Prefiltering for higher order advantage

Prefiltering, or limiting the spectral domain of data, improves maximum magnitude correlation peak detectors, both ordinary and higher order, for known and unknown sources. The only exception is the matched filter, which intrinsically contains prefiltering. For the cases studied, prefiltering generally has a higher order advantage, i.e., for higher order and in higher dimensions, it is even more effective than in one dimension for the ordinary correlation. Geometrical considerations can give some insight into this advantage. The tricorrelation detector with prefiltering performs best for all eight tested signals in the unknown source tests, and is the best detector for seven of the eight signals in the known source tests. Prefiltering for higher order correlation detectors involves only one-dimensional filtering and so is computationally efficient.