AMSAT-OSCAR 16
Encyclopedia
AO-16 is the in-orbit name designation of an amateur radio
satellite
(AMSAT
) of the OSCAR
series; formerly known as Pacsat. It was launched on 22 January 1990 from Kourou, French Guiana
on a Ariane 4
launch vehicle. It is in sun synchronous
low Earth orbit
.
A total of 10 megabytes of static RAM was used for message storage and a RAM disk. PACSAT communicated with ground stations through a single downlink channel and a total of four uplink channels. The multi-tasking operating system allows mailbox software and an AX.25 protocol driver to operate concurrently.
Only one 70-cm downlink transmitter is active at any one time. Due to performance degradation of the primary transmitter on 437.026 MHz, the secondary transmitter on 437.051 MHz is being used at the current time. All Microsats transmit using several watts of transmitter power making their signals easily received on the Earth below. AMSAT-OSCAR-16 accepts 1200 bps 3.5 kHz deviation Manchester encoded FSK on any of its uplink frequencies. It transmits using 1200 bps binary phase shift keying (BPSK), a very robust binary modulation scheme.
AO-16 uplinks are made with 2-Meter FM voice transmitters, while downlink reception requires a 70-cm SSB receiver or HF SSB receiver with a 70-cm converter. Several modem designs are available for Pacsat operation. These modems are also mode compatible with Fuji-OSCAR-20.
The uplink receivers are VERY sensitive. AX.25 connection to the spacecraft can be made with just a few watts of transmitter power and a modest antenna system. While testing a newly designed 1200 bps Pacsat modem, it was discovered that seven watts of transmitter power and an indoor antenna were all that was required to connect to oneself using AO-16 as a digipeater.
"Experimenter Days" were scheduled for PACSAT from time to time. During these periods, ground stations were encouraged to limit their uplink transmitter power to the minimum necessary to establish and maintain AX.25 connection with the digital transponder. Usually the transmitter power level was on the order of just a few watts.
Whole Orbit Data (WOD) collections was also performed by AO-16, and WOD files were available through the mailbox for all those who were interested in processing and analyzing spacecraft telemetry.
Amateur radio
Amateur radio is the use of designated radio frequency spectrum for purposes of private recreation, non-commercial exchange of messages, wireless experimentation, self-training, and emergency communication...
satellite
Satellite
In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon....
(AMSAT
AMSAT
AMSAT is a name for amateur radio satellite organizations worldwide, but in particular the Radio Amateur Satellite Corporation with headquarters at Silver Spring, Maryland, near Washington DC. AMSAT organizations design, build, arrange launches for, and then operate satellites carrying amateur...
) of the OSCAR
OSCAR
OSCAR is an acronym for Orbiting Satellite Carrying Amateur Radio. OSCAR series satellites use amateur radio frequencies to facilitate communication between amateur radio stations. These satellites can be used for free by licensed amateur radio operators for voice and data communications...
series; formerly known as Pacsat. It was launched on 22 January 1990 from Kourou, French Guiana
French Guiana
French Guiana is an overseas region of France, consisting of a single overseas department located on the northern Atlantic coast of South America. It has borders with two nations, Brazil to the east and south, and Suriname to the west...
on a Ariane 4
Ariane 4
Ariane 4 was an expendable launch system, designed by the Centre National d'Etudes Spatiales and manufactured and marketed by its subsidiary Arianespace. Ariane 4 was justly known as the ‘workhorse’ of the Ariane family. Since its first flight on 15 June 1988 until the last, on 15 February 2003, it...
launch vehicle. It is in sun synchronous
Sun-synchronous orbit
A Sun-synchronous orbit is a geocentric orbit which combines altitude and inclination in such a way that an object on that orbit ascends or descends over any given point of the Earth's surface at the same local mean solar time. The surface illumination angle will be nearly the same every time...
low Earth orbit
Low Earth orbit
A low Earth orbit is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km...
.
Discussion
Based on the success of UoSAT-OSCAR-11's Digital Communications Experiment, AMSAT-OSCAR-16 was designed to be a dedicated store-and-forward file server in space. Using 1200 bit per second Mode JD radio links, AMSAT-OSCAR-16 interacts with ground station terminal software to appear as a packet radio bulletin board system to the user. Anyone wishing to download files, personal mail from anywhere in the world, or news bulletins could request the information be "broadcast" to all under the footprint of the spacecraft, or directed specifically to that ground station. This broadcast protocol differs from terrestrial packet radio communications, but allows a greater number of ground stations access to the spacecraft's resources during the limited time of a pass.A total of 10 megabytes of static RAM was used for message storage and a RAM disk. PACSAT communicated with ground stations through a single downlink channel and a total of four uplink channels. The multi-tasking operating system allows mailbox software and an AX.25 protocol driver to operate concurrently.
Only one 70-cm downlink transmitter is active at any one time. Due to performance degradation of the primary transmitter on 437.026 MHz, the secondary transmitter on 437.051 MHz is being used at the current time. All Microsats transmit using several watts of transmitter power making their signals easily received on the Earth below. AMSAT-OSCAR-16 accepts 1200 bps 3.5 kHz deviation Manchester encoded FSK on any of its uplink frequencies. It transmits using 1200 bps binary phase shift keying (BPSK), a very robust binary modulation scheme.
AO-16 uplinks are made with 2-Meter FM voice transmitters, while downlink reception requires a 70-cm SSB receiver or HF SSB receiver with a 70-cm converter. Several modem designs are available for Pacsat operation. These modems are also mode compatible with Fuji-OSCAR-20.
The uplink receivers are VERY sensitive. AX.25 connection to the spacecraft can be made with just a few watts of transmitter power and a modest antenna system. While testing a newly designed 1200 bps Pacsat modem, it was discovered that seven watts of transmitter power and an indoor antenna were all that was required to connect to oneself using AO-16 as a digipeater.
"Experimenter Days" were scheduled for PACSAT from time to time. During these periods, ground stations were encouraged to limit their uplink transmitter power to the minimum necessary to establish and maintain AX.25 connection with the digital transponder. Usually the transmitter power level was on the order of just a few watts.
Whole Orbit Data (WOD) collections was also performed by AO-16, and WOD files were available through the mailbox for all those who were interested in processing and analyzing spacecraft telemetry.
External links
- D. Conners, "The PACSAT Project,"ARRL Amateur Radio Second Computer Networking Conference, pp. 1–3, March 19, 1983.
- T. Clark, "AMSAT's Microsat/Pacsat Program,"Proceedings of the AMSAT-NA Sixth Space Symposium, Atlanta, GA, pp. 41–47, Nov 1988, ARRL.
- L. Johnson and C. Green, "Microsat Project - Flight CPU Hardware,"Proceedings of the AMSAT-NA Sixth Space Symposium, Atlanta, GA, pp. 104-106, Nov 1988, ARRL.
- H. Price and R. McGwier, "PACSAT Software,"Proceedings of the AMSAT-NA Sixth Space Symposium, Atlanta, GA, pp. 145-149, Nov 1988, ARRL.
- T. Clark, C. Duncan, J. King, B. McGwier, "The First Flock of Microsats,"The AMSAT Journal, May 1989, pp 3-10.
- D. Loughmiller and B. McGwier, "Microsat: The Next Generation of OSCAR Satellites," Part 1,QST, May 1989, pp 37–40; Part 2,QST, Jun 1989, pp 53–54.
- Doug Loughmiller, "Successful OSCAR Launch Ushers in the 90's,"QST, Apr 1990, p. 52.
- Six for the Price of One - Part I,"The AMSAT Journal, Vol. 13, No. 1, Mar 1990, p. 1; Part II:The AMSAT Journal, Vol. 13, No. 2, May 1990, p. 1.
- John A. Magliacane, "Spotlight On: The Microsats,"The AMSAT Journal, Vol. 15, No. 4, Sep/Oct 1992
- Martin Davidoff, The Satellite Experimenter's Handbook, 2nd edition, The American Radio Relay League, Newington, CT., 1990.
- Mike Crisler, PACSAT Beginner's Guide, AMSAT.