Sequential detection for code acquisition with and without data modulation on

The theory of sequential detection has been applied in the past to the acquisition of the direct sequence spread spectrum signals. It is shown to achieve a two to ten fold acquisition time improvement over the conventional fixed dwell time approach and is robust in the case of very low signal-to-noise ratio. The published results employing this approach applied to the case that the spread spectrum signal does not have data modulation. Moreover, the effects of PN code correlation sidelobe are not considered. The approach described in the present paper incorporates the effects of PN code correlation sidelobe and data modulation. This allows the parameters such as bias and thresholds as a function of false alarm probability and missed defection probability to be accurately determined to achieve optimal acquisition performance. The acquisition performance parameters are derived in the paper. The theoretical results are shown to be in excellent agreement with the simulation results