PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM OBJECT = TEXT PUBLICATION_DATE = 1999-09-07 NOTE = " E-mail and other messages concerning MGS Radio Science on or about 1997/051." END_OBJECT = TEXT END From rsimpson Fri Feb 21 13:48:45 1997 Date: Fri, 21 Feb 97 13:48:44 -0800 From: rsimpson (Richard Simpson) To: joe@nova Subject: GWE Data Cc: rsimpson Status: R POCA time tags are really a mess. There are at least 24 instances in the short segment I have from PREPMO where time tags are out of order and the program thinks there's been a day change (and adds 86400 to the time tag value). Since there is a real day change during this file, it's not going to be sufficient simply to do a modulo 86400 operation on the time tags. Guess this is one of the reasons you've been so discouraged by the POCA problems. Still no hint as to why PREPMO itself went bonkers. --------------------------------------------------------------------- From trish@qmail.jpl.nasa.gov Thu Feb 20 20:56:21 1997 Message-Id: Date: 20 Feb 1997 20:53:10 -0800 From: "Trish Priest" Subject: Re: Gimbal Users Guide To: "Richard Simpson" X-Mailer: Mail*Link SMTP-QM 3.0.2 Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; Name="Message Body" Content-Transfer-Encoding: quoted-printable Status: RO Reply to: RE>Gimbal Users Guide Hello, Dick, John Armstrong and I just finished a rehearsal for the GWE. We gathered six and a half hours of 2-way data. (051-20:33 to 052-03:00). -Trish ----------------------------------------------------------------------- From john@snug.jpl.nasa.gov Fri Feb 21 18:43:11 1997 Received: (from john@localhost) by snug.jpl.nasa.gov (8.6.10/8.6.6) id SAA07918; Fri, 21 Feb 1997 18:42:45 -0800 Date: Fri, 21 Feb 1997 18:42:45 -0800 From: John Armstrong Message-Id: <199702220242.SAA07918@snug.jpl.nasa.gov> To: rsimpson@magellan.Stanford.EDU Subject: Re: MGS RST Rpt HEA7052B.TXT Cc: joe@nova.stanford.edu Status: RO Dear Dick and Joe, I agree that the doy51-52 gwe test data (poca) are riddled with inconsistencies. I ran my quick-look s/w on the file and was able to get to the point where I have PLL frequencies from the data and a poca file (which has lots of errors). Joe kindly sent me the latest version of salvagePoca. I am learning how to use it (and may not be using it quite right, yet), but it *seemed* to make more progress than your report indicated. (I had to hand edit the input poca file at a point where Joe's program indicated a hopeless inconsistency, then run salvagePoca again. But the second time, salvagePoca produced an output file w/o error messages). I was in the process of seeing if the salvaged poca file will work for reconstructing the sky frequencies, when I inadvertently blew away all my intermediate files. (Perils of hand-editing and not doing everything from scripts--there is a moral here). So I am starting over, and should have more comments tomorrow. One other thing: there are funny amplitude variations in three (major) bursts between about 23:15 and 00:10 (times from a low-resolution graph...not precise). The 10-sec average data show ~4-5 dB downward-going glitches. This might be associated with the time-tag/poca problem; alternatively, it might be "real" (i.e, in the data). I'll fax you plots when I have my act better pulled together. Best, John ------------------------------------------------------------------------ From joe Fri Feb 21 18:57:30 1997 Received: from neptune.stanford.edu. (neptune.Stanford.EDU [36.10.0.149]) by nova.stanford.edu (8.8.5/8.8.4) with SMTP id SAA07424; Fri, 21 Feb 1997 18:57:28 -0800 (PST) Date: Fri, 21 Feb 1997 18:57:28 -0800 (PST) From: Joe Twicken Message-Id: <199702220257.SAA07424@nova.stanford.edu> To: john@snug.jpl.nasa.gov Subject: Re: MGS RST Rpt HEA7052B.TXT Cc: rsimpson@nova.stanford.edu Status: RO Hi there John- You seem to be working late! The problems we had were not with the *salvagePoca* program that fixes the POCA files, but with the *prepmo* program that creates them in the first place. I modified that one to better deal with POCA entries out of order and was able to create a meaningful POCA file. Didn't try to salvage it though. I usually check my e-mail from home over the week-ends so let me know how things go for you... Joe ---------------------------------------------------------------------- From rsimpson Sun Feb 23 21:53:56 1997 Date: Sun, 23 Feb 97 21:53:48 -0800 From: rsimpson (Richard Simpson) To: john@snug.jpl.nasa.gov, rsimpson@magellan.Stanford.EDU Subject: Re: MGS RST Rpt HEA7052B.TXT Cc: joe@nova.stanford.edu Status: RO Our quick look processing is designed for 5-minute occultations with minimal POCA problems. Trying to make it work on 6.5 hours of GWE data is stretching what it was intended to do. Also, we aren't well- positioned to analyze 2-way data. But, if there appear to be more things we might check in conjunction with your own work, let us know. I barely fit this in before running off Friday evening. Will plan to look for the modulation you mentioned tomorrow. --------------------------------------------------------------------- From john@snug.jpl.nasa.gov Wed Mar 5 10:16:35 1997 Received: (from john@localhost) by snug.jpl.nasa.gov (8.6.10/8.6.6) id KAA20740 for rsimpson@magellan.stanford.edu; Wed, 5 Mar 1997 10:15:01 -0800 Date: Wed, 5 Mar 1997 10:15:01 -0800 From: John Armstrong Message-Id: <199703051815.KAA20740@snug.jpl.nasa.gov> To: rsimpson@magellan.stanford.edu Subject: 209-sec dss65 glitches Status: RO Dick- > John Armstrong has provided plots from the GWE Rehearsal (97/051-2) >showing short bursts of anomalous open-loop Doppler residual approximately >every 209 seconds. Amplitude of the pulses is about 0.03 Hz and each lasts >about 0.7 seconds. The time constant (1/loop bandwidth) of the phase detector I used was a substantial fraction of a second. So the pulses could be larger and shorter, and my analysis would not show it. In the MO era, this problem was DSS65-specific. Best, John ------------------------------------------------------------------------ From john@snug.jpl.nasa.gov Tue Mar 11 17:13:14 1997 Received: (from john@localhost) by snug.jpl.nasa.gov (8.6.10/8.6.6) id RAA02084; Tue, 11 Mar 1997 17:13:03 -0800 Date: Tue, 11 Mar 1997 17:13:03 -0800 From: John Armstrong Message-Id: <199703120113.RAA02084@snug.jpl.nasa.gov> To: rsimpson@magellan.Stanford.EDU Subject: Re: 209-sec pulses Cc: trish@qmail.jpl.nasa.gov Status: R Dick- >Question 7 was more along the lines of "where are the sticksion events?" >They were easy to see on MO, and have been predicted from the beginning >on MGS. Are they invisible while the HGA is close to the spacecraft >bus? We haven't seen anything like a sticksion event yet. I have not gotten to resids on the GWE rehearsal #1 that are clean enough to look for low-level sticksion yet. By calculation, they should be small: The body rate data on the first GWE test show that the z-axis rate (the one most relevant to MGS--the coord. system changed from MO, where the x-axis was the important one) having 2 events/100 min spin period with peak amplitude 5E-5. I think the units are "rad/sec". So if the phase center of the antenna is ~1 meter off the CM, delta_v ~ 5E-5 m/sec -> delta_f ~ 1 mHz. This is more than an order of magnitude smaller than a (typical) MO sticksion event. Also: the telemetry of the rates does not show obvious oscillation after the sticksion event, unlike MO. I put the file that Trish got for me of the GWE #1 body rates in your home directory on "titania", if you want to look at them. Best, John