If you want to really understand a technology, and if you’re like us, you’ll need to re-build it yourself. It’s one thing to say that you understand (analog) broadcast TV by reading up on Wikipedia, or even by looking at scope traces. But when you’ve written a flow graph that successfully transmits a test image to a normal TV using just a software-defined radio, you can pretty easily say that you’ve mastered the topic.
[Marble] wrote his flow for PAL, but it should be fairly easy to modify it to work with NTSC if you’re living in the US or Japan. Sending black and white is “easy” but to transmit a full color image, you’ll need to read up on color spaces. Check out [marble]’s project log.
Hackaday has another hacker who’s interested in broadcasting to dinosaur TVs: [CNLohr]. Check out his virtuoso builds for the ATtiny and for the ESP8266.
(Yes, the headline image is
one of his earlier trials with black and white from Wikipedia — we just like the look.)
14 thoughts on “Transmitting Analog TV, Digitally”
No, the headline image was lifted from wikipedia, and it’s not a trial image.
Thanks. I still like the look.
I was watching a video about PAL and NTSC just this morning – what a coincidence!
Yes, as I understand it PAL is just NTSC “perfected” (you can argue that all day long) and SECAM is what you get when you drink to much wine at lunch.
Systeme Essentially Contrary to American Method ;)
I thought it was
System Even Crueler than American Method
(the idea isn’t half bad – we have problems separating two color subcarriers, so let’s have just one, have it switch between red&blue (the SEC as SEquential Color in SECAM) and put the result into memory (the M in SECAM))
no I’m not 100% sure if I’m correct.
PAL flips phases 180° every scan line and uses the delay line to subtract two scan lines, which cancels out most errors. Disadvantage: first scan line is black&white. With VCRs the first couple scan lines are b&w. And since everything’s 16:9 nowadays that makes up for like 5% of the picture. Living in the past has its price. But VCRs break down less often than my internet connection and pushing three buttons and wait 10 seconds to watch a movie beats booting my computer and watching it online. I love analog TV. I don’t care about HD, just the movie itself.
When I was in the broadcast industry we use to call NTSC – Never the Same Colour Twice, as a reference to the tint adjust that NTSC sets have.
Never Twice Same Color is how I learned it.
I will try to find the time to make a video about it where I show the working setup.
Thanks! Now where are we going to get a bunch of old TVs?
I have at least four “portables” that the DTV switch made obsolete…
Post your address on a local classified one evening and you’ll be bricked into your driveway with them by morning :-D
The Chaos Computer Club had their 35th anniversary and decorated the party room with a bunch of CRT TVs. Some got a video game console hooked up, some a RasPi and played videos.
Before the party the TVs were stored in our room. Almost all of then got a analog receiver.
Old hack to create a TV station. Boost the signal from a old vcr or composite to channel adapter and you can then broadcast channel 3 / 4.
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