frequency interlacing

Frequency interlacing is a technique used in television broadcasting to efficiently use the available radio spectrum. It allows color information to be transmitted alongside the black-and-white (luminance) signal without causing interference on monochrome receivers.1

This is achieved by carefully timing the chrominance (color) signal segments to align with the empty spaces between the luminance signal segments. This precise timing, controlled by the chrominance subcarrier, ensures that the color information does not disrupt the black-and-white image and is seamlessly integrated in color receivers. This method was crucial for the development of compatible color television systems like NTSC, PAL, and SECAM.1