PDS_VERSION = PDS3 RECORD_TYPE = STREAM OBJECT = TEXT PUBLICATION_DATE = 1997-01-18 NOTE = "MGS RST Instrument Health Report HEA7018A.TXT" END_OBJECT = TEXT END Engineering Data ================ Engineering Data Statistical Summary from CSV2STAT: First SCET: 1997-01-17T00:00:00.410 Last SCET: 1997-01-17T23:59:59.907 CHANNL DN-LO DN-MD DN-HI EU-LO EU-MEDIAN EU-HIGH EU AVG/STDEV RECDS ------ ----- ----- ----- --------- --------- --------- --------- -------- ----- L-0200 203 204 205 4.06E+00 4.08E+00 4.10E+00 4.08E+00/1.10E-04 2833 L-0201 126 128 129 2.52E+00 2.56E+00 2.58E+00 2.56E+00/1.03E-04 2833 T-0315 151 153 156 1.71E+01 1.80E+01 1.86E+01 1.79E+01/1.10E-02 871 L-0200 (USO regulator voltage) and L-0201 (USO oven voltage) have been constant for the past 24 hrs; median T-0315 (USO temperature) has dropped another 0.3C. MOT/TWTA/Antenna swaps continued again during the 22:00 to 23:40 time period; channels indicating that activity have been omitted from this report. Open Loop Data ============== Data Collection --------------- No new data Frequency Analyses ------------------ Joe Twicken has completed his analysis of the open-loop data from USO Test #4. His results are summarized here. The ODS was acquired at DSS 15 from 06:15:00 to 08:30:00 at 5000 samples per second (1250 samples/second for each of 4 A/D's). The SPK file spk_c_961111-970321 was used to remove deterministic geometrical effects; the SPK file was created on 97/008. The ODS file contained 40501 1666-byte records. There were no missing or duplicate records. The POCA file was fixed with our "salvagePoca" program; no hand modification of the POCA file was required. An amplitude modulation with a period of about 7 minutes (4+ cycles in 30 minutes) is clearly evident in all the carrier amplitude estimates. The source of the amplitude modulation is not known; there is no comparable signature in the frequency domain, meaning that spacecraft motion (as in limit cycling proposed in HEA7016A.TXT) is an unlikely explanation. Unexpected ground station use of CONSCAN during the test is under investigation. The spacecraft spin is clearly evident in the carrier frequency estimates. Joe did not compensate for the spin when estimating Allan deviation. There also appear to be two sets of frequency spurs related to the carrier. In geometrically corrected data, these sets of spurs appear at 30 and 50 Hz from the carrier. Joe estimated the USO frequency to be 8423152915.99 Hz. The best linear fit to the USO frequency since 96/323 has a slope of 0.24 Hz/day. The Allan deviation for these data is shown below. The SNR during the acquisition of data was approximately 54 dB/Hz. t (sec) AD ------ ---------- 1.6384 2.6285e-13 3.2768 2.1063e-13 6.5536 1.5100e-13 26.2144 1.3857e-13 Using Joe's most highly integrated frequency estimates, I find a linear trend of -8.3e-6 Hz/sec during the two hour test. As noted in an earlier report, this appears to be a residual from an unknown source in our software. After removing the linear trend, an oscillation with a period of approximately 100 minutes remains. The oscillation is not sinusoidal, but is close enough for a simple analysis. Its 0.01 Hz magnitude at 8.4 GHz translates into a maximum velocity along the ray path of +/-0.36 mm/sec; integrated over 100 min, this corresponds to a displacement of the HGA phase center along the raypath of about +/-34 cm during the course of one rotation. The maximum velocity derived here appears to be about 40 times larger than the velocity inferred from 10-minute two-way tracking data by Bill Sjogren, so other causes for the 0.01 Hz residual need to be considered. For example, peak USO temperature (engineering channel T-0315) leads peak positive frequency residual by about 15 minutes. Influences from the reaction wheels also need to be considered. Closed Loop Data ================ No new data. Bill Sjogren has correlated high Doppler noise exactly with times during which the Goldstone planetary radar was transmitting. Steve Ostro was using 8.51 GHz with approximately 3 minute transmit-receive cycles on 1997/016.