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[Discuss-gnuradio] NTSC Receiver

From: Daniel Garcia
Subject: [Discuss-gnuradio] NTSC Receiver
Date: Fri, 23 Feb 2007 09:54:17 -0800 (PST)


I've completed a prototype for an NTSC decoder blockset for gnu radio. It's not very sophisticated but it lets you see video on the screen using gr-video-sdl. My development platform is Ubuntu 6.10 x86.

The signal starts out by using a custom AGC which simply scales the samples by dividing all samples by a local maximum. This puts most of the samples in the 0 to 1.0 range. Then the frame detector uses a simple threshold method to determine when pulses begin and end. The length of time between pulses is used to determine the type of pulse. A simple state machine keeps the output buffered correctly so the screen doesn't get out of whack.

Current features:

* Black/White reception (vertical and horizontal sync)
* Contrast/Brightness adjustment (still a little buggy)

Planned features:

* automatic black level
* color
* stereo audio
* better sync detection
* documentation

Any feedback would be appreciated.



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