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[jamsat-news:1422] * SpaceNews 15-Jan-01 *
SB NEWS @ AMSAT $SPC0115
* SpaceNews 15-Jan-01 *
MONDAY JANUARY 15, 2001
* PHASE 3D/AO-40 UPDATE *
AMSAT-DL President Karl Meinzer, DJ4ZC, provided the AMSAT News Service
with the latest information regarding the status of the AMSAT-OSCAR-40
Since my report from late December, command stations have
implemented the strategy which I had outlined. The first priority
was to determine which command-uplink channels were available. This
work was difficult, very time consuming (and for the satellite)
somewhat dangerous due to the unknowns. The command stations did
a magnificent job! Due to their combined efforts I can report the
1. After some blind transmissions to test the omni-antennas around
apogee (that failed to produce a response), the scheduler was activated
and programmed in such a way as to prevent lock-out. This strategy
turned out to be very prudent and the scheduler-operation went smoothly
and resulted in no additional anomalies.
2. The scheduler then took AO-40 through a number of modes, which
allowed the P3D team to determine the following:
a. V, U and L-1 receivers work
b. V, U and L high-gain antennas work
c. U and L low-gain antennas do not work
d. the status of the V-band low-gain antenna has not been finally
determined. Apogee blinds tests are in progress as I write this
to accurately determine the status of this antenna
3. The V-band transmitter was operated for one MA-unit. It demonstrated
a marked temperature increase, but no signal was heard. This was a
quick-look test and this result should not be considered final. Further
tests will be necessary (including the need to determine if the matrix
was set properly). These tests will have to wait until the spin rate
is reduced to ensure that the satellites heat-pipes will be able to
handle the dissipation for extended periods.
4. Magnetorquing was started to reduce spin and the first indications are
a loss of around 0.5 rpm - roughly consistent with theoretical predictions.
We can conclude that the system works. In order to use Earth-sensing data,
a small additional program needs to be installed which stores data at
apogee for later recovery when telemetry reception becomes available.
During the next days the attitude control system should be returned to
full functionality. It will be used to reduce the spin to a value consistent
with heat-pipe operation and also with the requirements to change attitude.
These changes are necessary for sun-angle constraints, communication
access and also to reduce the effect of our ongoing mass-loss on perigee
altitude. Newer model calculations show that the mass loss could be larger
than my previous estimates; thus it would be prudent to use the resulting
thrust to increase perigee altitude (right now it is decreasing it).
Once the spin/attitude situation is under control, we will continue the
check-out of other systems (such as):
1. Determine the status of the V-band transmitter (controlled experiments)
2. Determine the status of the U-band transmitter
3. Determine the serviceability of the ATOS (Arcjet) to determine
if it can be planned on for a strategy toward an improved orbit
4. Test the momentum wheels to determine if AO-40 can be put into a
three-axis mode which would greatly reduce the impact of the loss
of the omni-antennas
Present data so far indicates that although we have lost some systems in
AO-40, there has been no further deterioration after the second incident.
In particular, if ATOS and three-axis stabilization are still serviceable,
AO-40 will still be able to produce a large fraction of the Amateur Radio
service expected from it.
Personally, I am optimistic and I believe that the command-and
engineering team stand a good chance of turning AO-40 into an
extremely useful Amateur Radio satellite.
73, Dr. Karl Meinzer, DJ4ZC
* AMSAT-OSCAR-40 TELEMETRY SERVER *
An OSCAR-40 telemetry server has been set up on a Linux machine located
at the Goddard Spaceflight Center Radio Club (garc9.gsfc.nasa.gov).
It works in the following way:
The server listens on UDP port 2121 for packets containing the
8 byte P3T sync vector + the 514 byte AO-40 telemetry block.
Since UDP is connectionless the server could be receiving packets
from multiple stations at the same time. These packets are generated
by running a UDP converter application (available from Ron Parise,
WA4SIR) in conjunction with P3T, PSK400, or IZ8BLY's P3D Decoder
running in server mode.
To avoid having clients receive duplicate frames, the server keeps
a hash table that it can use to identify duplicates and discard them.
It also checks for a valid P3T sync vector and CRC.
The server also listens on TCP port 1024 for connections from P3T
running in client mode. Each time a frame is received, validated,
and dupe checked, it is sent out to all of the client connections
(the maximum number of connections is set to 200 at the moment).
[Info via Ron Parise, WA4SIR]
* ON1CAU WEB PAGE NEWS *
The ON1CAU Satellite Web Page has been updated. More information about
tracking interfaces, Online satellite tracking and predictions, Satellite
DX-clusters, Homebrewing, and S-band converters and transverters have
been added to the page. The URL is:
[Info via Berto, ON1CAU]
* SKN NOMINATIONS DUE *
So far, very few Best Fist nominations have been received for AMSAT-NA's
latest SKN on OSCAR, held 1 January 2001. Confusion caused by the frequent
mode changes of RS-12/13 undoubtedly affected the level of activity, but we
know from listening that far more stations participated than the current
number of nominations suggests.
If you haven't already nominated someone you worked for Best Fist, please
do so in a reply to this message, or in an e-mail to firstname.lastname@example.org.
Remember, the person you nominate does not have to have had the best
fist you heard, only the best fist you worked.
Results will be published via the AMSAT News Service as well as The
AMSAT Journal in early February.
[Info via Ray Soifer, W2RS]
* FEEDBACK/INPUT WELCOMED *
Comments and input for SpaceNews should be directed to the editor
(John, KD2BD) via any of the paths listed below:
WWW: http://www.qsl.net/kd2bd/ <--- Note the change!
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