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SSTV (partly) received from the ISS

Every now and again the amateur radio kit on the International Space Station is used to transmit Slow Scan TV images. The activity seems to be run by the Russian crew members, so the active periods are when the ISS is passing close to Moscow. The good news is that some of those passes are close to us too and it is possible to pick up at least partial images with very simple equipment. Here is how I managed to get a fuzzy partial image from a pass on Feb 14 2017...

No special equipment needed

ISS SSTV signals are PD180 format which is transmitted in the form of audio signals on 145.800 MHz in wideband FM (as used by Tim Peake), so potentially receivable on a any old mobile rig or cheap handheld. Personally I used my FT857 connected to a 2m vertical antenna, which is on my loft. I have the rig connected to an old netbook for WSPR etc (via a ZLP Electronics data interface but you could simply use an audio cable eg a 3.5mm to 3.5mm jack lead from Poundland).

And the software is free

It wasn't clear when the signals would be transmitted, so rather than sit in front of the PC for the two-day window I used Audacity, the open-source audio editing software to record it. Audacity has a VOX feature where it will record once audio as above a preset level. With squelch in operation on the radio it records nothing until a signal is detected.

Decoding SSTV can be done on a Windows PC using MMSSTV and on a Linux PC with QSSTV (possibly the latter would work on a Mac). Both software packages are free. The bad news is that after recording the signals I discovered neither software package had a way to successfully import an audio file! Fortunately the Google app Store rode to the rescue and after installing Robot360 on my phone I was able to decode the file by playing it on my netbook and holding my phone near the speaker. I'll get the file import sorted on the netbook sometime - it just needs Virtual Audio Cable software installing.

The iffy-looking result:

There is part of a screenshot from my phone below. You can see the Cyrillic equivalent of MAI-75 at the top, which is the ISS designation for the SSTV 'Experiment'. The photo is obviously a plane - shame it isn't all there! The timing was unfortunate as there was a pause between images just as the signal was at its best (S7 on my S-meter). The Robot360 app provides waveform and waterfall displays that are partially visible at the bottom of the screenshot .


ISS SSTV image



Hopefully there will be other SSTV transmissions from the ISS. I'll definitely have another go, perhaps using the beam to try to extend the reception period. With luck I'll also have sorted the Virtual Audio Cable by then.

If you want to have a go, the RSGB usually announce the SSTV events in the weekly News email and ISStracker.com has a live map showing where the ISS currently is (over Brazil as I write). Good luck!

73 de

Mike
G4RAA



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