Abstract: Disclosed herein is a method of receiving a spread-spectrum signal in a radio communication terminal device having a plurality of demodulators for demodulating a received spread-spectrum signal, comprising the steps of detecting when at least one of a plurality of demodulators is temporarily unable to properly demodulate the received spread-spectrum signal, determining whether or not there is a demodulator which is not being used other than the at least one of the demodulators, and continuing a demodulating process of the at least one of the demodulators, if there is a demodulator which is not being used. Thus, according to the present invention, the time in which the demodulator is unlocked is minimized, and a stable, high-quality signal can be received.

Abstract: A Viterbi decoding apparatus sets the initial path metric value of each state to a value weighted based on the initial value of a convolutional encoder, and decodes a data string one bit by one bit whenever performing tracing-back for one step with a fixed state determined based on a value of a tail bit as a start-point state when a path metric operation has reached the final operation. Moreover, the Viterbi decoding apparatus selects a maximum-likelihood state out of prospective states determined based on the value of the tail bit and performs tracing-back, until the path metric operation reaches the final operation after it has exceeded the number of data strings. Thus, it is possible to improve the decoding accuracy and the decoding speed.

Abstract: To be able to detect a plurality of correlations in a spread code cycle when receiving CDMA type signals spread with a prescribed spread code and performing correlation detections using a matched filters. A synchronicity detection device which detects a timing of a prescribed spread code already known included in a reception signal is equipped with a correlation coefficient generation means 130 which divides and generates a replica code of a spread code of a prescribed length while a phase advances at each interval of a prescribed width and matched filters 103 and 104 which perform detection of correlation values of reception signals and replica codes generated by the correlation coefficient generation means at each interval of a prescribed width.

Abstract: With respect to each of received signals from a plurality of base stations, an average value is calculated by using detected reception energy and reception energy detected in the past to determine a received signal to be demodulated by comparing the average values. Thereby a further accurate reception energy can be obtained compared to with the case of simply detecting reception energy, even if the detected reception energy temporarily and greatly varies, thus further avoiding malfunction compared to the prior art.