JPS5637745A - Gate signal extracting circuit for time-division multiple connection system - Google Patents

Abstract

PURPOSE:To realize the production of the gate signal to discriminate the preword part from the information word part for the reception signal, by providing the circuit to extract the phase modulation component plus the BPF which uses the output of the above-mentioned circuit as the input. CONSTITUTION:At the gate signal detecting circuit, the signal received 8 is delayed by a fixed time through the delaying circuit 14 and then supplied to the phase detecting circuit 15. While the part of the signal received 8 is branched to be supplied to the other terminal of the circuit 15 and then form the delay detecting circuit. In case the preword at the head part of the received burst-type signal is the signal which received a phase modulation to give the phases alpha and beta alternately to the carrier wave, the frequency signal of (1/2)fS (fS: timing signal) is transmitted to the output of the delay detecting circuit. And a big difference is produced to the signal quantity between the preword part and subsequent information word part after passing through the BPF16 whose central frequency is (1/2)fS. Accordingly, the gate signal which gives clear discrimination between both word parts is obtained after detection of the envelope curve through the wave detector 17 and according to the detection level, and then delivered to the terminal 9.