92. A system for identifying a television signal received from both a television receiver and a video recorder for determining audience viewing habits comprising: means for detecting predetermined changes in the operational modes of the television receiver and the video recorder; means for detecting the occurence of a first event in one of the operational modes; means responsive to both the detection of a first event and a detected viewing operational mode for detecting the occurrence of a second event in the signal to be identified; means responsive to a detected recording operational mode for detecting the occurence of a second event in the signal to be identified; means responsive to the detection of a second event for extracting a signature from a single frame of the video signal to be identified after the occurence of the second event; and means for storing the extracted signature and the detected operational mode.
92. A system for identifying a television signal received from both a television receiver and a video recorder for determining audience viewing habits comprising: means for detecting predetermined changes in the operational modes of the television receiver and the video recorder; means for detecting the occurence of a first event in one of the operational modes; means responsive to both the detection of a first event and a detected viewing operational mode for detecting the occurrence of a second event in the signal to be identified; means responsive to a detected recording operational mode for detecting the occurence of a second event in the signal to be identified; means responsive to the detection of a second event for extracting a signature from a single frame of the video signal to be identified after the occurence of the second event; and means for storing the extracted signature and the detected operational mode. 96. The system reicted in claim 92 wherein said second event detecting means includes means for detecting a scene change from one video scene to another video scene.