Abstract: Identification of a program being transmitted is encoded digitally on a sub-carrier modulated on the sound carrier of a television signal with each elementary code group occupying a television field interval, the information being transmitted in cycles of several television fields. The sub-carrier frequency is chosen so as to minimize interference with the picture or sound.A receiver is programmed to be in a standby state during a period during which the coded identification of desired programs are compared with detected program identifications. The receiver is shifted from channel to channel so long as the program desired for the particular time is not found. When it is found, the display circuits are turned on and the channel-shifting device is disabled, so long as the identification of the desired program continues to be detected.