Accession Number:

ADA461581

Title:

Multiecho Processing by an Echolocating Dolphin

Descriptive Note:

Journal article

Corporate Author:

CHIRP CORP LA JOLLA CA

Report Date:

2003-08-01

Pagination or Media Count:

13.0

Abstract:

Bottlenose dolphins Tursiops truncatus use short, wideband pulses for echolocation. Individual waveforms have high-range resolution capability but are relatively insensitive to range rate. Signal-to-noise ratio SNR is not greatly improved by pulse compression because each waveform has small time-bandwidth product. The dolphin, however, often uses many pulses to interrogate a target, and could use multipulse processing to combine the resulting echoes. Multipulse processing could mitigate the small SNR improvement from pulse compression, and could greatly improve range-rate estimation, moving target indication, range tracking, and acoustic imaging. All these hypothetical capabilities depend upon the animals ability to combine multiple echoes for detection andor estimation. An experiment to test multiecho processing in a dolphin measured detection of a stationary target when the number N of available target echoes was increased, using synthetic echoes. The SNR required for detection decreased as the number of available echoes increased, as expected for multiecho processing. A receiver that sums binary-quantized data samples from multiple echoes closely models the N dependence of the SNR required by the dolphin. Such a receiver has distribution-tolerant nonparametric properties that make it robust in environments with nonstationary andor non-Gaussian noise, such as the pulses created by snapping shrimp.

Subject Categories:

  • Biology
  • Statistics and Probability
  • Acoustics
  • Radiofrequency Wave Propagation

Distribution Statement:

APPROVED FOR PUBLIC RELEASE