Images from the International Space Station
There’s been a flurry of rumors and discussion that the International Space Station would be transmitting pictures to Earth using Slow Scan TV or SSTV over the amateur radio service this weekend. I learned later that it was an event, and they’d be transmitting SSTV on 145.800 MHz, using the PD120 protocol.
I had done some research on the topic of amateur radio TV, out of sheer curiosity. Folks would set up a camera and radio to broadcast, and then use a downconverter to feed their televisions. Folks would send images and full motion video. I’d heard the local repeater network even had a net for it, some years ago.
When a Northern Maine amateur radio club called the Piscataquis Amateur Radio Club (K1PQ) posted links to information and software about the ISS SSTV event on their page, I began to look into the subject, myself.
I installed QSSTV on my Linux laptop, and piped the audio from the GQRX SDR software defined radio software through the SSTV software. To test the setup, I used my Android phone and Baofeng handheld radio to send a photo from my camera roll over the UHF SSTV designated frequency on 5W, and saw that photo slowly materialize on my computer screen. Very cool!
For more information on this experiment, see my page SSTV – Transmitting Images
Once I knew the software worked, I checked the ISS schedule with my Heavens Above app, connected the SDR dongle to the Ed Fong DBJ-1 antenna on the roof, and waited. With each pass, I picked up large portions of photos. I think my hilly area caused some serious periodic fading of the signal, as the ISS rode across the sky. It must’ve gone behind a mountain and back again as the images would drop half the picture, and a second one would appear with the missing pieces.
For some much better quality photos of what they were sending down, check out the official submission gallery at https://www.spaceflightsoftware.com/ARISS_SSTV/index.php
I already plan on putting a taller mast out there, but I’m thinking a circularly polarized antenna like a Helix would come in handy for satellite work, as they tend to shift and pitch as they fly over.