Thursday, April 28, 2011

NTSC demystified - Math - Part 4

This post targets largely electrical engineers and involves a bit of math and basics of analog communication. A more formal treatment of the NTSC color signal along with results, which will assist digital NTSC color signal generation is presented.

Wednesday, April 27, 2011

NTSC demystified - Nuances and Numbers - Part 3

Ever since I understood how NTSC color worked, I've had a nagging question. How does the TV separate color info (color sub-carier) from the luminance information. If the same color was maintained all throughout the line, then the color carrier can be removed away by narrow band-reject filtering. But when the color changes (phase changes) , then how does the TV distinguish color from luminance which is also possibly changing ?

DSP Library for LPC17xx

NXP has most kindly provided a free assembly coded DSP library for its users. I needed to extract the fundamental frequency of an audio signal and with this library, the job got over in 5 minutes.

Wednesday, April 20, 2011

NTSC demystified - Color Encoding - Part 2

NTSC composite video is a compatible standard. This means that video signal works with older B&W TV Sets as well. So, we're looking to understand how color information is added to the B&W NTSC signal in such a way that Color TV sets can decode the color information while older B&W TV sets ignore the color information. Developing such a signal must have been a formidable task indeed !

Tuesday, April 19, 2011

NTSC demystified - B&W Video and Sync - Part 1

NTSC progressive scanning mode and simpler sync methods are not well documented and this issue is addressed here. Producing video signals by going to lowest hardware level is fun and satisfying. With the number of very capable digital controllers available to hobbyists today, it has become possible to generate analog video signals entirely in software. With the techniques and sync patterns presented here, generating "software video" becomes a much easier task.