Funcube Satellite Telemetry

Prompted by Michael’s effort at acquiring NOAA Weather Images I thought I’d see what other telemetry or data was easily and publicly available from satellites. Sever satellites operate amateur radio transponders and you can listen in on QSOs, but some also allow you obtain satellite and experiment telemetry.

My first attempt was to get the telemetry from Funcube-1 (AO-73).

FUNcube-1 is a complete educational single unit CubeSat satellite with the goal of enthusing and educating young people about radio, space, physics and electronics. It was launched in 2013. It transmits it’s telemetry data via BPSK and this is decoded by software provided by the team at https://funcube.org.uk/working-documents/funcube-telemetry-dashboard/ .

Setup

Since the pass was coming up within half an hour of having this bright idea I decided to use the equipment I had connected rather than hunt around for an SDR dongle. This meant that the input was the audio from my Yaesu FT-857 via a signalink USB Soundcard with an Diamond X-50 colinear at roof level as the antenna.

This is a poor setup for a couple of reasons. Firstly the bandwidth from the 857 is about 3kHz which isn’t enough to hold the signal from the satellite given the Doppler shift during the pass so I’d need to keep re-tuning. Secondly the co-linear antenna is designed for working terrestrial stations and has almost no reception overhead – so I’d loose the signal when it should be strongest as the satellite is overhead. And the transmitter is only using 300mW, but at least it’s line-of-sight!

I wanted to check that I was acquiring a signal with tools I was familiar with, so I fired up fldigi with the signalink as input and set the radio frequency about 10kHz above the transponder downlink frequency of 145.935 MHz. I also had set up the Funcube Dashboard with it’s default options and set it to also use the USB soundcard as input.

First contact

Shortly after the satellite cleared the horizon I started to hear a PSK signal and see it on fldigi. The tricky part was adjusting the radio frequency to compensate for the fast doppler shift. Here’s what the BPSK and doppler looked like in fldigi:

Thankfully the Funcube Dashboard is able to scan for the signal in the passband and was able to keep acquiring the data despite my fiddling with the frequency dial on the radio.

Results

Firstly there are messages uploaded to the satellite by authorised ground stations (I presume authorised as I don’t see any details of how to set these messages from the ground!)

There is also the actual telemetry from the satellite which gives the various temperatures and voltages on the cube and the black and silver chassis temperature (not in the pic below) which can be used as a form of a Leslie cube experiment.

Next Steps

This was very much a proof of concept into listening into these satellites. I’ve tried ‘working’ satellites before using SSB and FM transponders – a cumbersome process involving waving a yagi about with a radio or two hand from your neck! But since I’m mainly listening to these satellites I don’t need to stick to transceivers and tuned antennas – a funcube dongle / rtl-sdr and a diy QFH antenna will do a better job. So that’s the next plan – hook up the funcube dongle to the co-linear and see if I can pick up some telemetry from other satellites. I’m going to start by leaving it running with the Fox-1 telemetry analysis tool and see if that picks up anything.

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