In the delay detection demodulator of the /4 shift QPSK modulated wave signal the frequency control manner

摘要

PURPOSE:To reduce the procedure required for reading with a simple circuit configuration by monitoring data while sweeping frequency by a processor's command, and sending back to the sending side information that the reading of I pattern becomes possible. CONSTITUTION:Received carrier wave is separated into each base band signals I and Q, and only base band signals are respectively taken out from loop filters LPF1 and LPF2. Digitally converted base band signals ID and QD are successively stored in the RAM of processor PRCS. Further, the output of the RAM is converted by a D/A converter, and forms a feedback loop that returns to a voltage controller VCO via a loop filter LPF3. Further, at the receiving side, whether or not reading data is possible on a control channel is discriminated by processor PRCS, the voltage controller VCO is swept to make it possible to read data, and then the read data is returned to the sending side, whereby fine adjustments is carried out by an added signal, and whereby the procedure required for arithmetic operation can be reduced with a simple circuit configuration.