Procedures for the performance evaluation of underwater target tracking systems

Target tracking will be defined as the ability to reconstruct, in some operational time frame, the location of an underwater target in both space and time. This capability is extremely important for both military and civilian applications, with the former usually using passive acoustic techniques and the latter employing active acoustics. This paper will describe a set of algorithms and procedures which are general in nature and can be used to evaluate any underwater target tracking system. Basically, the algorithms provide a means for quantifying the accuracy and precision of the tracking system relative to the actual track of the target. The actual target track is known a priori either as a simulated track or as the output of a calibrated acoustic tracking range. The algorithms have been coded and the program is available for general utilization by the ocean engineering community. To demonstrate the application of the algorithms, the results of an actual system evaluation are discussed. In particular, the performance of a Doppler tracking system is described in terms of the metrics. This system was designed to be used aboard an aircraft. It employs a general purpose minicomputer and FFT spectrum analyzer to perform frequency line tracking and a maximum likelihood target tracking algorithm. The experimental data were obtained at the AUTEC tracking range and include the analog tape recorded outputs of a set of freely floating, independent, omnidirectional sonobuoys. The positions of the sonobuoys and the target were determined once per second by AUTEC and were used as the a priori information.