Signal processing circuit for spread spectrum communications

摘要

A digital correlator used in a receiving component of a spread spectrum communication system of a direct sequence modulation type is disclosed. A polarity of an input baseband signal is controlled by being inverted or not inverted according to a polarity of a spreading code signal by an amplifier, and the input baseband signal controlled is converted by an analog-to-digital converter into a digital signal. The digital signal is integrated for a prescribed period in an integrator, and a square of an integrated digital signal is calculated in a squaring device to obtain a squared value indicating a degree of a correlation between the input baseband signal and the spreading code signal. In cases where the input baseband signal and the spreading code signal correlate with each other, the squared value gradually increases with the passage of time. In contrast, in cases where the input baseband signal and the spreading code signal do not correlate with each other, the squared value is maintained to a low value. Therefore, the digital correlator can be manufactured by a simplified configuration.