Performance degradation of pseudonoise code lock detector due to radio frequency interference

The author computes the probabilities of detection and false alarm for a pseudonoise (PN) sequence code lock detector when a strong radio frequency interference (RFI) hits the communications link. A soft limiter, a hard limiter, and no limiter at the front end of the receiver are considered. Both continuous wave (CW) type RFI and pulse type RFI are analyzed. It is shown that a soft limiter or a hard limiter can protect the PN code lock detector against a typical pulse RFI, but in a CW RFI environment, the PN code lock detector performance with a soft limiter or a hard limiter will be worse than that with no limiter