Adaptive Track Detection for Multi-Static Active Sonar Systems
Abstract
Multi-static active sonar systems detect contacts of interest by transmitting coherent waveforms and detecting the echoes on one or more receiving sensors. When a target of interest is in a region where its echoes are detectable by more than one receiver it can, in general, be declared sooner by combining the measurements from all sensors. The track detection schemes used in active sonar systems are often based on the Wald Sequential Probability Ratio Test (SPRT) [1] and take as input the amplitudes of the target echoes associated to the track and where the statistical models for the amplitude of a target echo usually depend on a signal-to-noise ratio (SNR) parameter. Two popular multi-static track detection schemes accumulate a separate SPRT for each target at each sensor. Tracks are declared using one of two rules: if any of the separate SPRTs for a target exceeds the declare threshold then the target is declared (i.e., the OR detector), if the sum of the separate SPRTs goes over the declare threshold then the target is declared (i.e., the SUM detector). The main problem with both methods is that the track detection problem is composite; the distribution for the target present case depends on the SNR parameter, which is a priori unknown and different source/receiver combinations will typically observe different values of SNR on the same target. In practice, a fixed design value (e.g., 10 dB) is often chosen so that each sensor will separately achieve the desired probability of detection for SNR values greater than or equal to the design value. However, when combining measurements from two or more sensors, this approach can be suboptimal when only one sensor is observing a value of SNR at or above the design value and the SNR for the other sensors are lower than the design value.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 2006
- Accession Number
- ADA498860
Entities
People
- Christian G. Hempel
Organizations
- Naval Undersea Warfare Center