SSTV

13 Articles

Storing Image Data As Analog Audio

February 12, 2026 by 1 Comment

Ham radio operators may be familiar with slow-scan television (SSTV) where an image is sent out over the airwaves to be received, decoded, and displayed on a computer monitor by other radio operators. It’s a niche mode that isn’t as popular as modern digital modes like FT8, but it still has its proponents. SSTV isn’t only confined to the radio, though. [BLANCHARD Jordan] used this encoding method to store digital images on a cassette tape in a custom-built tape deck for future playback and viewing.

The self-contained device first uses an ESP32 and its associated camera module to take a picture, with a screen that shows the current view of the camera as the picture is being taken. In this way it’s fairly similar to any semi-modern digital camera. From there, though, it starts to diverge from a typical digital camera. The digital image is converted first to analog and then stored as audio on a standard cassette tape, which is included in the module in lieu of something like an SD card.

To view the saved images, the tape is played back and the audio signal captured by an RP2040. It employs a number of methods to ensure that the reconstructed image is faithful to the original, but the final image displays the classic SSTV look that these images tend to have as a result of the analog media. As a bonus feature, the camera can use a serial connection to another computer to offload this final processing step.

We’ve been seeing a number of digital-to-analog projects lately, and whether that’s as a result of nostalgia for the 80s and 90s, as pushback against an increasingly invasive digital world, or simply an ongoing trend in the maker space, we’re here for it. Some of our favorites are this tape deck that streams from a Bluetooth source, applying that classic cassette sound, and this musical instrument which uses a cassette tape to generate all of its sounds.

The DIY 1982 Picture Phone

April 29, 2025 by 19 Comments

If you’ve only been around for the Internet age, you may not realize that Hackaday is the successor of electronics magazines. In their heyday, magazines like Popular Electronics, Radio Electronics, and Elementary Electronics brought us projects to build. Hacks, if you will. Just like Hackaday, not all readers are at the same skill level. So you’d see some hat with a blinking light on it, followed by some super-advanced project like a TV typewriter or a computer. Or a picture phone.

In 1982, Radio Electronics, a major magazine of the day, showed plans for building a picture phone. All you needed was a closed-circuit TV camera, a TV, a telephone, and about two shoeboxes crammed full of parts.

Like many picture phones of its day, it was stretching the definition a little. It actually used ham radio-style slow scan TV (SSTV) to send a frame of video about once every eight seconds. That’s not backwards. The frame rate was 0.125 Hz. And while the resulting 128 x 256 image would seem crude today, this was amazing high tech for 1982.

Continue reading “The DIY 1982 Picture Phone” →

Pictures From A High Altitude Balloon

March 28, 2025 by 14 Comments

How do you get images downlinked from 30 km up? Hams might guess SSTV — slow scan TV — and that’s the approach [desafloinventor] took. If you haven’t seen it before (no pun intended), SSTV is a way to send images over radio at a low frame rate. Usually, you get about 30 seconds to 2 minutes per frame.

The setup uses regular, cheap walkie-talkies for the radio portion on a band that doesn’t require a license. The ESP32-CAM provides the processing and image acquisition. Normally, you don’t think of these radios as having a lot of range, but if the transmitter is high, the range will be very good. The project steals the board out of the radio to save weight. You only fly the PC board, not the entire radio.

If you are familiar with SSTV, the ESP-32 code encodes the image using Martin 1. This color format was developed by a ham named [Martin] (G3OQD). A 320×256 image takes nearly two minutes to send. The balloon system sends every 10 minutes, so that’s not a problem.

Of course, this technique will work anywhere you want to send images over a communication medium. Hams use these SSTV formats even on noisy shortwave frequencies, so the protocols are robust.

Hams used SSTV to trade memes way before the Internet. Need to receive SSTV? No problem.

Pi Pico Makes SSTV Reception A Snap

January 4, 2025 by 11 Comments

There’s a paradox in amateur radio: after all the time and effort spent getting a license and all the expense of getting some gear together, some new hams suddenly find that they don’t have a lot to talk about when they get in front of the mic. While that can be awkward, it’s not a deal-breaker by any means, especially when this Pi Pico SSTV decoder makes it cheap and easy to get into slow-scan television.

There’s not much to [Jon Dawson]’s SSTV decoder. Audio from a single-sideband receiver goes through a biasing network and into the Pico’s A/D input. The decoder can handle both Martin and Scottie SSTV protocols, with results displayed on a TFT LCD screen. The magic is in the software, of course, and [Jon] provides a good explanation of the algorithms he used, as well as some of the challenges he faced, such as reliably detecting which protocol is being used. He also implemented correction for “slant,” which occurs when the transmitter sample rate drifts relative to the receiver. Fixing that requires measuring the time it took to transmit each line and adjusting the timing of the decoder to match. The results are dramatic, and it clears up one of the main sources of SSTV artifacts.

We think this is a great build, and simple enough that anyone can try it. The best part is that since it’s receive-only, it doesn’t require a license, although [Jon] says he’s working on an encoder and transmitter too. We’re looking forward to that, but in the meantime, you might just be able to use this to capture some space memes.

Continue reading “Pi Pico Makes SSTV Reception A Snap” →

Ham Radio Memes In The 1970s

November 11, 2023 by 12 Comments

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.

Continue reading “Ham Radio Memes In The 1970s” →

This Standalone Camera Gets The Picture Through With SSTV

November 20, 2022 by 12 Comments

These days, sending a picture to someone else is as simple as pulling out your smartphone and sending it by email or text message. It’s so simple a child can do it, but that simple user experience masks a huge amount of complexity, from the compression algorithms in the phones to the huge amount of distributed infrastructure needed to connect them together. As wonderful and enabling as all that infrastructure can be, sometimes it’s just too much for the job.

That seems to have been the case for [Dzl TheEvilGenius], who just wanted to send a low-resolution image from a remote location. It turns out that hams solved that problem about 70 years ago with slow-scan television, or SSTV. While most of the world was settling down in front of “I Love Lucy” on the regular tube, amateur radio operators were figuring out how to use their equipment to send pictures around the world. But where hams of yore had to throw a considerable amount of gear at the problem, [Dzl] just used an ESP-32 with a camera and some custom code to process the image. The output from one of the MCU’s GPIO pins is a PWM audio signal which can be fed directly into the microphone input of a cheap portable transceiver.

To decode the signal, [Dzl] used one of the many SSTV programs available. There’s no mention of the receiver, although it could be pretty much anything from another Baofeng to an SDR dongle. The code is available in the article, as is an audio file of an encoded image, if you just want to play around with the receiving and decoding side of the equation.

We could see something like this working for a remote security camera, or even for scouting hunting spots. If you want to replicate this, remember that you’ll need a license if you want to transmit on the ham bands — relax, it’s easy.

Hackaday Links Column Banner

Hackaday Links: December 20, 2020

December 20, 2020 by 11 Comments

If development platforms were people, Google would be one of the most prolific serial killers in history. Android Things, Google’s attempt at an OS for IoT devices, will officially start shutting down on January 5, 2021, and the plug will be pulled for good a year later. Android Things, which was basically a stripped-down version of the popular phone operating system, had promise, especially considering that Google was pitching it as a secure alternative in the IoT space, where security is often an afterthought. We haven’t exactly seen a lot of projects using Android Things, so the loss is probably not huge, but the list of projects snuffed by Google and the number of developers and users left high and dry by these changes continues to grow. Continue reading “Hackaday Links: December 20, 2020” →