Saturday, 2 March 2013

STRaND-1 - First attempts

As I posted earlier this week a number of satellites were launched into orbit on board the PSLV-C20 rocket, this included the first UK CubeSat, STRaND-1.

STRaND stands for Surrey Training, Research and Nanosatellite Demonstration and STRaND-1 is hopefully the first of a long line of STRaND nanosatellites from the academic researchers at the Surrey Space Centre (SSC) based at the University of Surrey in conjuction with Surrey Satellite Technologies Limited (SSTL).

The innovative STRaND-1 CubeSat was built and tested in just three months and is designed to demonstrate the feasibility of using cheap smartphone electronics to control a spacecraft, since it contains a Google Nexus One Android phone as part of its experimental payload. STRaND-1 carries an amateur radio AX.25 packet radio downlink on 437.568 MHz using 9k6 bps FSK modulated data HDLC frame, NRZI encoding.

Official orbital elements (TLEs) have already been produced so the current position and prediction passes can be calculated and available on n2yo.com

At the time of this post STRaND-1 is passing over in UK in the early morning (South-North) and early evening (North-South), both times are not particularly convenient on weekdays due to work commitments, but last night I did manage to have my first proper attempt to capture some of the telemetry.

My 'ground station' consisted of a FUNCube Dongle and SDR-Radio (V1.5) with doppler correction enabled. It was connected to a small Moonraker ZL-Special 7-element antenna mounted on a small tripod with my Android phone running the Satellite-AR application mounted behind it. The Satellite-AR assists in pointing it in the correct direction as the pictures below demonstrate.



This slightly blury picture shows the satellite cluster containing STRaND-1 displayed in the Satellite-AR app, by moving the antenna on the tripod I attempt to keep this in the centre of the screen hopefully maximising the signal.


As you can see on the waterfall I did manage to receive the telemetry signal. It isn't a continuous signal, data is broadcast in short bursts with long gaps between the 'frames'


The next stage was to take this and using a number of software packages, including a TNC modem emulator and extract the data. The process is described here by Jan van Gils (PE0SAT) I have had a few attempts with my captured signals, unfortunately with little success I think due to the signal to noise ratio being too low.

This morning I was up nice and early to capture the pass at approximately 05:50, this time I used my FUNCube Dongle Pro Plus on another laptop, but for some reason the received signal was very poor. In desperation I took the antenna off the tripod and held it horizontally rather than vertically and did manage to get a signal, unfortunately it was at the end of the pass and STRaND-1 was heading over the horizon.

Still I am happy with my initial efforts.