Analogue wireless image transfer (!)

[Stevenson Gawen]

I posted this elsewhere initially... but then I thought one or two people here might find it somewhat interesting too...

For all the popularity of “analogue” in some photography circles, this particular kind of analogue gets very little attention.
I’m referring to Slow-scan Television or SSTV.
The principle is the same as the old fashioned fax machine - the image is scanned, line by line, and effectively each pixel is mapped to a certain frequency of sound, according to tone and/or colour.

I think the only use this technology gets these days is in amateur radio circles, as it allows image transmission in the very narrow bandwidth (~3kHz) available in the HF (high frequency) part of the radio spectrum that allows for easy long distance comms.

I’ve never been that enthusiastic myself, until it recently occurred to me that maybe the system, with its heavy “analogue imperfections” could have artistic applications...


Not necessarily via radio - via pure sound, just speaker to microphone works just as well, only a much shorter range.
Many different modes are supported, which could be another rabbit hole to go down, incidentally.
This one was done using the Wraase SC2 180 mode and took over a minute to transfer. The line near the lower edge is the result of a sneeze…

This one was using the Martin 2 mode and was much quicker.

It’s pretty easy to configure - I’m using this app on my phone: GitHub - olgamiller/SSTVEncoder2: Send images via SSTV to transmit via the phone speaker.
And qsstv to receive, running on my Linux laptop using the built in microphone. qsstv has a lot of radio-oriented features, but at least for receiving it works fine on its own.
With the phone volume turned up a range of at least 2m is possible. The mind boggles at what could be possible over a stadium PA system.

Myself in garden with unfashionable hat
What do you think - are we about to witness the Next Big Thing in analogue photography?

 

[Wes Hall]

Amazing Stevenson, thanks for getting some brand new info into my skull this early into 2024.

Radio is the future star clearly not killed by TV!

It sounded so much more fantastical in my head, with and sound creating an image, but the reality is still fun.

It would make some pretty interesting and convincing early Internet crime scene photos I bet!

 

[Stevenson Gawen]

Thanks Wes! Happy New Year btw.

It sounded so much more fantastical in my head, with and sound creating an image, but the reality is still fun.

Yep, it's one of those things, but as you say, still interesting... sorta!

pretty interesting and convincing early Internet crime scene photos I bet!

Mmm... that's an idea! Want to take on the challenge? I'm sure you've got a phone and a PC lying around somewhere...

Incidentally, I forgot to say in the initial post that MMSSTV seems a popular option for windows PCs.

Look up SSTV on wikipedia if you happen to feel the need for even more info...

 

[Wes Hall]

Happy NY to you too!

Ohhh I'm a Linux user so I reckon I should try to make at least some kinda image with it

May just alleviate some new year GAS flare ups

 

[Stevenson Gawen]

Happy NY to you too!

Ohhh I'm a Linux user so I reckon I should try to make at least some kinda image with it

May just alleviate some new year GAS flare ups

YEssss.....!

I'm on Q4OS at present (basically a lean variant of Debian) and installed qsstv via apt-get, and it basically worked for receiving out-of-the-box. I must confess I haven't worked out how to send with it yet, which seems daft. I must be missing something obvious.

 

[Ralph Turner]

Well well you learn something every day. I'd never heard of this technique until now. Impressive what those little phone speakers have managed. An intriguing technique.
I'm afraid it's set my imagination going. For greater transmission distance but still just using a phone, presumably some kind of horn arrangement adapted to the inbuilt speakers would help with projecting the sound and one of those high gain reflector microphone gizmos at the other end...mm. Also, would you get different image distortion signatures on the main image depending on the nature of any sonic interference (car diving by, birdsong, etc)? Mm, my imagination may have wandered off the path a little .
Anyway, seriously, thanks for sharing with us Stevenson.

 

[Ralph Turner]

Nick Rhodes of Duran Duran fame published a book back in the late 80s/early 90s called Interference (photographs of different tv interference patterns). My wife, being a huge DD fan, went to the attendant exhibition, met the man and bought the book. Some interesting images (though not all to my taste).
Anyway, with that in mind, it got me thinking. If different external noises have different effects upon the transmitted sstv image signal, maybe you could creat a set of images of different subjects, each with their attendant sonic interference signature within the final image.
Disclaimer - no 'shrooms were consumed before, during, or after the writing of this commentary..

 

[Pete Askew]

What an intriguing idea / approach. I have quite a few microphone and speaker systems so... I wonder what happens with a 'double' exposure?!

 

[Len Philpot]

One of the amateur astronomical events ("star parties") I usually attend is the Texas Star Party, held each spring ... well, most springs ... in far west Texas. It's timed to occur around the new moon phase, so the sky is dark for observing. For several years off and on -- mostly back in the early '90s IIRC -- it was held the same week as another star party held in Oz by an astronomical society in NSW. I think (?) it may have been the South Pacific Star Party, not sure. At any rate, there was apparently a fairly strong ham radio presence at these events and in those pre-broadband (effectively pre-Internet) days, astrophotographers at each event would swap images from the previous night between Texas and Australia via SSTV over ham radio.

 

[Ralph Turner]

@Len Philpot brilliant! I imagine that must have been quite something back then, seeing virtually live images in that way - something we take for granted these days.

 

[Len Philpot]

@Len Philpot brilliant! I imagine that must have been quite something back then, seeing virtually live images in that way - something we take for granted these days.

Yes, and the images were wet-darkroom film astrophotos. They were created often using hypered 2415 Tech Pan film, sitting in the cold at a guiding eyepiece (on the telescope), pushing four buttons on a hand paddle to keep a dancing guide star centered on crosshairs... for 30, 60 90 minutes or longer at a time. Per shot.

Disclaimer: I know how that was done, but I never had the constitutional fortitude to do it.

 

[Ralph Turner]

Good grief, sounds like one heck of mental challenge to keep one's eye and mind focussed (sorry for the pun) on that crosshair. I'm guessing Technical Pan was used for it's very fine grain and high resolution/contrast. I also have to admit to some ignorance regarding hypering. That's the second thing I've learned today. A good day for education . Anyway, hats off to those dedicated folks.

 

[Len Philpot]

From what I've heard and seen it was pretty mind-numbing at times, not to mention, nose- and finger-numbing as well. I think Tech Pan was popular for small grain and (when hypered) fast ASA/ISO performance. IIRC (which is suspect) they may have achieved ISO 10k+ equivalent performance from it. And to add insult to injury, some of these idiots, I mean heroes, would triple their time in the freezing cold to shoot three images through RGB filters to create composite color prints (since the color emulsions of the day were slow and / or grainy).

Kinda speaks to just how relatively faint some (I mean, all) of these astronomical images are. Can you see how digital astro-imaging kinda got a pretty quick foothold?

 

[Len Philpot]

Clarification -- The process of "guiding" was one of correcting for inaccuracies in the telescope mount's tracking ability and its polar alignment, not actually tracking itself. A mount will drive the scope across the sky in the opposite direction of the Earth's rotation, but even at best it's not accurate enough to allow for sharp long-exposure images. Hence, the hand paddle had four buttons to slew the scope very slowly in each direction. That control would be needed every few seconds possibly to correct for drift, but not needed to actually keep it tracking.

That's a little easier, but still tedious at best.

These days guiding can be software controlled, unattended and automatic (if everything works). Also hundreds, if not thousands, of shorter "subexposures" are taken then combined by software rather than a single longer exposure.

 

[Stevenson Gawen]

I'm afraid it's set my imagination going

Good!

If different external noises have different effects upon the transmitted sstv image signal, maybe you could creat a set of images of different subjects, each with their attendant sonic interference signature within the final image.

That's a very interesting idea - I'm not sure that any recognizable patterns are created though... have to try it. Would depend on the mode too - I notice that some just drop sync (or something) and give up with relatively low level 'interference' whereas some are much more robust.

astrophotographers at each event would swap images from the previous night between Texas and Australia via SSTV over ham radio.

Wow... Never heard of that. I've been involved with amateur (or ham) radio to varying extents for over 4 years now. Always something new to discover.

I think Tech Pan was popular for small grain and (when hypered) fast ASA/ISO performance. IIRC (which is suspect) they may have achieved ISO 10k+ equivalent performance from it. And to add insult to injury, some of these idiots, I mean heroes, would triple their time in the freezing cold to shoot three images through RGB filters to create composite color prints (since the color emulsions of the day were slow and / or grainy).

Double wow!

 

[Stevenson Gawen]

What an intriguing idea / approach. I have quite a few microphone and speaker systems so... I wonder what happens with a 'double' exposure?!

Sorry Pete, somehow I missed your comment when responding last night. Double exposure... mmm... like having two 'transmitters' going at the same time? I have no idea tbh... could be very interesting if the decoder can handle it.
Another thing to try!