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Introduction to DSP - time domain processing: cross correlation II

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

Using cross correlation to identify a signal

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.

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