Delayed and summed adaptive noise waveforms for target matched radar detection

In a radar system transmitting random noise, range to the target is determined by cross-correlating the return signal with a time-delayed replica of the transmit waveform. The correlation peak occurs at a lag corresponding to the round-trip time to the target. If the target has several characteristic scattering centers located at different ranges, several correlation peaks will occur. In many radar applications, it is only of interest to recognize a few specific targets in the scene and disregard many others, including clutter, that are not of interest. Automatic target recognition using high range resolution profiles is greatly facilitated by the detection of specific arrangement of scattering centers on a target of interest, which occur at predetermined, differential time delays from the radar. If the scattering center arrangement is known a priori, a composite noise waveform consisting of appropriately summed delays of the original signal can be transmitted. If the arrangement of the scattering centers exactly matches that of the transmit waveform, the composite correlation function is enhanced due to the summation of correlations at the individual delays, thereby resulting in improved target recognition. Targets that do not match the transmit waveform will not result in the enhanced correlation peak, and thus can be discarded. Experimental validations were performed for target arrangements with two and three scattering centers using a 1-2 GHz UWB noise radar.