ARISS Next Generation Radio System

Picture of ISS

ARISS Next Generation Radio System

Last Updated on May 14, 2021

On the second of September 2020, ARISS announced that the setup and installation of the first element of our next generation amateur radio system had been completed and amateur radio operations are now possible. This first element, dubbed the InterOperable Radio System (IORS), was installed in the International Space Station Columbus module. The IORS replaces the Ericsson radio system and packet module that were originally certified for spaceflight on July 26, 2000.

IORS Hardware on the ISS for Amateur Radio use

IORS Hardware on the ISS for Amateur Radio use

This has proven to be very popular in the early days of use by Australian amateur radio operators.

The initial operation of the new radio system is in FM cross-band repeater mode using an uplink frequency of 145.99 MHz with an access tone of 67 Hz and a downlink frequency of 437.800 MHz. System activation was first observed at 01:02 UTC on September 2.

The IORS was launched from Kennedy Space Center on March 6, 2020, on board the SpaceX CRS-20 resupply mission. It consists of a special, space-modified JVC Kenwood D710GA transceiver, an ARISS developed multi-voltage power supply, and interconnecting cables. The design, development, fabrication, testing, and launch of the first IORS was an incredible five-year engineering achievement accomplished by the ARISS hardware volunteer team. It will enable new, exciting capabilities for ham radio operators, students, and the general public. Capabilities include a higher power radio, voice repeater, digital packet radio (APRS) capabilities, and a Kenwood VC-H1 slow-scan television (SSTV) system.

In the photo below you can see the three antennas mounted on the Russian Zvezda Service Module.

Three antennas on the Russian Zvezda Service Module.

The ISS actually features four different vertical antennas on the spacecraft. They are made of flexible metal tape that is coated in Kapton, a polyimide film that can withstand extreme temperatures.

Antenna mounts for the VHF UHF antennas on the ISS

Antenna mounts for the VHF/UHF antennas on the ISS.


Three of the four antennas are identical and measure 0.5-meter (1.5 feet) in length and each can support both transmit and receive operations on 2 meters, 70 cm, L-band, and S-band. The numerous antennas help provide redundancy in case of an antenna failure. The fourth antenna has a 2.5-meter (8 foot) long vertical whip that can be used to support High Frequency (HF) operations, particularly on 10 meters. However, no HF radio is currently aboard the space station.

The video below shows the ISS pass over Melbourne on September 4 2020 and the contact through the newly installed repeater.

The insert in the corner shows you where the #ISS is at the same time you can hear the contacts and see the signal strength on the radio. The antenna is a 5 element horizontal yagi. No preamps and the results are S9+ signals most of the time.

The doppler is +/- 10kHz as the ISS is only 400km or so up. At the start of the pass, it’ll be 437.81 and by the end, it’ll be 437.79 MHz. Take this into account when you’re listening for it.

Mode: FM Voice Uplink Frequency: 145.990 MHz, PL 67.0 Hz
Downlink Frequency: 437.800 MHz

The ISS and VK amateur radio is a popular combination. It will be interesting to see if this trend continues.

A second IORS undergoes flight certification and will be launched later for installation in the Russian Service module. This second system enables dual, simultaneous operations, (e.g. voice repeater and APRS packet), providing diverse opportunities for radio amateurs. It also provides on-orbit redundancy to ensure continuous operations in the event of an IORS component failure.

Next-gen development efforts continue. For the IORS, parts are being procured and a total of ten systems are being fabricated to support flight, additional flight spares, ground testing and astronaut training. Follow-on next-generation radio system elements include an L-band repeater uplink capability, currently in development, and a flight Raspberry-Pi, dubbed “ARISS-Pi,” that is just beginning the design phase.  The ARISS-Pi promises operations autonomy and enhanced SSTV operations.

Source: arris.org and K0LWC