Slow Scan TV Transmission from the International Space Station

Saturday at 10:05 UTC we successfully received a Slow Scan Television transmission from the International Space Station. The receiver chain consisted of the USRP+TVRX, GNU Radio software for demodulating the FM signal into audio, and the freely available Digital Master 780 for decoding the SSTV data.

The transmitted picture was taken with a camera onboard the space station looking out through one of the windows. NA1SS is the amateur radio callsign used by US astronauts while they are on the space station.






Richard Garriott has been very active on amateur radio ever since he arrived at the space station. Besides the SSTV activities he has been having voice contacts with schools and radio amateurs around the world. You can listen to Richard making voice contacts with radio amateurs in Europe in this recording.

VHF/UHF Receiver

The picture below show a VHF/UHF receiver assembly based on the Universal Software Radio Peripheral and a standard TV-tuner. The board on the left is the S-band transceiver module described earlier.



The TV-tuner based VHF/UHF receiver can receive a 6MHz wide RF spectrum anywhere in the range 50-800MHz. It has a noise figure around 8dB, which is not good enough for Lunar comms; however, it is a good cheap starting point for breadboarding and experimentation. Using a modest yagi antenna and a low noise preamplifier, we have been able to receive signals from low Earth orbiting satellites.

Transceiver modules for the L and S bands

The RFX1200 and RFX2400 daughterboards provide complete radio frequency transceiver interfaces for the Universal Software Radio Peripheral in the L and S bands. The receivers have an AGC range of 70dB. The transmitter output is around 200mW for the RFX1200 and 50mW for the RFX2400. The transmitter and receiver frequencies can be controlled separately (split mode) and the boards are also capable of full duplex operation.