Broadband correlation processing

Theoretical analyses indicate significant losses for the complex (envelope) correlator versus the real (bandpass) correlator. These losses result from the elimination of carrier phase information. Detection losses can exceed 5 db. A novel baseband implementation of the real correlator reduces processing requirements relative to the classical bandpass realization. Doppler losses for the real and complex correlator are magnitude equivalent when there are no delay errors. Doppler losses depend strongly on signal center frequency, sensor spacing, and scenario, whereas, they are only weakly dependent on signal bandwidth. The real correlator can be effectively compensated for Doppler by translating the correlator outputs in delay space to account for the motion of the delay point over short correlator time intervals. Use of post-correlator piecewise Doppler compensation followed by coherent integration saves orders of magnitude in processing as compared to pre-correlator Doppler resampling (i.e., a 2- dimensional delay/Doppler correlator).