Amateur Radio – ISS

An amateur radio satellite is an artificial satellite built and used by amateur radio operators for use in the Amateur Radio service. They use amateur radio frequencies allocations to facilitate communication between amateur radio stations.

They can be used for free by licensed amateur radio operators for voice (FM, SSB) and data communications (AX.25, packet radio, APRS). Currently, over 5 fully operational amateur satellites in orbit act as repeaters, linear transponders or store and forward digital relays.

Throughout the years, amateur satellites have helped make 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.

Orbiting Satellite Carrying Amateur Radio

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.

For more information and operational Amateur Radio satellites, see

Amateur Radio on the International Space Station – ARISS

The ARISS program was created and is managed by an international consortium of amateur radio organizations and space agencies including National Aeronautics and Space Administration (NASA) in the USA, Rosaviakosmos in Russia, Canadian Space Agency (CSA) in Canada, Japan Aeronautics Exploration Space Agency (JAXA) in Japan and European Space Agency (ESA) in Europe.

The first Amateur Radio equipment was delivered to the International Space Station (ISS) in September 2000 and an Amateur Radio station was established onboard for use by Astronauts who are licenced Radio Amateurs. Commander William Shepherd, KD5GS, made the first Amateur contacts in November of that year.

Most of the astronauts on the International Space Station are licenced Radio Amateurs and sometimes during their spare time they talk to other Radio Amateurs back on earth. There is a special thrill in talking to an astronaut out in space!

What equipment do you need?

Almost any 144 MHz FM rig will receive the ISS, you can even use a general coverage VHF scanner with an external antenna. As far as the antenna is concerned the simpler the better. A ¼ wave ground plane has a high angle of radiation and works well. Large 144 MHz colinears are not as good because the radiation pattern is concentrated at the horizon while the ISS is above 15 degrees elevation for most of a pass.

You can receive the ISS outdoors using a 144 MHz hand-held with its helical antenna but a 1/4 wave whip will give far better results.

The ISS transmits using the 5 kHz deviation, used in much of the world. Most rigs can be switched been wide and narrow deviation filters so select the wider deviation. Hand-held rigs all seem to have a single wide filter fitted as standard.

What will you hear?

Much of the time the Space Station equipment operates in “automatic mode”. It can act as an AX.25 APRS Packet Repeater, voice repeater or transmit Slow Scan Television (SSTV) pictures. Voice and SSTV transmissions take place on 145.800 MHz FM, the AX.25 packet may be heard on 437.550 MHz.

The aim to start with is simply to listen to the sounds from the satellite. You can check the current mode of operation on the ISS Fan Club website.

The ISS amateur radio station is used for school contacts. These educational contacts enable students to communicate directly via Amateur Radio with the Astronauts and ask them questions.

When the astronauts put out a CQ call they also use 145.800 MHz FM but operate “split” listening for replies 600 kHz lower on 145.200 MHz. If you are lucky and hear them calling CQ just remember to activate your rigs repeater shift to ensure you reply on the correct frequency. You should never transmit on 145.800 MHz.

When to listen

The ISS is in a very low orbit and so is only in range 5 or 6 times each day and then only for a maximum of 10 minutes on the best orbit. This means you need to make sure you’re listening at the right time to hear it. There are a number of software and websites that tell you when to listen. Check out the software page or you can use the orbital predictions on the ISS Fan Club site.

ISS Amateur Radio Frequencies

FM VOICE for ITU Region 1: Europe-Middle East-Africa-North Asia

  • Downlink 145.800
  • Uplink 145.200

FM VOICE for ITU Region 2&3: North and South America-Caribbean-Greenland-Australia-South Asia

  • Downlink 145.800
  • Uplink 144.490

FM U/v VOICE Repeater (Worldwide)

  • Downlink 145.800
  • Uplink 437.800

FM V/u with PL VOICE Repeater (Worldwide)

  • Downlink 437.800
  • Uplink 145.990 with 67.0 PL

FM L/v VOICE Repeater (Worldwide)

  • Downlink 145.800
  • Uplink 1269.650

AX.25 1200 Bd AFSK Packet Radio (Worldwide)

  • Downlink 145.825
  • Uplink 145.825

For information on APRS on the ISS, please click here.

FM SSTV downlink (Worldwide)

  • Downlink 145.800

UHF Simplex (rarely used)

  • Downlink 437.550
  • Uplink 437.550
Other Notable ISS/Soyuz-TM Frequencies

143.625 FM – ISS VHF-1 – Main communications channel.

130.167 FM – ISS VHF-2 – Soyuz-TM VHF-1 – RS EVA

121.750 FM – Soyuz-TM VHF-2 – RS EVA

121.125 FM – RS EVA Ops

463.000 FM – RS TV