Transmit-Signal Design and Processing Strategies for Sonar Target Phase Measurement

Philip Atkins, Timothy Collins, NJ Foote

Research output: Contribution to journalArticlepeer-review

36 Citations (Scopus)


The majority of active sonar systems detect and classify a target based on the amplitude of the received echo strength or the induced Doppler shift. However, additional classification information is available from the phase shift introduced by some targets as a result of the acoustic boundary conditions. For example, reverberation returns from the sea surface and from the swim-bladders of various fish introduce an additional phase shift that is not usually present in returns from the seabed or man-made targets. Techniques based on the use of sub-band correlators are presented for measuring the phase shifts associated with certain stationary and moving targets when insonified by broadband transmissions. The performance of the target-phase measurement technique is derived for transmit signals used in existing sonar systems such as continuous wave (CW), linear frequency-modulated (LFM), and hyperbolic frequency-modulated (HFM) pulses in the presence of target or platform motion. The use of HFM signal processing with sub-band correlators to measure the Doppler shift of very slowly moving targets is presented. Modifications to sinusoidal frequency-modulated (SFM) and HFM transmission types are proposed in order to maintain a good compromise between overall detection and target-phase classification performance, i.e., between range resolution and phase measurement. Field trial results are presented for a plankton classification sonar system and a collision-avoidance system designed for operation near the sea surface.
Original languageEnglish
Pages (from-to)91-104
Number of pages14
JournalIEEE Journal of Selected Topics in Signal Processing
Issue number1
Publication statusPublished - 1 Jun 2007


  • sonar velocity measurement and waveform design
  • sonar target recognition
  • sonar signal processing
  • Acoustic signal processing


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