Many amateur satellites receive an OSCAR designation, which is an acronym for Orbiting Satellite Carrying Amateur Radio. The designation is assigned by AMSAT, an organization which promotes the development and launch of amateur radio satellites. Because of the prevalence of this designation, amateur radio satellites are often referred to as OSCARs.
These satellites can be used free of charge by licensed amateur radio operators for voice (FM, SSB) and data (AX.25, packet radio, APRS) communications. Currently, over 18 fully operational amateur radio satellites are in orbit.[2] They may be designed to act as repeaters, as linear transponders, and as store and forward digital relays.
Amateur radio satellites have helped advance the science of satellite communications. Contributions include the launch of the first satellite voice transponder (OSCAR 3) and the development of highly advanced digital"store-and-forward" messaging transponder techniques.
The Amateur Radio Satellite community is very active in building satellites and in finding launch opportunities. Lists of functioning satellites need updating regularly, as new satellites are launched and older ones fail. Current information is published by AMSAT. AMSAT has not been actively involved in the launch and operation of most amateur satellites in the last two decades beyond allocating an OSCAR number.
First amateur radio satellite OSCAR 1, launched in 1961Simple OSCAR beacon signal, 1962
The first amateur satellite, simply named OSCAR 1, was launched on December 12, 1961, barely four years after the launch of the world's first satellite, Sputnik I. The satellite had to be built in a very specific shape and weight, so it could be used in place of one of the launch vehicle ballast weights. OSCAR 1 was the first satellite to be ejected as a secondary payload (the primary payload was Discoverer 36) and to subsequently enter a separate orbit. It carried no on-board propulsion and its orbit decayed quickly. Despite orbiting for only 22 days, OSCAR 1 was an immediate success and led to follow-on missions. Over 570 amateur radio operators in 28 countries forwarded observations to Project OSCAR.
OSCAR 10
Most of the components for OSCAR 10 were "off the shelf". Jan King led the project. Solar cells were bought in batches of 10 or 20 from Radio Shack, and tested for efficiency by group members. The most efficient cells were kept for the project; the rest were returned to RadioShack. Once ready, OSCAR 10 was mounted aboard a private plane, and flown a couple of times to evaluate its performance and reliability. Special QSL cards were issued to those who participated in the airplane-based tests. Once it was found to be operative and reliable, the satellite was shipped to Kennedy Space Center, where it was mounted in the launch vehicle's third stageWhich one. OSCAR 10's dimensions were: Height: 1.35 m (53in) Width: 2.0 m (78.75in) Weight: 140kg at launch; 90kg post engine firings.[3]
Other satellites
USSR postal stamp depicting amateur radio satellitе RS-2
Es’hail 2 / QO-100 [4] Launched November 15, 2018.In geostationary orbit covering Brazil to Thailand.
Narrowband Linear transponder
2400.050 - 2400.300MHz Uplink
10489.550 - 10489.800MHz Downlink
Wideband digital transponder
2401.500 - 2409.500MHz Uplink
10491.000 - 10499.000MHz Downlink
Hardware
The first amateur satellites contained telemetry beacons. Since 1965, most OSCARs carry a linear transponder for two-way communications in real time. Some satellites have a bulletin board for store-and-forward digital communications, or a digipeater for direct packet radio connections.
Currently, amateur satellites support many different types of operation, including FM voice and SSB voice, as well as digital communications of AX.25FSK (Packet radio) and PSK-31.
Mode designators
Uplink and downlink designations use sets of paired letters following the structure X/Y where X is the uplink band and Y is the downlink band. Occasionally, the downlink letter is rendered in lower case (i.e., X/y). With a few exceptions, the letters correspond to IEEE's standard for radar frequency letter bands...[5]
Prior to the launch of OSCAR 40, operating modes were designated using single letters to indicate both uplink and downlink bands. While deprecated, these older mode designations are still widely used in casual conversation.
Due to the high orbital speed of the amateur satellites, the uplink and downlinkfrequencies will vary during the course of a satellite pass. This phenomenon is known as the Doppler effect. While the satellite is moving towards the ground station, the downlink frequency will appear to be higher than normal. Hence, the receiver frequency at the ground station must be adjusted higher to continue receiving the satellite. The satellite in turn, will be receiving the uplink signal at a higher frequency than normal so the ground station's transmitted uplink frequency must be lower to be received by the satellite. After the satellite passes overhead and begins to move away, this process is reversed. The downlink frequency will appear lower and the uplink frequency will need to be adjusted higher. The following mathematical formulas relate the Doppler shift to the velocity of the satellite.
Where:
=
doppler corrected downlink frequency
=
doppler corrected uplink frequency
=
original frequency
=
velocity of the satellite relative to ground station in m/s. Positive when moving towards, negative when moving away.
Due to the complexity of finding the relative velocity of the satellite and the speed with which these corrections must be made, these calculations are normally accomplished using satellite tracking software. Many modern transceivers include a computer interface that allows for automatic doppler effect correction. Manual frequency-shift correction is possible, but it is difficult to remain precisely near the frequency. Frequency modulation is more tolerant of doppler shifts than single-sideband, and therefore FM is much easier to tune manually.
FM satellites
Yagi antenna being used to communicate through an FM satellite.
A number of low Earth orbit (LEO) OSCAR satellites use frequency modulation (FM).[6] These are also commonly referred to as "FM LEOs" or the "FM Birds". Such satellites act as FM amateur radio repeaters that can be communicated through using commonly available amateur radio equipment. Communication can be achieved with handheld transceivers using manual doppler correction.[7] Satellite passes are typically less than 15 minutes long.[8]
Launches
Past launches
The names of the satellites below are sorted in chronological order by launch date, ascending. The status column denotes the current operational status of the satellite. Green signifies that the satellite is currently operational, orange indicates that the satellite is partially operational or failing. Red indicates that the satellite is non operational and black indicates that the satellite has re-entered the Earth's atmosphere (or never successfully left it). The country listing denotes the country that constructed the satellite and not the launching country.
SuitSat, an obsolete Russian space suit with a transmitter aboard, was officially known as "AMSAT-OSCAR 54". Coincidentally, "Oscar" was the name given to an obsolete space suit by its young owner in the 1958 novel Have Space Suit—Will Travel, by Robert A. Heinlein. This book was first published a year after the launch of Sputnik 1, the world's first artificial satellite.
This radiocommunication service is classified in accordance with ITU Radio Regulations (article 1) as follows: Radiocommunication service (article 1.19)
The allocation of radio frequencies is provided according to Article 5 of the ITU Radio Regulations (edition 2012).[13]
In order to improve harmonisation in spectrum utilisation, the majority of service-allocations stipulated in this document were incorporated in national Tables of Frequency Allocations and Utilisations which is within the responsibility of the appropriate national administration. The allocation might be primary, secondary, exclusive, and shared.
primary allocation: is indicated by writing in capital letters (see example below)
secondary allocation: is indicated by small letters (see example below)
exclusive or shared utilization: is within the responsibility of national administrations
RADIOLOCATIONY Amateur Amateur-satellite Space research (space-to-Earth)
77.5–78 AMATEUR
AMATEUR-SATELLITE Radio astronomy Space research (space-to-Earth)
78–79 RADIOLOCATION
Amateur Amateur-satellite Radio astronomy Space research (space-to-Earth)
79–81 RADIOLOCATION
RADIO ASTRONOMY Amateur Amateur-satellite Space research (space-to-Earth)
134–136 AMATEUR
AMATEUR-SATELLITE Radio astronomy
136–141 RADIO ASTRONOMY
RADIOLOCATION Amateur Amateur-satellite
241–248 RADIO ASTRONOMY
RADIOLOCATION Amateur Amateur-satellite
248–250 AMATEUR
AMATEUR-SATELLITE Radio astronomy
Additional allocations
In addition to the formal allocations in the main table such as above, there is also a key ITU-R footnote RR 5.282 that provides for additional allocations:-
5.282 In the bands 435-438 MHz, 1 260-1 270 MHz, 2 400-2 450 MHz, 3 400-3 410 MHz (in Regions 2 and 3 only)
and 5 650-5 670 MHz, the amateur-satellite service may operate subject to not causing harmful interference to other
services operating in accordance with the Table (see No. 5.43). Administrations authorizing such use shall ensure that
any harmful interference caused by emissions from a station in the amateur-satellite service is immediately eliminated
in accordance with the provisions of No. 25.11. The use of the bands 1 260-1 270 MHz and 5 650-5 670 MHz by the
amateur-satellite service is limited to the Earth-to-space direction.
Of these, the 435-438MHz band is particularly popular for amateur/educational small satellites such as Cubesats.
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).
The L band is the Institute of Electrical and Electronics Engineers (IEEE) designation for the range of frequencies in the radio spectrum from 1 to 2 gigahertz (GHz). This is at the top end of the ultra high frequency (UHF) band, at the lower end of the microwave range.
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.
A communications satellite's transponder is the series of interconnected units that form a communications channel between the receiving and the transmitting antennas. It is mainly used in satellite communication to transfer the received signals.
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.
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.
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.
TurkSat-3USat is a Turkish communications nanosatellite developed by the Space Systems Design and Test Laboratory and Radio Frequency Electronics Laboratory of Istanbul Technical University (ITU) in collaboration with the Türksat company along with Turkish Amateur Satellite Technology Organization (TAMSAT). It was launched on 26 April 2013.
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.
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.
X band or SHF Satellite Communication is widely used by military forces for beyond line of sight communications. X band is used because it provides a compromise between the characteristics of different frequency bands which is particularly suited to the needs of military users. The characteristics include interference and rain resilience, terminal size, data rates, remote coverage and whether it is reserved for governmental use.
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.
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.
PSAT-2 is an experimental amateur radio satellite from the U.S. Naval Academy, which was developed in collaboration with the Technical University of Brno in Brno, Czech Republic. AMSAT North America's OSCAR number administrator assigned number 104 to this satellite; in the amateur radio community it is therefore also called Navy-OSCAR 104, short NO-104.
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.
References
↑ ITU Radio Regulations, Section IV. Radio Stations and Systems – Article 1.57, definition: amateur-satellite service / amateur-satellite radiocommunication service
↑ John A. Magliacane, KD2BD. "AMSAT Spotlight". Archived from the original on 1996-10-28.{{cite web}}: CS1 maint: bot: original URL status unknown (link) CS1 maint: numeric names: authors list (link)
↑ ITU Radio Regulations, Section IV. Radio Stations and Systems – Article 1.57, definition: amateur-satellite service / amateur-satellite radiocommunication service
↑ ITU Radio Regulations, CHAPTER II – Frequencies, ARTICLE 5 Frequency allocations, Section IV – Table of Frequency Allocations
Martin Davidoff: The Radio Amateur's Satellite Handbook. The American Radio Relay League, Newington, ISBN978-0-87259-658-0.
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