The use of linear prediction filters in square law detection of covert signals

The author considers the performance of a square law detector for direct sequence spread spectrum binary phase shift keying (DSSS-BPSK) signals in the presence of broadband interference when filtering is employed to excise the interference. A linear predictive filter operating at steady state is considered as the excision filter. It is demonstrated that large gains can be achieved by the use of predictive filters. The degrading effects of the interference upon the system performance are eliminated when the interference bandwidth is relatively small compared with that of the DS signal. However, for relatively large interference bandwidths, the predictive filters are unable to remove the interference without removing a large percentage of the DS signal energy. The effects due to frequency location and power of the interference as compared with those of the DS signal are examined