Abstract: An attention signal receiver in which emergency broadcast transmissions are detected from various locations. A scanning circuit sequentially activates means to produce a plurality of oscillating frequencies which mix or beat with the incoming r.f. signals. An attention signal is a two tone signal that includes both a 960 H.sub.z frequency signal and a 853 H.sub.z frequency signal. The audio stage of the receiver is connected to a two tone decoder that passes only a 960 H.sub.z signal and a 853 H.sub.z signal. A squelch circuit is also connected to the audio stage of the receiver. Connected to the output of the tone decoder is a one second time delay circuit and a ten second time delay circuit. If an attention signal is detected for a period of time in excess of 1 second, the one second time delay circuit stops the scanning of the scanning circuit to lock in the receiver to the first carrier detected with an attention signal. The ten second time delay circuit normally disables the squelching circuit.

Abstract: Apparatus for monitoring the use of television receivers to obtain information for the rating of television programs. The apparatus makes a comparison between the intercarrier frequency signal (i.e., phase) produced by extracting from an operating television receiver tuned to a channel the visual and aural IF frequencies and the respective intercarrier frequency signals (i.e., phase) produced by successively extracting from transmitting sources of television channels the visual and aural IF frequencies. The intermediate frequency signals of the television receiver are sampled and converted into an intercarrier frequency signal. A voltage controlled tuner is tuned to the radio frequency carriers of the various television channels in a hunting sequence. The output signals of the voltage controlled tuner are intermediate frequency signals, which are converted into intercarrier signals.