OPTICAL TRANSMITTING AND RECEIVING APPARATUS

摘要

OPTICAL TRANSMITTING AND RECEIVING APPARATUS Speech signals are optically coupled from a transmitter to a receiver using low duty-cycle infrared pulses. A conditioning circuit converts an a.c. input signal to be transmitted into a unipolar signal, whose magnitude controls the frequency of an oscillator which determines the frequency of the infrared pulses. In the receiver the detected pulses are low-pass filtered in a voice-band filter the output of which is coupled to a telephone line and/or a loudspeaker. A plurality of similar transmitters can be provided to enable signals from an arbitrary number of people to be coupled to a common receiver.