LTSpice - how to simulate simple NTSC video signal

Thread Starter


Joined Oct 7, 2016

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 ( , 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.



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