Musical tone signal sequence detector - has comparator based circuit to identify specific musical note sequence

摘要

The identification circuit is designed to respond to a specific audio signal sequence composed of three or more musical notes. The signal sequence is processed by a radio or television amplifier (1) that then provides inputs to several note receivers (2) that are tuned to the specific note frequency. The units generate an output when the signal is present for an uninterrupted period. Outputs are processed by delay stages (6), with the exception of the nth stage that uses an inverter (8). A coincidence stage (9) generates an identifying output that triggers an output stage (10). The system may be used for automatic lead in for TV advertisements.