Conditioning lofargrams using empirical mode decomposition

M. J. Levonen*, L. Persson, S. McLaughlin

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Recorded sonar data is processed in many different ways to extract target information from the source signals. Trying to separate different sources of sound, or identifying vessels by examining the emitted tonals, is often done in the time-frequency domain, e.g. using the lofargram. Narrowband components appear as long-time duration lines and transients as broadband short-time duration pulses. The transients may be generated by the same source as the tonal lines or by other sources in the vicinity, or they can be a part of the additional ambient noise. If transients and narrowband components are mixed in the estimation window, distortion and masking of the lines may occur especially in low SNR regimes. A method for improving the visibility of relevant spectral lines in a lofargram is applied. Instead of using filtering or outlier rejection methods to condition the data, the signal is decomposed by using the method of empirical decomposition.

Original languageEnglish
Title of host publicationProceedings of the 7th Nordic Signal Processing Symposium - NORSIG 2006
Number of pages4
ISBN (Print)1424404126
Publication statusPublished - 2006
Event7th Nordic Signal Processing Symposium 2006 - Reykjavik, Iceland
Duration: 7 Jun 20069 Jun 2006


Conference7th Nordic Signal Processing Symposium 2006
Abbreviated titleNORSIG 2006

ASJC Scopus subject areas

  • Computer Science Applications
  • Signal Processing
  • Mathematics(all)


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