JPS6424543A - Timing synchronizing circuit for modem - Google Patents

Abstract

PURPOSE:To securely synchronize a reception timing signal with a transmission timing phase in a short time by obtaining phase difference information which does not depend upon an amplitude according to N sampled values obtained in one rotation of a reception timing phase. CONSTITUTION:A signal with a transmission timing waveform is sampled at a frequency N (N: positive integer larger than 3) times as high as a modulation speed according to the reception timing phase to calculate the sum of squares of N sampled values of a sampling means in one rotation of the reception timing phase and also normalize specific sampled values among N values with the sum of the squares, thereby calculating the phase difference information which does not depend upon the amplitude of the signal with the transmission timing waveform. Then phase difference corresponding to plural pieces of phase difference information are stored previously and the reception timing phase is shifted according to a phase difference discriminated by a phase discriminating means corresponding to the calculated phase information of a calculating means to control the reception timing phase to the transmission timing phase. Consequently, the reception timing phase can accurately be synchronized with the transmission timing phase.