Patent ID: 6094449
Filing Date: 2000-07-25
Classification: H04B

Abstract:
A spread spectrum communication synchronization acquisition demodulating apparatus of a spreading code synchronizing circuit provided in a radio communication apparatus for performing a data communication in which when a spread spectrum signal which is obtained by modulating transmission data and subjecting the modulated data to spread spectrum processing using a spreading code and then transmitted from a transmission side is demodulated as a reception signal to reproduce reception data at a reception side, the spread spectrum signal is subjected to despread spectrum processing using the same spreading code as the transmission side and then demodulated at the reception side, comprising:a signal converter for converting the reception signal to a base band signal;a sample hold circuit for sampling the base band signal, holding the sampled base band signal and outputting the sampling signal;a first demodulation correlator for correlating the sampling signal and the spread signal based on the spreading code to obtain a first correlation value;a symbol integrator for demodulating the first correlation value on the basis of any one of a theoretical value of a symbol corresponding to the first correlation value when the symbol is known or a judgment value after demodulation when the symbol is unknown and integrating the demodulation result over plural symbols to calculate the power of the integration of the plural symbols, thereby obtaining a power value;a short-time integration path search unit for integrating the power value for the integration time corresponding to the plural slots and selecting higher power values, the number thereof corresponding to the number of the first correlators, in the magnification order of the power per slot from a larger power per slot to a lower power per slot;a long-time integration path search unit for integrating the power value for an integration time longer than that of said short-time integration path search unit by the time corresponding to plural slots and selecting higher power values, the number thereof corresponding to the number of the first correlators, in the magnification order of power per slot from a larger power value to a lower power value;a demodulation path selection unit for selecting a reception timing for demodulation from the timings of the power values selected in said short-time and long-time integration path search units in the order of the magnification of power per slot;a second correlator for correlating the reception signal and the spread signal on the basis of the reception timing for demodulation to obtain a second correlation value;a detector for detecting the second correlation value and outputting a detection signal; anda signal composite unit for outputting a judgment value on the basis of a composite signal which is obtained by transmitting the detection signal to a RAKE/SD (Space Diversity) unit through the corresponding path to perform any one of RAKE synthesis and space diversity (SD) synthesis.