Code division multiple access mobile communication system

摘要

A code division multiple access (CDMA) mobile communication system with improvements to permit stable reception with a minimum of bit error. The system comprises a voltage-controlled oscillator for supplying a carrier to a radio frequency quadrature demodulator, and a frequency controller for detecting a frequency error from a phase correction signal of the first step to generate a control signal that controls the oscillator. The frequency controller includes an extracting circuit and an integrating circuit. The extracting circuit extracts a phase change based on the frequency error derived from the phase correction signal of the first step and from a signal preceding that signal by a predetermined delay time. The integrating circuit integrates the phase change and outputs the integrated result as the control signal. The predetermined delay time is preferably set within a range not exceeding the delay time needed for averaging by an averaging circuit that receives the phase correction signal of the first step and outputs a phase correction signal. The carrier to a radio frequency quadrature modulator is preferably supplied from the voltage-controlled oscillator.