Friday, 18 October 2013

My APRS broadcasts received by the ISS

This evening I managed to successfully send some APRS messages to the International Space Station that were successfully digirepeated. It might not be a major technical achievement but after monitoring and decoding many passes in the past to now actually send something myself 300 miles up to something traveling at 5 miles/second left me feeling a little chuffed!

I screen capped the evidence from the website which documents Amateur Radio data digipeated by the ISS. In order to appear on the page, a position report in a valid APRS format must be received and then digipeated through the ISS system, then be heard by an internet gateway station, which then forwards it on to the APRS Internet System.

Okay it sounds a bit more impressive when put like that ;-)

The map showing received stations, M6GTG is me!
The detail of my report
List of stations with time stamps, showing me!
List of digirepeated messages
The equipment I used was very similar to that I used for the APRS IGate setup last month.

It consists of a small embedded PC running embedded XP, the sound card output was connected to the microphone input of my Baofeng UV-5R+ operating in VOX mode set to 145.825MHz. The radio was connected through my power/SWR meter in to the X-50 antenna. I used the UV-5R+ instead of the UV-3R since it has a little more power and better audio. I had a SWR of around 1:1.2 and outputting 4W.

The software I used was UISS from ON6MNU and the AGWPE packet engine. It has taken a little time to work out how to setup UISS into auto-beacon mode and putting in the time of the next decent pass (approx 45 degrees elevation) I set it to broadcast position and text data messages every 30 seconds.

The embedded PC running UISS
UV5R+ in VOX mode on 145.825MHz
The power meter showed 4W output, SWR about 1:1.2

I stood out in the dark, hoping to see the ISS pass over but the cloud cover was too thick and monitored using a handheld scanner. I heard my transmissions obviously and the ISS broadcasts as it repeated received messages, but I didn't know if any were mine till I got back to the PC.

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