07 April, 2021

Now active via the International Space Station

I happened to set my 2m receiver to the APRS (Automatic Packet Reporting System) frequency of the International Space Station (ISS), 145.825 MHz, and lo and behold stations in Central and Southern Europe started to appear. This is not rocket science, but for me it's a first. (Well actually the ISS is a kind of rocket ...)

Here in Oslo, using the local APRS service, I can also receive Swedish and Danish stations when conditions are good, but never Spain, Italy, Greece, Romania, Ukraine, Russia or Turkey. When a message appeared from NA1SS itself, the station onboard the ISS, I felt that I had really nailed it (see image). But ISS had more in store for me.

I'm using a Yaesu FTM-350 with a built-in APRS decoder. The antenna is a roof mounted HL-B61N vertical (1.7 m long). It fits well with the low elevation angle of the ISS from here of maximum 21 degrees. This is because I am at 59.8 degrees N and the inclination of the ISS is only 51.6 degrees. There are about three passes per day when the ISS is within range and at its closest it is about 1030 km away. 

After some fiddling with the setup I actually managed to transmit to the ISS also. It took me some passes to realize that it is necessary to set "ARISS" as the digi path in the APRS setup. I was then received both by myself and others. 

That felt like quite some achievement and will probably be the furthest I will ever communicate with this rig. As seen below, I was received in Austria, Germany, and Norway and relayed to the internet and the wonderful service of aprs.fi. My transmitter was keyed manually and set for High output (50 Watts).

The passes are predicted by the Heavens Above website, and a plot of the ground track can be found using the ESA  tracker. The amateur stations on the ISS are not always active and the status update page has the latest information.

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