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 (FM, SSB) and data communications (AX.25, packet radio, APRS). Currently over 20 fully operational satellites in orbit act as repeaters, linear transponders or store and forward digital relays.

Throughout the years OSCAR satellites have helped make significant breakthroughs in the science of satellite communications. A few advancements include the launch of the first satellite voice transponder (OSCAR 3) and the development of highly advanced digital "store-and-forward" messaging transponder techniques. To date, over 70 OSCARs have been launched with more to be launched in the future.



USSR postal stamp depicting amateur radio satellite

The first amateur satellite, simply named OSCAR 1, was launched on December 12, 1961, barely four years after the launch of world's first satellite, Sputnik I. OSCAR 1 was the first satellite to be ejected as a secondary payload and subsequently enter a separate orbit. Despite being in orbit for only 22 days OSCAR 1 was an immediate success with over 570 amateur radio operators in 28 countries forwarding observations to Project OSCAR.

OSCAR satellite communications

Currently OSCAR satellites support many different types of operation including FM voice, SSB voice, as well as digital communications of AX.25 FSK (Packet radio) and PSK-31.

Mode designators

Historically OSCAR uplink (transmit to) and downlink (receive from) frequencies were designated using single letter codes.
  • Mode A: 2 m uplink / 10 m downlink
  • Mode B: 70 cm uplink / 2 m downlink
  • Mode J: 2 m uplink / 70 cm downlink
New 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.
Band 15 m 10 m 2 m 70 cm 23 cm 13 cm 9 cm 5 cm 3 cm 1.2 cm 6 mm
21 MHz 29 MHz 145 MHz 435 MHz 1.2 GHz 2.4 GHz 3.4 GHz 5 GHz 10 GHz 24 GHz 47 GHz

Doppler shift

Due to the high orbital speed of the OSCAR satellites, the uplink and downlink frequencies 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 and therefore, the receiver frequency at the ground station must be adjusted higher in order 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 in order to be received by the satellite. After the satellite passes overhead and begins to move away, this process reverses itself. 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.

fd = doppler corrected downlink frequency
fu = doppler corrected uplink frequency
f = original frequency
v = velocity of the satellite relative to ground station in m/s.
Positive when moving towards, negative when moving away.
c = the speed of light in a vacuum (3\times10^8  m/s).
Change in frequency Downlink Correction Uplink Correction
\Delta f=f\times\frac{v}{c}

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.

Satellites previously launched

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. The country listing denotes the country that constructed the satellite and not the launching country.

Name (a.k.a) Status Launched Country
OSCAR (OSCAR 1) Decayed 1961-12-12 USA
OSCAR II (OSCAR 2) Decayed 1962-06-02 USA
OSCAR III (OSCAR 3, EGRS-3) Non-Operational 1965-03-09 USA
OSCAR IV (OSCAR 4) Decayed 1965-12-21 USA
Australis-OSCAR 5 (OSCAR 5, AO-5, AO-A) Non-Operational 1970-01-23 Australia
AMSAT-OSCAR 6 (OSCAR 6, AO-6, AO-C, P2A) Non-Operational 1972-10-15 USA
AMSAT-OSCAR 7 (OSCAR 7, AO-7, AO-B, P2B) Semi-Operational 1974-11-15 USA
AMSAT-OSCAR 8 (OSCAR 8, AO-8, AO-D, P2D) Non-Operational 1978-03-05 USA/Canada/Germany/Japan
UoSat-OSCAR 9 (UOSAT 1, UO-9) Decayed 1981-10-06 UK
AMSAT-OSCAR 10 (Phase 3B, AO-10, P3B) Non-Operational 1983-06-16 USA/Germany
UoSat-OSCAR 11 (UoSat-2, UO-11, UoSAT-B) Semi-Operational 1984-03-01 UK
Fuji-OSCAR 12 (JAS 1, FO-12) Non-Operational 1986-08-12 Japan
AMSAT-OSCAR 13 (Phase 3C, AO-13, P3C) Decayed 1988-06-15 Germany
UOSAT-OSCAR 14 (UoSAT-3, UO-14 UoSAT-D) Non-Operational 1990-01-22 UK
UOSAT-OSCAR 15 (UoSAT-4, UO-15, UoSAT-E) Non-Operational 1990-01-22 UK
AMSAT-OSCAR 16 (Pacsat, AO-16, Microsat-1) Semi-Operational 1990-01-22 USA
Dove-OSCAR 17 (Dove, DO-17, Microsat-2) Non-Operational 1990-01-22 Brazil
Weber-OSCAR 18 (WeberSAT, WO-18, Microsat-3) Non-Operational 1990-01-22 USA
LUSAT-OSCAR 19 (LUSAT, LO-19, Microsat-4) Non-Operational 1990-01-22 Argentina
Fuji-OSCAR 20 (JAS 1B, FO-20, Fuji-1B) Non-Operational 1990-02-07 Japan
AMSAT-OSCAR 21 (RS-14, AO-21, Informator-1) Non-Operational 1991-01-29 Russia
Radio Sputnik 12 Non-Operational 1991-02-05 Russia
Radio Sputnik 13 Non-Operational 1991-02-05 Russia
UoSat-OSCAR 22 (UOSAT 5, UO-22 UoSAT-F) Non-Operational 1991-07-17 UK
KitSAT-OSCAR 23 (KITSAT 1, KO-23, Uribyol-1) Non-Operational 1992-08-10 Korea
Arsene-OSCAR 24 (Arsene, AO-24) Non-Operational 1993-05-12 France
KitSAT-OSCAR 25 (KITSAT B, KO-25, Kitsat-2, Uribyol-2) Non-Operational 1993-09-26 Korea
Italy-OSCAR 26 (ITAMSAT, IO-26) Non-Operational 1993-09-26 Italy
AMRAD-OSCAR 27 (EYESAT-1, AO-27) Operational 1993-09-26 USA
POSAT-OSCAR 28 (POSAT, PO-28, Posat-1) Non-Operational 1993-09-26 Portugal
Radio Sputnik 15 (RadioSkaf-15, RS-15, Radio-ROSTO) Semi-Operational 1994-12-26 Russia
Fuji-OSCAR 29 (JAS 2, FO-29, Fuji-2) Semi-Operational 1996-08-17 Japan
Mexico-OSCAR 30 (UNAMSAT-2, MO-30, Unamsat-B, Kosmos-2334) Non-Operational 1996-09-05 Mexico/Russia
Thai-Microsatellite-OSCAR 31 (TMSAT-1, TO-31) Non-Operational 1998-07-10 Thailand
Gurwin-OSCAR 32 (GO-32, Gurwin-1b, Techsat-1b) Non-Operational 1998-07-10 Israel
SEDSat-OSCAR 33 (SEDSat, SO-33, SEDsat-1) Semi-Operational 1998-10-24 USA
Pansat-OSCAR 34 (PAN SAT, PO-34) Non-Operational 1998-10-29 USA
ARISS (ARISS) Operational International
Sunsat-OSCAR 35 (SUNSAT, SO-35) Non-Operational 1999-02-23 South Africa
UoSat-OSCAR 36 (UOSAT 12, UO-36) Non-Operational 1999-04-21 UK
ASU-OSCAR 37 (AO-37, ASUsat-1, ASUSAT) Non-Operational 2000-01-27 USA
OPAL-OSCAR 38 (OO-38, StenSat, OPAL) Non-Operational 2000-01-27 USA
Weber-OSCAR 39 (WO-39, JAWSAT) Non-Operational 2000-01-27 USA
Saudi-OSCAR 41 (SO-41, Saudisat 1A) Non-Operational 2000-09-26 Saudi Arabia
Saudi-OSCAR 42 (SO-42, Saudisat 1B) Non-Operational 2000-09-26 Saudi Arabia
Malaysian-OSCAR 46 (MO-46, TIUNGSAT-1) Non-Operational 2000-09-26 Malaysia
AMSAT-OSCAR 40 (AO-40, Phase 3D, P3D) Non-Operational 2000-11-16 USA
Starshine-OSCAR 43 (SO-43, Starshine 3) Decayed 2001-09-30 USA
Navy-OSCAR 44 (NO-44, PCSat) Semi-Operational 2001-09-30 USA
Navy-OSCAR 45 (NO-45, Sapphire) Non-Operational 2001-09-30 USA
BreizhSAT-OSCAR 47 (BO-47, IDEFIX CU1) Non-Operational 2002-05-04 France
BreizhSAT-OSCAR 48 (BO-48, IDEFIX CU2) Non-Operational 2002-05-04 France
AATiS-OSCAR 49 (AO-49, Safir-M, RUBIN 2) Non-Operational 2002-12-20 Germany
Saudi-OSCAR 50 (SO-50, Saudisat-1C) Operational 2002-12-20 Saudi Arabia
CubeSat-OSCAR 55 (Cute-1) Operational 2003-06-30 Japan
CubeSat-OSCAR 57 (CubeSat-XI-IV) Operational 2003-06-30 Japan
CanX-1 Non-Operational 2003-06-30 Canada
DTUSat Decayed 2003-06-30 Denmark
AAU Cubesat Non-Operational 2003-06-30 Denmark
RS-22 (Mozhayets 4) Operational 2003-09-27 Russia
AMSAT-OSCAR 51 (Echo, AO-51) Semi-Operational 2004-06-28 USA
VUSat-OSCAR 52 (HAMSAT, VO-52, VUSat) Operational 2005-05-05 India / Netherlands
PCSat2 (PCSAT2) Decayed 2005-08-03 USA
AMSAT-OSCAR 54 (AO-54, SuitSat, Radioskaf) Decayed 2005-09-08 International
eXpress-OSCAR 53 (XO-53, SSETI Express) Non-Operational 2005-10-27 ESA
CubeSat-OSCAR 58 (CO-58, Cubesat XI-V) Operational 2005-10-27 Japan
UWE-1 Non-Operational 2005-10-27 Germany
NCube-2 Non-Operational 2005-10-27 Norway
CubeSat-OSCAR 56 (CO-56, Cute-1.7) Non-Operational 2006-02-21 Japan
K7RR-Sat Non-Operational 2006-07-26 USA
CP2 Non-Operational 2006-07-26 USA
HAUSAT 1 Non-Operational 2006-07-26 South Korea
ICE Cube 1 Non-Operational 2006-07-26 USA
ICE Cube 2 Non-Operational 2006-07-26 USA
ION Non-Operational 2006-07-26 USA
KUTESat Non-Operational 2006-07-26 USA
MEROPE Non-Operational 2006-07-26 USA
nCUBE 1 Non-Operational 2006-07-26
RINCON Non-Operational 2006-07-26 USA
SACRED Non-Operational 2006-07-26 USA
SEEDS Non-Operational 2006-07-26 Japan
Voyager Non-Operational 2006-07-26 USA
PicPot Non-Operational 2006-07-26 Italy
HITSat-OSCAR 59 (HITSat, HO-59) Non-Operational 2006-09-22 Japan
GeneSat-1 Operational 2006-12-16 USA
Navy-OSCAR 60 (RAFT, NO-60) Decayed 2006-12-21 USA
Navy-OSCAR 61 (ANDE, NO-61) Decayed 2006-12-21 USA
Navy-OSCAR 62 (FCAL, NO-62) Decayed 2006-12-21 USA
Libertad-1 Non-Operational 2007-04-17 Colombia
CAPE-1 Semi-Operational 2007-04-17 USA
CP3 Non-Operational 2007-04-17 USA
CP4 Non-Operational 2007-04-17 USA
Pehuensat-OSCAR 63 (PEHUENSAT-1, PO-63) Decayed 2007-10-01 Argentine
Delfi-OSCAR 64 (Delfi-C3, DO-64) Semi-Operational 2008-04-28 Netherlands
Cubesat-OSCAR 65 (Cute-1.7+APD II, CO-65) Operational 2008-04-28 Japan
Cubesat-OSCAR 66 (SEED II, CO-66) Operational 2008-04-28 Japan
COMPASS-1 Semi-Operational 2008-04-28 Germany
RS-30 (Yubileiny) Operational 2008-05-23 Russia
PRISM (HITOMI) Operational 2009-01-23 Japan
KKS-1 (KISEKI) Operational 2009-01-23 Japan
STARS (KUKAI) Unknown 2009-01-23 Japan
Castor Unknown 2009-07-30 USA
Pollux Non-Operational 2009-07-30 USA
Aggiesat2 Decayed 2009-07-30 USA
PARADIGM (BEVO-1) Decayed 2009-07-30 USA
Sumbandila-OSCAR 67 (SumbandilaSat, SO-67) Operational 2009-09-17 South Africa
SwissCube Operational 2009-09-23 Switzerland
ITUpSAT1 Operational 2009-09-23 Turkey
UWE-2 Operational 2009-09-23 Germany
BEESAT Operational 2009-09-23 Germany
Hope Oscar 68 (XW-1, HO-68) Non-Operational 2009-12-15 China
AubieSat-1 (AO-71) Operational 2011-10-28 USA

Low Earth Orbit FM OSCARs

A number of low earth orbit (LEO) OSCAR satellites use frequency modulation (FM). These are also commonly referred to as "FM LEO's" or the "FM Birds". Such satellites act as FM amateur radio repeaters that can be communicated through using omni-directional antennas and commonly available amateur radio equipment. Due to the relative ease of tuning FM as compared to SSB and the decreased distance of LEO satellites from earth stations communication can be achieved even with handheld transceivers and using manual doppler correction. The orbit of these satellites however causes the available time in which to communicate to be limited to only a few minutes per pass.

List of FM LEO satellites
Satellite name OSCAR
Uplink (MHz) Downlink (MHz) CTCSS (Hz) Status
Hope Oscar 68 &10000000000000068000000HO-68 145.825 FM 435.675 FM 67.0 Non-Operational
Sumbandila Oscar 671 &10000000000000067000000SO-67 145.875 FM 435.345 FM N/A Operational
AMSAT-OSCAR 512 &10000000000000051100000AO-51 145.880 FM 435.150 FM N/A Semi-Operational
AMSAT-OSCAR 512 &10000000000000051200000AO-51 145.920 FM 435.300 FM 67.0 Non-Operational
AMSAT-OSCAR 512 &10000000000000051299999AO-51 145.880 FM 2401.200 FM N/A Non-Operational
AMSAT-OSCAR 512 &10000000000000051399999AO-51 1268.700 FM 435.300 FM 67.0 Non-Operational
AMSAT-OSCAR 512 &10000000000000051500000AO-51 1268.700 FM 2401.200 FM 67.0 Non-Operational
Saudi-OSCAR 50 &10000000000000050000000SO-50 145.850 FM 436.795 FM 67.0
(74.4 to activate)
Saudi-OSCAR 41 &10000000000000041000000SO-41 145.850 FM 436.775 FM N/A Non-Operational
SUNSAT-OSCAR 35 &10000000000000035100000SO-35 145.825 FM 436.250 FM N/A Non-Operational
SUNSAT-OSCAR 35 &10000000000000035200000SO-35 436.291 FM 145.825 FM N/A Non-Operational
SUNSAT-OSCAR 35 &10000000000000035299999SO-35 1265.000 FM 436.2500 FM N/A Non-Operational
ISS3 &10000000000000000000000ARISS 437.800 FM 145.800 FM N/A Operational
AMRAD-OSCAR 274 &10000000000000027000000AO-27 145.850 FM 436.795 FM N/A Operational
AMSAT-OSCAR 16 &10000000000000016000000AO-16 145.920 FM 437.026 DSB-SC5 N/A Semi-Operational
UoSAT-OSCAR 14 &10000000000000014000000UO-14 145.975 FM 435.070 FM N/A Non-Operational
Note 1: SO-67 is in initial operational testing. Currently activated primarily on weekends.[1]

Note 2: AO-51 could operate as many as two repeaters at once, with different frequency pairs, but it is now limited to one pair. Due to failing batteries, AO-51's control team must manually upload control software after each eclipse to activate.[2][3]

Note 3: The ISS FM repeater is rarely activated.[4]

Note 4: AO-27 FM Repeater is active on 7.5% duty cycle only.[5]

Note 5: The AO-16 downlink transmits in DSB-SC instead of FM, but the satellite otherwise operates like the other FM Birds.[6][7]

Multinational effort

Currently 23 countries have launched an OSCAR satellite. These countries, in chronological order by date of launch, include: The United States of America, Australia, Spain, the United Kingdom, Japan, Brazil, Argentina, Pakistan, Russia, France, Portugal, Korea, Italy, Mexico, Israel, Thailand, South Africa, Malaysia, Saudi Arabia, Germany, India, Colombia, and the Netherlands.

Satellites in development

Related names

SuitSat, an obsolete Russian space suit with a transmitter aboard, is officially known as OSCAR 54. In a twist of fate, "Oscar" was the name given to an obsolete space suit by its young owner in the book Have Space Suit—Will Travel, by Robert A. Heinlein. This book was originally published a year after the launch of the first artificial satellite (Sputnik).


  1. ^ "SA AMSAT" (HTML). Southern African Amateur Radio Satellite Association. http://www.amsatsa.org.za/. Retrieved 7/27/2011. 
  2. ^ "AMSAT-OSCAR 51 (Echo)" (HTML). The Radio Amateur Satellite Corporation. http://www.amsat.org/amsat-new/satellites/satInfo.php?satID=1. Retrieved 7/26/2011. 
  3. ^ |url = http://www.amsat.org/amsat-new/echo/CTNews.php |title = AMSAT AO-51 Control Team News |publisher = AO-51 Command Team and Operations Group |format = HTML |archiveurl = |archivedate = |deadurl = |accessdate = 7/27/2011 |quote = }}
  4. ^ "ISS Fan Club" (HTML). ISS Fan Club. http://www.issfanclub.com/. Retrieved 7/27/2011. 
  5. ^ "Official AO-27 HomePage" (HTML). AO-27 Control Operators Association. http://www.ao27.org/AO27/index.shtml. Retrieved 7/27/2011. 
  6. ^ "2010 AMSAT Field Day Competition" (PDF). The Radio Amateur Satellite Corporation. 2010. p. 1. http://www.amsat.org/amsat-new/awards/2010fd.pdf. Retrieved 7/26/2011. "...the FM voice satellites like AMSAT-OSCAR 16, AMRAD-OSCAR-27, SaudiSat-Oscar-50, or AMSAT-OSCAR-51..." 
  7. ^ "AMSAT OSCAR 16 (PacSAT)" (HTML). The Radio Amateur Satellite Corporation. http://www.amsat.org/amsat-new/satellites/satInfo.php?satID=11. Retrieved 7/26/2011. "Mode FM Voice Repeater (Downlink is DSB. Operation is Intermittent)" 

External links

  • AMSAT Corporation a nonprofit corporation that coordinates construction and launch of the satellites
  • Project OSCAR organization that built "OSCAR-1"
  • NASA J-Track Amateur Track amateur satellites in real-time
  • SSTL Builders and operators of the UoSat series satellites
  • Work-Sat Work the FM satellites - with equipment most hams already own!

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