Instrumentation for dolphin echolocation experiments

Abstract

The use of personal computers has contributed significantly in dolphin echolocation research by providing an inexpensive instrument to measure echolocation signals, monitor and control experimental devices, and to store data. Dolphins typically emit short duration (50–100 μs), broadband click signals with repetition rates that can vary from tens of clicks per second to several hundred clicks per second. In this paper, three electronic measurement devices used with Apple II computers in dolphin echolocation experiments will be discussed. The first device measures the number of clicks emitted, the intervals between clicks, the peak‐to‐peak amplitude of each click, and the time of activation of various switches. The second device measures the frequency spectrum (between 30 and 135 kHz) of each emitted click signal in real time, with a resolution of 15 kHz. The third device is a phantom electronic target simulator that digitizes each emitted click and then retransmits the click signal under control of the computer. The development of these three devices has been a process of evolution in sophistication over a period of several years of dolphin echolocation research conducted at the Naval Ocean Systems Center.