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Crosscorrelation Detectors

July 19th Fact-of-the-Day

A crosscorrelation detector compares a received signal waveform point-by-point with an internally-generated reference signal constructed to predict what the shape of the received signal should be at many closely-spaced future points in time. The detector output signal is a measure of the degree of shape similarity between the received signal and the local prediction signal. For example, in the simple case of detecting Morse code bursts of CW, the shape of an incoming signal would be compared point-by-point with a locally generated RF sine-wave. However, unlike the usual method of CW heterodyne detection, the local sine-wave would have the exact same frequency and phase as the received signal. Practical application obviously requires extraordinary frequency precision on both ends of a circuit or some means of automatic frequency and phase synchronization. However, the payoff is a detector significantly better than most at detecting signals buried in noise. ©2005 Martek International All rights reserved.


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