[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

11/4 SEDSAT Update

Hi Everyone,
	Time for another SEDSAT update.  

In this lengthy message:

* Uplink Status
* Operational Profile Estimates
* Database going online
* New SGS Software
* Telem Specs available shortly
* Clarification "Project Manager"

We are now coordinating four different uplink stations in the US:

Myself (KC7NYV) in Tucson, AZ
Stan Wood (?), Lou McFadin (W5DID) & Co in Orlando, FL
Jim White (WD0E) in Denver, CO
Tim Cunningham (N8DEU) in Huntsville, AL

As of yet, I have been the only one attempting uplinks since SEDSAT
launched, as other people were bringing equipment online and the exact
details of uplinking were being made clear.  I still have not had any
success, and I believe I've worked out all the software bugs,
computer/radio/modem hardware problems, and now am relatively sure that I
need to check my deviation and tune my antenna.  I'll be getting access to
a Network analyzer and a spectrum analyzer Wednesday evening and should be
ready to test on tomorrow evenings' passes.

Stan Wood is nearly ready to test the uplink, and should be ready to do it
Wednesday as well -- the same with Jim White (who was probably set up all
along, but was unavailable tonight). Dennis Wingo is working with Tim
Cunningham, and I am not sure of their progress, but to my knowledge they
have not attempted an uplink test yet.

I'd like to thank all the people I've previously mentioned, as well as
Harold Price and the Huntsville crew for coaching me along in all this,
and hopefully we'll have some success soon!  

For those of you curious what the "uplink test" is, it can be one of two
things:  The first is simply setting the spacecraft clock, and seeing
wether that works or fails.  The second is getting into "CONV" mode with
the satellite and echoing characters back and forth.  These can't be done
by anyway, and we of course want to restrict this activity to a small
group of people so it can be coordinated well.

At the advice of Stan Wood, I've finally hunkered down and started
scouring the telemetry reports I've been getting in detail, and have
organized the "uptime" information.  I have accurate data back to October
29 (about 4 days after launch), but it is sketchy before that, as no one
was logging both time and uptime.  The results are that the satellite is
typically up an average of 25:15 before power cycling.  Looking at most of
the data, the earliest packets after power cycle that I'm seing are about
13:00 hours, which is about 3 hours after you should start to hear it
(when it begins transmitting 10 hours after power cycle).  I don't know if
this is due to the satellite not transmitting on time, or due to
observational geometry on the globe (no time for me to look).  Below is
the summary of the data I have, followed by an approximate schedule of
SEDSAT operation over the next week, assuming it follows a similar profile
(and we don't establish uplink):

They are grouped into run cycles, so multiple entries indicate multiple
data.  Call signs are those people whose data was used for the

Who	Where		Boot Time UT	Start TX UT 	Run Time
KC7NYV	Tucson		11/3/98 16:11	11/4/98 2:11	25:15:10
KC7NYV	Tucson		11/2/98 14:55	11/3/98 0:55	25:07:56
VK5AKJ	Australia	11/2/98 14:55	11/3/98 0:55	
VK5AKJ	Australia	11/1/98 13:48	11/1/98 23:48	25:16:45
VK5AKJ	Australia	10/31/98 12:31	10/31/98 22:31	25:19:50
KC7NYV	Tucson		10/30/98 11:11	10/30/98 21:11	26:08:26
VK5AKJ	Australia	10/30/98 11:11	10/30/98 21:11	
ZL1BIV	New Zealand	10/29/98 9:03	10/29/98 19:03	26:05:44
ZL1BIV	New Zealand	10/28/98 6:57	10/28/98 16:57	23:34:47
CT1EAT	Portugal	10/28/98 6:57	10/28/98 16:57	
N8DEU	Huntsville	10/27/98 7:22	10/27/98 17:22	?
ZL1BIV	New Zealand	10/27/98 7:21	10/27/98 17:21	?
ZL1BIV	New Zealand	10/27/98 7:21	10/27/98 17:21	?
CX6DD	Uraguay		10/27/98 7:35	10/27/98 17:35	?

Using the average uptime, and propagating forward linearly, here is the
satellite schedule for the next week. Keep in mind that every day can be
+/- 30 minutes, and this can accumulate from day to day.  Hopefully we
won't have to rely on this schedule! Remember that the satellite is
"alive" and operating (but not transmitting) for 10 hours before it begins
to transmit.

Boot Time (UT)	Beginning of TX (UT)	Beginning of TX (EST):
11/4/98 17:26	11/5/98 3:26		11/4/98 22:26
11/5/98 18:42	11/6/98 4:42		11/5/98 23:42
11/6/98 19:57	11/7/98 5:57		11/7/98 0:57
11/7/98 21:13	11/8/98 7:13		11/8/98 2:13
11/8/98 22:28	11/9/98 8:28		11/9/98 3:28
11/9/98 23:44	11/10/98 9:44		11/10/98 4:44
11/11/98 0:59	11/11/98 10:59		11/11/98 5:59

In order to prevent myself from wasting too much time crunching
spreadsheets, I will attempt to get much of the data into our database in
the next day or two, to simplify analysis of the satellite.  A public
interface will be available, but on a trial basis only (over the web).  In
the meantime, I will post as much of the data as I can at
http://www.seds.org/sedsat/tracking/telemetry (particularly, mine, in
comma separated format).

For those eager to get their hands on the telemetry spec, I will
distribute the draft of it later this evening.  

A new version of the SGS ground station software has been coded, and now
accounts for UTC offset, tells us who you are (call sign) and should
support automated WiSP operation.  There was a bug in the UTC calculations
this evening, though, so I'm waiting for that to be corrected before I
post it.  For those of you who *can* run it, please do. Otherwise, keep on
sending the KISS files if you have the time and the will.  We do
appreciate it!

A java version of our telemetry decoder should be available by tomorrow,
and we at the University of Arizona will be developing that as the "main"
software for ground station operation as the mission continues. The end
goal is for it to interface directly with our database for both upload and

The current NORAD elements (#33, Orbit 123) appear to be accurate.  I have
not heard telemetry before I was supposed to or after I was supposed with
this set. Here they are for reference:

1 25509U 98061B   98306.17855029  .00000778  00000-0  15125-3 0   336
2 25509  31.4482 346.5323 0369756 325.0260  32.6596 14.23735048  1239

Finally, for those of you relaying details of these reports to other news
publications (thanks!), I'm *not* the "Project Manager" of SEDSAT-1.  Far
from it, I'm just running a ground station here in Tucson, and happened to
have been preparing for SEDSAT's arrival for some time, and took some
initiative to see things through.  The title "Project Manager" in my sig
file below is related to my project at the University of Arizona to build
our own satellite (UASat).  If you're curious (or want to help out some
how) check out our web site at http://www.physics.arizona.edu/ssp/

Christopher A. Lewicki KC7NYV 520.977.0758 Maintainer of SEDS.LPL.Arizona.EDU
     Program Manager, University of Arizona Student Satellite Project

Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org