Decoding SSTV from ISS

Forum for discussion of SSTV topics. Slow Scan television (SSTV) is a picture transmission method used mainly by amateur radio operators, to transmit and receive static pictures via radio in monochrome or colour.

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Re: Decoding SSTV from ISS

Postby kd2bd » Sat Oct 09, 2021 4:34 am

The 40th anniversary of the launch of UoSAT-1 (OSCAR-9) passed a few days ago. Among all the beacon transmitters and scientific experiments carried onboard the satellite, a monochrome Earth imaging CCD camera was included to transmit SSTV images to listeners on Earth. However, plans changed shortly before launch, and it was decided that the images would handled and sent in a digital format, instead.

The format consisted of an array of 256x256 pixels, each 4-bits wide and sent as synchronous AFSK at 1200 bits per second. Each line was preceded by a line sync code, and each frame was preceded by 32 line sync codes in a row. At 1200 bits per second, it would take 3.77 minutes to transmit one image.

In September 1987, I began monitoring UoSAT-1 and UoSAT-2 (OSCAR-11), and on September 23, 1987 I happened to capture an OSCAR-9 CCD transmission on tape.

22 years later I came across the recording, and decided to program a PIC16F88 to finally decode the picture. The PIC took clock and data signals from a homebuilt G3RUH AFSK demodulator, "got into sync" with the synchronous data stream, looked for and identified the line and frame sync codes, and then sent each detected pixel to my Linux PC as a series of asynchronous RS-232 bytes where they were finally assembled into a 256x256 Portable Grey Map image.

The results were less than impressive, but seemed typical for what OSCAR-9's camera had been capable of producing:

uo9ccd.png
uo9ccd.png (11.64 KiB) Viewed 1905 times

uo9ccd-annotated.png
uo9ccd-annotated.png (13.94 KiB) Viewed 1905 times

I had previously seen only one or two other OSCAR-9 images, both in printed materials. Based on the quality of the images, I thought they might have been rendered using a dot-matrix printer. Probably not, as this early satellite image of Sardinia and Corsica reveals similar artifacts:

Sardinia-Corsica-UoSat-1.jpg
Sardinia-Corsica-UoSat-1.jpg (38.84 KiB) Viewed 1905 times

The Navy-OSCAR 104 (NO-104) satellite launched in 2019 carried a CCD camera into orbit and transmitted images in an SSTV format on 435.350 MHz FM, but I do not believe it is still operational.

73 de John, KD2BD
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Decoding SSTV from ISS

Postby acl » Sat Oct 09, 2021 5:49 am

Steve,

Mine is G6ACL (my initials). I let it lapse and it is virtually impossible to reclaim from the agency involved in policing the airwaves over here as the WEB site requires proof of passing the RAE. With the demise of 625 television transmission. the rush is to sell off the airwaves off to the highest bidder. Talking about selling sand to the Arabs they are selling air here. There is strong representation about 'robbing' amateur bands from the HAM operators fraternity.

Anyway nuff said. Tried the Goonhilly SRD site out and it works. See screenshot below.

Regards Chris Lewis

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Re: Decoding SSTV from ISS

Postby Steve Anderson » Sat Oct 09, 2021 2:08 pm

acl wrote:...it is virtually impossible to reclaim from the agency involved in policing the airwaves over here as the WEB site requires proof of passing the RAE.

I have thought about resurrecting my UK callsign a few times, but until I go to a RAST meeting I don't know what the reciprocal arrangements are, if any. It may also require me to visit the UK. Surely the agency concerned has records of the fact you have already passed the RAE as you were issued with a callsign previously? I'm fairly certain I don't have any paperwork issued to me previously regarding my RAE exam result or the issuance of my callsign.
acl wrote:Tried the Goonhilly SRD site out and it works. See screenshot below.

I'll give the Goonhilly website a try. I've not had much success with other SDRs though.

Thank John for the satellite info and photos...how things have improved since those days. It reminds me of the first images of the far side of the moon, the quality was a bit better, but not by much...On October 7, 1959, the Soviet probe Luna 3 took the first photographs of the lunar far side, eighteen of them resolvable, covering one-third of the surface invisible from the Earth.

https://en.wikipedia.org/wiki/Luna_3

Steve A.

Luna_3_moon.jpg
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Re: Decoding SSTV from ISS

Postby Klaas Robers » Sat Oct 09, 2021 8:00 pm

Then it is much better here in NL. When you passed the exam, you are registred, I think on paper. Even decades later this is still retrievable and you can ask for a licence, if still available with the same call sign, or a different call sign that you can choose. Not so long ago the complete range from PA0 to PI9 has been opened and if the call is still free, you can get it.

However PI0 to PI9 is reserved for Institutions, PI3 is 2-metre relay stations, PI2 is 70 cm relay stations, PI7 is beacons, PI4 is for radio clubs and PI5 for schools.

And you are allowed to change your call if you like that. We had a time where calls were just issued alphabetically, PA3AAA tot PA3ZZZ. but as before that you could choose, this was coming back later.

PD is still reserved for novices. This is nice. I see of my students in the radioamateur course, that they choose firstly their initials for their PD-call, just like Chris ACL did, and then they see that this is of no use (you never use your initials in radio communication). Then for their Full Licence they choose the consonants of their first name. You can easily reconstruct a name from these consonants, vowels give almost no information, so you can leave them out.
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Re: Decoding SSTV from ISS

Postby Steve Anderson » Sun Oct 10, 2021 11:16 am

Klaas Robers wrote:...You can easily reconstruct a name from these consonants, vowels give almost no information, so you can leave them out.

In my case I should have/would have chosen G(something)STV e.g. G6STV which also rather nicely hints of SSTV!

Though these days it appears more likely to be M(something)STV.

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Re: Decoding SSTV from ISS

Postby Klaas Robers » Sun Oct 10, 2021 6:55 pm

And for me, in the Netherlands: PA5STV..... But when I got my call in 1966 there was not yet something like SSTV. I know a guy here in the region who is PA5CAL.
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Re: Decoding SSTV from ISS

Postby Steve Anderson » Sun Oct 10, 2021 7:32 pm

Yea, I hadn't thought of G5STV, it doesn't really matter, either the callsign is already assigned, or simply not available. And I don't live in the UK. But, who knows, maybe HS5STV is available? Though that does add an unwanted extra 's'. 'HS', Thailand, then '5', then 'STV' for Steve. Whatever it's unlikely to happen.

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Re: Decoding SSTV from ISS

Postby Klaas Robers » Sun Oct 10, 2021 8:15 pm

I had the idea that there are hardly 2-m receivers-only, 2-m transmitters-receivers are plenty, but you need a license for it.

However there are scanners for VHF, that include also 2-metres. A scanner helps you to get a receiver that can receive the SSTV broadcasts of ISS. Scanners are normally very cheap.
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Decoding SSTV from ISS

Postby acl » Sun Oct 10, 2021 11:22 pm

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Re: Decoding SSTV from ISS

Postby Steve Anderson » Mon Oct 11, 2021 6:14 pm

Interesting, especially at the price. My only concern would be, will it get though Thai customs? Admittedly it's not expensive, so even if it were 'confiscated' it's not the end of the world. The antenna connector is not quite what I would have expected, i.e. a 50-Ohm BNC, as I would prefer to add an external antenna to it when using indoors. But thanks, it's more than worth considering...

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Re: Decoding SSTV from ISS

Postby Lowtone » Sun Oct 17, 2021 5:16 am

I never got SSTV from the ISS but i was able to get voice signal with a device like this transciever
https://www.youtube.com/watch?v=uSMUgDq ... %A9Lowtone
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Re: Decoding SSTV from ISS

Postby Steve Anderson » Sun Oct 17, 2021 7:21 pm

Klaas Robers wrote:I had the idea that there are hardly 2-m receivers-only, 2-m transmitters-receivers are plenty, but you need a license for it.

It appears (after a brief search) that I might be able to renew my old UK license. However it seems to require my old paperwork from the UK which I'm sure I don't have*. Surely they have records? I was G1CLW, issued around 1983/84 or so in Hampshire, UK, I think, maybe Devon (Plymouth), I just can't recall.

Given if that's possible I might me able to get a reciprocal license here, well, nothing ventured, nothing gained....as I mentioned, I'll try attend the next RAST meeting and maybe get some useful information there...

Steve A.

*No, I don't have it after a fairly exhaustive rummage through my old UK paperwork. 1983/84 is coming on 40 years ago after all...so no surprise there...
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Callsign retrieval

Postby acl » Mon Oct 18, 2021 12:00 am

Steve,

Register here to prove you had a callsign in the UK.

I have just done it.
Last edited by acl on Mon Oct 18, 2021 5:44 pm, edited 2 times in total.
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Re: Decoding SSTV from ISS

Postby Steve Anderson » Mon Oct 18, 2021 1:19 pm

Thanks Chris, I'll give it a go...I'll report progress or otherwise...

Steve A.

Right! I got absolutely nowhere, just went around in circles, gave up.

I suggest removing the previous image with your personal details within...or at least blur them

The website is qrz.com
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Re: Decoding SSTV from ISS

Postby M3DVQ » Thu Oct 21, 2021 1:04 am

Steve Anderson wrote:Surely they have records?


Like you say though it was 40 years ago, and the agency responsible has changed twice in the meantime. The records might still exist in the archives, but I can understand Ofcom not bothering to spend money entering lapsed licence records into the computer or wanting to go retrieving them. Especially for amateur licences as we're mostly a burden to them anyway!
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