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[jamsat-news:531] * SpaceNews 12-May-97 *

* SpaceNews 12-May-97 *

BID: $SPC0512


			  MONDAY MAY 12, 1997

SpaceNews originates at KD2BD in Wall Township, New Jersey, USA.  It
is published every week and is made available for non-commercial use.

WEBERSAT-OSCAR-18 is currently in MBL (Microsat Boot Loader) mode.  There
are no picture transmissions taking place at the present time.  The primary
downlink (437.102 MHz) is currently active with strong BPSK signals.

LUSAT-OSCAR-19 is currently active on its secondary downlink of 437.125 MHz.
The satellite is reporting an uptime of over 690 days.  The beacon text reads
as follows:
22 de Enero de 1997.
7 as !
7 years !
Gracias a todos los amigos que lo hicieron posible.

Amsat - LU8DYF.

ITAMSAT-OSCAR-26 is currently transmitting telemetry and OBC status
information on 435.822 MHz.  Over the past weekend, the beacon was
transmitting the following text message:

IHT97 software loaded. WOD enabled 
IO-26 Command Team.

DOVE-OSCAR-17 is also in MBL mode.  Telemetry is being sent in an
abbreviated format.  The following packets were copied on 10-May-97:

V:9J EC:B0 ST:0804 IL:2F00:0CE9 IV:1800 EL:0D96 AH:0000 WS:2900

21:0E 2E:9B 31:AE 32:AE 0A:A3 0D:BC 10:AE 

DOVE-OSCAR-17 controller Jim White, WD0E explained several months ago
that new software is being uploaded to the satellite.  The format and
content of the current data transmissions reflect the latest attempt
in troubleshooting the satellite and uploading new operating software.
The satellite is presently sending data from a RAM based version of the
Microsat Boot Loader program.  The first line in packet above contains data
about the operation of this software.  The first characters in each item are
the ID.  Data values in hex follow the colon.

V is the software version number.  EC is the EDAC error counter, and is
accurate data.  ST represents status data whose meaning changes with the
interaction between MBL software and ground control software.

IL represents the memory address at which the current software is running
followed by the offset to the IV value.  This is an assembly language module
written by Bob Diersing, N5AHD.   The satellite has 256k bytes of EDAC memory
in which programs and data are stored.  The load address of 2000 hex is in
16 byte paragraphs.  The program is loaded 131072 bytes above the bottom of
memory (2F00h = 12032d X 16d = 192512d).  The next value (0CE9h) is the
offset in bytes to the location of the value (IV) that controls how often
telemetry is sent.  Knowing this value allows controllers to safely change
it with a patch command.  In January, controllers were using a version of
MBL loaded at 2F00h to load the first two modules of the normal software.
The first one (the kernel) loads in low memory.  The second loads just
above MBL at 3000h.  The area of memory from 2F00h to 3000h isn't used by
the operational software so controllers are able keep a copy of MBL there
to use when the satellite is reset.

This version of software sends acknowledgements and occasional telemetry
on 2 meters, eliminating the need to use the S-band transmitter whose
modulator failed after launch.  When the satellite resets to the ROM
MBL, controllers can simply use it to execute the RAM MBL copy at 2F00h
and use it to load other software.

IV represents the value of the telemetry timer.  1000h roughly corresponds
to 10 seconds, 1800h is about 1 minute.  However in space, the software must
listen to and try to make sense of all the stuff it hears on its uplinks.
That activity takes priority over everything else the software does.  If
the satellite copies many signals, it doesn't get a chance to gather and
send telemetry as often.  As a result, it sends telemetry at an interval
that varies from a few seconds to a couple of minutes depending on what
it copies on its control link receivers.

EL is the length of the module, D96 hex (3478 decimal) bytes.  AH is a
counter that represents the number of times the routine in the software
that communicates over the AART bus timed out waiting for a response from
another hardware module.  This counter has shown there is no problem with
the bus.  WS indicates the segment of memory being washed at the time this
data was gathered.  It changes randomly because all of EDAC is being washed
at a fairly rapid rate and there is no timed sequence for gathering the data.

The remaining data is analog telemetry in the same format as the 'normal'
DOVE software, channel number followed by raw value in hex.  This is
converted into engineering units by converting the hex data to decimal
and applying the appropriate calibration coefficients that have been
published.  Most of this data, however, is not accurate.

* STS-84 NEWS *
Ken Ernandes reports that STS-84 pre-launch nominal OMS-2 orbital data is
now available on the AMSAT Web page at the following URL:


This data includes the time-independent TDR/EFG nominal state vector and the
AMSAT and Two-Line Keplerian elements.  The Keplerian elements were computed
from the State Vector and the scheduled launch time using VEC2TLE.  The
scheduled launch time is 15-May-97 at 08:07:51 UTC.

The corresponding Two-Line Keplerian elements are as follows:

1 99984U          97135.36851925  .00383797  60709-6  72207-4 0    14
2 99984  51.6579 251.1201 0103915   4.3240 184.3216 16.17747945    15

If the launch date or time changes, updated Keplerian elements can be
computed from the State Vector and the new time using VEC2TLE.  Note
that the 99984 Catalog Number is temporary.  A permanent Catalog Number
and International Designator will be assigned after STS-84 is launched.

As with previous missions, the AMSAT Web page will be maintained with
current orbital data for STS-84 during the mission.  The STS-84 Nominal
Mission Orbit Profile and State Vectors are also available on the AMSAT
Web page at the following URL:


This file has a text summary of the major orbital events for the STS-84
mission and time-independent TDR/EFG state vectors for each event.  The
corresponsing Keplerian elements can be computed from the vectors (and
providing a launch date and time) using VEC2TLE.  VEC2TLE Version 9648
may be downloaded from:  http://www.amsat.org/amsat/sarex/orbit.html

[Info via Ken Ernandes, N2WWD]

Comments and input for SpaceNews should be directed to the editor (John,
KD2BD) via any of the paths listed below:
WWW       : http://www.njin.net/~magliaco/
INTERNET  : kd2bd@amsat.org, magliaco@email.njin.net

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