UACE2017 Proceedings: High Duty Cycle Sonar Performance as a Function of Processing Time-Bandwidth for LCAS’15 Data

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  • Session:
    Large Time-Bandwidth acoustic signals for target detection and tracking
  • Paper:
    High Duty Cycle Sonar Performance as a Function of Processing Time-Bandwidth for LCAS’15 Data
  • Author(s):
    Doug Grimmett, Randall Plate
  • Abstract:
    Unlike conventional Pulsed Active Sonar (PAS) which listens for echoes in between short-burst transmissions, High Duty Cycle (HDC) sonar transmits with nearly 100% duty cycle. For LFM waveforms this can result in transmitted signals with very large time-bandwidth product, with its bandwidth spread over the entire transmission repeat cycle. In the processing for such waveforms, the total bandwidth may be split up into sub-bands by processing shorter time blocks, resulting in multiple detection opportunities per transmission repeat cycle. The potential advantage is an increased number of continuous detection opportunities, leading to improved target localization, tracking, and classification, due to there being less time lapse between measurement scans. The corresponding disadvantage is that probability of detection and ranging accuracy may be lower per individual detection opportunity. The effect of real acoustic channels will also impact the choice of optimum HDC processing time. In this paper, the HDC processing time interval and sub-bandwidth is investigated using sonar data collected during the Littoral Continuous Active Sonar 2015 (LCAS’15) seatrial for a non-maneuvering surrogate target. A processing chain including target tracker is used to evaluate both signal processing and overall tracking performance dependence as functions of processing time and bandwidth for a set of relevant metrics. Processing metrics such as signal-to-noise ratio, probability of detection, and false alarm rate, as well as tracking metrics such as track hold time, false track rate, and localization accuracy are computed. The optimum sub-band processing time is shown for each metric, and the relative advantages and disadvantages of reducing processing time/bandwidth are analyzed and explained.
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Contact details

  • Contact person:
    Mr Doug Grimmett
  • e-mail:
  • Affiliation:
    SPAWAR Systems Center Pacific
  • Country:
    United States

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