Two frequency remote control system for TV set - has AND gate coupled to delayed and opposite polarity output of discriminator

摘要

The receiver includes a frequency discriminator, having an S-shaped characteristic curve, for generating an output signal of one polarity when a signal of frequency f2 is received and a second output signal of opposite polarity when a signal of frequency f2 is received. A delay circuit is coupled to the output of the frequency discriminator and includes means triggered by the first output signal to generate a third output signal. A logic circuit has a first input coupled to the output of the frequency discriminator for receiving the second output signal and a second input coupled to the output of the delay circuit. The logic circuit generates an output signal only when an input signal is present on both inputs.