If you have a fondness for old and unusual ham gear, [Saveitforparts] has a great video (see below) about a Robot slow scan receiver he found at a junk store. Slow scan or SSTV is a way to send pictures via low-bandwidth audio, such as you often find on the ham bands. The idea is you take a picture, send some squeaks and blips over the air, and in about 8 or 10 seconds, a single frame of video shows up at the receiver. Hams aren’t the only ones who used it. The Apollo missions used an SSTV system in some cases, too.
I’ve been a ham radio operator for a very long time. When I first heard about SSTV, I thought it sounded cool that you could be talking to someone and then show them a picture of your station or your dog or your kids. But when I looked into it, the reality was far different. In the pre-internet days, SSTV-equipped hams hung out on a handful of watering hole frequencies and basically just sent memes and selfies to each other. Everyone would take turns, but there wasn’t really any conversation.
This actually still goes on, but the hardware isn’t a big deal anymore. The Robot in the video had to decode the signal from audio and store the image somehow. On old gear — some of it homebrew — it was simply persistent phosphor that would eventually fade, but, of course, eventually, images were stored in some form of digital memory. These days, you are likely to use a PC soundcard to both send and receive the necessary audio.
But in the mid-1970s, the Robot, with its 6-inch screen and $295 price tag, was a marvel. It would rapidly become obsolete, though, as SSTV practitioners moved to more advanced formats that used color and had better performance.
Honestly, we were surprised the old machine worked as well as it did, handily decoding some prerecorded SSTV signals. Overall, it’s great to see this classic piece of gear again. The International Space Station sometimes sends SSTV. Of course, if you ever needed to send a picture over a noisy medium, you might want to borrow the ham radio technique.
Sounds like my experience so far with Mastodon, cool new tech, but just a few of us hanging out sharing memes. It’s the way it always is I’m afraid.
Insert astronaut always has been meme here.
At 3:30 it also becomes a Cat Scan.
+1
Oh my how that brings back fond memories of the 70’s. I received my first Ham ticket in 1974 and a few years later a friend had a ROBOT unit very close to what is shown here. Cool tech then and still cool today, in my eyes anyway :-) de wa4jat
They’re still cool, worth being saved/kept! 😎
There are software solutions worse than that, actually.
Especially pure 8s SSTV is being decoded most stable on the old gear.
Also because it decodes the sync pulses correctly and their use of gray code.
Most modern software solutions are free-running all the time, which leads to to skewed/tilted image.
Here, an old DOS program like JV-Fax or GSHPC might be superior, even.
I’m not kidding, I tried:
A simple 741 comparator modem can sometimes outperform a modern SSTV program using soundcard.
Old SSTV recordings on tape are good for checking this.
(One of the better software/soundcard solutions was Multimode on Mac, I think.)
That being said, Robot 8 or 7s/8s SSTV is still interesting for little projects, for having fun.
It has little requirements and works on every platform (radio, phone etc).
Here’s a modern, high-end hardware solution that blows modern SSTV programs on Windows/Linux out of the water: https://www.qsl.net/kd2bd/TriplePIC.html
PS: Traditionally, different SSTV modes were preferred around the world.
Europe: Martin M1/M2
US: Scottie S1/S2
Japan: Robot 36 (?)
International (or prior): 7s/8s b/w
Very cool. I remember lusting over that Robot gear in QST. Who knows — your video may spark (!) a resurgence of old-school, low speed, low res, Robot-style SSTV! 73 Bill N2CQR
Fine, quick article. 🙂
I’d like to add that 8s/7s SSTV still is special, kind of.
It’s very quick and can thus be used in the middle of a real conversation.
That was the original meaning of SSTV, I think.
It also used sync signals, which meant that the pictures were straight.
The downside was that if a sync signal was lost, so was a complete line.
Another minor difference was that early SSTV had an aspect ratio of 1:1, while Robot 8 used 4:3 (same as 20th century TV screen format).
The SSTV that’s being used today is different. It’s like sending QSL cards or rapports back and forth.
I’d also like to mention that technology in the 70s was a bit further, even.
There used to be Robot Model 300 and 400.
One used a storage tube monitor with a TV camera pointing at it, thus holding the picture for 30min or so.
The second was all digital (a framebuffer) and support 16 shades of grey scale, using gray code for storag.
It was later upgraded to color and named 400C.
The first method was frame-sequential color, with individual R/G/B frames.
That’s what the JPL club station had used for Voyager/Viking presentations, I believe.
Originally, this involved using a monochrome video camera (usually tube based; Vidicon, Orthicon etc) with a color wheel attached and three separate color memories in the scan converter.
(Amiga uses in late 80s still did that, too.
See DigiView frame grabber.)
Green image frame was often used by monochrome users, because it was closest to real grayscale ..
Then line-sequential color got more popular. The Robot 1200C could already do it, I believe.
Such digital scan converters also had introduced an ID system (VIS code).
Other manufacturers had made similar converters, of course.
Otherwise it wouldn’t be amateur radio.
Here in Germany, a guy named Wraase made some, for example.
Nowadays, a small community still uses Robot 8 (8s SSTV) due to its simplicity.
There are Arduino projects generating an SSTV image in software, tinkerers who use glow-in-the-dark paint and metal cans to substitute the old radar screens etc.
Btw, Also notable is Robot36, which was used by MIR orbital complex in the 90s.
It was among the most complex SSTV modes. It provided a good quality for how fast it was (average VHS quality).
ISS now uses PD-120 (VGA resolution). Vy73s
PS: I forgot to mention. Early home computers like the ZX Spectrum were barely able to handle 8s SSTV (but they did, with reduced quality).
That means that the classic SSTV had sort of a short revival in the early to mid 80s.
That’s maybe worth to remember.
Things weren’t always as obsolete as they may seem in retrospect.
(Especially in East Europe, vintage systems just began to take off in late 80s).
On IBM PC, I remember, there was an early program called RDSSTV which decoded 8s SSTV via gameport card.
It worked by using a trick (hack) involving a transformer (saturation).
G1FTU SSTV – Sample Picture RX
https://www.youtube.com/watch?v=VPIoIiMzJ7E
IBM PC SSTV (offline demo, CGA)
https://www.youtube.com/watch?v=P-vAs9PUeHk
Just like ham radio operators used wifi to send data over a Simplex or duplex network
Hook up your atari, commodore, or Tandy/IBM to a TNC and a dial up modem
Have a 256k-512k or even a Meg of ram
And send packets over the radio.
Even incorporate a bbs
Predates tcp/ip
Even connect to bbs using a tnc modem and another ham radio transceiver
Only downside you only can receive from one person at a time, unless you can multiplex data and use pl tones and poll thru the different radios transceivers, at the cost of a slower transfer speed,depends how much bandwidth u got, 70 cm would better, that’s why nowadays u use 2.5 and 5ghz
Here in Europe we had developed DAMA to fix that problem (it was part of TF, The Firmware):
DAMA = Demand, Assigned, Multiple, Access
If DAMA is used, multiple stations can connect to one digipeater on same channel in a more efficient way. Less collisions will happen.
The TF firmware can also be used stand-alone on PC side, there is a DOS TSR (TFPCX, TFX).
So a KISS TNC or Baycom modem/PC-COM modem can be used with it.
– That works in a modern day DOS VM, too, btw.
TNC2 compatible TNCs and other popular TNCs (AEA, MFJ) of the day can be retrofitted with TF, as well.
http://home.snafu.de/wahlm/tfdownload.html
Anyway, I hope that modern TNC implementations like Direwolf or Soundmodem will learn from TF one day, and implement DAMA. 🙂