lines using the RMS (see Section 3.3.1.1). See Section 9 for a more complete description. 3.3.2 Network Operations Control Center (NOCC) The NOCC generates and transmits information to each DSCC prior to tracking support. It also receives, displays, logs and distributes data generated at the DSCC during tracking support. 3.3.2.1 NOCC Support Subsystem The NOCC Support Subsystem (NSS) generates Radio Science, antenna pointing, tracking, receiver, and uplink predicts. The NSS also provides DSCC schedules and transmits a subset of the Project's SOE to be used at the stations during tracking support. 3.3.3 Radio Science Mission Support Area The Radio Science Multi-Mission Support Area contains the real-time control center for the Radio Science System. The control center includes a NOCC workstation (see Section 5), voice lines, and a second workstation which receives near real-time monitoring data from GCF. The voice lines are provided to the Project's real-time operations personnel to aid in operations monitoring. ------------------------------------------------------------------------------ Section 4 Team Organization & Responsibilities 4.0 Introduction 4.1 RSST Individual Responsibilities 4.2 RST Flight Project Interfaces 4.3 RST DSN Interfaces 4.0 Introduction The Radio Science Support Team (RSST) provides coordination for all flight project activities supporting Radio Science experiments. The RSST operates as a single, comprehensive focal point for experiment-related Project functions and provides long range planning for experiment interfaces with multi-mission organizations. It serves as the operational interface between the Radio Science investigators and the other elements of the Flight Projects and the Deep Space Network. The RSST represents the interests of the investigators (whether they reside at JPL or any research institute world-wide) at meetings relevant to the investigation. Specifically, the RSST: 1. Plans the implementation of the Radio Science experiments along with the investigators, defines the requirements on all aspects of the experiments, and resolves (or helps to resolve) intra- and inter- experiment conflicts. 2. Submits and integrates Radio Science requirements into the plans of the flight project, DSN, MGSO, and other multi-mission organizations. 3. Provides specifications for spacecraft and DSN equipment based on the experiment's needs for hardware, software and procedures, monitors the development of the equipment and participates in testing the hardware or the output product. 4. Reviews (and, when requested, participates in the negotiations leading to) the schedule of station tracking coverage. 5. Develops and integrates spacecraft and ground operation sequences for the acquisition of experiment data by interfacing with the mission design teams, sequence teams, spacecraft engineering teams, navigation teams, mission control teams, and other elements of the projects. 6. Coordinates with the mission control teams and the DSN the process of data acquisition by conducting real-time operations and collecting the data observables. 7. Logs, archives, and validates the data products in order to prepare the data observables for scientific analysis by the investigators. The Radio Science Support Team is part of the Radio Science Systems Group of the Telecommunications Systems and Research Section. The group currently supports Radio Science experiments on the Galileo, Ulysses, Mars Global Surveyor, and Cassini flight projects. In recent years, the group provided support for Radio Science experiments on Voyager, Magellan, Giotto, Clementine, and Pioneer. Figure 4.1 shows the organization of the Radio Science Systems Group. 4.1 RSST Individual Responsibilities 4.1.1 Science Coordinator/Experiment Representative The Science Coordinator/Experiment Representative (SC/ER) coordinates all the RSST tasks listed above, provides overall team direction, coordinates the teams's resources, and ensures that schedules and staff plans are optimized to achieve the maximum return of quality data for the Radio Science experiments. The SC/ER develops the observation strategy, performs mission analysis trade- off studies, performs inter-experiment science integration, provides sequence inputs, and monitors the progression of the uplink process. She/He is the focal point for experiment requirements to the projects, keeps abreast of upcoming and on-going spacecraft activities which could affect the Radio Science investigations, and continually updates the rest of the Support Team on the status of the mission. During real-time operations, the SC/ER monitors the progress of the experiment and provides recommendations to the operations personnel to optimize its performance. For some flight projects, if the Science Coordinator or Experiment Representative is also an investigator he/she may be called Investigation Scientist or Coordinating Scientist. 4.1.2 Instrument Engineer The Radio Science Instrument Engineer's primary responsibilities are to develop, maintain, and interpret instrument (spacecraft and Ground Data System) requirements, monitor, and, when appropriate, participate in the planning, design, scheduling, and implementation of the instrument's components by interfacing with appropriate organizations (e.g., the DSN, Project spacecraft team). The Instrument Engineer performs instrument trade- off studies, designs the instrument operation configuration and verifies that all instrument and data interfaces (including GDS) satisfy team requirements. It is also the responsibility of the Instrument Engineer to test the data products during and after instrument implementation to ensure that the quality meets team requirements. He/she, along with the Software System Engineer, develops the software tools necessary for data validation and processing. The Instrument Engineer is the lead data analyst for the USO, telecommunication subsystem, and DSN systems stability. The Instrument Engineer also assists in Radio Science real-time operations. 4.1.3 Operations Engineer The Radio Science Operations Engineer's primary responsibility is the verification of the proper conduct of pre-pass, real-time, and post-pass operations of the Radio Science data acquisition activities. Specifically, he/she verifies the presence and accuracy of the activity's Sequence Of Events (SOE) and predictions required by the station based on the information provided to him/her by the SC/ER. She/He handles communications regarding action or information required from the DSN station with the Project's Mission Controller (ACE) via the appropriate voice nets. He/she coordinates with the RS System Administrator the availability of data displays needed for monitoring the activity, and insures that the Radio Science real-time support area and related facilities are properly equipped and staffed for real-time monitoring. Also, he/she is responsible for compiling the Operations Report, a log of the ground and spacecraft events that assists the investigators in properly analyzing the data. 4.1.4 Software System Engineer The Radio Science Software System Engineer's primary responsibilities include evaluation of existing Radio Science software, identifying software development tasks, and overseeing development, implementation, testing, documentation and delivery of software. He/she reports to the various projects on the software development status via periodic presentations. The secondary responsibilities include using the Radio Science software for data analysis and validation, and assisting in Radio Science real-time operations. 4.1.5 System Administrator The Radio Science System Administrator is responsible for the proper operation of the RSST computing equipment and peripherals. Her/His primary responsibility is the administration and upgrade of the RODAN computer facility (which includes the PRIME 4050 and the SUN workstation cluster), its interfaces (e.g., RODAN-GCF ) and the planning, implementation, and maintenance of future RSST computing facilities (including PC's, Mac's, and workstations). Secondary responsibilities include the proper operation of the Real-time Monitoring System (RMS) (done in coordination with the RS Operations Engineer). The System Administrator also assists in Radio Science real-time operations. 4.1.6 Data Products Engineer The Radio Science Data Products Engineer's primary responsibility is to request and receive, log, validate, archive, and distribute to Investigators the Radio Science data products (described in Section 6.0). She/He also maintains data interface agreements. Secondary responsibilities include performing system back-ups and related tasks on the RODAN computer as well as assisting in Radio Science real-time operations. 4.1.7 Radio Science Analyst The Radio Science Analyst conducts specialized scientific and engineering analysis needed for the planning, implementation, or data processing of Radio Science experiments. The Analyst also assists in Radio Science real-time operations. 4.2 RST Flight Project Interfaces 4.2.1 Galileo SEQ Team The Galileo Sequence Team (SEQ) is responsible for developing the command loads which incorporate both engineering and science activities for each sequence in the Mission. 4.2.2 Galileo MCT The Galileo Mission Control Team (MCT) is the source of the SFOS and ISOE. From the final product at the end of Sequence & Command Generation (S&CG), the Mission Control Team (MCT) generates the Galileo SFOS and SOE. It is the responsibility of the Radio Science Team to insure that these products reflect the expected Radio Science data acquisition parameters and schedules. 4.2.3 Galileo ACE The Galileo ACE is the primary interface for the Radio Science Team to affect real-time changes to SOE's and station configuration for the purpose of Radio Science data acquisition. 4.3 RST DSN Interfaces 4.3.1 Network Operations Project Engineer (NOPE) The Galileo NOPEs are responsible for the overall operational support of the Deep Space Network for the flight project. The NOPEs prepare and issue the Network Operations Plan which defines the configuration of all DSN systems for the flight project including those relevant to Radio Science. 4.3.2 System Cognizant Operations Engineer (SCOE) The SCOE is responsible for supporting Network Radio Science System testing, providing technical expertise on the DSN RS system, and providing technical advisory support as necessary to define system performance. He also provides backup to all those in the Radio Science Unit of the Network Advance Systems Group (NASG). 4.3.3 Other NASG/Radio Science Unit Personnel There are three other positions within the Radio Science Unit of the Network Advanced Systems Group with responsibilities related to the Radio Science System. The Radio Science Network Operations Analyst (NOA) provides the technical interface between real-time operations and DSN system performance, monitors and reports DSN Radio Science systems and operations performance, investigates and resolves discrepancy reports, and acts as a backup to the RS Operations Specialist and to the RS Analyst. The Radio Science Operations Specialist performs operations function in support of all DSN Radio Science activities, represents DSN Operations in the development of Radio Science Operations Plans, and provides assistance and backup to the RS SCOE and the RS NOA. The Radio Science Analyst provides testing and data analysis support for Radio Science System test activities and assists the RS SCOE and the RS Operations Specialist. 4.3.4 Comm Chief The Comm Chief is responsible for the configuration and operation of the GCF communications between all DSCC's and the NOCC. The Comm Chief is also responsible for re-establishing the RODAN-GCF interface should it fail (this interface is normally ON). 4.3.5 Ops Chief The Ops Chief is the DSN's lead person for all real-time DSN operations in support of flight projects. 4.3.6 TrackCon The Track Controller is responsible for the real-time control of one or more stations supporting a Flight Project tracking pass. The TrackCon also serves as the real-time analyst for all incoming Tracking, VLBI, and Radio Science data and for all outgoing prediction data transfers for those stations and flight projects. Table 4-1 Key Radio Science Personnel Radio Science Support Team Sami Asmar Supervisor, RSSG 3-0662 Jennifer Caetta System Administrator 3-0665 Mick Connally Mars Global Surveyor Exp. Rep. 3-1072 Paula Eshe Data Products Engineer 3-0663 Randy Herrera Galileo Science Coordinator 3-0664 Tony Horton Operations Engineer 3-1142 Trish Priest Assistant Galileo Sci. Coord. 3-0661 Phyllis Richardson Gnd Inst Engr/Syst Engr 3-1073 Radio Science Operations area. . . . . . . . . . . . . . . 3-0666 Deep Space Network Sal Abbate R.S. Sys. Cog. Ops. Eng. 584-4461 Michelle Andrews Asst Galileo NOPE 584-4425 Pat Beyer Galileo TDS Manager 4-0055 Jo Conley Asst Galileo NOPE 584-4483 Dave Recce Deputy Galileo NOPE 584-4462 Byron Yetter Galileo NOPE 584-4422 Comm Chief . . . . . . . . . . . . . . . . . . . . . . . . 3-5800 Data Chief . . . . . . . . . . . . . . . . . . . . . . . . 3-7974 Ops Chief. . . . . . . . . . . . . . . . . . . . . . . . . 3-7990 Support Chief. . . . . . . . . . . . . . . . . . . . . . . 3-0505 Track Controller . . . . . . . . . . . . . . . . . . . . . 3-5858 "The Cave" . . . . . . . . . . . . . . . . . . . . .3-7756 3-7757 Flight Projects Galileo ACE. . . . . . . . . . . . . . . . . . . . . . . . 3-5890 Table 4-2 Radio Science Investigators & Staff Galileo - Propagation Taylor Howard, Team Leader Stanford Univ. Von Eshleman Stanford Univ. (retired) Michael Flasar Goddard SFC Dave Hinson Stanford Univ Arvydas Kliore JPL Richard Woo JPL Michael Bird Univ. Bonn, Germany Peter Edenhofer Univ. Bochum, Germany Martin Paetzold Univ. Koeln, Germany Galileo - Celestial Mechanics John Anderson, Team Leader JPL Frank Estabrook JPL John Armstrong JPL James Campbell JPL Timothy Krisher JPL Eunice Lau JPL Ulysses Solar Corona Michael Bird, Principal Investigator Univ. Bonn, Germany Peter Edenhofer Univ. Bochum, Germany Martin Paetzold Univ. Koeln, Germany Sami Asmar JPL Gravitational Waves Bruno Bertotti, Principal Investgtr. Univ. Pavia, Italy Sami Asmar JPL Luciano Iess CNR-IFSI, Italy Hugo Wahlquist JPL Gianni Comoretto Osser Astro Arcetri, Italy Giacomo Giampieri JPL (RRA) Alfonso Messeri CNR-IFSI, Italy Roberto Ambrosini Ist. Radioastro., Italy Alberto Vecchio Univ. Pavia, Italy Giotto Peter Edenhofer, Team Leader Univ. Bochum, Germany Michael Bird Univ. Bonn, Germany Martin Paetzold Univ. Koeln, Germany Herbert Porsche DLR, Germany Hans Volland Univ. Bonn, Germany Mars Global Surveyor G. Leonard Tyler, Team Leader Stanford Univ. John Armstrong JPL Georges Balmino CNES, France F. Michael Flasar GSFC David Hinson Stanford Univ. Richard Simpson Stanford Univ. William Sjogren JPL David E. Smith GSFC Richard Woo JPL Cassini Arvydas Kliore, Team Leader JPL Roberto Ambrosini Ist. Radioastro., Italy John D. Anderson JPL Bruno Bertotti Univ. Pavia, Italy Nicole Rappaport JPL F. Michael Flasar GSFC Robert G. French Wellesley Col. Luciano Iess CNR-IFSI, Italy Essam A. Marouf SJ State Univ. Andrew F. Nagy Univ. Michigan Hugo Wahlquist JPL Huygens Doppler Wind Experiment Michael Bird, Principal Investigator Univ. Bonn, Germany Magellan - Occultations Paul Steffes Georgia Tech. Jon Jenkins NASA Ames G. Leonard Tyler Stanford Univ. Venus Gravity Field William Sjogren JPL ------------------------------------------------------------------------------ Section 5 Operations 5.0 Introduction 5.1 Reference Products 5.2 Monitoring Systems 5.3 Procedures 5.4 GLL USO Tests/Redshift Experiment 5.5 GLL Solar Wind Scintillation Experiment 5.6 Jupiter Occultation Experiment (J0) 5.0 Introduction This section deals with operations for Radio Science activities, which are broken up into three phases: pre-pass, real-time, and post-pass. However, there are some common products which are important for all three phases. Similarly, there are some common procedures which can be used during all three phases. Section 5.1 describes the common products and Section 5.3 describes the common procedures. Products or procedures which are specific to an experiment are described in the sections following (5.4 to 5.6). The following key organizations are concerned with Radio Science operations and will be mentioned in the text: the Radio Science Team (RST) or Radio Science Support Team (RSST), the Mission Control Team (MCT), the Network Operations Control Team (NOCT), and the Deep Space Network (DSN) or Deep Space Station (DSS). 5.1 Reference Products and Descriptions This section will list and describe reference products used by the Support Team during pre-pass, real-time, and post-pass operations. Most are produced by other teams. 5.1.1 Network Operations Plan (NOP) The purpose of the NOP is to provide a mission overview; categorize the Deep Space Network (DSN) operations, functions and interfaces; detail the DSN Support configurations; present DSN operating procedures; and describe the support necessary for the DSN to prepare, test for (including training), and provide the committed support to the mission. For Radio Science, this document provides controlling and high-level requirements and configurations needed to support RS activities. This is primarily accomplished through specific tables within the document. Each table contains the parameters for configuring and calibrating the Radio Science System equipment at the DSN sites for each experiment. The experiments are listed in Volume II, Chapter 12, of the NOP. The Network Operation Project Engineers (NOPEs) and the responsible RSST member meet to negotiate the specifics for the experiment. The details of each sub-section are negotiated between the NOPEs and the RSST at the time of sequence (uplink) development, allowing sufficient time for the NOPEs to issue an update to the NOP. Under normal circumstances, the SOE (see below) will reference the appropriate NOP sub-section at the start of every pass containing a Radio Science observation. 5.1.2 Predictions The DSN's Network Support Subsystem (NSS) generates the predictions for frequency tuning for both open- and closed-loop receivers, and antenna pointing. These products are transmitted in binary form approximately one week in advance of scheduled activities. The responsibility of product transmission falls on the Network Operation Control Team (NOCT). The following prediction sets will be described: closed-loop receiver predicts, antenna pointing predicts, planetary predicts, and open-loop receiver (DSN Spectrum Processor or DSP) predicts. 5.1.2.1 Closed-loop Predictions Closed-loop receiver predicts are generated for all Radio Science activities. These include standard tracking predictions which are used by the Metric Data Assembly (MDA) to compute Doppler pseudo-residuals, and frequency tuning predictions which are used to tune the closed-loop receivers for initial signal acquisition. A hardcopy of this product has the following parameters: spacecraft and pass numbers, station for which the predicts have been generated, frequency on which they are based (S-band or X-band), Doppler mode (1-way, 2-way, 3-way, or mixed mode). Other parameters are the Beginning Of Track (BOT), spacecraft rise, and round-trip light times. Predicts for Doppler modes can be provided with centers of any length. Usually, one second centers are chosen for high resolution in Doppler variation. 5.1.2.2 Planetary and Antenna Predictions Planetary Predictions (or 3-day predicts) are sent to the station three days before a pass. These are gross antenna predicts (not high resolution). They are referenced to Earth's center, "Geocentric Earth True Equator and Equinox," and include year, day of year, station declination and right ascension angles plus round-trip-light time parameters. Later antenna pointing predicts provide high resolution antenna position for any point in time during the pass. The position is provided in azimuth, elevation, hour angle, and declination. Antenna pointing predictions are generated for all passes. 5.1.2.3 DSP (open-loop) Predictions The open-loop predictions are used to tune the second local oscillator of the open-loop receiver. Open-loop predictions have spacecraft and pass numbers and an identifier which signifies that they are Radio Science (i.e., open- loop) predicts. Time-tagged frequency predicts are provided as well as receiver ramp durations for all modes expected during the pass. A station identifier is provided to indicate proper station usage. Radio Science open-loop receiver predictions are required for those Galileo passes where the DSP has been scheduled for recording. In the case of unique one-time activities (such as occultations and fly-bys), the RSST has negotiated with the DSN to compare predict sets (DSN-generated and RST- generated). The DSN has agreed that the DSN predicts must agree with the RST predicts to within 30 Hz. If the difference is greater than this and the DSN cannot resolve the difference before pre-cal of the affected track, then the RST-generated predicts will be used to tune the open-loop receiver. 5.1.2.4 Predict Set ID The Predict Set ID is a set of three characters used to identify a file containing predicts. The first two characters are the Franz Code, random letters assigned by the operator who created the predict set. The other character indicates the Doppler mode (1-way, 2-way, 3-way, or mixed mode) of the predict set. An example of a predict set ID follows: 3-way = XZ9, 2-way = XZ8, 1-way = XZ7, and Mixed Mode = XZ3 (where XZ represent random letters). All predict sets use this type of identification. 5.1.3 Sequence of Events (SOE) & Space Flight Operations Schedule (SFOS) The Project SOE is generated during the uplink development process. It is a second-by-second schedule of all events occurring both on the spacecraft and at the station. There are several other related products: the Keyword File, the Pass/DSN SOE, and the Translated SOE. The Keyword File is a DSN specific sub-set of the Project SOE. The Keyword File identifies events using mnemonic and cryptic abbreviations and contains coded time-stamped directives and notices for station personnel such as mod index changes and times, station configuration codes for calibration as well as pre- and post-calibration times, group activity start and stop times, and Doppler mode changes and times. The Pass/DSN SOE is a (slightly) reformatted pass-specific sub-set of the Keyword File. This SOE is still in mnemonic form. This product is routinely transmitted to the stations. The Translated SOE is derived from the Pass SOE and is the translated version containing some expanded information and is more readable that the Pass/DSN SOE. This product is usually transmitted to the stations. The DSN Keyword File and the Pass SOE (or the Translated SOE) are the controlling products for any activity supported by the DSN; therefore, they contain all activities and information necessary to enable the station personnel to support a pass during a Radio Science experiment. Various forms of the SOE are used by the organizations responsible for real-time activities such as the Mission Control Team, the Network Operations Control Team, and the Radio Science Support Team. Often, the SOE will contain a "Spec Advisory", a notation that an out-of-the-ordinary activity is to take place. A Briefing Message is normally sent to the station(s) by the NOPEs in advance of the activity that explains not only the Spec Advisory but also the experiment in detail. Several copies of the SOE are delivered to the Radio Science Real-Time Area in the week before activities are scheduled. One copy is highlighted by the Operations Engineer for RST usage; another copy is kept by the Data Production Engineer for inclusion in passfolders. RSST personnel preparing to monitor a pass verify that the SOE corresponds to the expected activities or observation. Any discrepancies are discussed with the ACE (or Ops Engr) immediately and noted in the logsheet. The Mission Control Team (MCT) is responsible for supporting any correction or "redline" activities. The Operations Engineer verifies that all redlines have been included in the SOE. Another related product is the SFOS. It is a day-by-day synopsis of Project activities including spacecraft events, meetings, and reviews. This product is ONLY an overview of experiment activities. The SOE (in its various forms) remains the defining document. 5.1.4 The Seven-Day Schedule The Seven Day schedule is another product of the lengthy chain of negotiation which results in allocations of station time. This product is the final allocation schedule for the DSN incorporating any last minute planned changes in allocations. It calls out the configuration and necessary equipment for support of a given track. It shows the amount of time scheduled for a particular station to perform pre-calibration, acquisition, post-track calibration, and identifies what type of support a given station is to provide (radio source tracking, test support, actual spacecraft tracking, etc.). The 7-Day schedule is designed for seven days of support starting on Sunday. For planning purposes, a forecast week is provided but items are subject to change. 5.1.5 Multi-Mission Logsheet Before the start of every pass, the RSST member on duty begins to fill out a Multi-Mission Logsheet (See Figure 5-1). The Operations Engineer provides this logsheet that serves as a checklist for the real-time monitoring of the experiment. In this section, bold indicates a parameter that appears on the logsheet. Starting at the uppermost line, the DSS, S/C ID, PASS number (from the SFOS), DOY, DATE, and SCHEDULED AOS (Acquisition of Signal) and LOS (Loss of Signal) are entered by the RSST member on duty. The START RST VALIDATION TIME is entered at the time that the RSS system validation begins (as opposed to initial acquisition). RTLT (Round-Trip Light Time), OWLT (One-Way Light Time), CONE ANGLE (same as Sun-Earth-Probe (SEP) angle), and ANT MAX ELEVATION (ANGLE and TIME) can be found in the SFOS. During pre-cal, the station personnel use the VoiceNet to relay to the TrackCon the INITIAL ACQUISITION conditions (for the RCVR/EXC BLOCK III, IV, V). The WEATHER STATUS is also reported at this time. The section under MDA HIGH RATE DOPPLER must be completed after the station has gone 2-way (if scheduled to do so). The DOPP RESIDS is obtained from the NOCC (or RMS) displays (Figure 5-3). The DOPPLER MODE CHANGE TIME, the time at which the expected Doppler mode comes into lock, is reported by the station to the TrackCon over the VoiceNet. The PREDICT SET ID can also be found on the NOCC displays (Figure 5-4). The last section that is completed is titled, RSSD/RIV/SPA-FFT/TAPE. For experiments where the open-loop system (DSP) is recording and the Spectrum Digitizer FFT (or just the FFT) is being used, this portion of the logsheet is COMPLETELY filled out. The RSSD MODE and SAMPLE RATE are obtained from the NOCC "RSSD Status" (Figure 5-4). The FILTER OFFSET and the PREDICT SET ID are obtained from the NOCC "SPA-FFT Status" (Figure 5-5). The TAPE STATUS is obtained from the NOCC "Tape Status" (Figure 5-6). The RMS (root-mean-squared) values for the RIV and the RSSD are obtained from the NOCC "RSSD Values" display (Figure 5-7). The section under RIV/RSSD STATUS PAGES is completed using the NOCC "RIV Status" and "RSSD Status" displays (Figures 5-8 and 5-4). The section under RSCP/FFT CFG portion is completed from NOCC (or RMS) displays using the FFT display (Figure 5-9). 5.2 Monitoring Systems There are three systems which the RSST uses to monitor the progress of an experiment: the VoiceNet, the NOCC Workstation, and the RMS. Each of these systems will be explained in detail in the following sections. Significant items communicated over the VoiceNet should be noted in the logsheet to become part of the permanent record of the track. Displays are generated by both the NOCC Workstation and the RMS and provide the RSST with an excellent window into the status and configuration of experiments being supported. Copies of all these plots and displays become products of the validation process and are added to the passfolder. RSST personnel on duty are responsible for obtaining or creating those copies. 5.2.1 VoiceNet Communications A description of the voice nets is presented in Table 5-1. In order to verify that the VoiceNet will be working during a Radio Science track or observation, a voice check should be made at the beginning of the track. All personnel using the VoiceNets must properly identify themselves prior to asking questions or making a request of the Ops Team. The proper way of contacting any other organization or individual on the VoiceNet is by identifying the recipient and then the sender (The call sign to be used by Radio Science personnel is "Galileo RSSG"). For instance, for an RSST member to call the Galileo ACE, the following would be said by the RSST member: "Galileo ACE [1 second pause] Galileo RSSG". An example of a voice check follows: RSST Member: "Ops Chief [1 second pause] Galileo RSSG with a Voice Check. How Do You Copy? Over" Wait for the Ops Chief to respond that he/she heard your call sign and that he/she heard you. In contacting the TrackCon or the station over the VoiceNet to clear any discrepancy, reference should be made to the appropriate sub-section in the NOP (if not superseded by the SOE line item or TWX). Table 5-1 VoiceNet Identification INTER - 5: Standard Project operational net to NOCC for communication between Galileo ACE and Ops Chief. INTER - 8: Standard Project operational net to NOCC for communication between Ulysses ACE and Ops Chief. GDSCC - 1: Standard NOCC-to-DSN Complex control net (Goldstone) - Listen Only GDSCC - 2: Standard NOCC-to_DSN Complex control net (Goldstone) - Listen Only (Coordination net) CDSCC - 1: Standard NOCC-to-DSN Complex control net (Canberra) - Listen Only CDSCC - 2: Standard NOCC-to-Dsn Complex control net (Canberra) - Listen Only (Coordination Net) MDSCC - 1: Standard NOCC-to-DSN Complex control net (Madrid) - Listen Only MDSCC - 2: Standard NOCC-to-DSN complex control net (Madrid) - Listen Only ( Coordination Net) CCT - 1 & 2: Standard NOCC intra net CMTRY: Commentary (and music) 5.2.2 NOCC Workstation The NOCC workstation, nws24, allows us to see the same displays as are available in the Darkroom and used by the Network Operations Control Team (NOCT). The data flow mechanism is a database broadcast from the NOCC servers to the remote workstations (NWSs). The complete set of displays is available to the Radio Science Team without the necessity of contacting the Darkroom for a switch in what is being broadcast. The workstation, nws24, is located in the Radio Science Mission Support Area (264-325). Information from all three SPCs can be seen simultaneously. Displays of MDA, SRA, and transmitter status are available as well as parameter values from the various pieces of equipment constituting the DSP-R. An FFT of the open-loop signal can also be displayed. Data is held for up to 2 days. Figure 5-10 is an example of the initial display which pops-up when a session is begun. One can click on either a subsystem (e.g., TRK, TLM, CMD, etc.) or an SPC (e.g., SPC 10, SPC 40, etc.). If one clicks on an SPC, the display switches to that of Figure 5-11. Here, one can click on any of the boxes below the subsystem labels to see more info for that particular subsystem. For instance, if one clicks on the TRK box for spacecraft 77, Figure 5-12 is displayed. To go further, the operator can click on the box for FEA (Front End Area) DSS-14 and Figure 5-13 is displayed. More information about Receivers A and B or about the Exciter can be revealed by clicking on those boxes, respectively. On the other hand, if one clicks on DTK (DSCC Tracking subsystem) in Figure 5-12, then Figure 5-14 is displayed. On this display, the values of Doppler residuals, noise, and other Doppler parameters are given as well as the predict set id. Returning to Figure 5-11, one can click on DSP1 under RS for spacecraft 77 to see the status of the Radio Science System. Figure 5-15 is the block diagram which is brought up. Clicking on any of these boxes will allow the operator to keep track of the DSP and of the experiment. Figures 5-16 through 5-22 are examples of the displays produced by clicking on the individual boxes. One additional display is available: the FFT display (Figure 5-23). This is brought up using the left button on the mouse (more about functions available with the mouse below). The RST person on duty must make hardcopies of all appropriate status pages and displays. These materials become part of the passfolder. The NOCC capabilities are as follows (all are available directly from login; no other setup is required). Obtain the user name and password from either the Ops Engineer or the Sys Admin. 1. NOCC Hierarchical Displays: For each station several types of information are available and of interest to the Support Team Members. TRK: FEA: ANT Az/El settings, Conscan and Subreflector status DMD Temperature, Wind, Precipitation TXR Power level, ID number, Beam status (on/off) RCV AGC and Loop bandwidths EXR Ranging Mode, Frequency DTK: MDA S/X High Bandwidth (1/1 or 10/1 SR) Doppler info TLM: Rcvr number, Lock status, AGC, SNT Link Number, Pass Number Bit Rate CMD: Command Summary, system Store\&Forward and Throughput info RS: Most important section for Radio Science. Includes RIV Values and Status, RSSD Values and Status and SPA-FFT Status. LMC: TXR beam status (on/off), power level TXR ID number, operational status, waveguide switch setting BLKIII 34m Rcvr A,B info BLKIV 70m Rcvr A,B info BLKV RCP1/2, configuration and stream status BLKV RCP1/2, exciter, txr, carrier, link configuration status PMD: MON-5-9: (a) Multimission TXR1, TXR2 (b) Multimission RCVR MON-5-15: (a) RCVA, RCVB, TRK (b) CMD/EXC/TXR/TRK (c) VLBI (d) TLM1, TLM2-FSS, TLM3-RSD, TLM4-RCP1/2 (e) BLKV stream RCP1/2 CMC: MON-5-201C summary, FTS1, FTS2, CMS1, CMS2 2. Root Window Mouse-activated Programs: By clicking on an empty space in the background (root) window, menus will pop up which give the NOCC workstation user access to many other programs. Left Button (Programs) DSN Generates a DSN status summary/NOCC Hierarchical Display. SCP Displays Same as above, with other options. History (Graphical/Tabular) Allows user to bring up displays of monitored variables during a recent (within 1-3 days) pass. Log Browser (local/nocc/external) Allows user to browse through the logs of recent (within 1-3 days) passes. SSI/FFT Plot Plots an fft (within 10 seconds) of real-time signal. Clock Three different UTC clocks. Display Lock Used to secure terminal if user needs to leave and would like to have no one touch the displays. Help Generates Mosaic manual page display. Logout Exit the NOCC workstation system. Middle Button: (Tools) Printer Control Allows user to change printer designation. Window/Screen Dump Used to get printouts of the displays. Screen/Print (inverse/mono/color) Preferential printout method, since it allows Inverse printing (less toner needed!) Ftp, Remote Access For access to other NOCC machines. Refresh Screen Will reset backdrop to black, in case system messages scrolled onto it. Restart re-generates the welcoming array of displays. Right Button: (System) Xterm Generates a shell xterm window for {\it rms}. Emacs Starts up Emacs editor. NM Reset Forces reload of data variables from GIF through the displays. 3. Mosaic Help Display: The manual for the NOCC workstations can be found in the Mosaic window which appears upon login (also available from the root window menu). 4. At this point, data should be valid and updating. If there are problems, call or email Jen Caetta (3-0665, caetta@biollante) and report the observed error messages and problems. 5.2.3 Real-time Monitoring System (RMS) The present Real-time Monitoring System (RMS) is a software tool that runs on a SparcStation 330 and is currently undergoing re-development. It is being upgraded to run on a SparcStation 5. It display plots of data vs. time (or frequency) covering the two broad categories of data in which the RST is interested: tracking (closed-loop) data and radio science (open-loop) data. The data that will be received by the RMS are described in DSN document 820-13 (Modules TRK-2-15, MON-5-9, and RSC-11-12). RSST personnel will use the RMS along with the NOCC workstation and the VoiceNet to inspect the data quality. Details on operation will be available at a later date. 5.3 Procedures The procedures for monitoring a pass in real-time are basically the same for all observations. The following is a breakdown of some significant items that should be noted or verified (not a comprehensive listing). 5.3.1 Station Configuration & Calibration Prior to every track, station personnel perform equipment configuration and calibration. This includes important tasks such as setting the attenuators on the Radio Science IF-VF Converter (RIV), loading predict sets into the DSP, and building the link from the CMC. If possible, RSST personnel covering the pass in real-time are present for this activity and note important items in the logsheet (Section 5.1.5 explains how to fill out the logsheet). Since the station will be communicating some of the information pertinent to Radio Science to the Controller in the Darkroom at the start of the track, this time period is of particular importance to the Radio Science Team. Depending on the experiment, predict sets may be archived from the CMC into the DSP one or several days in advance of the experiment. 5.3.2 Tracking Data Monitoring The Metric Data Assembly (MDA) receives data and status information from the Receiver-Exciter Subsystem (closed-loop system) and from the Transmitter Subsystem. It produces closed-loop Doppler and is standard for all spacecraft tracks (w/ and w/o Radio Science). For Radio Science experiments, a higher Doppler sample rate is normally requested to obtain better resolution. Sample rates are part of the SOE and NOP and are reported in real-time. Sometimes coordination with Navigation on sample rate is necessary to ensure that large volumes of Doppler samples can be received without a conflict of supporting resources. During operations, plots of AGC and Doppler pseudo-residuals may be displayed to monitor the received signal strength and the behavior of the Doppler. If the Doppler residuals become large or erratic, the ACE and/or the Track Controller should be made aware of the situation and corrective measures should be taken. If the problem persists and spacecraft causes can be eliminated, a Discrepancy Report (DR) should be opened. The RSST member on duty can request a DR number from the Controller, if he/she has not already opened one. Before monitoring any RS pass, RSST personnel on duty determine the Doppler rate(s) for the pass from the SOE, NOP, and/or TWX. Appropriate actions via VoiceNet, phone, etc. are taken to insure that the tracking data is obtained. RSST personnel complete the appropriate areas of the logsheet based on the information obtained from all sources (RMS, NOCC Workstation, 7-Day Schedule, & VoiceNet). See Section 3.0 of this Handbook for a more detailed description of the Ground System equipment. 5.3.3 Radio Science System Monitoring The Radio Science System consists of various downconverters and the DSP (open-loop) recorder. Usage of the RSS is dependent upon the experiment requirements and will be scheduled on that basis. The DSP is configured according to the NOP that governs a specific experiment, and verified against the SOE (recommended configurations appear in Chapter 12 of the NOP Volume II for Galileo). The Spectrum Digitizer FFT Display (or just the FFT Display) is a separate but related piece of equipment at the station that generates an FFT of the pre- or post-digitized signal from the DSP. The display is transmitted to the RMS and the NOCC Workstation and is used by the RSST to monitor (and thereby maintain) signal performance of the Radio Science System during periods of open-loop data recording. Before monitoring any RS pass, RSST personnel on duty determine the configuration for the FFT and the DSP for the pass from the SOE, NOP, SFOS, 7-Day Schedule, Redline Changes, and/or TWX if applicable to the activity. RSST personnel should use these products to guide them through the support of real-time activities. See Section 3.0 of this Handbook for a more detailed description of the Ground System equipment. During real-time operations, the station's FFT provides visual confirmation of signal presence and signal location within the bandpass. The NOCC Workstation's FFT display should be enabled while supporting real-time activities. Other displays such as the seven pages of the DSP-R (POCA Status, POCA Values, RIV Status, SPA-FFT Status, the FFT display, RSSD Status, and RSSD Values) should also be enabled and running. The RSST member on duty should use the VoiceNet, phone, etc. to insure appropriate action is taken throughout the pass to obtain the RS data. He/She should complete the multi-mission logsheet with as much information from all sources (NOCC w/s, VoiceNet, RMS, etc.) as seems appropriate to the activity, making special note of failures and anomalies. 5.3.4 Sequence-of-Events Confirmation The Sequence Of Events (SOE), its redlines, and the corresponding DSN Keyword file and Translated SOE will be the controlling products for real-time operations during all Radio Science activities. It is important that all operations groups (RSST, MCT, NOCC and the participating DSCC) follow the same script. During the pass, the RSST personnel on duty individually confirm each item. Confirmation of each event provides visibility into the status of the ground data system at each station. 5.3.5 Real-time Monitoring The most critical time period is the first hour or so of the pass (until the two-way signal is finally received on the ground in the case of two-way passes). That is, a critical validation period exist from Beginning of Track (BOT) until all RS parameters have been validated (including verifying the presence of the signal in the FFT). This is the time period when problems can occur in configuration of the equipment and acquisition of the signal. The Operations Engineer in consultation with the Science Coordinator/Experiment Representative determines the level of support required for each pass and informs the RSST personnel. Once the initial validation period has completed, the station should not make adjustments unless a failure occurs and/or they are directed to do so. In some cases, monitoring of the entire pass is unnecessary (check with the Ops Engr). This might mean that the NOCC workstation will be left running unattended for a major portion of a pass. If this is the case, the exiting RSST member "locks" the NOCC workstation screen. If the NOCC workstation is to be shut down, the procedures in Section 5.2.2, Part 2, are followed. Whenever on-duty personnel are exiting, they inform the ACE and/or TrackCon that they are going off-shift and remind her/him of phone numbers to call regarding experiment outages and emergencies. Following the recording period or at End Of Track (EOT), timely delivery of the products should begin (See Section 6.0). With implementation of the RSSD, RSST personnel on duty should remind the TrackCon to remind the station to mail one of the two 8mm tapes to the Radio Science Data Production Engineer at JPL (Paula Eshe) and store one on site. The 8mm ODRs are mailed with the next consolidated shipment although for some experiments the shipment will be expedited. 5.3.6 Failures & Emergencies In case of unexpected equipment (hardware or software) or procedural failures, the TrackCon starts a Discrepancy Report (DR). A number is assigned and the NOCT (DSN) is responsible for tracking and closing all such DRs. If the failure was particularly serious, an Incident/Surprise/Anomaly (ISA) Report is also written by the RSST member who discovered the incident or by the Science Coordinator/Experiment Representative. These are tracked and closed by the specific flight project affected. RSST personnel on-duty will note any DRs on the logsheet and briefly describe the failure, especially noting any loss of RS data. An ISA can be written by any member of a flight project. Copies of ISAs written by RSST personnel are kept as part of the logsheet. In the case of a serious Radio Science Equipment failure or question, the Ops Engineer and/or the Science Coordinator/Experiment Representative should be notified. The phone numbers for all RSST personnel are located in Section 4. In case of a spacecraft emergency, the RSST member on duty notes as much as possible on the logsheet without interfering with the Project's attempts to stabilize the situation. A voice-mail message to the rest of the RSST (especially the Science Coordinator/Experiment Representative) is appropriate. The RSST member who is covering the next pass is notified as soon as possible. In case of facilities emergencies (power outages, air conditioning failures, computer crashes, etc.), the Support Chief (during regular hours), the Ops Chief (during swing or night shifts), or the System Administrators (Jennifer Caetta or Phyllis Richardson) are notified IMMEDIATELY (as appropriate). See Chapter 4 for a listing of phone and beeper numbers. 5.4 Galileo USO Tests/Redshift Experiment Regular USO tests were scheduled to continue until September 16, 1995. The spacecraft is scheduled to switch to suppressed carrier mode on September 18. After this date, USO tests will be done using only tracking data (i.e., no open-loop recordings). See Section 2.0 for a description of the goals of this experiment. 5.5 Galileo Solar Wind Scintillation Experiment The Solar Wind Scintillation Experiment '95 was originally scheduled to be a Doppler experiment. But, a late-date change to the Project's telecom strategy has precipitated a change in the data-taking strategy that the RSST had originally developed. The expectation now is that the SWSE '95 will be done partially as a Doppler-only experiment and partially with the use of the DSP. The Radio Science Support Team will monitor the prime shift passes. The dates of the experiment are 95-328 through 96-013. The Doppler sample rate will be 10 samples per second. The SWSE will be Doppler-only while the spacecraft is in suppressed carrier mode from 95-328 through 95-341. On DOY 342, the spacecraft will be returned to residual carrier mode until 96-031. The RSST has requested that the DSP be added to the link on a best-efforts-basis beginning on DOY 342 and continuing through 96-013, the last of the experiment. The Experiment extends from sequence JAB thru JOEA, JOEB, JOEC and ends in JOCA. Due to the late change in the experiment data-taking strategy, a full description of the DSP-schedule and the schedule of passes as well as a description of the tape delivery process were not available at the time of printing. Table 5-2: DSP Configuration for Galileo Solar Wind Scintillation Experiment for 70 meter stations (DSS: 14, 43, or 63) Parameter DIRECTIVE Setting Notes Filter offset RIVOF -150 Hz Sample rate SRATE 200 XR SR XL SL samp/sec IVC switch CNF PRIME Chan. assign. RCH1 CNF FIL=1 ATT=119 XR (J1) RSSD A/D-1 RCH2 CNF FIL=1 ATT=xxx SR (J2) RSSD A/D-2 RCH3 CNF FIL=1 ATT=119 XL (J3) RSSD A/D-3 RCH4 CNF FIL=1 ATT=119 SL (J4) RSSD A/D-4 82/100 Hz BW filter Output to FFT SDIN SR FFT Signal Source Bit resolution SDRES 8 bits - A/D Resolution SD Enable/Disable SDEN E FFT Enable to JPL 5.6 Jupiter Occultation Experiment (J0) The first and best Jupiter Occultation of the earth will begin on December 8, 1995. Ingress is at 3:22 am PST. Egress is scheduled to occur at 6:53 am PST on the same day. The experiment will actually begin (start of recording) at 2:02 am PST and we will continue recording data until 08:25 am which corresponds to the end of the track. A timeline is shown in Figure 5-2. 5.6.1 Configuration Table 5-3: DSP Configuration for Galileo Jupiter Occultation Experiment for 70-meter station (DSS 63) Parameter DIRECTIVE Setting Notes Filter offset RIVOF -3750 Hz Sample rate SRATE 5000 SR SL samp/sec IVC switch CNF PRIME Chan. assign. RCH1 CNF FIL=3 ATT=119 XR (J1) RSSD A/D-1 RCH2 CNF FIL=3 ATT=xxx SR (J2) RSSD A/D-2 RCH3 CNF FIL=3 ATT=119 XL (J3) RSSD A/D-3 RCH4 CNF FIL=3 ATT=xxx SL (J4) RSSD A/D-4 2500 Hz BW filter Output to FFT SDIN SR FFT Signal Source Bit resolution SDRES 8 bits - A/D Resolution SD Enable/Disable SDEN E FFT Enable to JPL 5.6.2 Operations Script ( See Ops.Script.1.GIF thru Ops.Script.15.GIF) Phone Numbers See Table 4-1 for a listing of RSST and other DSN (NOPE and RS) phone numbers. Jennie Johannesen (NAV) . . . . . . . . . . . . . . . . . . . . . .4-3352 Percy Montoya (OEA - Radio Science) . . . . . . . . . . . . . . .584-4482 Ricardo Unglaub (OEA - RAYPATH) . . . . . . . . . . . . . . . . .584-4458 Ken Clark (OEA - RAYPATH alternate) . . . . . . . . . . . . . . .584-4456 Ed Gardner (OEA - Predicts) . . . . . . . . . . . . . . . . . . .584-4487 Peter Nguyen (OEA - Predicts alternate) . . . . . . . . . . . . .584-4536 ------------------------------------------------------------------------------ Section 6 Data Products 6.0 Introduction 6.1 Data Product Delivery 6.2 Special Post-Pass Activities 6.3 Data Validation and Processing 6.0 Introduction Data handling operations for each Radio Science activity will begin upon completion of the Radio Science event. During this period, activities will consist of data product delivery (tapes, files, playback etc.) to the RSST, validation of data products, and the processing of the data. The RSST may require post-pass calibrations if problems arise during the pass. Section 6.1 specifies procedures and operation schedules for the delivery of data products. Section 6.2 describes special post-pass activities such as data calibration and playbacks. The processing and analysis of the data are discussed in Section 6.3. 6.1 Data Product Delivery The Galileo USO test data product delivery strategy and schedules are given in Table 6-1. The Galileo Solar Wind Scintillation Experiment data product delivery strategy and schedules are given in Table 6-2. The Galileo Jupiter Occultation Experiment data product delivery strategy and schedule are given in Table 6-3. These tables along with the following subsections describe each of the products as they relate to the specific activities. The format and interface agreement numbers for the Galileo data products are specified in Table 6-4. 6.1.1 Open-Loop Data The open-loop data are recorded at the DSCC site on an 8mm helical scan tape known as an ODR (Original Data Record). The tape contains up to 4 channels of digitized receiver data from the open-loop receiver, as well as POCA (Programmable Oscillator Control Assembly), tuning, timing, configuration, and status information. When applicable, the ODR tape(s) will be logged and delivered to the RSST. After each tape is written, the tape ID number, start and stop recording times, tape drive ID number, station ID, and pass number should be written onto the label. Full duplication of all ODR tapes is required. The duplicates will be shipped to JPL while the original tapes will remain at the DSN complex until the duplicates are delivered to the RSST and have been validated. The tapes are to be shipped to JPL in the next available consolidated shipment. Once at JPL, the tape is to be delivered to the Galileo Radio Science Data Products Engineer (Attn: P. Eshe) at Mail Stop 264-325 where it will then be given an RSST tape ID. 6.1.2 Closed-Loop Tracking Data Magnetic tapes containing closed-loop tracking data in the form of an ATDF will be borrowed from the Radio Metric Data Conditioning Team (RMDCT) and copied. Arrangements are in progress to replace this process with electronic file transfer. 6.1.3 Spacecraft Trajectory Data (CRSPOSTA Files) The Celestial Reference Set (CRSPOSTA) file contains spacecraft trajectory vectors for use in processing the Radio Science data. For each pass or set of passes, a CRSPOSTA file derived from the best available navigation solution will be required for Galileo. The RSST will request the file from Project NAV via a request memo. GNAV will deliver the requested CRSPOSTA files to a computer on the RODAN network using the Ethernet connection. In the event the Ethernet is down for an extended period of time, the RSST will initiate the proper tape movements to and from IPC in order to access the file. For Galileo, the present SIS (210-12) specifies the NAVIO format as the CRS product to be delivered to the Orbiter Engineering Team (OET) and Radio Science. However, in practice, Radio Science receives the file in an ASCII format (CRSPOSTA), and OET receives it in a different data format. 6.1.4 NOCC Passfolder The NOCC hard copy data will be requested by the RSST. The Passfolder includes the Controller's Log (Network Operations Log) and the Tracking System Pass Summary (NATTRK Log). Radio Science frequency predictions will be sent electronically to RSST. 6.1.5 Radiometric Tracking Calibration Data Radiometric Tracking Calibration Data will be available on a permanently catalogued file residing on the UNISYS. These data include the changes induced in the various tracking data types based on media measurements. 6.1.6 Timing And Polar Motion Files This file contains estimates of the position of the Earth's rotation poles and universal time from astronomical observations. The information in this file allows for the Earth's rotation to be accounted in the analysis of Doppler data. 6.1.7 SPICE Kernels SPICE is a system for supplying scientist with necessary ancillary information for data analysis. The name "SPICE" comes from the five "kernels" in which this information is delivered. Each kernel is a file containing information which can then be manipulated using a series of software subroutines provided by JPL's Navigation and Ancillary Information Facility (NAIF), the "NAIF Toolkit". The five kernels are: S Kernel This file provides information on the Spacecraft trajectory in inertial space and is provided by the spacecraft navigation teams. P Kernel This file provides the ephemeris of the Planets and moons of the solar system and is also provided by the spacecraft navigation team. I Kernel This file provides Instrument-specific information, such as pointing offsets. The science Team Leaders and Principal Investigators are responsible for this file. C Kernel This file provides the spacecraft attitude in inertial Coordinates. The AACS analyst on the Spacecraft Team is responsible for the C kernel. E Kernel The Event kernel provides a listing of spacecraft and ground events that might affect collected scientific data. The ISOE, as provided by the MCT, and notes provided by the Science Investigation Teams will comprise this kernel. 6.1.9 Navigation Information Files This file contains information used to model solar radiation pressure such as the configuration and orientation of the spacecraft bus, the solar array, and the HGA. TABLE 6-1. Data Product Delivery Strategy and Schedule -- Galileo USO Tests PRODUCT DELIVERY STRATEGY DELIVERY SCHEDULE ATDF(S) Borrow original ATDF from When ATDF is made. RMDCT, make copy, and return original. ODR(S) Only if open-loop data was On next acquired. The station will consolidated ship the ODR(s) to Galileo Data shipment. Products Eng. 264-325 (Attn. P. Eshe) CRSPOSTA A request memo is sent to Within a few days FILE J. Johanneson, GNAV. Will of request memo. notify via forms delivered in mail, specifying file names and file locations. NOCC Request made to Rosa Anguiano Within one week. Passfolder (507-215). Passfolder then mailed to P. Eshe TABLE 6-2. Data Product Delivery Strategy and Schedule -- Galileo Solar Wind Scintillation Experiment PRODUCT DELIVERY STRATEGY DELIVERY SCHEDULE ATDF(S) Borrow original ATDF from When ATDF is made. RMDCT, make copy, and return original. ODR(S) The station will ship the On weekly duplicate ODR(S) to JPL NDC consolidated ship the ODR(s) to Galileo Data shipment. Products Eng. 264-325 (Attn. P. Eshe) Playback To be generated only if Within one week IDR(S) specially requested. NOCC Request made to Rosa Anguiano Within one week. Passfolder (507-215). Passfolder then mailed to P. Eshe TABLE 6-3. Data Product Delivery Strategy and Schedule -- Galileo Jupiter Occultation PRODUCT DELIVERY STRATEGY DELIVERY SCHEDULE ATDF(s) Borrow original ATDF from When ATDF is made. RMDCT, make copy, and return original. ODR(s) Only if open-loop data was Delivery of expedited acquired. The station will data should be within ship the ODR(s) to Galileo Data one week following Products Eng. 264-325 (Attn. P. Eshe) experiment CRSPOSTA A request memo is sent to Within a few days FILE J. Johanneson, GNAV. Will of request memo. notify via forms delivered in mail, specifying file names and file locations. NOCC Request made to Rosa Anguiano Within one week. Passfolder (507-215). Passfolder then mailed to P. Eshe Playback To be generated only if specially IDR(s) requested. Table 6-4. Galileo Data Product Interface Agreements DATA PRODUCT SOURCE USER FORMAT # IFA # Archival Tracking DSN RSS SIS 1001-14 NAV-1 Data File (ATDF) Original Data DSN RSS DSN 820-13 DSN-22 Record (ODR) RSC 11-13 SIS 233-03 Playback DSN RSS DSN 820-13 DSN-21 Intermediate IDR-12-1A Data Record (IDR) SIS 233-09 Spacecraft NAV RSS SIS 210-12 NAV-32 Trajectory Data (CRSPOSTA) NOCC Passfolder DSN RSS Paper DSN-24 6.2 Special Post-pass Activities Currently, there are no requirements for post-pass calibrations for the Radio Science passes. However, it is important that any post-pass calibrations be performed with the same equipment used during the recording period. If any equipment had changed due to failures or if spare parts were used, then that information should be obtainable through the NOPE. Any post-test calibration tapes should be included in the shipment of all other tapes (ODRs). There are no requirements for any post-pass System Performance Tests (SPTs). However, one may be requested if deemed necessary during specific passes. The DSP may be requested after the test for any specially requested tape duplication and/or post-pass calibrations. 6.3 Data Validation, Processing, and Archival This section explains what is done with Radio Science data after it is delivered to the RSST. Software called Radio Science Validation and Processing (RSVP) is used for both validating and processing Galileo Radio Science data. RSVP may be run on any of the SUN SPARC stations on the RODAN network. RSVP has a graphical user interface (GUI) which enables the user to select from a variety of validation and processessing options. These options are explained in more detail in the following sections. A modular design enables new processing techniques and new data formats to be added quickly and easily. Figure 6-1 is a block diagram illustrating the overall program design. Data is usually provided by the DSN on 8-mm Exabyte tapes, but RSVP can read data in the form of disk files and CDs as well. The RODAN network also has the capability of reading 9-track tapes. All current data formats and several older formats are supported by RSVP. Validation and processing currently utilize Matlab routines for plotting. This is temporary while a Tcl/Tk graphing package is being implemented. The new graphing software will have the similar functionality to that of TEKJOY on the PRIME computer. 6.3.1 Data Validation The validation process includes the software and procedures required to ensure that the data collected in support of Radio Science observations are usable by the Radio Science Investigators. The following subsections describe the validation process. 6.3.1.1 Closed-Loop Tracking Data Validation Galileo closed-loop tracking data, in several old formats as well as the current format (820-13, TRK-2-25), may be validated using RSVP. The data validated includes Doppler pseudo-residuals and signal strengths (AGCs). Plots of Doppler pseudo-residuals and AGCs can also be generated by the program and archived. The user may specify the station, frequency band, and type of tracking data (Doppler (1-way, 2-way, 3-way, or any combination), ranging, etc.) 6.3.1.2 Open-Loop Data Validation RSVP is also used to validate open-loop data tapes (ODRs and/or IDRs) for Galileo. The user may look at header information such as time tags, POCA frequencies, rms voltage sample values, and min/max rms values. These values may be written to a file and plotted using a Matlab program called "mainmenu.m". The digitized sample values may also be selected and saved to a file. The Matlab program "mainmenu.m" can be used to plot the digitized sample values versus time, as well as histograms of sample values. Signal presence may be verified by using "mainmenu.m" to produce plots of power spectral density according to specifications provided by the user. 6.3.2 Data Processing The ODRs/IDRs and/or ATDFs from selected Radio Science activities are processed using the program RSVP, which evaluates the frequency stability and phase noise of the signal received from the spacecraft, and estimates the frequency and frequency rate of the USO. The spacecraft trajectory from the CRSPOSTA files is used by the program set to estimate the "predicted" or "model" frequency which is then differenced from the observed frequency, which is extracted from the data. The frequency stability in terms of Allan deviation is then estimated from the resulting residuals. Figure 6-2 depicts this process. RSVP is currently being used both to measure the stability of Radio Science data, using the Galileo USO as the signal source, and to estimate the USO frequency. An output file containing summary records for the Gravitational Redshift experiments is periodically delivered to the Experimenter. 6.3.2.1 Open-Loop Data Pre-Processing (Data Conditioning) Since the open-loop data is made up of raw voltages, a signal must be detected before it can be processed. Therefore, RSVP includes both decimation and phase-lock loop modules. 6.3.2.2 Ancilliary Data Preparation The FORTRAN program TRAJVECT has been ported directly from the PRIME computer. It has been modified slightly in order to run on the SUN workstations and has been incorporated as a module in RSVP. This program takes the CRSPOSTA file obtained from Galileo NAV and produces a set of heliocentric state vectors for both the station and the spacecraft. These vectors are later used in the program RESIDUAL. 6.3.2.3 Sky Frequency Determination The sky frequency determination modules reconstruct the observed sky frequencies from the Doppler counts (from an input ATDF) or from the detected open-loop baseband frequencies and POCA tuning frequencies (from input files generated by the open-loop detection software which in turn use the ODR tapes as input). 6.3.2.4 Corrections The FORTRAN program RESIDUAL was also ported from the PRIME computer to the SUN workstations with a minimum of changes and has been incorporated into RSVP. RESIDUAL computes frequency residuals from observed sky frequencies and predicted frequencies (estimated from TRAJVECT output trajectory file). In this process, corrections for spacecraft spin and gravitational redshift are made. STBLTY, the next program module, reads in residuals computed from RESIDUAL and performs stability analysis. It computes Allan variance, phase noise, absolute frequency, and frequency drift rate. In this step, ionospheric, charged-particle, and tropospheric corrections may be performed. In the next release of RSVP, the user will have the ability to select each type of correction separately. 6.3.2.5 Resulting Products For Galileo USO tests, a database of various USO parameters and statistics is maintained. A Matlab program will be able to fit and remove an aging model from the estimated spacecraft transmitted frequencies from a set of USO passes. 6.3.3 Data Product Copying and Archiving All data products (ODRs/IDRs, ATDFs, CRSPOSTA files, media calibration files, etc.) are archived on 8-mm Exabyte tapes and CDs using a Phillips CD writer and a Young Minds system. Data is also copied and distributed to the appropriate Radio Science investigators via either ftp, CD, or tape. ------------------------------------------------------------------------------ Appendix A DSN Radio Science Open-Loop System DSN RADIO SCIENCE OPEN-LOOP SYSTEM Note: This appendix was taken, as is, from Document 810-5, REV. D; VOL. I, DSN/ FLIGHT PROJECT INTERFACE DESIGN, module RS-10 A. PURPOSE This module presents the capabilities of the Radio Science System (RSS) for supporting various radio science experiments. B. SCOPE This module outlines the RSS system functions, architecture, and data interfaces. System performance characteristics, and operational configurations are also covered. Though radio science experiments can include Deep Space Communications Complex (DSCC) uplink support and closed- loop receiver tracking, this module is restricted to a description of the RSS open-loop recording capability, which is used solely for radio science support. Details of closed-loop Doppler tracking can be found in TRK-20. Details of the Exciter-Transmitter functions can be found in the TCI modules, and in CMD-10. C. LOCATION OF MATERIAL D. GENERAL INFORMATION The DSN Radio Science System supports radio science experiments, which use spacecraft radio frequency signals to remotely probe features of the solar system . By measuring perturbations of the radio frequency wave as it travels between the spacecraft and the ground stations, characteristics of obstacles or media in the path may be studied. Targets for radio science experiments include planets, planetary atmospheres, and rings. Non-planetary subjects include gravitational radiation and solar plasma. Details of DSN RSS applications may be found in JPL Pub. 80-93, "The Deep Space Network as an Instrument for Radio Science Research". Observables for radio science experiments are the frequency, phase, and amplitude of the communication signal's carrier. The DSN RSS has been designed to enable accurate retrieval of this information. D.1. System Functions The functions of the Radio Science System can be summarized as follows: 1. Generation and transmission of an uplink carrier signal to the spacecraft with a pure spectrum, including low phase noise, and stable frequency. 2. Acquisition, downconversion, digitization, and recording of the downlink carrier with minimal distortion to its frequency, phase and amplitude characteristics. D.2. System Architecture The Radio Science capability of the DSN encompasses several subsystems. For any experiment, common subsystems include Microwave (UWV), Antenna (ANT), Frequency and Timing (FTS), DSCC Monitor and Control (DMC). The Ground Communications Facility (GCF) and the Network Operations Control Center (NOCC) are used to monitor experiments as they are being conducted. Some experiments require two-way tracking, and so the Exciter (RCV/EXC) and Transmitter (TXR) subsystems are used. These subsystems may all be used in conjunction with the Radio Science open-loop receivers. In addition, experiments may use closed- loop Doppler and ranging. The Radio Science System is pictured in Figure 1. The Open-Loop Receiver Subsystem is pictured in Figure 2. There are two kinds of open-loop receivers, the Radio Science IF-VF Downconverter (RIV) used by the 70M and 34HEF subnet, and the Multimission Receiver (MMR) used by the 34STD subnet. Antennas supported by the RIV have a VLBI-Radio Science Downconverter (VRD) to perform the RF-IF downconversion; those supported by the MMR use the MMR Downconverter. As shown in the diagram, each DSCC is supported by one open-loop receiving string, which consists of a RIV and MMR receiver and a DSCC Spectrum Processor (DSP) data handler. Two variations on this architecture are the inclusion of a second RIV/DSP string at DSCC-40, and the absence of an MMR (and therefore open-loop tracking capability for DSS-12) at DSCC-10. A summary of the complexes and their capabilities is in Table 1. D.3. System Description The basic requirement for the Radio Science open-loop receiving system is to record all the information which is contained in a specified bandwidth. To accomplish this, the bandpass of interest, centered around some radio frequency, is shifted to video band (near baseband) for digital sampling. A maximum of four RF channels may be accepted by the Radio Science open-loop system for processing. These RF channels are drawn from the set XRCP, SRCP, XLCP, and SLCP, corresponding to the two possible polarizations of both S- and X-band signals. D.3.1 Downconversion D.3.1.1 RIV Downconversion The downconversion in the RIV is carried out in steps, as shown in Figure 3. The initial RF-IF downconversion occurs in the VRD, which is located in the antenna. The IF signals are transmitted to the Signal Processing Center (SPC) via rigid coaxial cable. The RIV is located in the SPC, in the Dual Cabinet Assembly (DCA). The DCA contains the RIV and the RIV Controller (RIC). The RIV performs several stages of downconversion, the first of which is done via a programmable local oscillator. The DANA synthesizer is driven by the Programmable Oscillator Controller Assembly (POCA), which uses predicts to determine a best carrier frequency. The DANA output is scaled to the incoming IF channels, and mixes both S-derived and X-derived signals down to 50 MHz plus a characteristic offset determined by frequency band and bandwidth selected. Along with mixing, the RIV dictates a bandwidth for recording through one of six crystal filters, selected by operator command. A listing of four filters currently installed comprises Table 2a; a listing of all filters available for ready installation is Table 2b. The RIV also contains an attenuator, which is set by station operators based on the average predicted signal strength for a tracking pass. The attenuator prevents a signal from either saturating or underdriving the analog to digital converters (A/Ds) which will do the bandpass digitization. After the signal has been digitized within the VF bandwidth, it is possible to reconstruct the original RF frequency received at the antenna though use of the formulas in Table 4. The RIV formulas reverse the specific downconversion (multiplication and addition) steps in the RIV receiver. D.3.1.2 MMR Downconversion The MMR receivers were the predecessors to the RIVs. In this older design, the first local oscillator (LO) has a programmable frequency output, and not the second LO as in the RIV. Consequently, it is during the RF to IF downconversion that the signal is centered within a passband. For the MMR system, both the RF-IF and IF-VF converters are referred to as the "MMR". The RF-IF MMR, located in the antenna, receives the same POCA/DANA frequency information as the RIV, though scaled to S and X RF rather than IF. The two channels of the RF-IF MMR are then sent by hard-line cable to the IF- VF MMR, located in the SPC. As with the RIV, the IF-VF MMR has several stages of fixed-frequency downconverters, attenuators, and a set of crystal filters for anti-aliasing. Table 2c lists the MMR filters installed at SPC 40 and 60. Filters are selected through the MMR Controller (MRC). After the signal has been digitized within in the VF bandwidth, it is possible to reconstruct the original RF frequency received at the antenna though use of the formulas in Table 4. The two sets of MMR formulas reverse the specific downconversion (multiplication and addition) steps in the MMR receivers for Australia and Spain, respectively. D.3.2 Sampling and Recording The outputs of the MMR or RIV are within kilohertz of DC. This offset from DC is that which was included in the POCA/DANA tuning for a particular filter configuration. The offset/filter relationships are listed in Table 2a,b,c. This offset, along with the filter bandwidth, is important in the selection of the sampling frequency to be used when the VF signal is sent to the Radio Science Signal Digitizer (RSSD). The RSSD has four input channels, which may be assigned to any combination of four RIV channels (including redundant assignments) from any one antenna. Inside the RSSD, a selected pair of inputs may be sampled at a rate independent of that chosen for the other pair. The RSSD can digitize the data as 8-, 12-, or 16-bit samples. Sampling frequencies for the different sample sizes are available from a discrete set, which is listed in Table 3. Sampling frequencies commonly associated with certain filters are indicated in Table 2a. Once sampled and digitized, the bandpass of interest is represented as a time-series of voltages. Frequency domain reconstruction of these samples will produce a noise bandwidth of 1/2 the sampling frequency, with a representation of the carrier signal located at some position relative to the center of this bandwidth. The absolute value of this center frequency is determined by the DANA frequency which was being used at the time of the observation. Reconstruction of the true received RF frequency (the "sky frequency") requires undoing, mathematically, the various stages of downconversion in the RS receiver string. Formulas for frequency reconstruction are given in Table 5. The RSSD is part of a larger assembly called the Radio Science Communication Processor (RSCP). The RSCP serves as both data formatter and data distributor, for both outside users and various storage media. The RSCP normally provides data in two formats, real-time data blocks (per 820-13/RSC- 11-11B) and 8mm (Exabyte) tape compilations (per 820-13/RSC-11-13). Table 3 provides a complete list of RS data interfaces. The RSCP and an associated assembly, the Spectrum Processing Assembly-Radio Science (SPA-R), together comprise the DSCC Spectrum Processor-Radio Science (DSP-R) Subsystem. The SPA-R is a master controller, connecting the RSCP, RIC or MRC, and POCA. A future evolution of the system will have the SPA-R and RSCP combined. Status information available from the DSP includes configuration data such as filter selection and channel assignment, monitor data such as A/D voltage levels and POCA frequencies, and real-time FFT spectral images of the incoming signal. The FFT display is called the Spectrum Signal Indicator (SSI). Since the open-loop receivers have by definition no automatic mechanism for locating a signal, the SSI display is the only way to tell if a signal is indeed in the bandpass being recorded. D.4 SYSTEM INTERFACES D.4.1 System Inputs The RS open-loop receiving system requires predicted values for spacecraft downlink frequency for the tuning of the POCA/DANA over the course of a tracking pass. Predict files are generated by NOCC Support Subsystem and transmitted to the station electronically. D.4.2 System Outputs Table 6 lists the software interfaces which govern data produced by the RSS. (i) Advanced Multimission Operations System (AMMOS) Users The DSP, through the RSCP, routes SFDU-formatted data blocks (RSC-11-12, RSC-11-11B, etc.) to the Station Communications Processor (SCP) to be transmitted to the Ground Communications Facility (GCF) at JPL. The GCF will then route the data in real-time to AMMOS workstations, as well as archiving it in the on-line Project Database (PDB) for later retrieval. In addition, 8mm (Exabyte) ODR tapes (RSC-11-13) are created at the station; these are available at user request. Monitor data from other systems (MON-5-15, TRK-2-15, etc.) can also be accessed through AMMOS workstations from both real-time broadcast and the PDB. Closed-loop Doppler information, packaged as Archival Tracking Data Files (ATDFs) or Orbital Tracking Data Files (OTDFs), are available as files from the PDB, or as 9-track tapes. (ii) Other Users All monitor data is sent in real-time, in SFDU-formatted blocks, from the station to JPL. The GCF routes the data to the NOCC Gateway (NG). Monitor data of interest (RSC-11-12, MON-5-9, etc.) is sent through serial interface to RODAN, which is the RS-specific monitoring and analysis system. Open-loop carrier samples (RSC-11-13) are recorded on 8mm ODR tapes at the DSCC sites and shipped to JPL. Data can also be played back at the end of the pass; in that case, an IDR tape will be available from the GCF Data Record and Generator Assembly (GDR). Closed-loop Doppler information is packaged as ATDFs on 9-track tapes. D.4.3 Radio Science Stability Analyzer The Radio Science Stability Analyzer (RSA) is part of the FTS Subsystem. The purpose of this assembly is to provide real-time analysis of the performance of the RS System. The RSA can accept either VF input, directly from the RIV, or digital samples from the DSP-R. The RSA has the capability to process four channels at a time, to a maximum sampling rate of 100KHz. The performance characteristics generated by the RSA include plots of frequency residuals and Allan variance. The RSA cannot perform analysis on data from actual tracking passes, as it does not have the capability of removing spacecraft Doppler signatures. Therefore, the RSA can be used only with a Test Transmitter or Test Translator as signal source. D.5 SYSTEM PERFORMANCE Performance metrics of the system are presented in this section. D.5.1 Frequency Stability Long-term frequency stability tests are conducted with the exciter/transmitter subsystems and the RS open-loop subsystem. An uplink signal generated by the exciter is translated at the antenna by the Test Translator to a downlink frequency. The downlink signal is then passed through the RF-IF downconverter present at the antenna, and into the RS receiver chain. In doing this test, contributions from the FTS and ANT cannot be measured. FTS noise is cancelled out, due to the fact that the test path is essentially zero light time, and the same FTS signals therefore reach each component of the uplink and downlink simultaneously. ANT noise is also excluded in this test, as the test signal is not actually transmitted and received with the antenna dish. Estimated FTS and ANT values, based on test data, can be factored in to measured stability. Though this test method only measures two-way stability of the system, two-way tests have so far met the more stringent one-way requirements, and are the only tests performed. Frequency stability is quoted as the Allan variation over a specified integration time. Table 6 has two-way measured system performance as well as estimated system performance (including FTS and ANT) for the 34 HEF and 70M subnets. D.5.2 Phase Stability (Spectral Purity) Phase stability testing characterizes stability over very short integration times; that is, spurious signals very close to the carrier. The phase noise region is defined to be frequencies within 100kHz of the carrier. Both amplitude and phase variations appear as phase noise. Phase noise is quoted in dB relative to the carrier, in a 1 Hz band a specified distance from the carrier: dBc-Hz at 10 Hz, for example. Table 7 contains sets of phase noise levels, at specified frequencies, for the 34 HEF and 70M subnets. D.5.3 Amplitude Stability Amplitude stability testing measures the amplitude variation produced by the open-loop receiving system on a constant amplitude test signal input. Amplitude stability is specified in terms of peak-to-peak amplitude variation over a specifed period of time. Table 8 contains amplitude stability of the 70M and 34HEF subnets. Table 1: DSN Equipment and Capabilities DSCC-10 DSCC-40 DSCC-60 Antenna 34S 34H 70M 34S 34H 70M 34S 34H 70M DSS number 12 15 14 42 45 43 61 65 63 Uplink S X S S X S S X S Downlin S&X SorX S&X S&X SorX S&X S&X SorX S&X Fiber Optic FTS N Y Y N Y Y N Y Y RS Channels 0 2 4 2 2 4 2 2 4 RIV 0 --- 1 --- 0 --- 2 --- 0 --- 1 --- MMR 0 0 0 1 0 0 1 0 0 DSP ----- 1 ----- ----- 2 ----- ----- 1 ----- Table 2a: RIV Filter Selections (As Installed) Filter Select X-band S-band Typical Usage 1 bandwidth (Hz) 82 82 offset (Hz) -550 -150 sampling rate (per sec) 200 200 Gravity Wave 2 bandwidth 415 415 offset -2750 -750 sampling rate 1K 1K Solar Conjunctions 3 bandwidth 2K 2K offset -13750 -3750 Mars Observer sampling rate 5K 5K Occultations 4 bandwidth 6250 1700 offset +3750 +1023 Pioneer Venus sampling rate 15K 5K Occultations 5 bandwidth 45K 45K offset -275K -75K sampling rate 50K 50K Sideband Analysis 6 bandwidth 20K 20K offset -137500 -37500 sampling rate 50K 50K Bistatic Radar Table 2b: Available RIV Filters (Installed and Spare) Filter Band Bandwidth (Hz) Offset (Hz) Designation 1 X 82 -550 2 S 82 -150 3 X 415 -2750 4 S 415 -750 5 X 2000 -13750 6 S 2000 -3750 9 X 7000 -55770 10 S 7000 -15210 11 X 3500 -27500 12 S 3500 -7500 15 X 20K -137500 16 S 20K -37500 17 X 45K -275000 18 S 45K -75000 19 X 6250 +3750 20 S 1700 +1023 21 S 8540 -15000 22 S 4500 -7500 Table 2c: MMR Filter Selections Filter Select X-BAND S-BAND 1 bandwidth (Hz) 100 100 offset (Hz) -550 -150 2 bandwidth 500 500 offset -2750 -750 3 bandwidth 1K 1K offset -5500 -1500 4 bandwidth 3K 818 offset +1500 +409 5 bandwidth 7500 2045 offset +3750 +1023 6 bandwidth 15K 4091 offset +7500 +2045 7 bandwidth 30K 8182 offset +15K +4091 Table 3: Available Sampling Rates for Differently Sized Samples 8-bit Samples (Samples per second): 200,250,400,500,1k,1250,2k,2.5k,3125,4k,5k,6250, 10k,12.5k,15625,20k,25k,31250,50k 12-bit Samples (Samples per second): 200,1k,1250,2k,5k,10k 16-bit Samples (Samples per second): 1250 Table 4: Received RF Frequency Reconstruction Formulas RIV Receivers (70 M and 34 HEF) FS_band_sky = 3 x (Fsyn + (790x10^6)/11) + 1950x10^6 - (Offset_S + (FRecorded - 1/4 FSampRate)) FX_band_sky = 11 x (Fsyn - 10x10^6) + 8050x10^6 - (Offset_X + (FRecorded - 1/4 FSampRate)) MMR Receivers (34 M STD) DSS 42 (Australia) FS_band_sky = 3 x (3/2 Fsyn + 600x10^6) + 300x10^6 - (Offset_S + (FRecorded - 1/4 FSampRate)) FX_band_sky = 11 x ((3/2 x Fsyn + 600x10^6) + (100x10^6 x 8/11)) + 300x10^6 - (Offset_X + (FRecorded - 1/4 FSampRate)) DSS 61 (Spain) FS_band_sky = 48 x Fsyn + 300x10^6 - (Offset_S + (FRecorded - 1/4 FSampRate)) FX_band_sky = 11 x ((16 x Fsyn) + (100x10^6 x 8/11)) + 300x10^6 - (Offset_X + (FRecorded - 1/4 FSampRate)) LEGEND: FS_band_sky S-Band frequency received at antenna (RF signal) FX_band_sky X-Band frequency received at antenna (RF signal) Fsyn Synthesizer frequency reported for a given second Offset_S S-band filter offset Offset_X X-band filter offset FSampRate Digital sampling rate FRecorded Carrier frequency as recorded in the digitized spectrum Table 5: Software Interfaces for Radio Science Data Types DATA TYPE INTERFACE Open-Loop Samples - Real-time 820-13, RSC-11-11B - IDR (ODR playback) 820-13, RSC-11-4A - ODR 820-13, RSC-11-13 DSP/ RS Receiver Monitor/ Spectral Monitor (SSI) 820-13, RSC-11-12 Meteorological Data 820-13, TRK-2-24 Delay in Earth Ionosphere 820-13, TRK-2-23 Tracking System Monitor (Antenna Pointing Angles/Subreflector 820-13, MON-5-15 (AMMOS) Position/Noise Temperature, etc.) 820-13, MON-5-9 (other) Closed-Loop (Doppler and Ranging) Configuration Monitor and Data 820-13, TRK-2-15 Table 6: RS System Frequency Stability With 34HEF and 70M Subnets 34 Meter HEF Subnet INTEGRATION DSCC-10 DSCC-40 TIME FTS ANT STATIC Test DYNAMIC Test meas estim meas estim 1 sec 2.0e-13 0.5e-13 5.5e-14 2.9e-13 1.2e-13 3.1e-13 10 sec 4.0e-14 1.0e-14 9.7e-15 5.9e-14 2.7e-14 6.4e-14 100 sec 8.0e-15 N/A 1.6e-15 N/A 1.9e-15 N/A 1000 sec 1.5e-15 1.0e-15 1.3e-15 2.9e-15 5.8e-16 2.6e-15 3600 sec N/A N/A 2.5e-15 N/A 9.3e-16 N/A 5000 sec N/A N/A 6.4e-16 N/A 1.3e-15 N/A 70 Meter Subnet INTEGRATION DSCC-40 DSCC-40 TIME FTS ANT STATIC Test DYNAMIC Test meas estim meas estim 1 sec 2.0e-13 0.5e-13 4.3e-13 5.1e-13 3.7e-13 4.7e-13 10 sec 4.0e-14 1.0e-14 7.0e-14 9.1e-14 1.0e-13 1.2e-13 100 sec 8.0e-15 N/A N/A N/A 1.3e-14 N/A 1000 sec 1.5e-15 1.0e-15 1.8e-15 3.1e-15 2.2e-15 3.4e-15 3600 sec N/A N/A N/A N/A 2.1e-15 N/A 5000 sec N/A N/A N/A N/ A 2.8e-15 N/A Notes N/A: not available "Dynamic" test involves ramped uplink; "static" test uses constant frequency FTS and ANT contributions are 1-way Measured values are those specifically registered in test Estimated values are the root-sum-squared combination of 2 FTS, 2 ANT, and measured values, producing estimated total system performance in 2-way mode See text (Section 5.1) for further description of test procedures Table 7: RS System Phase Noise With 34HEF and 70M Subnets 34 Meter HEF Subnet DSCC-60 Offset from Carrier Noise, dBc 1 Hz -54.07 10 Hz -60.17 100 Hz -74.0 70 Meter Subnet DSCC-40 Offset from Carrier Noise, dBc 1 Hz -54.07 10 Hz -60.17 100 Hz -74.0 Table 8: RS System Amplitude Variation With 34HEF and 70M Subnets 34 Meter HEF Subnet X-band S-band Averaging Time variation variation 20 Min TBD TBD 4 Hr TBD TBD 70 Meter Subnet X-band S-band Averaging Time variation variation 20 Min TBD 0.06 dB 4 Hr TBD 0.30 dB Acronyms AMMOS Advanced Multimission Operations System (JPL real-time data system) ANT Antenna Subsystem ATDF Archival Tracking Data Files DC Direct Current (frequency of 0 Hertz) DSCC Deep Space Communication Complex DSN Deep Space Network DSP Deep Space Communications Complex Spectrum Processor DSS Deep Space Station FFT Fast Fourier Transform FTS Frequency and Timing Subsystem GCF Ground Communications Facility IDR Intermediate Data Record IF Intermediate Frequency (around 300 MHz) MMR Multimission Receiver ODR Original Data Record OTDF Orbital Tracking Data File POCA Programmable Oscillator Controller Assembly PDB Project Data Base RIV Radio Science IF-VF Converter RF Radio Frequency (approximately 2-10 gigahertz) RODAN Radio Science Data Analysis Network RSA Radio Science Stability Analyzer RSCP Radio Science Communications Processor RSS Radio Science System SLCP S-band Left Circularly Polarized SPC Station Processing Center SSI Spectrum Signal Indicator SRCP S-band Right Circularly Polarized TBD To Be Determined XLCP X-band Left Circularly Polarized XRCP X-band Right Circularly Polarized VF Video Frequency (approximately 0-150 kilohertz) ------------------------------------------------------------------------------ Appendix B Abbreviations and Acronyms A/D Analog-to-Digital Converter ACE Galileo/Ulysses/MO Mission Controller ADC Analog-to-Digital Converter AGC Automatic Gain Control signal level AMMOS Advanced Multi-Mission Operations System AMS Antenna Microwave System AOS Acquisition Of Signal at a DSS APA Antenna Pointing Assembly APC Advanced Personal Computer (NEC Computer) ARA Area Routing Assembly ARD Antenna Reference Distribution ASAP Standard Radio Science Time Requirement ATDF Archival Tracking Data File (closed-loop data tape) ATR All The Rest AUX OSC Auxiliary oscillator in a spacecraft BLK III Closed-loop receiver (design phase III) BLK IV Closed-loop receiver (design phase IV) BLK V Receiver (design phase V) BOA Beginning of Activity BOT Beginning of Track BPI Bits Per Inch BPF Band Pass Filter BWG Beam Waveguide C/A Closest Approach CBM Cured By Magic (see DR) CCP Central Communications Processor CCR Closed Cycle Refrigerator (for the maser) CCS Computer Command Subsystem CDB Central Database CDU Command Detector Unit CEP Critical Events Period CMC Complex Monitor and Control COH Coherent downlink CONSCAN Conical Scanning of a Radio source used to accurately point the antenna CPL Command Procedure Language (for PRIME computer) CRG Coherent Reference Generator CRS CTA-21 Radio Science Subsystem CRS Celestial Reference Set (Spacecraft Trajectory Vectors) CRSPOSTA CRS ASCII Format CUL Clean Up Loop D/A Digital-to-Analog Converter DAC Digital-to-Analog Converter DAS Data Acquisition System dBc Decibel relative to carrier dBc/Hz dBc per Hertz, magnitude relative to carrier spectral density DC Direct Current (frequency equals zero) DCO Digitally Controlled Oscillator DDP Digital Display Processor DL Predicted one-way downlink frequency DMC DSCC Monitor and Control DMT Data Management Team DOY Day Of Year (UTC) DR Discrepency Report (see CBM) DRA Digital Recording Assembly DRG Data Records Generator DRS Radio Science Software Data Records Subsystem DSCC Deep Space Communications Complex DSN Deep Space Network DSP DSCC Spectrum Processor DSS Deep Space Station DTK DSCC Tracking Subsystem DTR Digital Tape Recorder (spacecraft) DTV Digitial TV monitoring display device EOA End of Activity EOT End of Track ER Experiment Representative ERT Earth Received Time ETX Exciter-Transmitter Subsystem FDS Flight Data System FFT Fast Fourier Transform FPS Floating Point Systems (maker of the Array Processor used by the RSST) FRO Frequency Offset FTP File Transfer Protocol FTS Frequency and Timing Subsystem GC Ulysses Ground Controller (Ulysses ACE) GCF Ground Communications Facility GCR Group Coded Recording GDS Ground Data System GLL Galileo Project GNAV Galileo Navigation Team GPS Global Positioning System GSD Great Science Data! GWE Gravitational Wave Experiment (Ulysses) HB Radio Science HandBook HGA High-Gain Antenna (spacecraft) IA Interface Agreement ICD Interface Control Document IDR Intermediate Data Records tape (playback tape) IF Intermediate Frequency IMOP Integrated Mission Operations Profile (Galileo) IMOP What I do after I spill something. IOM InterOffice Memorandum IPC Information Processing Center (JPL computer facility) IPS Inches Per Second ISOE Integrated Sequence of Events IVC IF Selection Switch JPL Jet Propulsion Laboratory L(f) Single sideband phase noise spectral density as a function of offset frequency (f) from carrier LAN Local Area Network LCP Left-handed Circularly Polarized LGA Low Gain Antenna (Spacecraft) LMC Link Monitor and Control LNA Low Noise Amplifier LO Local Oscillator LOS Loss Of Signal at a DSS LPF Low Pass Filter MCA Master Clock Assembly MCCC Mission Control Computer Center MCT Mission Control Team MDA Metric Data Assembly MGC Manual Gain Control MGDS Mission Ground Data System MI Modulation Index MISD Mission Director's Voice Net MMR Multi-Mission Receiver (at 34-m STD stations) MMRS Multi-Mission Radio Science (MGS SUN SPARCStation) MONIDR Monitor Intermediate Data Record MOU Memorandum of Understanding MSA Mission Support Area MTS MCCC Telemetry Subsystem NAR Noise Adding Radiometer NATTRK Network Analysis Team Tracking Analyst NAV Project Navigation Team NB Narrow-Band NBOC Narrow-Band Occultation Converter NCOH Non-Coherent downlink NDC Network Data Center NDPA Network Data Processing Area NDPT Network Data Processing Team NDS Network Display Subsystem NERT Near Real-time NG NOCC Gateway NIST National Institute of Standards and Technology NIU Network Interface Unit NMP Network Monitor Processor display system NOA Network Operations Analyst NOCC Network Operations Control Center NOCG Network Operations Control Group NOCT Network Operations Control Team NOP Network Operations Plan NOPE Network Operations Project Engineer NOSG Network Operations Scheduling Group NRV NOCC Radio Science/VLBI Display Subsystem NRZ Non-Return to Zero NSP NASA Support Plan NSS NOCC Support Subsystem NTK Network Tracking Display System OCI Operator Control Input OD Orbit Determination by the Project's Navigation Team ODF Orbit Data File ODR Original Data Record OEA Operations Engineering Analysis OIA Operational Interface Agreement O/L Open-Loop OLR Open-Loop Receiver OOPS Technical term used by RSST for errors in HB OPCH DSN Operations Chief ORT Operational Readiness Test OVT Operational Verification Test OWLT One-Way Light Time PAS Radio Science Software Planning and Analysis Subsystem PBNBIDR Playback Narrow Band Intermediate Data Records PC Personal Computer PDB Project Data Base PE Phase Encoded PIDR Parkes Intermediate Data Record PLL Phase-Lock Loop PLO Programmed Local Oscillator POCA Programmable Oscillator Control Assembly PPM Precision Power Monitor PRA Planetary Ranging Assembly RASM Remote Access Sensing Mailbox RAYPATH DSN program used to generate light-time file modeling atmospheric effects and used as an input for the generation of predictions RCP Right-handed Circularly Polarized REC Receiver-Exciter Controller RF Radio Frequency RFS Radio Frequency Subsystem (spacecraft) RIC RIV Controller RIS Radio Science IF Switch RIV Radio Science IF-VF Converter Assembly RMDCT Radio Metric Data Conditioning Team RMS Real-time Monitoring System (formally TSS) RODAN Radio Occultation Data Analysis Computer Facility ROLS Radio Occultation Limbtrack Systems ROVER Wide-band backup recording system (obsolete) RSWG Radio Science Working Group RSS Radio Science System RSSD DSP-R Signal Digitizer Assembly RSST Radio Science Support Team (Not Galileo Remote Sensing Science Teams; SSI, NIMS PPR and UVS) RSSS Radio Science Support System (alias RODAN) RST Radio Science Team (Investigators and RSST) RSVP Radio Science Validation and Processing Software RTDS Real-Time Display System RTLT Round-Trip Light-Time RTM Real-Time Monitor (supplies data to NOCC graphics/display systems) SCE Solar Corona Experiment (Ulysses) SCET SpaceCraft Event Time SCOE System Cognizant Operations Engineer SCP Station Communications Processor SCT SpaceCraft Team SDT Science Data Team SEF Sequence of Events File SEG1 Sequence of Events Generation program (generates SFOS, ISOE and DSN keyword file) SEL Station Event List SEP Sun-Earth Probe Angle SEQGEN SEQuence of events GENeration program (generates SEFs) SFDU Standard Format Data Unit SFOC Space Flight Operations Center SFOS Space Flight Operations Schedule SG SFOC Gateway SIRD Support Instrumentation Requirements Documents SIS Software Interface Specification SLE Signal Level Estimator SNR Signal-to-Noise Ratio SNT System Noise Temperature SOE Sequence of Events SOM Software Operations Manual SOP Standard Operations Procedures SPA Spectrum Processor Assembly SPC Signal Processing Center SPD S-band Polarization Diversity (microwave subsystem) SPE Static Phase Error SPR System Performance Record SPT System Performance Test SRA Sequential Ranging Assembly SRD Science Requirements Document SSA Solid State Amplifier (spacecraft S-band downlink) SSB Single Sideband SSI Spectral Signal Indicator (not Solid-State Imaging!) SSS SSI Input Channel Selection (DSP OCI) TBD To Be Determined, since we don't know the answer TBS To Be Subjected to further scrutiny TCG Time Code Generator TCM Trajectory Correction Maneuver TCT Time Code Translator TID Time Insertion and Distribution TLC Tracking Loop Capacitor TMO Time Offset (OCI) TMU Telemetry Modulation Unit TSF Track Synthesizer Frequency TSS Test Support System (now called RMS) TWM Traveling Wave Maser TWNC Two-Way Non-Coherent switch (spacecraft) TWNC Too Wishy-washy, Nebulous and Confusing TWT Traveling Wave Tube TWTA Traveling Wave Tube Amplifier (spacecraft) TWX Teletype message TXR DSS transmitter ULS Ulysses Project UNAV Ulysses Navigation Team USO Ultra-Stable Oscillator UTC Universal Time, Coordinated VAP Video Assembly Processor VCO Voltage Controlled Oscillator VEEGA Venus-Earth-Earth-Gravity-Assist VF Video Frequency VTR Video Tape Recorder XA Doppler-compensated ground-transmitter DCO frequency for spacecraft receiver's best-lock frequency XRO X-band receiver only (microwave subsystem) determination experiment ------------------------------------------------------------------------------ Appendix C The Radio Science Directory ( See RS.Directory.1.GIF thru RS.Directory.5.GIF ) ------------------------------------------------------------------------------ Project Galileo, Document 870-7, Rev. C, August 15, 1990. Deep Space Network/Flight Project Inter