Spread spectrum receiver having multiple search windows to prevent misalignment during call

Abstract

A spread spectrum receiver includes a number of rake fingers for receiving a spread spectrum signal. Each rake finger despreads the spread spectrum signal with a despreading code. A rake combiner combines the outputs of the rake fingers. Control circuitry sets despreading codes of a first bit sequence to the rake fingers at respective timing offsets of incremental values so that there exists a timing difference of one chip interval between successive rake fingers. The control circuitry then successively varies the timing offsets in search of a call processing signal. Responsive to an output of the rake combiner indicating that the call processing signal is received, the control circuitry determines its timing offset relative to the refererence, and sets despreading codes of a second bit sequence to the rake fingers at respective timing offsets of the incremental values based on the determined timing offset to receive an information signal. If the receiver loses track of the correct timing of the information signal, the control circuitry successively varies the respective timing offsets of the rake fingers in search of the lost signal.