Enhanced signal interception in the presence of interference

We consider the problem of intercepting a direct sequence spread spectrum waveform which is embedded in both narrowband interference and additive white Gaussian noise. The receiver we analyze is a broadband radiometer which has been enhanced in the following manner. Prior to entering the square-law device in the radiometer, the received waveform is passed through a transform domain processor which serves as a notch filter to null out the narrowband interference before it can contribute unwanted energy to the output of the radiometer. A central-limit theorem is established for the receiver's output which forms the basis for analyzing the performance of the receiver. For various combinations of system parameters, numerical results are presented in the form of receiver operating characteristics. >