Importance

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Abstract

A correlation detector is provided which can establish initial acquisition quickly, and achieve high accuracy tracking by extracting crosscorrelation components in a receiver for CDMA communication, and a communication system using the correlation detector is also provided. During the initial acquisition, a received signal 21 is supplied to a matched filter 43. When an acquisition decision circuit 45 decides that the matched filter 43 detects the acquisition, it controls a switching circuit 42 to supply the received signal 21 to multipliers 47 and 48, and resets a VCCG 29 and a spreading code replica generator 30. After establishing the acquisition, a received spreading code is quasicoherent detected, and the detected spread signal is multiplied by a phase advanced replica and a phase retarded replica. Correlation detection signals are produced from the products, and squared components of the correlation detected signals are generated, summed in the opposite phase, and averaged along the time axis. The averaged signal is inversely modulated by a decision signal of received data to obtain a phase error signal, the decision signal being obtained by multiplying the received spread signal by a replica in synchronism with the received spread sinal, and by integrating the product over a plurality of chips to compensate for a receive phase error. The replica generator is driven by a clock signal whose phase is controlled by the phase error signal.

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First Claim