[Discuss-gnuradio] NTSC Sync Processing

[Prateek Dayal]

Dear All,

I have been playing around with the sync signal of the NTSC composite
signal. (I have used a comparator to extract the sync). In actual TV,
the sync is passed through an integrator and a differentiator to
extract the vertical and horizontal pulses. I have tried to implement
the same using low pass and high pass FIR filter, but the results do
not seem very good. There is lot of noise effect on the signal (esp
horizonatal).

I have an alternative in mind. To extract the horizontal pulses, I can
correlate a synthesized sync pulse of duration about 5 line width.
ie., something like

--____--____--____--____--____

the peak of it should identify the horizontal pulse location for me.
Also as it is 5 line width, a vertical pulse will not be identified as
a horizontal pulse. This process can be repeated every 100 or 200
lines to make some corrections if required. Similarily the vertical
pulse can be detected by correlating with a pulse of 2.5 line width.

My question is if this should be feasible and better than conventioal
approach and also some clues on how to implement this in gnuradio. Is
there a correlator block ???

Regards,

-- 
Prateek Dayal
B.Tech 4th Year
ECE
IIT Guwahati

www.geocities.com/pmd_iitgw