Re: TV Video Overlay circuitry?

mitch wrote:

> I need to produce a simple, very low cost product which is a TV set-top
> box to be connected inline with the TV signal cable

Which type of signal ? ( see below )

> that will generate
> simple preprogrammed animated overlays. The TV program image will not
> be affected, just overlaid.
>
> I have Googled this but only find add-on graphics cards for PCs which
> cost several hundred dollars. I need something which can be mass
> produced cheaply.
>
> Could this be manufactured cheaply (say under $10-$20)?
> What kind of circuitry/chips would I need?
> How do I program the animations?
> Where can I find out about this?
>
> Could someone please point me in the right direction?

First off you need to determine if the set-top box is doing the overlay to
an RF signal or simply a video signal. Or indeed demodulating a RF signal
and supplying a video signal to the TV set.

There's 3 common ways to get a picture signal into a TV set.

1. RF signal ( using an aerial / antenna connector )
2. Composite video ( usually on an RCA jack )
3. RGB input ( in Europe this would be on a SCART connector - dunno
about USA - the mini-DIN 'SVHS connector' also does RGB )

All of these possibilites require differerent levels of complexity. RF in /
out requires an RF receiver and re-modulator for example where as the other
2 don't.

If you need to ask these questions I seriously hope you don't plan to
attempt the project yourself.

Graham

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