On Chroma Dots and how to determine if they are present

[wa2ise]

Originally Posted by VintagePC

NTSC definitely has it, it's visible on sets where you have more than 3.5MHz bandwidth, since the colour subcarrier is at that frequency.

The chroma subcarrier has 227 1/2 cycles per horizontal line. Most B&W TV sets made after 1954 limit the luma bandwidth to suppress the chroma subcarrier. Usually done by the way the picture IF strip is adjusted. Older sets can show the entire 4.2MHz of luma bandwidth as there was no chroma subcarrier added in back then.

The chroma subcarrier looks like a fine checkerboard moving vertically in areas of the picture with saturated color. The size of this checkerboard pattern is such that you could have about 330 checkers in a horizontal line (two checkers per cycle of subcarrier).