Abstract: An audience rating system for digital television and radio, using identification codes in control streams of time-multiplexed digital transmissions. When a television set or radio, that is being monitored pursuant to the system, is turned on and tuned into a channel, and each time that the channel is changed, an identification code for each audio, video or auxiliary digital stream of the channel is extracted from the control stream, and recorded along with the time. In the first preferred embodiment, the multiplexed digital transmission is received separately by the television set or radio (or an attached IRD) and a meter connected to it. In the second preferred embodiment, the meter does not receive the multiplexed digital transmission separately, but has access to elementary streams extracted from the transmission by an IRD, and extracts identification codes for the channels being received from their elementary streams.

Abstract: An audience rating system for digital television and radio, using identification codes in control streams of time-multiplexed digital transmissions. When a television set or radio, that is being monitored pursuant to the system, is turned on and tuned into a channel, and each time that the channel is changed, an identification code for each audio, video or auxiliary digital stream of the channel is extracted from the control stream, and recorded along with the time. The time is also recorded when the television set or radio is turned off. This data makes it possible to determine what stations, channels, and programs members of the audience being monitored are watching or listening to at any particular time. In the first preferred embodiment, the multiplexed digital transmission is received separately by the television set or radio (or an attached IRD) and a meter connected to it.