AMSAT-OSCAR 7
Encyclopedia
AO-7 is the second Phase 2 amateur satellite
launched into Low Earth Orbit
on 15 November 1974. It remained operational until a battery failure in 1981. On 21 June 2002 the satellite was heard again on its 2 meter beacon (145.9775 MHz CW) after 21 years of silence, and 27 years in space.
AMSAT reported AO-7 still semi-operational on 6 April 2006, with reliable power only from its solar panels; the report stated the cause of the outage was a short circuit
in a battery and the restoration of service was due to its becoming an open circuit. The satellite eclipses on every orbit during the northern summer and autumn; the rest of the year it is in continuous sunlight and alternates between transmission modes A and B.
1979 allocation of 435-438 MHz by the ITU
for the Amateur Satellite Service which places the uplink in the 70cm weak signal segment. Additionally, the IARU
bandplan has the 432.1 MHz range (which is used for mode B uplink) marked for "weak signal" in all three Regions.
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....
launched into 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...
on 15 November 1974. It remained operational until a battery failure in 1981. On 21 June 2002 the satellite was heard again on its 2 meter beacon (145.9775 MHz CW) after 21 years of silence, and 27 years in space.
AMSAT reported AO-7 still semi-operational on 6 April 2006, with reliable power only from its solar panels; the report stated the cause of the outage was a short circuit
Short circuit
A short circuit in an electrical circuit that allows a current to travel along an unintended path, often where essentially no electrical impedance is encountered....
in a battery and the restoration of service was due to its becoming an open circuit. The satellite eclipses on every orbit during the northern summer and autumn; the rest of the year it is in continuous sunlight and alternates between transmission modes A and B.
Firsts
AO-7 demonstrated several uses of new technologies and operations- First satellite-to-satellite relay, through AO-6.
- Early demonstrations of low-budget medical data relay and Doppler location of ground transmitters for search-and-rescue operations were carried out using this satellite.
- The Mode-B transponderTransponderIn telecommunication, the term transponder has the following meanings:...
was the first using "HELAPS" (High Efficient Linear Amplification by Parametric Synthesis) technology developed by Dr. Karl Meinzer as part of his Ph.D. - First to fly a Battery Charge Regulator (BCR).
Legal issues
The uplink frequency predates the WARCWorld Administrative Radio Conference
The World Administrative Radio Conference was a technical conference of the International Telecommunications Union where delegates from member nations of the ITU met to revise or amend the entire international Radio Regulations pertaining to all telecommunication services throughout the world...
1979 allocation of 435-438 MHz by the ITU
Itu
Itu is an old and historic municipality in the state of São Paulo in Brazil. The population in 2009 was 157,384 and the area is 641.68 km². The elevation is 583 m. This place name comes from the Tupi language, meaning big waterfall. Itu is linked with the highway numbered the SP-75 and are flowed...
for the Amateur Satellite Service which places the uplink in the 70cm weak signal segment. Additionally, the IARU
International Amateur Radio Union
The International Amateur Radio Union is an international confederation of national amateur radio organisations that allows a forum for common matters of concern and collectively represents matters to the International Telecommunication Union...
bandplan has the 432.1 MHz range (which is used for mode B uplink) marked for "weak signal" in all three Regions.