Setup Your Radio For The ISS Crossband Repeater

Programming Your Radio For The ISS Crossband Repeater

ISS (listen) 437.800 MHz cross band FM repeater activated

The new crossband repeater on the ISS has an uplink frequency of 145.990 mHz and a downlink frequency of 437.800 mHz. In order to access the crossband repeater, it requires a 67 Hz tone on your radio. Also this is an FM repeater. The best way to handle doppler is to pre-program the frequencies into your radio

Is the ISS 437.800 MHz cross band Repeater activated?

Initial operation of the new radio system is in FM cross band repeater mode using an uplink frequency of 145.990 MHz with an access tone [CTCSS] of 67 Hz and a downlink frequency of 437.800 MHz. 

As of September 2, 2020, the new FM Crossband repeater on board the International Space Station is activated.  The System activation was observed at 01:02 UTC on September 2. Special operations will continue to be announced. 

This is great news as it has been quite a while since anything significant has happened with Ham radio on board the ISS. Early reports indicate that the receiver is quite sensitive and can be used with just an handheld such as a Baofeng.

If you have never done any space communications via ham radio, there are some things to get acquainted with. The most important one is Doppler Shift. This can be a bit tricky. What is happening is that as ISS is moving and transmitting, you have to have to adjust your receive/downlink frequency. It is the same phenomenon as a passing train blowing its whistle, and you hear the tone of the whistle drop as it passes by you. In the case of the ISS, what you have to do is to listen a little bit higher when it is coming at you. 

As it is more overhead, you will hear it become noisy in your receiver. Just tune down 5 kHz, and you wil hear it. As the ISS moves away from you, you will have to tune down another 5 kHz.

Below is a screenshot of a portion of my chirp file for my FT-857. I have programmed 5 channels for the ISS Crossband Repeater. This allows me to easily adjust for doppler as things get quite busy when working the ISS Crossband repeater.

enjoy.