AMSAT-OSCAR 7

Last updated
AMSAT-OSCAR 7 (AO-7)
AMSAT-OSCAR 7.jpg
Image Of The Satellite Amsat-OSCAR 7
Mission type Amateur radio satellite
Operator AMSAT
COSPAR ID 1974-089B OOjs UI icon edit-ltr-progressive.svg
SATCAT no. 7530
Website amsat.org
Mission durationPlanned: 10 years
Elapsed: 50 years
Spacecraft properties
Launch mass28.8 kilograms (63 lb)
Dimensions36.0 cm x 42.4 cm octahedron
Start of mission
Launch date15 November 1974, 17:11 UTC
Rocket Delta 2310
Launch site Vandenberg SLC-2W
Orbital parameters
Reference system Geocentric
Regime Low Earth
Perigee altitude 1,447.5 kilometers (899 Mi)
Apogee altitude 1,465.6 kilometers (910 Mi)
Inclination 101.59 degrees
Period 114.9 Minutes
QSL AMSAT OSCAR-7 (SWL).jpg
←  OSCAR 6
OSCAR 8  →

AMSAT-OSCAR 7, or AO-7, is the second Phase 2 amateur radio satellite constructed by the Radio Amateur Satellite Corporation (AMSAT). It was launched into Low Earth Orbit on November 15, 1974 and remained operational until a battery failure in 1981. After 21 years of apparent silence, the satellite was heard again on June 21, 2002 – 27 years after launch. At that time the public learned that the satellite had remained intermittently functional and was used surreptitiously for communication by the anticommunist opposition Fighting Solidarity during martial law in Poland. [1]

Contents

AO-7 is the oldest amateur satellite still in use, and is one of the oldest operational communications satellites. [2] It carries two amateur radio transponders. Its "Mode A" transponder has an uplink on the 2-meter band and a downlink on the 10-meter band. The "Mode B" transponder has an uplink on the 70-centimeter band and a downlink on the 2-meter band. The satellite also carries four beacons which are designed to operate on the 10-meter, 2-meter, 70-centimeter and 13-centimeter bands. The 13-cm beacon was never activated due to a change in international treaties. [3]

AMSAT reported AO-7 still operational on June 25, 2015, with reliable power only from its solar panels; the report stated the cause of the 21-year outage was a short circuit in the 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. All transponders and beacons are operational. [4]

Build

AO-7 was the second Phase 2 satellite (Phase II-B). At launch, the satellite had a mass of 28.6 kg (63 lb) and it was placed into a 1,444×1,459 km orbit. It is shaped as an octagonal prism 360 mm high and 424 mm in diameter. It has a circularly-polarized, canted turnstile VHF/UHF antenna system and HF dipole. Four radio masts mounted at 90 degree intervals on the base of the satellite and two experimental repeater systems provided store-and-forward for Morse code and teletype messages ("codestore") as it orbited around the world. The Mode-B transponder was designed and build by Karl Meinzer, DJ4ZC and Werner Haas, DJ5KQ. The Mode-B transponder was the first using “HELAPS” (High Efficient Linear Amplification by Parametric Synthesis) technology was developed by Dr. Karl Meinzer as part of his Ph.D. research. AO-7 has redundant command decoders of a design similar to the unit proven highly successful in AMSAT-OSCAR 6. The decoder has provisions for 35 separate functions, and is designed to provide a reliable means of controlling the emissions of the repeaters, beacons and other experiments aboard the spacecraft. [4]

Firsts

AO-7 demonstrated several uses of new technologies and operations [5]

constellation allowing intersatellite communication from the United States with AMSAT-OSCAR 6 and AMSAT-OSCAR 7. AO-6 AO-7.jpg
constellation allowing intersatellite communication from the United States with AMSAT-OSCAR 6 and AMSAT-OSCAR 7.

The uplink frequency predates the WARC 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. Accessing the Mode B uplink is permitted in the United States under a waiver from the FCC. [7]

Use by Polish anticommunist opposition

In the summer of 1982 the Fighting Solidarity in Wrocław learned that AO-7 became periodically functional, when its solar panels got enough sunlight to power up the satellite. It was then used to communicate with Solidarity activists in other Polish cities and to send messages to the West. Satellite communication was invaluable at that time, as the regular telephone network was tapped by the government and shut down when martial law was imposed in December 1981. Ham radios were not of much use as they were easy to track. On the other hand, a satellite link required highly directional antennas which were impossible to track by the regime. In 2002 Pat Gowen (G3IOR), inspired by the history of Fighting Solidarity, attempted to communicate with AO-7 and confirmed it to be operational. [1]

Current status

As of November 2024, contacts with AO-7 are reported daily. [8]

Related Research Articles

The Ku band is the portion of the electromagnetic spectrum in the microwave range of frequencies from 12 to 18 gigahertz (GHz). The symbol is short for "K-under", because it is the lower part of the original NATO K band, which was split into three bands because of the presence of the atmospheric water vapor resonance peak at 22.24 GHz, (1.35 cm) which made the center unusable for long range transmission. In radar applications, it ranges from 12 to 18 GHz according to the formal definition of radar frequency band nomenclature in IEEE Standard 521–2002.

AMSAT is a name for various amateur radio satellite organizations worldwide. In particular, it often refers to the Radio Amateur Satellite Corporation, headquartered in Washington, D.C. AMSAT organizations design, build, arrange launches for, and then operate (command) satellites carrying amateur radio payloads, including the OSCAR series of satellites. Other informally affiliated national organizations exist, such as AMSAT Germany (AMSAT-DL) and AMSAT Japan (JAMSAT).

AMSAT-OSCAR-40, also known as AO-40 or simply OSCAR 40, was the on-orbit designation of an amateur radio satellite of the OSCAR series. Prior to launch, the spacecraft was known as Phase 3D or "P3D". AO-40 was built by AMSAT.

<span class="mw-page-title-main">AMSAT-OSCAR 51</span>

AMSAT-OSCAR 51 or AO-51 is the in-orbit name designation of a now defunct LEO amateur radio satellite of the OSCAR series; formerly known as ECHO, built by AMSAT. It was launched on June 29, 2004 from Baikonur Cosmodrome, Kazakhstan on a Dnepr launch vehicle. It is in Sun synchronous low Earth orbit.

HAMSAT also known as HAMSAT INDIA, VU2SAT and VO-52 is a microsatellite weighing 42.5 kilograms (93.7 lb), providing amateur radio satellite communications services for Indian and international amateur radio operators. This satellite carries the in-orbit designation of VO-52, and is an OSCAR series satellite.

The 10-meter band is a portion of the shortwave radio spectrum internationally allocated to amateur radio and amateur satellite use on a primary basis. The band consists of frequencies stretching from 28.000 to 29.700 MHz.

<span class="mw-page-title-main">Amateur radio repeater</span> Combined receiver and transmitter

An amateur radio repeater is an electronic device that receives a weak or low-level amateur radio signal and retransmits it at a higher level or higher power, so that the signal can cover longer distances without degradation. Many repeaters are located on hilltops or on tall buildings as the higher location increases their coverage area, sometimes referred to as the radio horizon, or "footprint". Amateur radio repeaters are similar in concept to those used by public safety entities, businesses, government, military, and more. Amateur radio repeaters may even use commercially packaged repeater systems that have been adjusted to operate within amateur radio frequency bands, but more often amateur repeaters are assembled from receivers, transmitters, controllers, power supplies, antennas, and other components, from various sources.

<span class="mw-page-title-main">Unified S-band</span> Tracking and communication system developed by NASA and JPL

The Unified S-band (USB) system is a tracking and communication system developed for the Apollo program by NASA and the Jet Propulsion Laboratory (JPL). It operated in the S band portion of the microwave spectrum, unifying voice communications, television, telemetry, command, tracking and ranging into a single system to save size and weight and simplify operations. The USB ground network was managed by the Goddard Space Flight Center (GSFC). Commercial contractors included Collins Radio, Blaw-Knox, Motorola and Energy Systems.

AMSAT-OSCAR 16, also known as AO-16 and PACSAT, is the in-orbit name designation of an amateur radio satellite of the OSCAR series. It was built by AMSAT and was launched on 22 January 1990 from Kourou, French Guiana on an Ariane 4 launch vehicle. It is in Sun synchronous low Earth orbit.

An amateur radio satellite is an artificial satellite built and used by amateur radio operators. It forms part of the Amateur-satellite service. These satellites use amateur radio frequency allocations to facilitate communication between amateur radio stations.

<span class="mw-page-title-main">OSCAR 4</span> Amateur radio satellite

OSCAR IV was the fourth amateur radio satellite launched by Project OSCAR and the first targeted for Geostationary orbit on 12 December 1965. The satellite was launched piggyback with three United States Air Force satellites on a Titan IIIC launch vehicle. Due to a booster failure, OSCAR 4 was placed in an unplanned and largely unusable Geostationary transfer orbit.

<span class="mw-page-title-main">LituanicaSAT-1</span>

LituanicaSAT-1 was one of the first two Lithuanian satellites. It was launched along with the second Cygnus spacecraft and 28 Flock-1 CubeSats aboard an Antares 120 carrier rocket flying from Pad 0B at the Mid-Atlantic Regional Spaceport on Wallops Island to the International Space Station. The launch was scheduled to occur in December 2013, but later was rescheduled to 9 January 2014 and occurred then. The satellite was broadcasting greetings of Lithuanian president, Mrs. Dalia Grybauskaitė. The satellite was deployed from the International Space Station via the NanoRacks CubeSat Deployer on 28 February 2014. All LituanicaSAT-1 subsystems have been turned on, tested and proved to be working properly. The mission is considered a complete success by its team of engineers. The mission ended upon the reentry and disintegration of the satellite on 28 July 2014.

<span class="mw-page-title-main">FUNcube-1</span>

FUNcube-1 is a complete educational single unit CubeSat satellite with the goal of enthusing and educating young people about radio, space, physics and electronics. It is part of a program which aims to launch more of these educational CubeSats. It is the first satellite with outreach as its primary mission.

<span class="mw-page-title-main">Es'hail 2</span>

Es'hail 2 is a Qatari satellite, launched aboard a SpaceX Falcon 9 rocket on November 15, 2018. Es'hail 2 was built by Japan's Mitsubishi Electric company, and operates at 26° East longitude along a geostationary orbit to provide direct-to-home television services in the Middle East and North Africa region. The satellite features 24 Ku-band and 11 Ka-band transponders to provide direct broadcasting services for television, government and commercial content distribution. In addition to commercial services, the payload of Es'hail 2 includes a linear transponder with a bandwidth of 500 kHz and 8 MHz for the amateur radio satellite service, with uplink on 2.4 GHz and downlink on 10.45 GHz.

<span class="mw-page-title-main">C band (IEEE)</span> Range of radio frequencies from 4 to 8 GHz

The C band is a designation by the Institute of Electrical and Electronics Engineers (IEEE) for a portion of the electromagnetic spectrum in the microwave range of frequencies ranging from 4.0 to 8.0 gigahertz (GHz). However, the U.S. Federal Communications Commission C band proceeding and auction, designated 3.7–4.2 GHz as C band. The C band is used for many satellite communications transmissions, some cordless telephones, as well as some radar and weather radar systems.

Fox-1D, AO-92 or AMSAT OSCAR 92 was an American amateur radio satellite. Fox-1D was a 1U CubeSat developed and built by AMSAT-NA. Fox-1D carried a single-channel transponder for mode U/V in FM. Fox-1D had an L-band converter, which allowed the FM transponder to be switched on an uplink in the 23 centimetres (9.1 in) band.

Fox-1B, AO-91 or AMSAT OSCAR 91 is a United States amateur radio satellite. It is a 1U Cubesat, was built by the AMSAT-NA and carries a single-channel transponder for FM radio. The satellite has a whip antenna for the 70 cm and 23 cm bands (uplink), and a second antenna for the 2 m band (downlink). Fox-1B is the second amateur radio satellite of the Fox series of AMSAT North America.

OSCAR 8 is an American amateur radio satellite. It was developed and built by radio amateurs of the AMSAT and launched on March 5, 1978 as a secondary payload together with the Earth observation satellite Landsat 3 from Vandenberg Air Force Base, California, United States.

Weber-OSCAR 18 is an American amateur radio satellite.

Fox-1E, AO-109 or AMSAT OSCAR 109 is an American amateur radio satellite. It is a 1U Cubesat, was built by the AMSAT-NA and carries a 30KHz linear transponder radio. Fox-1E is the fifth amateur radio satellite of the Fox series of AMSAT North America.

References

  1. 1 2 Kołodziej, Andrzej (2015-05-15). "Jak Solidarność Walcząca wykorzystała satelitę do zbudowania systemu łączności" [How Fighting Solidarity used a satellite to build a communication system]. nowahistoria.interia.pl (in Polish). Retrieved 2017-04-28.
  2. ↑ "Venerable AO-7 Satellite Approaching a Return to Full Solar Illumination". The National Association of Amateur Radio. September 20, 2020. Retrieved April 8, 2023.
  3. ↑ ARRL staff (24 June 2006). "ARRLWeb: It's Aliiiiive! AMSAT-OSCAR 7 Satellite Returns from the Dead". American Radio Relay League. Archived from the original on 4 November 2005. Retrieved 26 September 2010.
  4. 1 2 "AMSAT - Satellite Detail - AMSAT-OSCAR 7". AMSAT. 6 April 2006. Archived from the original on 5 June 2011. Retrieved 1 March 2008.
  5. ↑ "AMSAT-OSCAR 7 Satellite Summary". AMSAT. 31 May 2003. Archived from the original on 21 December 2009. Retrieved 16 December 2009.
  6. ↑ Klein, Perry (October 1975). "Intersatellite communication using the AMSAT-OSCAR 6 and AMSAT-OSCAR 7 radio amateur satellites". IEEE Proceedings. 63 (10). IEEE: 1526–1527. Bibcode:1975IEEEP..63.1526K. doi:10.1109/PROC.1975.9988. S2CID   41507183.
  7. ↑ FCC Safety and Special Action (19 April 1974). "FCC waiver for AMSAT AO-7, Oscar 7". Archived from the original on 22 January 2023.
  8. ↑ "AMSAT Live OSCAR Satellite Status Page". Radio Amateur Satellite Corporation. Retrieved 2022-01-10.
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