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Satellite News, May 29 1994
Date sent: Mon, 30 May 1994 06:36:29 +0200
From: [email protected]
Subject: SATELLITE NEWS 29 MAY 1994
To: [email protected]
Send reply to: [email protected]
SB AMSAT @ ZAF $SAT0529.001
SATELLITE NEWS 29MAY94 1OF3
SA AMSAT
SATELLITE NEWS 29 MAY 1994
IN THIS BULLETIN:
- AMSAT NA FILES REPORT TO USA NTIA RE SPECTRUM ALLOCATION
- MORE ABOUT THE LUSAT CRASH
- CLEMENTINE PROJECT IN JEOPARDY
- G3IOR LOOKS AT AO13
AMSAT TELLS US NTIA WHAT THE AMATEUR SATELLITE SERVICE REQUIRES
The Radio Amateur Satellite Corporation has responded to
proposals contained in a notice from the National
Telecommunications and Information Administration (NTIA). That
notice, entitled Preliminary Spectrum Reallocation Report, was
released in February and was prepared pursuant to Title VI of the
Omnibus Budget Reconciliation Act of 1993. In that Act, Congress
mandated that the U.S. Government re-allocate to the private
sector 200 MHz of spectrum below 5 GHz, 100 MHz of it below 3
GHz. Since Amateur Radio's use of the microwave bands is on a
secondary basis to Government applications, mostly military, this
proceeding could have a significant impact on our future access
to these frequencies.
In its comments filed May 11 by AMSAT-NA VP for Government
Liaison Perry Klein (W3PK), AMSAT-NA asked the NTIA for wider
amateur and amateur-satellite service bands at 13cm than proposed
in its Preliminary Report. It proposed that 2300 to 2310, 2390
to 2400 and 2402 to 2417 MHz be turned over to FCC for allocation
to commercial users. In omitting 2400 to 2402 MHz from this
re-allocation, NTIA noted amateur satellite use of this band.
This would presumably leave 2400 to 2402 and 2417 to 245 MHz
available to amateurs. The present 13cm amateur band consists
of 2300-2310 and 2390- 2450 MHz.
AMSAT-NA proposed a primary amateur/amateur satellite allocation
of 2400-2410 MHz plus access to as much of the 2410 to 2450 MHz
band as possible on a shared basis. In support of this request,
AMSAT-NA cited the likelihood of greatly increased demand for
amateur satellite operations in the 13 cm band in coming years,
far more than can be accommodated within 2400-2402 MHz; the
unsuitability of 2417-2450 MHz for amateur satellite downlinks
because of interference from such devices as microwave ovens; and
the need to coordinate amateur-satellite allocations
internationally so that they are available on a global basis.
In addition, AMSAT-NA proposed that a narrow band of 1-2 MHz,
somewhere between 2300 and 2400 MHz, be allocated to the amateur
service on a primary basis to accommodate the experimental
weak-signal tropo and EME work now carried out around 2304 MHz.
AMSAT-NA comments were prepared by a group consisting of Perry
Klein (W3PK), Ray Soifer (W2RS), Jan King (W3GEY) and Bill Tynan
(W3XO).
/EX
SB AMSAT @ ZAF $SAT0529.002
SATELLITE NEWS 29MAY94 2OF3
LO-19's & IO-26's On-board Computers Crash After A Single Event
Upset (SEU)
It was reported last week that LUSAT-OSCAR-19's On-Board Computer
(OBC) had "crashed" after having experienced what is known in the
aerospace industry as a Single Event Upset (SEU). This
phenomenon is caused by high energy particles in space
"effecting" changes in the "state" inside of memory chips and/or
other electronic components. In simple terms, an SEU will change
a bit from a "1" to a "0" or visa-versa in Random Access Memory
(RAM) chips. All MICROSATs have software specifically designed
to handle this problem. However, this software is not
"bullet-proof." The software can only correct one "state" change
at a time. If two "state" changes occur simultaneously, there
is a good possibility that they will occur in RAM memory
locations that will eventually lead to an OBC "crash."
The problem with LO-19 was first noticed on 16-MAY-94 over
Argentina when LU1JBR was working it then he noticed suddenly
that the satellite simply "disappeared." On the evening of
17-MAY-94, LO-19's ground command station, operated by Norberto
Pennini (LU8DYF) was able to successfully reset the OBC.
AMSAT-LU ground station LU8DYF requests that all users of
LO-19 to PLEASE REFRAIN FROM USING IT FOR SEVERAL WEEKS! The
reloading of the software will take several weeks along with
extensive tests to be performed to insure all is working
properly. AMSAT-LU requests that if anyone was collecting
telemetry between 17-MAY-94 at 02:00 UTC until 18-MAY-94 around
02:00 UTC that they please forward it to the following addresses:
via packet radio to LU8DYF @ LU8DYF.BA.ARG.SOAM and/or LU8DYF @
ON ANY ACTIVE SATELLITE, or via Internet to:
[email protected]. This will certainly assist in the recovery
efforts by helping the AMSAT-LU group understand this crash. All
users are asked to please be patient as the AMSAT-LU ground
command team reloads the operating system software for LO-19.
Alberto Zagni (I2KBD) also reports that the same high energy
eruption that caused the LO-19's OBC to "crash" has also cause
IO-26's OBC to "crash." I2KBD reports that the problem occured
about the same time period and feels that this was due to the
fact the Sun was spewing out a lot of highly charged particles.
I2KBD says that it will take several days to get the "kernal"
and Integrated Housekeeping Tasks (IHT) software reloaded. He
too asks that all IO-26 users to please be patient as they bring
IO-26 back "on-line."
AO-13: Current Transponder Operating Schedule:
L QST *** AO-13 TRANSPONDER SCHEDULE *** 1994 May 07-Jul 11
Mode-B : MA 0 to MA 170 |
Mode-BS : MA 170 to MA 218 |
Mode-S : MA 218 to MA 220 |<- S beacon only
Mode-S : MA 220 to MA 230 |<- S transponder; B trsp. is OFF
Mode-BS : MA 230 to MA 250 | Alon/Alat 230/-5
Mode-B : MA 250 to MA 256 |
Omnis : MA 250 to MA 120 | Move to attitude 180/0, Jul 11
[G3RUH/DB2OS/VK5AGR]
Conference of South African Satellite Developers
The following article appeared in the IEEE Newsletter this week:
South African Satellite developers will gather in scenic
Stellenbosch on October the 4th, 1994 for the Small Satellites
and Control Symposium 94, jointly sponsored by the Control,
and Aerospace and Electronic Systems Chapters, in association
with SA AMSAT. This major conference, which forms part of the
Stellenbosch Engineering Faculty's 50th birthday celebrations,
promises to be one of the largest local assemblies of
satellite developers. Presentations of papers have been
invited from industry, the universities and the amateur
satellite development association.
A number of papers on the SUNSAT satellite, developed at the
University of Stellenbosch, will be presented. It is a 50 kg
low earth orbit spacecraft in the microsatellite class, with
an imaging and store-and-forward capability. The engineering
model of the satellite, which has recently been completed,
illustrates the operation of the camera which is expected to
produce 15 m resolution stereoscopic images.
Greensat is a larger earth resource observation satellite
produced by Houwteq Denel, near Grabouw in the Cape. Papers
on this 320 kg satellite, which has received considerable
interest at international exhibitions, will also be presented
at the Stellenbosch conference. Several high technology
companies from the South African industry, who have developed
subsystems for Greensat, were also invited to present their
work at the conference.
An amateur organisation, which has long been active in the
area of satellite development, is co-sponsoring the
conference. The Southern African Amateur Radio Satellite
Association (SA AMSAT) is a group of volunteers who are
interested in satellites and scientific communications
technology as a hobby. The group is closely affiliated to
AMSAT groups world-wide. It promotes technology literacy
amongst the youth through its various projects and is
associated with the International Phase 3D Amateur Radio
Satellite construction project. The group is supportive of
the SUNSAT project and provides international liaison and
frequency co-ordination.
The importance of automatic control on these modern satellites
will be illustrated by papers from this discipline. However,
the conference theme has been defined broad enough to consider
control systems applications to a wide range of aerospace and
other dynamics systems.
A special invitation is extended to researchers and practising
satellite and control systems engineers and scientists, who
have not yet contacted the organisers, to submit papers for
the conference. Camera-ready papers (i.e. not only proposals)
may be submitted before the 20th of June, by mailing it to the
chairman of the Small Satellites and Control Symposium:
Prof. Arnold Schoonwinkel
Dept. of Electrical and Electronic Engineering
Stellenbosch University
7600 Stellenbosch
Tel (021) 8084926 Fax (021) 8084981
/EX
SB AMSAT @ ZAF $SAT0529.003
SATELLITE NEWS 29MAY94 3OF3
CLEMENTINE FAILURE
After successfully completing a mission using advanced ballistic
missile defense technologies to map the entire surface of the
moon, the Ballistic Missile Defense Organization's Clementine
satellite suffered an on-board malfunction at 9:39 AM EST on
07-May-94. The likely result of this malfunction will be to
prevent Clementine from performing the planned close fly by of
the near-Earth asteroid Geographos in August 1994, and for the
satellite to point its cameras and sensors.
Preliminary analysis has traced the cause of the malfunction to
the on-board computer which controls most of the satellite's
systems including the attitude control thrusters. The computer
activated several thrusters during a 20 minute telemetry
interrupt with the ground station, thus depleting all the fuel
in the Attitude Control System (ACS) tanks. It has not been
determined as yet whether the fault was in the computer software
or in the computer's electronic chips. The primary processor on
the computer is a radiation hardened Military Standard 1750A
computer, which is not experimental technology.
Clementine's mission control center in Alexandria, VA. is
continuously monitoring the satellite. It has been determined
that all instruments and systems are continuing to function well
with the exception of the ACS.
Although it may be difficult to Clementine to make the close fly
by of the asteroid, the satellite will continue to perform its
intended military mission to test 23 advanced technologies. The
Clementine engineering team is examining several mission options
which would continue to yield useful data. Since January 25,
1994, Clementine's cameras have recorded over 1.5 million images
including the topographical surface of the moon. Analyzing this
data, including results of the search for the existence of ice
on the lunar surface, will continue to occupy scientists for many
years.
The Clementine project is managed by BMDO, built by the Naval
Research Laboratory, and its instruments constructed by industry
and the Lawrence Livermore Laboratory. It has been a landmark
project since it demonstrates that small, highly capable
satellites can be built and launched for under $100 million and
in less than two years, using advanced miniaturized technology
and a streamlined management approach.
CHARACTERISTICS of OSCAR-13
This week Pat Gowan G3IOR looks at OSCAR 13
This second functioning Phase III-B satellite was launched
by ESA's ARIANE-4 from French Guiana on 15 June 1988 into
a highly elliptical 'Molniya' type orbit with a 36,000 Kn
Apogee and a 2546 Km Perigee. Due to Lunar and Solar effects the
orbit is becoming more elliptical, and the lowering perigee
atmospheric frictional drag is set to shorten the life of this
spacecraft. The period is some 11 hours. Four transponders are
carried that are placed on according to ground command control.
Frequencies for AMSAT-OSCAR 13 (AO-13)
General Beacon 145.812 MHz (PSK,CW,RTTY)
Engineering Beacon 145.985 MHz (PSK,CW,RTTY)
Mode B Uplink 435.423 - 435.573 MHz (SSB,CW)
Mode B Downlink 145.825 - 145.975 MHz (SSB,CW,inverting)
General Beacon 435.651 MHz (PSK,RTTY)
Engineering Beacon 435.677 MHz (PSK,RTTY)
Mode L Uplink 1269.351 - 1269.641 MHz (SSB,CW)
Mode L Downlink 435.715 - 436.005 MHz (SSB,CW,inverting)
Mode J Uplink 144.423 - 144.473 MHz (SSB,CW)
Mode J Downlink 435.940 - 435.990 MHz (SSB,CW,inverting)
Beacon 2400.325 MHz (PSK,RTTY)
Beacon 2400.664 MHz (PSK,RTTY)
Mode S Uplink 435.603 - 435.639 MHz (SSB,CW,FM)
Mode S Downlink 2400.711 - 2400.747 MHz (SSB,CW,FM)
RUDAK Uplink 1269.710 MHz (Inoperative)
RUDAK Downlink 435.677 MHz (Inoperative)
The 145.812 MHz beacon sends CW telemetry at the hour and half
hour, RTTY at the quarter and three-quarter hours, and PSK all
the rest of the time. Updated information on mode switching
and status is supplied by this beacon. The 145.985 MHz beacon
is much stronger, and is mainly used in controlled
magnotorquing by the command stations DB2OS, G3RUH and VK6AGR.
The Mode 'B' uplink requirements for A-O-13 are accomplished by
using 25 - 50 watts of CW or LSB from any conventional 70cm TX
to a 12 X/Y Yagi or a 10 turn RHCP Helix with
azimuth/elevation pointing. The dowlink requires an
azimuth/elevation pointing 10 element RHCP Yagi or 8 turn
Helix to a low noise pre-amplifier at the antenna feeding any
USB 2m RX.
Mode 'J' requires exactly the same antennas as for Mode
'B', with reversed transmitters and receivers, with a Low Noise
pre-amplifier on the 70 cm receiver.
'L' mode needs a pair of 23cm 20 element Quad Loop Yagis fed
with at least 100 watts of CW or SSB. The downlink needs are as
for Mode 'J'.
S' Mode needs some 50 watts of 435 MHz CW or SSB from the same
70cm antenna, and an azimuth/elevation controlled 20 turn Helix
for 2400 MHz with a good low noise front end. A 13cm to 2m or
13cm to 10m converter may be used feeding the main station
2 or 10m receiver.
ends ZS5AKV
/EX
Pat Terry, Computer Science, Rhodes University, GRAHAMSTOWN 6140, RSA
[email protected] or cspt@giraffe.ru.ac.za or [email protected]
Voice +27-461-318291 or +27-461-318292 FAX +27-461-25049
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