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Re: Video Converter

On Tuesday, August 7, 2012 9:13:08 PM UTC-5, Alex Freed wrote:
> On 8/7/2012 5:55 PM, kevin wrote:
> 
> >
> 
> > you still need a way to sniff a 3.something mhz burst
> 
> 
> 
> >signal 50-60 times a second and a mux to switch the
> 
> >signals tween the boxes (which sounds so ghetto)
> 
> >
> 
> 
> 
> This is the easy part. NTSC (and PAL) TVs have a "color killer" circuit 
> 
> that detects a presence of the color burst and turn on the color 
> 
> decoding. If there is none, a filter is turned off to extend the 
> 
> bandwidth. More or less the same functionality.
> 
> 
> 
> Detecting the burst is not all that hard. You have to have a PLL that 
> 
> locks on the color carrier (3.58 MHz). Apply this restored carrier 
> 
> rotated 90 degrees and gated color burst to a phase detector and you get 
> 
> pulses on every line.
> 
> 
> 
> 
> 
> -Alex.

sounds reasonable enough, I might give it a poke this weekend