LTSpice - how to simulate simple NTSC video signal

Thread Starter

mpownby

Joined Oct 7, 2016
9
Greetings,

I am trying to understand how a circuit works (attached schematic). I am pretty sure that it takes an NTSC video signal in as a source and a) separates out the sync, and b) can also decode manchester data on a per line basis. I am really curious to learn how this circuit works and think that maybe trying to simulate it in LTSpice may be helpful. I only want to simulate the resistor/transistor/cap stuff, once it gets to the TTL parts, I can take it from there. The problem is that I don't know how to create the voltage source that changes over time. I have a good grasp of how the NTSC voltage looks. I mainly just need some guidance on how to create a voltage source that fluctuates between 0, 0.3V, and 1V (should be close enough) depending on the current time. If anyone could point me toward a tutorial or example that does this, that would be awesome.

I already found something here ( http://www.analog-innovations.com/subcircuits.html , VidGen link ) but have no clue how to use it and it seems to be just generating a single line. I want to generate the vsync pulse and a few visible lines and I don't need to mess with stuff like color burst.

Any help would be appreciated.
 

Attachments

Alec_t

Joined Sep 17, 2013
12,160
I'm curious as to why you wish to simulate NTSC, given that analogue TV transmission has ceased in most countries?
 
Top