Slow-Scan Television | Hacker News Reader

Slow-Scan Television

en.wikipedia.org

117 pointsbookofjoe24 comments

oh boy an amateur radio submission <3

If you want to see a bunch of samples some people collect them and shoot them off here: http://worldsstv.com/

Also, the dominant software for this (mmsstv) was originally a japanese language program. I strongly suspect that SSTV's aesthetic is informed not just by the transmission artifacts but also more generally by japanese maximalism. if you have ever seen a jp television broadcast with way too much text on the screen you know what I mean. The image editor's defaults combined with ident requirements makes that kind of aesthetic the happy path.

That site unfortunately seems broken, I only see the mal-decoded UTF-8 byte-order marker "ï»¿" on the page. The HTML contains little more than that and some apparently non-functional Javascript.

(Why did Firefox remove the ability to change character encoding?? WTF are they smoking at Mozilla?)

I don't control that website so I can't fix that, but it Works On My Machine (tm).

Works fine for me — Chrome on 2012 MacBook Pro, no VPN/blockers etc.

Odd; it works for me in Firefox (tried both the current Release version and latest Nightly).

Back around 1970 or 1971 I became friends with a graduate student by the name of Ralph Taggart at Michigan State who was one of the true pioneers of SSTV. He had just a technicians license at the time so we partnered and I was the operator helping him access the HF bands through the university station W8SH.

He later became a NatSci professor at MSU and is now retired. We participated together in the first SSTV contest contacting hams all over the US and a few in Europe and one in South Africa.

SSTV grew more popular but never reached critical mass with hams. Younger hams these days are far more interested in the new digital modes.

Reminded of pirates broadcasting their Anime waifus via SSTV over The Buzzer [0] during the early days of the Ukraine war [1]

[0] https://en.wikipedia.org/wiki/UVB-76 [1] https://www.youtube.com/watch?v=vBMg0lj_G44

The ISS occasionally transmits images with this method[0]. They usually do some "SSTV events" where they have a series of images sent over a period of 2-3 days (allowing people the chance to receive many different images from the series as the ISS passes a respective area a few times during the period). You can browse a gallery of user-submitted received transmissions at https://www.spaceflightsoftware.com/ARISS_SSTV/

[0] https://amsat-uk.org/beginners/iss-sstv/

I had a lot of fun a decade back pulling ISS SSTV off of a home-made Yagi behind my hackerspace with an old buddy. It was in the middle of Phoenix and there was no chance we could actually see the ISS because of light pollution but it sure was there!

nice! Yeah, I've picked up a ton of images from them with just a cheap $20 baofeng I got from a coworker, and my phone's built-in mic! Images from space! so cool! hahah :) (now I do have a yagi of my own, but haven't had a chance to tune into one of the ARISS SSTV events since building the antenna)

Yep. A few years ago, I pulled an old HT out of my junk drawer and one of my old Linux laptops, and copied an SSTV transmission from ISS.

https://i.imgur.com/Mc8pOkH.png

In the past they have done week long SSTV events, often over the Christmas / New Year period. They haven't had a long one in a while as the SSTV unit was malfunctioning, but just a couple of weeks ago they did a successful test so I think they might do another long one soon.

The broadcasts are very loud and you can pick them up with a basic hand-held radio using the provided antenna. If anybody's interested, get a radio capable of listening to the 2m amateur band (specifically 145.8 MHz), a satellite tracker app (eg. Look4Sat for Android) and preferably a way to record what you hear. Later you can decode the transmission with a program like MMSSTV or QSSTV. You can decode it live but I feel safer getting a good recording. The ARISS-SSTV images blog [0] is what I check to see when an event is coming up.

Bit of trivia is that the SSTV unit was brought up to the ISS by (or at least with) Richard Garriott, who created Ultima and sent out some of the first SSTV images.

[0] https://ariss-sstv.blogspot.com/

There are apps like Robot36 that can decode sstv right on your phone. Just holding the phone near the radio's speaker will get you a recognizable image, though not great. I imagine getting the proper cable setup would work quite well.

I remember having a lot of fun with this.

Fun fact: Portal (video game series) actually has radio that transmits a SSTV image as an Easter Egg.

Yep, I believe they patched this in as part of the announcement of Portal 2. That's where I first heard about SSTV

If you are a Linux user get pavucontrol+papfrefs, set a loopback device and run QSSTV. Under OpenBSD, you can dump the file with sndiod in mon mode (OpenBSD FAQ, Multimedia section) but there's no easy SSTV decoder yet, you might find one in GitHub.

I also used SSTV Encoder from F-Droid on Android.

It's much more interesting if ran via an analog loop (at least an AUX cable connecting microphone and headphone jacks, or better an external microphone), it gives interesting noise effects.

AFAIR, I also experimented with recording it and then playing via https://github.com/bodqhrohro/taporwave, but don't remember if it was decoded well as header tones could be corrupted.

I definitely have results of converting raw video to raw audio via ffmpeg and then back, this approach is not sensitive to header pulses (but colour images are borked regardless of the mode).

`ffmpeg -y -t 5 -i /downloads/video/webm/414827e0-9583-407f-9940-3840b7b1085f.webm -f rawvideo -s 176x144 /dev/stdout|ffmpeg -y -f u8 -ar 8000 -i /dev/stdin -f ogg /dev/stdout|ffmpeg -y -f ogg -i /dev/stdin -f u8 -ar 8000 /dev/stdout|ffmpeg -y -f rawvideo -s 176x144 -i /dev/stdin /tmp/swine.mp4` : https://0x0.st/HvAM.mp4

AUX: https://0x0.st/HvAu.mp4

Microphone: https://0x0.st/HvAS.mp4

Analog loop (low volume): https://0x0.st/HvAa.mp4

Analog loop (overload): https://0x0.st/HvA1.mp4

Taporwave: https://0x0.st/HvAj.mp4

Don't even remember what: https://0x0.st/HvAQ.mp4

No pigs were harmed during the experiments!

I love it how many folks now use SSTV to send memes and shitposts. As a bonus the shortwave propagation path often gives it a deepfried look.

I'm a bit confused here - all the transmission modes listed require at least 8 seconds to transmit an image, but it also says NASA used SSTV to transmit video at 10fps? How does that work?

It's a poorly sourced paragraph. Could the author be confusing all early space television systems as being SSTV, when just some of them were?

Oblig. Aphex Twin Easter Egg mention:

https://forum.watmm.com/topic/8121-another-hidden-aphex-imag...

The audio from "A sample SSTV transmission" is worth listening to.

Playing Super Mario on an NES entirely by using radio transmission to your TV is wild.

But that’s just regular analog TV with a private transmitter, right?

Slow-scan television is something quite different because it has so much less bandwidth. From the article:

“Analog broadcast television requires at least 6 MHz wide channels, because it transmits 25 or 30 picture frames per second (see ITU analog broadcast standards), but SSTV usually only takes up to a maximum of 3 kHz of bandwidth. It is a much slower method of still picture transmission, usually taking from about eight seconds to a couple of minutes, depending on the mode used, to transmit one image frame.”

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