Monday, 22 April 2013

All three Phonesats received and decoded

Yesterday the delayed Antares rocket launched and successfully deployed the three Phonesats

After downloading the TLE this morning and checking the orbital prediction I found as luck would have it that a decent pass would occur when I am home during my lunch break.

So it was out with the 70cm yagi on the tripod fixed pointing south at around 45 degrees elevation and my older FUNCube Dongle on the laptop running SDRSharp (SDR#). It was pleasant sitting on the bench at the top of the garden in the sunshine with the dogs eating my lunch waiting for the pass, and yes at around 14:17BST (13:17UTC) I started to get signals, which came in very strongly.

I recorded the IQ file for later analysis and decoding

I originally tried decoding using Multipsk which I have used extensively to decode APRS from the International Space Station but wasn't having any luck so I downloaded the free and simple to use Qtmm AFSK1200 Decoder, I simply feed it the audio (using virtual audio cable) and it was soon decoding. However I did have to widen the bandwidth quite a lot to accommodate the full signal. 

The resulting decodes were saved into a text file, here is a selection

15:35:11$ fm KJ6KRW-2 to CQ-0 via TELEM-0 UI  PID=F0
15:35:45$ fm KJ6KRW-0 to CQ-0 via TELEM-0 UI  PID=F0
15:36:59$ fm KJ6KRW-1 to CQ-0 via TCPIP-0 UI  PID=F0

Note due to quite large doppler shift I had to keep replaying the IQ file to adjust for it and the time shown is the time I decoded it, not the time it was received.

Going to the Phonesat website, you can register and submit the packet data which checks and displays the decoded information, which I did.

I had to discard the first and last decimal point in the data to successfully submit it the website

I also managed some good signals using the discone in the loft.

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