MLA Ground Calibration Test Data – Rev. A Xiaoli Sun/Instrument Scientist NASA GSFC, Code 694 March 1, 2006 Introduction MLA calibration tests were embedded in the instrument Comprehensive Performance Tests (CPT), which were performed before, during, and after the instrument thermal vacuum tests at NASA GSFC between April and May, 2003. There were also several special calibration tests in addition to the CPTs. The detailed test setup and instrument configuration are described in Appendix A. There were also two special tests in addition to those described in Appendix A. They were the range offset calibration tests, and end-to-end timing calibration tests. The test data were all collected via GSEOS in the form of recorder files. They were then parsed into text data files along with the appropriate file headers and column headers. Each row represented a data set sampled at a given time in the Mission Elapsed Time (MET). There were two main groups of tests, those conducted at the instrument level at NASA GSFC, and those conducted after integration with the spacecraft. The test data files were grouped and annotated accordingly by file names and file folder names. There are also a few other file folders that contain miscellaneous data and information about the tests, such as test plans, procedures, notes, and digital photographs of the test setup. There were a total of ten CPTs, each address a special aspect of the instrument performance. The full or subset CPTs were performed fourteen times throughout the instrument thermal vacuum tests. Special tests were conducted at certain stages of the instrument environmental tests. The data structure and format are described in the following. Almost all the raw data are given in ASCII files with the extension “txt”, “dat”, or “prn”. Data files without extensions are text files as well. For some of the tests, a log of the commands sent to the instrument was also given in order to synchronize the test data with the stimuli. These files had the file extension “log”. Some of the raw data files were compressed and they have "zip” as the file extension. There were also a few instrument ‘table dump’ files containing a dump of all the instrument parameters for the tests. These files had the extension “dmp”. Some scripts for instrument setup and data interpretation were also included that had the file extension “py” and “pyc” for Python language used for during MESSENGER testing. Microsoft Excel was used for most of the CPT data processing with file extension “xls”. Matlab was used to analyze the clock oscillator data with the file extension “mat” for data, “m” for scripts, and “fig” for plots. Kaleidagraph was used to plot and analyze the data for certain tests with the file extension “QPC” for plots and “QDA” for data used in the plots. Test procedures are also included with file extension “doc”. Block diagrams of the test setup were drawn using Canvas with file extension “CNV”. LabView was used to convert time between UTC time, GPS time, and various conventions such as those used by Excel (with zero defined as 1/1/1904 00:00:00). The LabView program has the file extension “vi”. Line plots were sometimes converted from their native form to generic graphic formats like “png”, “jpg”, “gif”, “tif(f)” and “ps” for Postscript. There were also a few photographs showing the test configuration, laser spot images, and oscilloscope screens with the file extension of “jpg”, “bmp”, or “img”. Photoshop was also used occasionally to enhance the picture, with the file extension of “psd”. Some block diagrams were also converted from Canvas to “jpg”, “gif”, and etc. Summaries of the test results are given in various reports in Microsoft Powerpoint or Word with file extension “ppt” and “doc”. Sometimes the reports were converted to “pdf” format when there were issues with compatibilities between PC and Macintosh. CPT 1 through 3: These CPT’s were ranging tests. The test stimuli from the Bench Check Equipment (BCE), which simulated the Mercury surface returns, were kept at the same pulse width and energy level but the range swept between a prespecified limits. CPT 1 had the range increased over about 30 meters in fine steps to exercise the lower 8 bits of the range measurement unit (RMT). CPT 2 had the range varied over 7.7km and CPT 3 to test the middle 8 bits of the RMU. CPT 3 had the range varied over 200 km to exercise the high bits of the RMU. The receiver channels were enabled one at a time in four separate tests, Test A had Channel 1 high threshold signal path (Ch1Hi) enabled. Test B had Channel 1 low threshold path (Ch1Lo) enabled, Test C had Ch2Lo enabled, and Test D had Ch3Lo enabled. The raw data from CPT 1-3 were given as either one big file or three separate files, all of the same format. The file name convention was “Ranging_Science_Test_Ch_day_month_date_year_hour_minute_second.txt” with Ch being Hi or Lo, and the date and time string represented the test start time filled by the computer. The columns in each file were: Instrument MET; time in MET Ch: 1Hi, 1Lo, 2, or 3; Range: measured laser pulse time of flight in unit of 1e-11 second; start pulse begin: time of the rising edge of the out going laser pulse in unit of 1e-11 sec; start pulse end: time of the falling edge of the out going laser pulse in unit of 1e-11 sec; start puse width: out going laser pulse width, difference between the rise and fall edges; chx begin: rising edge time of the return pulses in unit of 1e-11 sec; chanx end: falling edge time of the return pulses in unit of 1e-11 sec; chan x width: return pulse width, difference of rise and fall edges; Rb time tag: not used (left over from earlier tests, contain no useful information); hz to rupt: time from the 1 pps tick to the subsequent RUPT in units of 1e-9 sec (RUPT represents the trigger time of the first of the 8 laser shots in the packet) plus a constant (~15 ms)); rmu temp: RMU board temperature in degree Celsius; det board temp: detector board temperature; altimeter det temp: detector case temperature; analog board temp: analog circuit board temperature. There were also monitor data from the BCE that gives the time of the MLA output laser pulse energy, the stimulus pulse energy, and time of flight, for each MLA detected return pulses. The BCE monitors were considered to be the ‘ground truth’ and served as the measurement standard. The BCE monitors were time tagged with respect to both instrument MET and UTC (the BCE generated the clock signal to the instrument and therefore synchronized with the instrument). One need to pair up the MLA data with the BCE data for each laser shot in order to compare the MLA measurements with the BCE monitors to determine the MLA performance. The BCE monitor data file names were: RANGING_BCE_TEST_day_month_date_year_hour_minute_sec.txt and the data in each column of the files were: UTC: time of the MLA laser shot in UTC BCE MET: laser shot time in BCE version of the MET, it was at the same rate as the instrument MET but might contain several second offset Rub Timetag: time difference between the 1pps tick from the Rb clock source and the 1pps input to the instrument (This should be zero when the instrument used the same Rb clock source. When MLA used the GPS based clock, this time tag gave a measure of the clock frequency offset between the instrument clock and the Rb clock used by BCE.) Eventlog: time stamps of the laser shot from the GPS receiver Program Delay: time delay programmed into the delay generator in BCE BCE TIU: time of flight from the transmitted laser to the returned laser pulse RP Energy: return pulse energy (need to use the BCE calibration data to convert them to the actual pulse energy onto the MLA detector. There were also laser monitoring files from the instrument and BCE. It recorded the MLA transmitted laser pulse energy as one of the vital sign of the instrument. There were two files, one from the instrument and one from the BCE monitor. The file names for the instrument output were: laser_monitor_hwlite__day_month_date_year_hour_minute_sec.txt With the following instrument data in each column: instrument met: MET of the instrument instrument subsec: originally intended to be the MET subseconds for each laser shot, no longer valid laser diode cur: current to the pump laser diode array, 8 bit integer tx pulse energy: laser pulse energy monitored by the instrument, 8 bit integer laser pulse width: laser pump duration in microseconds tx start: time of rising edge of the out going laser pulse recorded by RMU tx stop: time of the falling edge of the out going laser pulses recorded by RMU txwidth: : output laser pulse width in unit of 1e-11 sec The file name for the BCE laser monitor output was laser_monitor_BCE_day_month_date_year_hour_minute_sec.txt, and data in each column was: UTC: time of the laser shot in UTC BCE MET: time of the laser shot in BCE MET (synchronized with instrument MET but might contain a few second offset Start Pulse Energy: MLA output laser pulse energy as monitored by a laser pulse energy meter, see the BCE calibration file for conversion factor. There was also a companion instrument house keeping data file: laser_monitor_status__day_month_date_year_hour_minute_sec.txt, which recorded the power supply voltages, currents, and all the temperature sensors in the telemetry, with names of the sensors uniquely labeled in the column headers. CPT 4 This CPT was to test the MLA range gate function. Similar to the ranging tests, the delay of the return pulses from the BCE first increase from the mid of the range gate to beyond the range gate and then decreased to below the range gate for a total of four different range gate settings. The return pulses that were outside of the range gate boundaries should not be registered by the instrument. The file name for test data was CPT_4_Rangegate_day_month_date_year_hour_minute_sec.txt, and the data in each column was: GPS Time(UTC): GPS time of the laser shot BCE TIC 1-8: (not used) BCE MET: same as in ranging test INSTR MET: same as in ranging test Hz To Rupt: same as in ranging test Tx Pulse Begin: transmitted laser pulse rising edge time as recorded by RMU Tx Pulse End: same as above but for pulse fall edge time Range Window: center of the range window in km Valid Bit 1-8: valid measurement indicator, for Ch.1Hi, “0” indicates a valid measurement and “1” indicates an invalid measurement ChRx Pulse Begin: rising edge time of the return pulse measured by RMT ChRx Pulse End: same as above but for pulse falling edge time ChRx PW (ns) : return pulse width in unit of 1e-11 sec Threshold readback 1_4,5_8: readback value of the threshold applied Cmded Threshold: commanded threshold value*100 RMU Temp: RMU temperature in deg C CPU Temp: CPU board temperature in deg C Ch1Hi Noise Ct 1_4,5_8: Ch.1Hi false alarm count over 0.5 sec BCE Pwr (uW): CW background light monitored by BCE (need to use the conversion factor given in the BCE calibration file to obtain the actual power on the detector BCE NRG (pj): return pulse energy monitored by BCE. CPT 5 This test verify the receiver dynamic range. The return signal from BCE was held at a fixed delay and four signal levels, seven background light levels, and three detector gain settings. The receiver detection threshold level was adjusted autonomously and should follow the background level. The receiver should first miss the signal and gradually acquire it. The file names were: CPT_5x_Science_day_month_date_year_hour_minute_sec.txt, with x= A, B, C, or D, denoting the channel being tested and A->Ch.1Hi, B->Ch.1Lo, C->Ch.2Lo, and D->Ch.3Lo. The data in each column was: bce met: laser shot time in BCE MET utc: laser shot time in UTC as time stamped by the GPS receiver in BCE rub timetag (ns): time difference of the GPS 1pps tick to the Rb clock 1pps tick cw_power (uW): cw background light as monitored by BCE rp energy (pj): return pulse energy as monitored by BCE intstrument met (s): laser shot time in instrument MET avg 1pps to rupt offest (ns): time from the 1 pps tick to the RMU RUPT signal vga gain D/A: detector gain in counts/10 vga count D/A: detector gain setting in counts vga count A/D: detector gain read back in counts vga gain A/D: detector gain read back in actual gain value tx begin (10ps): transmitted laser pulse rising edge time in unit of 1e-11 sec tx width (10ps): transmitted laser pulse width in unit of 1e-11 sec ch1h (v\i): Ch.1Hi valid bit, “1” invalid detection, “0” valid detection ch1h rx begin (10ps): return signal pulse rising edge time ch1h rx width (10ps): return pulse width in unit of 1e-11 sec chx (v\i): Ch.1x valid bit, with x the channel under testing, and x-> Ch.1Lo, Ch2, Ch3 chx id: identification number for the channel under testing chx rx begin: return pulse rising edge time in unit of 1e-11 sec chx rx width (10ps): return pulse width in unit of 1e-11 sec ch1h noise shot 1-4 cnt: total Ch.1Hi noise threshold crossings during laser shots 1 to 4 ch1h noise shot 5-8 cnt: total Ch.1Hi noise threshold crossings during laser shots 5-8 ch1h thresh 1 cnt: Ch.1Hi threshold setting in counts during laser shots 1 to 4 ch1h thresh 1 (mv): Ch.1Hi threshold setting in mV during laser shots 1 to 4 ch1h thresh 5 cnt: Ch.1Hi threshold setting during laser shots 5 to 8 ch1h thresh 5 (mv): Ch.1Hi threshold setting during laser shots 5 to 8 ch1l noise shot 1-4 cnt: Ch.1Lo total noise counts during laser shots 1 to 4 ch1l noise shot 5-8 cnt: Ch.1Lo total noise counts during laser shots 5 to 8 ch1l thresh 1 cnt : Ch.1Lo threshold setting in count during laser shots 1 to 4 ch1l thresh 1 (mv): Ch.1Lo threshold setting in mV during laser shots 1 to 4 ch1l thresh 5 cnt : Ch.1Lo threshold setting in count during laser shot 5 to 8 ch1l thresh 5 (mv): Ch.1Lo threshold setting in mV during laser shot 5 to 8 rmu temp: RMU circuit board temperature in deg C det board temp: detector board temperature in deg C altimeter det temp: detector case temperature in deg C analog board temp: analog circuit board temperature in deg C CPT 6 This tests determines the receiver sensitivity at a fixed threshold. The return signal from BCE was held at the same delay but the signal level was raised from below the detection threshold to well above the threshold. The file names were: CPT7x_Sci_day_month_date_year_hour_minute_sec.txt, with x= A, B, C, or D, denoting the channel being tested and A->Ch.1Hi, B->Ch.1Lo, C->Ch.2Lo, and D->Ch.3Lo. The data in each column was: BCE MET(sec): laser shot time in BCE MET Instrument MET(sec): laser shot time in instrument MET 1PPS to RUPT Offset(ns): time from the 1pps tick to the RMU RUPT signal Ch1Hi-Thresh Shot 1 (readback AD): Ch.1Hi threshold read back for Shots 1 to 4 Ch1Hi-Thresh Shot 5 (readback AD): Ch.1Hi threshold read back for Shots 5 to 8 Ch1Lo-Thresh Shot 1 (readback AD): Ch.1Lo threshold read back for Shots 1 to 4 Ch1Lo-Thresh Shot 5 (readback AD): Ch.1Lo threshold read back for Shots 5 to 8 Ch2 Thresh Shot 1 (readback AD): Ch.2Lo threshold read back for Shots 1 to 4 Ch2 Thresh Shot 5 (readback AD): Ch.2Lo threshold read back for Shots 5 to 8 Ch3 Thresh Shot 1 (readback AD): Ch.3Lo threshold read back for Shots 1 to 4 Ch3 Thresh Shot 5 (readback AD): Ch.3Lo threshold read back for Shots 5 to 8 Gain(AGC*10): detector gain setting *10 Dac Commanded VGA Setting(AGC*10): detector gain setting, commanded A/D Readback VGA Setting: read back of the detector gain Computed VGA Gain: calculated detector gain per read back RP Atten: attenuator setting for the BCE return signal in dB BCE Eng (fJ): return pulse energy monitored by BCE CW Power(uW): cw background light monitored by BCE Noise Count Ch1Hi (dec): noise counts of Ch.1Hi Noise Counts Chi1Lo (dec): noise counts of Ch.1Lo Altimeter Det Temp (deg C): detector board temperature in deg C RMU Temp (deg C): RMU circuit board temperature in deg C Det Temp (deg C) : detector case temperature in deg C Analog Temp (deg C): analog board temperature in deg C CPU Temp (deg C): CPU board temperature in deg C Laser Start Pulse Begin(ps): transmitted laser pulse time at the pulse rising edge Laser Start Pulse End(ps): transmitted laser pulse time at the pulse trailing dege Laser Start Pulse Width(ps): transmitted laser pulse width Ch1Hi Valid (1=valid): Ch.1Hi valid bit Ch1Hi Pulse Begin(ps): Ch.1Hi received pulse time in unit of 1e-11 sec Ch1Hi Pulse End(ps): Ch.1Hi received pulse time in unit of 1e-11 sec Ch1Hi Pulse Width(ps): Ch.1Hi received pulse width in unit of 1e-11 sec Ch 2 Valid(0=valid): Ch.2Lo valid bit Ch2 Pulse Begin(ps): Ch.2Lo received pulse time at the pulse rising edge Ch2 Pulse End(ps): Ch2.Lo received pulse time at the pulse trailing edge Ch2 Pulse Width(ps): Ch.2Lo received pulse width Tx Pulse Energy: transmitted laser pulse energy in raw counts Range Gate Start (km): beginning of the range gate in km Range Gate Stop(km): end of the range gate in km ChID LE: identification number of the triggered channel for pulse rising edge ChID TE: identification number of the triggered channel for the pulse trailing edge CPT7 These were the so-called noise vs. threshold test where the noise counter outputs were monitored while the detection threshold at each channel was raised. The file names of the test data was: CPT_7x_NvsThresh_ day_month_date_year_hour_minute_sec.txt, with x=a, b, or c. CPT_7a was a full range noise vs. threshold test with various combinations of the detector gain and cw background light level. CPT_7b was the same as CPT_7a but with finer threshold steps. CPT_7c was a subset of CPT_7b with zero cw background light on the detector. The data in each column in the files were: BCE MET: laser pulse time in BCE MET INSTR MET: laser pulse time in instrument MET Hertz To Rupt: time from 1pps tick to the subsequent RMU RUPT signal Instr Mode: instrument mode, stand-by or science VGA Setting: detector gain setting, commanded VGA Tlm: detector gain setting, read back Attenuation level (dB) : BCE attenuator setting for the cw background light CW Pwr (?W): cw background light monitored by BCE Cmded Threshold: threshold setting, commanded, in counts Commanded Threshold Ch1Hi (mV) : Ch.1Hi threshold setting, commanded, in mV Readback Threshold Ch1Hi (mV): Ch.1Hi threshold, read back in mV Noise Ct Ch1Hi (Sum): noise counts from Ch.1Hi, sum of 8 shots duration Commanded Threshold Ch1Lo (mV) : threshold setting for Ch.1Lo, commanded, in mV Readback Threshold Ch1Lo (mV): threshold at Ch.1Lo, read back, in mV Noise Ct Ch1Lo (Sum): noise counts from Ch.1Lo, sum of 8 shots duration Commanded Threshold Ch2 (mV): threshold setting for Ch.2Lo, commanded, in mV Readback Threshold Ch2 (mV): threshold at Ch.2Lo, read back, in mV Noise Ct Ch2 (Sum): noise counts from Ch.2Lo, sum of 8 shots duration Commanded Threshold Ch3 (mV): threshold setting for Ch.3Lo, commanded, in mV Readback Threshold Ch3 (mV): threshold at Ch.2Lo, read back, in mV Noise Ct Ch3 (Sum): noise counts from Ch.3Lo, sum of 8 shots duration Alt Det Temp: detector case temperature in deg C RMU Temp: RMU circuit board temperature in deg C Det Bd Temp: detector board temperature in deg C Analog Temp: analog board temperature in deg C CPU Temp: CPU board temperature in deg C Laser Temp: Laser temperature in deg C Avg Start Det E: (not useful data) CPT8 This is an orbit simulation test with MLA obtained the predicted range from the spacecraft and centering the range gate at the predicted ones, while the BCE adjusted the delay to synchronize with the predicted range and varying the signal and cw background light to simulate the conditions in orbit around Mercury. This test was not conducted until the spacecraft level integration and test due to delays in the flight software development. There was no test data from the instrument environmental tests at NASA GSFC. The tests were successful during the spacecraft level tests. The complete set of test data were given in binary format due to the volume of the data. The binary data file and a detailed analysis using special decoding software are also contained in the same file folder. A subset of the data was recorded with the file names: cpt8_instrument_ day_month_date_year_hour_minute_sec.txt and cpt8_bce_ day_month_date_year_hour_minute_sec.txt. The data in each column were: Instrument data: Instrument met: laser shot time in MET avg 1pps to rupt offset: time from the 1pps tick to the subsequent RMU RUPT signal vga setting: detector gain setting range gate start (km): start of the range gate in km range gate stop (km): end of the range gate in km range gate start (ns): start of the range gate in ns range gate stop (ns): end of the range gate in ns scraftrange (km): predicted range from the spacecraft in km scraftrange (ns): predicted range from the spacecraft in ns start pulse begin: pulse rising edge time of the transmitted laser pulses start pulse width: pulse width of the transmitted laser pulses ch rx pulse (v/i): valid bit for the received pulse ch rx pulse begin: pulse rising edge time of the received pulse, Ch.1Hi ch rx pulse width: pulse width of the received pulse, Ch.1Hi lo pulse x (v/i): valid bit of the first threshold crossing detection, for x = 0,1,…7 lo pulse ch id x: channel identification number of the xth threshold crossing lo pulse begin x: pulse rising edge time of the xth threshold crossing ch1 high noise shot 1-4 cnt: Ch.1Hi noise counts over the 0.5 seconds from Shots 1 to 4 ch1 high noise shot 5-8 cnt: Ch.1Hi noise counts over the 0.5 seconds from Shots 5 to 8 ch1 high thresh 1 cnt: Ch.1Hi threshold setting in count for Shots 1 to 4 ch1 high thresh 1 (mv): Ch.1Hi threshold setting in mV for Shots 1 to 4 ch1 high thresh 5 cnt: Ch.1Hi threshold setting in count for Shots 5 to 8 ch1 high thresh 5 (mv): Ch.1Hi threshold setting in mV for Shots 5 to 8 ch1 low noise shot 1-4 cnt: Ch.1Lo noise counts over the 0.5 seconds from Shots 1 to 4 ch1 low noise shot 5-8 cnt: Ch.1Lo noise counts over the 0.5 seconds from Shots 5 to 8 ch1 low thresh 1 cnt: Ch.1Lo threshold setting in counts for Shots 1 to 4 ch1 low thresh 1 (mv): Ch.1Lo threshold setting in mV for Shots 1 to 4 ch1 low thresh 5 cnt: Ch.1Lo threshold setting in counts for Shots 5 to 8 ch1 low thresh 5 (mv): Ch.1Lo threshold setting in mV for Shots 5 to 8 ch2 noise shot 1-4 cnt: Ch.2Lo noise counts over the 0.5 seconds from Shots 1 to 4 ch2 noise shot 5-8 cnt: Ch.2Lo noise counts over the 0.5 seconds from Shots 5 to 8 ch2 thresh 1 cnt: Ch.2Lo threshold setting in counts for Shots 1 to 4 ch2 thresh 1 (mv): Ch.2Lo threshold setting in mV for Shots 1 to 4 ch2 thresh 5 cnt: Ch.2Lo threshold setting in count for Shots 5 to 8 ch2 thresh 5 (mv): Ch.2Lo threshold setting in mV for Shots 5 to 8 ch3 noise shot 1-4 cnt: Ch.3Lo noise counts over the 0.5 seconds from Shots 1 to 4 ch3 noise shot 5-8 cnt: Ch.3Lo noise counts over the 0.5 seconds from Shots 5 to 8 ch3 thresh 1 cnt: Ch.3Lo threshold setting in counts for Shots 1 to 4 ch3 thresh 1 (mv): Ch.3Lo threshold setting in mV for Shots 1 to 4 ch3 thresh 5 cnt: Ch.3Lo threshold setting in counts for Shots 5 to 8 ch3 thresh 5 (mv): Ch.3Lo threshold setting in mV for Shots 5 to 8 RMU temp: RMU board temperature in deg C Det temp: detector board temperature in deg C CPU temp: CPU board temperature in deg C analog temp: analog board temperature in deg C. BCE data: bce met: time of the laser shot in BCE MET utc: time of the laser shot in UTC rub timetag: time from the GPS 1pps tick to the Rb clock source 1 pps tick event_time: (no useful data) delay: BCE delay generator setting (from transmitted to the received pulses) time interval: time of flight monitored by BCE cw power: cw background power monitored by BCE rp energy: return pulse energy monitored by BCE ext det: (not defined) rp atten: attenuator setting for the return pulse cw atten: attenuator setting for the cw background light from BCE. CPT9 This test was designed to verify the receiver response to different return pulse widths. A laser diode was used to generate variable width pulses. The range and signal amplitude were all fixed. As the return pulse width increased, the instrument first had the Ch.1Lo triggered and Ch.2Lo and Ch.3Lo being locked out, then Ch.2Lo triggered and Ch.1Lo and Ch.3Lo locked out, and finally Ch.3Lo triggered and Ch.1Lo and Ch.2Lo locked out. This test was performed occasionally during the environmental tests. The file name of the test data was; CPT_9_Science_ day_month_date_year_hour_minute_sec.txt, and data in each column were bce met: laser shot time in BCE MET utc: laser shot time in UTC per GPS receiver rub timetag: time from the GPS 1pps tick to the Rb clock source 1 pps A delay: BCE pulse generator setting, Ch.A delay B delay: BCE pulse generator setting, Ch.B delay C delay: BCE pulse generator setting, Ch.C delay D delay: BCE pulse generator setting, Ch.D delay (the return pulse width into MLA was Ch.B delay – Ch.A delay) RP atten (db): return pulse attenuator setting in dB … (the rest was identical to those from CPT8) CPT10 This test was the software maintenance test. It verified and validated the ability to patch, dump, checksum memory, perform parameter table modifications, program diagnostics, code and algorithm, execute self-test & diagnostic modes, etc. No test data were generated. Risley FOV Sweep Tests: These tests were used to verify the receiver bore sight by retro-reflecting a small portion of the transmitted laser beam and then varying the beam incident angle slightly with the use of a set of motorized Risley prisms. The receiver monitored the received laser pulse energy by fixing the threshold level and measuring the duration, or pulse width, of the pulse waveform above the threshold. Although it was not a linear response between the pulse width and pulse energy, the test results could be used to assess the center of the receiver field of view (FOV) with respect to the transmitted laser-beam pointing angle. The file name of the test data was: Risley_FOVX_ day_month_date_year_hour_minute_sec.txt and Risley_FOVY_ day_month_date_year_hour_minute_sec.txt, for the X and Y axes, respectively. The column data were: current step: position of the step motor for the Risley prisms in X or Y axis met: time of the laser shot start valid id: (no useful information) start pulse begin: time of the pulse rising edge time of the transmitted laser pulse start pulse width: pulse width of the transmitted laser pulse ch1h valid id: (no useful information) ch1h begin: time of the received laser pulse rising edge ch1h width: pulse width of the received laser pulse chlo: (contains no useful information) chlo id: identification number of the triggered channel chlo begin: time of the pulse rising edge of the received pulse chlo width: pulse width of the received pulse. The same data were also used to obtain MLA range measurement bias vs. environment factors, that is, the measured range to a fixed target under different temperature in thermal vacuum testing. The average range measurement when the laser was at the center of the receiver field of view were plotted using Kaleidagraph and the mean and standard deviation were also calculated. These data files have an extension of “.QPC” and “QDA” for Kaleidagraph. Laser Pointing Jitter Tests These tests measured the real time laser pointing jitter with respect to the instrument coordinate system. It was measured by imaging the laser beam and an instrument fiducial reference with a CCD camera. A summary of the test data and some sample images are given in a file folder. The original image files were too large. MLA Thermal Balance Tests The noise vs. threshold tests, CPT7c and CPT7d, were performed repeatedly during the instrument thermal balance tests. The file name and formats were the same as those described above. Zero Range Bias Test: There are two sets of tests used to verify the offset in the instrument range measurement (range measured with a target held at zero distance from the instrument reference plane). The first set of tests were the same as the Risley FOV sweep test, where the retro-reflector served as the target at a given distance from the instrument reference plane. These tests only gave a relative range offset and changes over temperature. The same Risley FOV sweep test data were used for this purpose. The second set of tests had to be conducted to measure the absolute range offset at room temperature. The tests were conducted at the end of the thermal vacuum test. The transmitted laser pulse was launched into an optical fiber and delayed by a series of optical fiber spools before feeding back to the instrument. The system delay through the optical fibers and the test fixture were calibrated independently using a short laser pulse source of the same wavelength, a high speed photodiode, and a high speed oscilloscope. CPT6 was performed during the test and the test data file name and format are identical to those in CPT6. CPT’s after Integrating with MESSENGER Spacecraft Orbit Simulation – CPT 8 The main tests performed during the spacecraft integration and test period were the orbit simulation tests, or CPT8. There were two sets of orbits used in the tests, the off nadir pointing orbit and the ‘the day in the life at Mercury.’ The former was also called phasing test in which the spacecraft performed an off nadir pointing maneuver that MLA was expected to become out of range after the maneuver started. The second orbit sets were typical MESSENGER noon-midnight orbits. The test data file name and format are already described above. End-to-End Timing Tests These tests verify and calibrate the offset in the epoch times of the laser pulse emissions. CPT1 to CPT3 were conducted during these tests. The spacecraft team provided the formula to convert MET to UTC based on all the system delays through the spacecraft time keeping subsystem. MLA BCE provided the time stamp of each laser pulse in UTC via the GPS receiver. The time stamps from the instrument and the BCE were paired up by aligning the laser emission time jitter patterns. The timing offset is calculated as the difference in the time stamps for the same laser shot. MESSENGER Clock Oscillator Tests Characterization test of the MESSENGER Flight Spare Precision OCXO A flight spare of the precision oven-controlled-crystal-oscillator (OCXO) was tested under thermal vacuum for about three weeks at GSFC. The test data file names were: MlaOcxoTvacxxx.txt, with xxx an abbreviated notation. The data in each file column were (column not labeled in this case): date time Sample sequence number supply voltage in volts supply current in amperes case temperature in deg C case temperature standard deviation clock frequency in Hz, with 1 second gate time and averaged over about 45 seconds clock frequency standard deviation in Hz A summary of the test results was also given in ‘MessengerOcxoTvacTestResults.pdf.’ MESSENGER Clock Frequency Monitoring during Spacecraft Thermal Vacuum Test at GSFC The MESSENGER clock frequency from the two redundant integrated electronics module, IEM-A and IEM-B, were monitored at the test ports through out the spacecraft thermal vacuum tests at GSFC. The clock source could either be the coarse clock oscillator or the precision clock oscillator (i.e., OCXO). Bother IEM-A and IEM-B output clock signals at all time. It was the spacecraft software that chose which clock oscillator to use and which IEM to use. The file name of the test data was MessengerClkFreqTvacChxy.txt, with x the channel number, 1 for IEM-A and 2 for IEM-B, and y an index of the test. These were the absolute clock frequency referenced to the Ce clock source maintained by GSFC. The data in each column were: Data: date per PC clock Time: time of the day per PC clock Sequence number: 1, 2, … Clock frequency divided by 256, averaged over about 1 minute Standard deviation of the clock frequency divided by 256 There were also companion clock oscillator temperature data from the spacecraft. The file name was OCXO_ day_month_date_year_hour_minute_sec.txt, and data in each column were MET: spacecraft MET DOY: day of year of 2004 GMT: time of day IEM: IEM in use by the spacecraft VOLTS: supply voltage to the OCXO’s IEMA OCXO TEMP: IEM-A OCXO case temperature in deg C IEMA OCXO TEMP: IEM-B OCXO case temperature in deg C. MLA ground test data description 1