David Honess M6DNT has written an article describing how to receive ISS Slow Scan TV images using just a Raspberry Pi computer and an RTL-SDR USB dongle
SSTV is a picture transmission method for sending and receiving static pictures via radio. The International Space Station transmits the pictures on 145.800 MHz FM to amateur radio operators and other radio enthusiasts around the world.
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The most recent ISS SSTV event took place February 8-10, details at