Signal identification system
First Claim
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1. A signal identification system comprising:
- encoding means comprising means for choosing a variable sequence of frequency bands from a plurality of different predetermined frequency bands in the bandwidth of a given signal;
means for eliminating the chosen sequence of frequency bands from the given signal to form a sequence of corresponding notches in the given signal; and
means for inserting a sequence of code signals into the notches, each code signal comprising frequencies within the bandwidth of the notch or notches into which it is inserted; and
decoding means including delay means adapted to delay the insertion of the code signals into the notches until the decoding means ascertains that the amplitude of the code signal is sufficient to be detectable within the given signal, and to determine whether the code signal is present in the given signal.
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Abstract
A signal identification system, suitable for producing an identification code on a sound track recording is described. The system includes an encoder 209 effective to eliminate a variable sequence of frequency bands from an audio signal and insert a sequence of code signals into the frequency bands. As the sequence of frequency bands varies throughout the sound track recording, the presence of the code is difficult to detect.
448 Citations
10 Claims
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1. A signal identification system comprising:
- encoding means comprising means for choosing a variable sequence of frequency bands from a plurality of different predetermined frequency bands in the bandwidth of a given signal;
means for eliminating the chosen sequence of frequency bands from the given signal to form a sequence of corresponding notches in the given signal; and
means for inserting a sequence of code signals into the notches, each code signal comprising frequencies within the bandwidth of the notch or notches into which it is inserted; and
decoding means including delay means adapted to delay the insertion of the code signals into the notches until the decoding means ascertains that the amplitude of the code signal is sufficient to be detectable within the given signal, and to determine whether the code signal is present in the given signal. - View Dependent Claims (2, 3, 4, 5)
- encoding means comprising means for choosing a variable sequence of frequency bands from a plurality of different predetermined frequency bands in the bandwidth of a given signal;
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6. An encoding system for the coding of a given signal comprising:
- means for choosing a variable sequence of frequency bands from a plurality of different predetermined frequency bands in the bandwidth of a given signal;
means for eliminating the sequence of chosen frequency bands from the given signal to form a sequence of corresponding notches in the given signal; and
means for inserting a sequence of code signals into the notches, each code signal comprising frequencies within the bandwidth of the notch or notches into which it is inserted. - View Dependent Claims (7, 8, 9)
- means for choosing a variable sequence of frequency bands from a plurality of different predetermined frequency bands in the bandwidth of a given signal;
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10. A decoding system for decoding a signal in which a code signal has been incorporated in a variable sequence of predetermined frequency bands in the signal, the decoding system including means for inspecting a plurality of combinations of the predetermined frequency bands.
Specification