How do I model UHF TV signal?

Question

This may be a strange question, but I would like to programmatically model a UHF TV receiver. Anyone can give me some pointers? I have been looking at the code from emulators, but they are too specific for my purposes right now.

To be more specific: Given some (probably synthesized) UHF analogue signal (in either NTSC or PAL), I would like to decode that signal and show the image on a window, using, say an X11 window.

Answer 1

Take a look at xanalogtv from XScreenSaver, it generates an analog signal, which it then decodes and displays.

Answer 2

UHF is just a frequency range and can carry anything. The format of the video itself is called composite video or CVBS (color, video, blanking, sync), of which PAL, NTSC etc are, so to speak, subformats. The signal a TV receives is some UHF carrier frequency which is frequency-modulated with the video and sound signals. UHF carries many TV stations and the first thing a TV does is to tune in on a particular channel to isolate the video signal which it then feeds to its PAL or NTSC decoding circuitry which in turn generates signals that drive the CRT.

With that said, I think what one would have to do is to arm oneself with a TV's block diagram (like this one http://smendes.com/el31l/blockdiagram.jpg .) and write a software emulation for each of the boxes:) (except the CRT stuff, of course.) "Luckily", underneath it's all "just" maths and most parts lend themselves to a nice mathematical description, involving lots of differential equations (I think this is how electronics are designed in the first place, i.e. before being prototyped and/or mass produced. Each branch of electronics (say, acoustics, filter design, amplifier design and whatnot) has some sort of mathematical apparatus associated with it.) In the end, your program will parse PAL as does an analog TV, the analog computer that it is)) You could also take a look at SDR, which stands for "software defined radio" which I think is the same principle.