Range Detection of Targets using Hydroacoustics in the Laboratory

Investigations were conducted in the laboratory on the accuracy in terms of range resolution of a commercial sonar system (420 kHz) in detecting underwater targets. Accurate range resolution of fish is necessary for reliable estimates of numbers and for detecting the presence and behaviour of fish near the bottom. Results indicated that the existing sounder was limited in target separation below 25 cm at a transmitted pulse of 0.1 ms under laboratory conditions. Modifications to equipment resulted in an improved range resolution (to approximately 10 cm) of targets in both vertical and horizontal tank experiments.