PURPOSE: To reduce an error rate in the demodulation state by the reduction in the power level of a signal from each station by reducing the fluctuation in the signal power of each station in the demodulation state by the increase in the number of channels so as to keep the quantization accuracy constant in the receiver for a mobile communication system where simultaneous speech is conducted among mobile stations based on the code division multiple address communication system.

CONSTITUTION: Analog signals sent from plural mobile stations are multiplexed in air and the multiplexed signal is received by an antenna 10. The frequency of the signal received by the antenna 10 is decreased up to a base band frequency at a reception section 20. The signal with the base band frequency is converted into a signal whose maximum amplitude is constant by an AGC 30. An output signal S30 of the AGC 30 is A/D-converted by an A/D converter 40 and outputted to a demodulation power controller 50. The demodulation power controller 50 normalizes the power of the signal of each station and outputs to a demodulation section 60. The demodulation section 60 uses a spread code for each station to take correlation for the demodulation.