Receiving SSTV from the ISS with SDR (simple and automatic) 

Glad you enjoyed the video. The ISS isn't always transmitting SSTV, but they are good at notifying the community when SSTV events are planned. I have seen different "travellers" and have a couple ideas. Sometimes they appear to sweep across the entire band in one direction, I think that might be some type of fixed radar system. Other signals jump around in frequency, you don't see them shifting. It's more that they just disappear on one frequency and instantly jump to another frequency. I think that is called "trunking" and it's a common way for police or commercial users to share frequencies, often combined with with encryption. I haven't dug too deep into it but I think there are ways to decode trunked signals using an SDR or possibly two SDRs as long as the signals aren't actually encrypted. Hope that makes sense, SDRs are a lot of fun!