Fast DS-SS Acquisition Implementation for High Sensitivity Receivers

Pseudorandom codes are used in direct sequence spread spectrum (DSSS) receivers to synchronize the received signals with locally generated replica. A coarse synchronization called acquisition is followed by a finer synchronization, tracking. Both of these procedures bring received and replica signals to a small timing offset and find the residual frequency modulation which is left after carrier wipe-off. The acquisition stage is computationally challenging procedure for the receivers operating in weak signal conditions as the signal search space increases due to long integrations needed for high sensitivity. For example, these conditions can be observed indoors for satellite ranging and communication portable receivers. We present new very fast technique for acquiring signals indoors in conditions that require a significant number of computations. In our approach, many arithmetic operations are shared and external aid can be used to reduce the search space. Significant gains in arithmetic complexity are achieved