101. A system as recited in claim 92 wherein said means for extracting said signature includes means for low pass filtering a video signal of the television signal to provide a video envelope signal, means for periodically sampling said video envelope signal to provide a series of video samples, and means for digitizing said video samples to provide said signature.
101. A system as recited in claim 92 wherein said means for extracting said signature includes means for low pass filtering a video signal of the television signal to provide a video envelope signal, means for periodically sampling said video envelope signal to provide a series of video samples, and means for digitizing said video samples to provide said signature. 104. A system as recited in claim 101 wherein said video envelope signal sampling means includes means for taking a predetermined number of samples of said video envelope signal and means for taking the averages of predetermined consecutive samples to generate a plurality of average signals, each average signal defining one of the features that comprises the feature string.