DOPPLER FREQUENCY MEASUREMENT CIRCUIT AND SYNCHRONIZATION CIRCUIT

摘要

PROBLEM TO BE SOLVED: To select measurement of an accumulation degree with high accuracy, a main wave and a delayed wave and to demodulate a signal with high quality in the case of PN synchronization acquisition and PN synchronization holding in the receiver of the spread spectrum communication system. SOLUTION: A delay profile 12 measured by a delay profile measurement section 11 is given to a Doppler frequency measurement section 13 to measure a Doppler frequency 14 from a time change in the delay profile 12. Circuits 18, 20 are used to select a time constant of the filter and a switching interval 21 of a main wave and a delayed wave based on the Doppler frequency 14 and the result is used to average the delay profile 12 and to select the main wave and the delay wave then a high accumulation 17 is measured by an IIR (infinte impulse response) filter 15 (or FIR(finite impulse response) filter) and the main wave and the delay wave are selected with high accuracy by a main wave delay wave selection circuit 19 to demodulate a signal with high quality.