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Introduction to DSP

Time domain processing

Cross correlation to identify a signal

Cross correlation (correlating a signal with another) can be used to identify a signal by comparison with a library of known reference signals.

The diagram shows how the unknown signal can be identified.

• A copy of a known reference signal is correlated with the unknown signal.
• The correlation will be high if the reference is similar to the unknown signal.
• The unknown signal is correlated with a number of known reference functions.
• A large value for correlation shows the degree of similarity to the reference.
• The largest value for correlation is the most likely match.

Cross correlation is one way in which sonar can identify different types of vessel.

• Each vessel has a unique sonar 'signature'.
• The sonar system has a library of pre-recorded echoes from different vessels.
• An unknown sonar echo is correlated with a library of reference echoes.
• The largest correlation is the most likely match.

Last updated: 10th December 1997 | http://www.bores.com/courses/intro/time/2_ident.htm

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