Acquisition of Direct Sequence Signals with Modulation and Jamming

The effects of data modulation and/or narrow-band interference on the acquisition time of direct sequence (DS) systems are assessed when particular acquisition schemes are selected. Finally, the results of these analyses are used to propose receivers which mitigate the deleterious effects of the data or jamming. The analyses demonstrate that the I-Q detector, modified for a data modulated carrier, is superior to the correlator/square-law detector despite the latter´s robustness to data. When the average pulsed jammer power is constrained, the analyses illustrate that the jammer´s duty factor does not impact acquisition time when the pulse repetition frequency (PRF) is high; a duty factor of unity maximally degrades acquistion performance when the PRF is low. A proposed adaptive receiver provides considerable jamming protection; the acquistion performance of such a receiver bounds the performance of all adaptive acquistion receivers.