Overview: Real-time notes by Dick Simpson for Magellan bistatic radar passes on 31 May 1994. Four orbits were observed at DSS 63; signals were recorded at S and/or X band. The spotlight target was Maxwell Montes. To the extent possible radio occultations, which followed the spotlight experiment immediately, were also captured on tape. Items in UPPER CASE are from the pre-experiment timeline; items in lower case are the notes made in real time. ================================================================= 10:55 BEGIN PRE-CAL USE CONFIGURATION FOR 4-CHANNEL DSP RECORDING. CARRY OUT THE SPECIAL AMBIENT LOAD CALIBRATION (STEPS 1-9 IN THE MESSAGE TO THE STATION) FOR EACH OF THE FOUR CHANNELS. 10:58 10 sec loss of data as spacecraft switched to TX A ACE and TELECON discussed SOE; ACE was confused by the number of documents for bistatic operation (two keyword files, SOE, and notes from RS personnel, none of which agree). 11:07 Telemetry being received. DSS65 receives only X and there should be no X-band modulation with TX A. TELECON confirms that TX A is operating; temperatures are going up "as we speak." May lose telemetry as operating temperature rises. 11:15 TELECON reports no AGC reading being received from DSS 65; ACE confirms. AGC readings were lost during TX swap; DSS 65 reports PPM is RED. 11:35 DSS 63 was told to skip transmitter calibrations; transmitter will not be needed for this pass. 11:39 Ambient load temperatures: 22.85 (X) and 24.85 (S); displays show S-band channels are being badly overdriven. 11:42 All channels now clipping; attenuator settings: 35, 30, 40, 40. 11:45 DSS 63 reports that all channels have been set for 1 V rms; ambient load temperatures: 23.05 (X) and 24.94 (S). Attenuator settings: 50, 48, 50, 50. 11:46 DSS 63 reports that attenuator on Channel 4 should actually be 48; it seems to be updating very slowly. 11:47 Display shows Channel 4 attenuator now changed to 48. 11:50 DSS 63 reports many NBOC errors; clearing errors requires going to DSP idle. 11:55 Cold sky measurements; DSS 63 reports attenuators: 38, 36, 38, 36 for 1 V rms. Ambient load temperatures: 23.2 (X) and 25.0 (S). RMS levels are approximately: 1.3, 1.0, 1.25, and 1.05 volts. 11:55 DSS 63 decides to reconfigure so that radio science is run from a separate LMC; this should reduce errors. 11:58 DSS 63 preparing to load one-way predicts; measurements to present have been made using two-way predicts. 12:09 DSS 63 reports telemetry in lock 12:10 DSS 63 BEGIN TRACK CONFIRM CONSCAN OFF 12:15 DSS 63 confirms CONSCAN OFF 12:15 SWITCH FROM 3-WAY TRACKING TO 1-WAY TRACKING ================================================================= First orbit may have gone well. Very few displays were available at JPL, meaning we had to rely heavily on what the crew at DSS 63 reported. They chose to reconfigure so that all radio science equipment would run from a separate LMC; that apparently reduced the NBOC error rate to zero, but made it impossible to get displays at JPL. The display problem was fixed toward the end of the orbit, but I don't know how it was fixed. Tapes during the orbit may not have contiguous samples; station personnel were told to match the tape switch times in the SOE (which had been intended only for guidance). A spurious signal was seen drifting through the SSI during the spacecraft maneuver. Its frequency didn't match the direct signal frequency, and it appeared to be much stronger than any direct signal. Later we concluded that it was only present in the S-band SSI displays and that its frequency behavior was consistent with its being from a fixed-frequency ground source. The occultation at the end of the BSR pass may have been partially captured. Reconfiguration of the DSP occurred during the occultation period; it was impossible to tell at JPL. ----------------------------------------------------------------- 12:15 BEGIN DSP RECORDING 12:15 ADD 25 DB ATTENUATION TO CHANNELS 1,3 (XR,XL) ADD 15 DB ATTENUATION TO CHANNELS 2,4 (SR,SL) 12:15:30 DSP begins recording 12:23:00 DSP TAPE SWITCH 12:23 Tape switch forced by operator 12:23 No displays at JPL since LMC reconfiguration 12:27:27 ENGINEERING TELEMETRY OFF 12:25 SSI display appears; direct signal visible at about 9500 Hz. 12:27:26 DSS 65 lost telemetry; AGC = -147 dBm on S-band 12:29:27 LOS (SPACECRAFT BEGINS TURN TO TARGET) 12:30 Signal decreasing in SSI; frequency about 11500 Hz. 12:30:26 Telemetry lost 12:31:00 DSP TAPE SWITCH 12:32:00 REMOVE 25 DB ATTENUATION FROM CHANNELS 1,3 (XR,XL) REMOVE 15 DB ATTENUATION FROM CHANNELS 2,4 (SR,SL) 12:33 DSS 63 confirms attenuators at 38 and 36 dB levels (per pre cal) and voltages running approximately 1 V rms. 12:36 Small (spurious) signal visible in SSI at about 4 kHz, moving up. 12:38 Spurious signal has moved to about 6.5 kHz and disappeared. 12:39:00 DSP TAPE SWITCH 12:41:54 ENGINEERING TELEMETRY ON (NOT OBSERVABLE ON GROUND) 12:42:00 ADD 25 DB ATTENUATION TO CHANNELS 1,3 (XR,XL) ADD 15 DB ATTENUATION TO CHANNELS 2,4 (SR,SL) 12:42:30 Spurious signal at about 13.5 kHz 12:43 Tony has gone to 264-325; he calls to report that he can see some displays. His NRV text window shows RMS levels of about 0.15, 0.23, 0.08, and 0.49 V. Sample rate = 50000, Filter = 6, and offset is correct. All things considered, the situation appears to be nominal. Voltages are low because of added attenuation at this time. 12:47:00 DSP SWITCH TAPES 12:48:38 LOS (OCCULTATION) 12:49 DSP to IDLE; DSS 63 returns to "original" configuration. 12:49:07 DSP recording 12:50:16 Displays now visible at JPL; POCA values look OK 12:55:00 DSP SWITCH TAPES 12:55 Attenuators: 63, 51, 63, 51 (dB) RMS levels: 82, 776, 148, 761 (mV) 12:55:00 FOR EACH OF 4 CHANNELS (XR,SR,XL,SL) SWITCH MASER TO AMBIENT LOAD FOR 2 MINUTES. REPORT TIME AND PHYSICAL TEMPERATURE OF EACH AMBIENT LOAD TO JPL FOR EACH CHANNEL. WHEN ALL MASERS HAVE RETURNED TO COLD SKY, REMOVE 25 DB ATTENUATION FROM CHANNELS 1,3 (XR,XL), REMOVE 15 DB ATTENUATION FROM CHANNELS 2,4 (SR,SL), AND END DSP RECORDING (NO LATER THAN 13:20). 12:56 RMS levels: 226, 739, 222, 805 (ambient load) 12:58 DSS 63 is adjusting attenuators for 1 V rms (this was not supposed to happen) Attenuators: 38, 36, 38, 36 RMS levels: 1052, 1161, 1214, 1023 13:06 Attenuators: 38, 36, 38, 36 (presumably to cold sky) RMS levels: 1016, 1143, 1217, 1021 13:08 DSS 63 reports that record times after 12:23 were as per the times in the SOE (apparently operator forced; do not expect tape samples to be contiguous across tape boundaries) 13:10:41 DSP to idle 13:11:00 DSP changed to Configuration 2 (S-band only) ================================================================= The second orbit appeared to go smoothly. Though we were told that the AUX OSC was running about 10 degrees cold, the S- band frequency looked very good without adjustment. Later (orbit 3) we set FRO=-1300 to improve centering of the signals at X-band. The spurious signal continued to drift through the SSI. Occultation data have been recording, but the DSP stopped at least twice during the occultation period. ----------------------------------------------------------------- 13:20:00 CHANGE TO DSP CONFIGURATION FOR S-BAND ONLY 13:26:44 AOS (OCCULTATION EGRESS) 13:27 AOS; telemetry in lock 13:50:00 BEGIN DSP RECORDING ADD 15 DB ATTENUATION TO BOTH CHANNELS (2,4) 13:50 DSP recording Direct signal at 11050 Hz SCT reports AUX OSC is running about 10C colder than expected; but carrier appears to be exactly as expected. 13:55 Attenuators: 38, 51, 38, 51 (only 2d and 4th are relevant) RMS levels: 321, 529, 319, 529 13:56:20 POCA equivalent S-band sky freq = 2298034718 Hz 13:57:20 Change SSI to Channel B (S-LCP) 13:59 S-band telemetry OK, but none being received on X-band; Magellan ACE claims X-band telemetry is expected (not true). 14:00:24 ENGINEERING TELEMETRY OFF 14:00:50 Engineering data OFF; signal level up a bit in SSI. 14:02:24 LOS (SPACECRAFT BEGINS TURN TO TARGET) 14:02:56 Signal begins to drop 14:03:20 Signal gone 14:04:50 Attenuators: 38, 51, 38, 51 RMS levels: 227, 494, 222, 495 14:05:00 REMOVE 15 DB ATTENUATION FROM BOTH CHANNELS (2,4) 14:05:30 Attenuators: 38, 36, 38, 36 RMS levels: 1188, 1080, 1233, 1095 14:05:30 Weak (spurious) signal visible at about 4 kHz. 14:06:00 DSP SWITCH TAPES 14:06:15 POCA equivalent S-band sky freq = 2298004011 Hz 14:07 Spurious signal at approximately 7.5 kHz. 14:09:40 Spurious signal has moved to approximately 13 kHz 14:10:10 Spurious signal remains at approximately 13 kHz 14:10:15 Spurious signal gone 14:10:50 POCA equivalent S-band sky freq = 2298089172 Hz 14:12:40 POCA equivalent S-band sky freq = 2298048846 Hz 14:13:40 Spurious signal at approximately 4 kHz 14:14:05 Spurious signal at approximately 12 kHz, moving quickly to right. 14:14:51 ENGINEERING TELEMETRY ON (NOT OBSERVABLE FROM GROUND) 14:15 Spurious signal gone 14:16:00 ADD 15 DB ATTENUATION TO BOTH CHANNELS (2,4) 14:18:20 Attenuators: 38, 51, 38, 51 RMS levels: 214, 498, 212, 496 14:20:10 Weak signal visible at about 10.5 kHz 14:20:47 AOS (SPACECRAFT RETURNS TO EARTH POINT) 14:21 DSP to idle (a couple times) (time approx) 14:21:35 LOS (OCCULTATION INGRESS) 14:22:00 DSP SWITCH TAPES 14:24:29 DSP recording Spurious signal visible at about 17 kHz 14:26 Spurious signal at approximately 15 kHz 14:28 DSS 63 will let future tapes run to completion, rather than forcing start/stop times. 14:29 Spurious signal at about 9 kHz 14:30 Spurious signal at about 6 kHz 14:30:00 FOR BOTH CHANNELS (SR,SL) SWITCH MASER TO AMBIENT LOAD FOR TWO MINUTES. REPORT TIME AND PHYSICAL TEMPERATURE OF AMBIENT LOAD TO JPL FOR EACH CHANNEL. WHEN BOTH MASERS HAVE RETURNED TO COLD SKY, REMOVE 15 DB ATTENUATION FROM BOTH CHANNELS AND END DSP RECORDING (NO LATER THAN 14:50). 14:30:30 S-band maser to ambient load Attenuators: 38, 51, 38, 51 RMS levels: 749, 790, 742, 767 Ambient load temperatures: 25.75 (X), 25.90 (S) 14:32 Cold sky measurement(?) Attenuators: 38, 36, 38, 36 RMS levels: 1153, 1041, 1159, 1083 14:34:10 POCA equivalent S-band sky freq = 2298016855 Hz 14:35:55 DSP idle ================================================================= Execution during the third orbit was essentially trouble- free. We used FRO=-1300 Hz to improve centering of the direct signal during the pre-turn observing period. Occultation data were recorded, but I requested a change in the attenuators which was implemented about in the middle of the occultation period. ----------------------------------------------------------------- 14:50:00 CHANGE TO CONFIGURATION FOR X-BAND ONLY 14:59:42 AOS (OCCULTATION EGRESS) 15:00 AOS; telemetry in lock 15:25:00 BEGIN DSP RECORDING 15:25 DSP begin recording Signal at 6850 Hz 15:26:00 ADD 25 DB ATTENUATION TO BOTH CHANNELS (1,3) 15:26:04 POCA equivalent S-band sky freq = 2298044827 Hz 15:27:44 Attenuators: 63, 36, 63, 36 RMS levels: 207, 1544, 207, 1535 15:29 FRO = +900 Hz moves signal to left (wrong way) 15:31:24 FRO = -1300 Hz centers X band signal. 15:33:04 POCA equivalent S-band sky freq = 2298019815 Hz 15:33:21 ENGINEERING TELEMETRY OFF 15:35 Attenuators: 63, 36, 63, 36 RMS levels: 203, 1498, 200, 1490 15:35:21 LOS (SPACECRAFT BEGINS TURN TO TARGET) 15:35:40 Signal drops 15:37:00 REMOVE 25 DB ATTENUATION FROM BOTH CHANNELS (1,3) 15:37:00 Attenuators changed at DSS 63 15:37:19 Attenuators: 38, 36, 38, 36 RMS levels: 999, 1130, 967, 1156 15:43:14 POCA equivalent S-band sky freq = 2298021678 Hz 15:43:29 POCA equivalent S-band sky freq = 2298087937 Hz 15:44:32 RMS levels: 937, 1213, 936, 1122 15:47:48 ENGINEERING TELEMETRY ON 15:50:00 ADD 25 DB ATTENUATION TO BOTH CHANNELS (1,3) 15:51:29 Attenuators: 63, 36, 63, 36 RMS levels: 147, 78, 148, 74 15:53:27 Direct signal at 9 kHz 15:53:44 AOS (SPACECRAFT RETURNS TO EARTH POINT) 15:54:32 LOS (OCCULTATION INGRESS) 15:55:09 Signal level dropping 15:55:15 Attenuators: 53, 36, 53, 36 RMS levels: 221, 220, 219, 207 16:00:00 Masers into ambient load. Ambient load temperatures: 26.9 (X), 26.5 (S) Attenuators: 53, 36, 53, 36 RMS levels: 558, 647, 558, 638 16:01:00 FOR BOTH CHANNELS (XR,XL) SWITCH MASER TO AMBIENT LOAD FOR TWO MINUTES. REPORT TIME AND PHYSICAL TEMPERATURE OF AMBIENT LOAD TO JPL FOR EACH CHANNEL. WHEN BOTH MASERS HAVE RETURNED TO COLD SKY, REMOVE 25 DB ATTENUATION FROM BOTH CHANNELS AND END DSP RECORDING (NO LATER THAN 16:25). 16:02:00 Masers to cold sky Attenuators: 38, 36, 38, 36 RMS levels: 1040, 1189, 1002, 1233 16:04 DSP to idle ================================================================= Execution during the fourth orbit was essentially trouble- free. The occultation was captured without interruption; very little frequency drift was observed during the occultation, however. ----------------------------------------------------------------- 16:25:00 CHANGE TO CONFIGURATION FOR S-BAND ONLY 16:32:39 AOS (OCCULTATION EGRESS) 17:00:00 BEGIN DSP RECORDING 17:00 LAN reset at JPL; displays gone 17:01:00 ADD 15 DB ATTENUATION TO BOTH CHANNELS (2,4) 17:01:18 Displays return S-band signal at 12250 Hz (FRO remains at -1300 Hz) 17:02 Attenuators: 38, 51, 38, 51 RMS levels: 311, 540, 323, 533 17:03:33 POCA equivalent S-band sky freq = 2298027152 Hz 17:06:18 ENGINEERING TELEMETRY OFF 17:06:23 S-band signal increases about 8 dB Attenuators: 38, 51, 38, 51 RMS levels: 396, 693, 591, 687 17:07:55 Spurious signal has been moving in from the left (0 Hz); it is now at about 7 kHz. 17:08:18 LOS (BEGIN SPACECRAFT TURN TO TARGET) 17:09:30 Direct signal gone Spur now at 12250 Hz (same frequency as direct signal), moving to higher frequencies. 17:10:00 REMOVE 15 DB ATTENUATION FROM BOTH CHANNELS (2,4) 17:10:33 Attenuators: 38, 36, 38, 36 RMS levels: 1319, 1050, 1340, 1125 17:12:30 Spurious signal now at 20 kHz (upper edge of SSI display) 17:12:58 POCA equivalent S-band sky freq = 2297999006 Hz 17:15:48 POCA equivalent S-band sky freq = 2297992901 Hz 17:16:08 POCA equivalent S-band sky freq = 2298011408 Hz 17:16:33 POCA equivalent S-band sky freq = 2298086818 Hz 17:19:08 POCA equivalent S-band sky freq = 2298014950 Hz 17:20:45 ENGINEERING TELEMETRY ON (NOT OBSERVABLE FROM GROUND) 17:20:43 RMS levels: 1143, 1008, 1168, 1049 17:22:00 ADD 15 DB ATTENUATION TO BOTH CHANNELS (2,4) 17:23:08 Attenuators 38, 51, 38, 51 RMS levels: 219, 497, 222, 494 17:25:13 POCA equivalent S-band sky freq = 2297984831 Hz 17:26:15 Signal reappears 17:26:41 AOS (SPACECRAFT RETURNS TO EARTH POINT) 17:27:25 Signal dips (begin occultation) 17:27:30 LOS (OCCULTATION INGRESS) 17:28:40 Signal gone from SSI 17:38:30 Attenuators: 38, 51, 38, 51 RMS levels: 232, 498, 226, 498 Spurious signal is drifting left (to lower frequencies) at approximately the POCA is drifting. 17:40:00 FOR BOTH CHANNELS (SR,SL) SWITCH MASER TO AMBIENT LOAD FOR TWO MINUTES. REPORT TIME AND PHYSICAL TEMPERATURE OF AMBIENT LOAD TO JPL FOR EACH CHANNEL. WHEN MASERS HAVE RETURNED TO COLD SKY, REMOVE 15 DB ATTENUATION FROM BOTH CHANNELS, AND END DSP RECORDING (NO LATER THAN 18:00). 17:40:00 Masers to ambient load 17:40:08 RMS levels: 737, 789, 757, 800 Ambient load temperatures: 27.45 (X), 26.96 (S) 17:42:00 Masers back to cold sky 17:42:43 Attenuators: 38, 36, 38, 36 RMS levels: 1195, 1034, 1155, 1052 17:47:43 DSP to idle. 18:00:00 END OF EXPERIMENT Compiled by Dick Simpson