Demodulator for radio data signals - provides data pulse of one of two levels depending on sign of difference between phases of received signal and delayed signal

摘要

The system demodulates radio data signals transmitted by phase modulation of a suppressed carrier. The received carrier frequency signal is delayed by one half period of the bit period of the radio data signal. The received and the delayed carrier frequency signals are vectorially added. A rectangular signal is fed out from the result of the addition. The phase of this signal depends on the received and the delayed signals. A data pulse signal is fed out from the rectangular signal and the retrieved 57 kHz carrier. The data pulse has one of two levels depending on the sign of the measured phase difference. ADVANTAGE - No response time from phase control loops. Easily and inexpensively realised as integrated circuit and does not require expensive adapting processes. Only digital components required.