Importance

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Abstract

A communications system (34) that monitors a state of a plurality of radios (10). In one embodiment, the communications system (34) automatically and continuously monitors the number of radios (10) tuned to each of a plurality of available radio stations. Each radio (10) generates a coded signal depending on which radio station the radio (10) is currently tuned to. The coded signal is applied to a frequency generator (32) that generates a unique frequency signal for each code that is then transmitted by the radio (10). Each radio (10) tuned to the same station would transmit the same unique frequency signal at substantially the same power level. The frequency signals transmitted by all of the radios (10) are received by a receiver (34), such as a satellite-based receiver (34), that separates the signals by frequency. The power received for each different frequency signal is then measured to give a total power output for that frequency. An estimation of the number of transmission for each different frequency signal is determined as the measured power level minus the expected receiver noise power, divided by the expected received power from a transmission from a single radio (10).

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First Claim