Abstract

A device is disclosed which simultaneously performs sync preamble correlation detection and frequency offset estimation functions for a spread spectrum receiver. The device performs a parallel frequency search, executed by a plurality of frequency sensitive circuit channels connected in parallel. These parallel circuit channels first apply phase corrections to the subcorrelator outputs and then linearly reintegrate the corrected outputs. In each channel the phase corrections applied to each successive subcorrelator output vary with the frequency offset subregions to which the channel is designed to match. By applying approximated phase corrections of 0°, 90°, 180° or 270° in lieu of the exact phase corrections required to remove the phase shift, the need for multiplication operations in the reintegration process is eliminated, as well as the need for storing large numbers of weighting coefficients. As a result, the reintegration process involves only addition and subtraction operations and the non-linear integration process is eliminated. The detector also establishes an estimate of the input signal frequency offset at the time of detection of the preamble correlation.