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Animal Sonar pp 581-587 | Cite as

Harmonic Structure of Bat Echolocation Signals

  • Karl Zbinden
Part of the NATO ASI Science book series (NSSA, volume 156)

Abstract

A wide range of different harmonic patterns is found in echolocation signals of bats. Often a gradual change from single harmonic pulses to multiple-harmonic ones can be observed when FM-bats detect and approach their prey in free flight. Multiple-harmonic pulses may also be used for orientation in space under reverberant conditions or for target discrimination. The appearance of the harmonic structure of a bat pulse is influenced by the Q of vocal tract resonances. At low Q multiple harmonics increase the signal bandwidth and thus improve the ranging and discriminative properties of a pulse. At high Q dumbell pulses are created.

Keywords

Target Velocity Range Resolution Ambiguity Function Harmonic Structure Main Ridge 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Symbols

ACR

autocorrelation

AD

Ambiguity diagram

Doppler factor e

c−v/c+v

where c

velocity of sound in air and v=target velocity

BWeff

effective bandwidth

BWs

spectral bandwidth

CF

constant frequency

EFM

exponential frequency modulation

fc(eff)

(effective)centre frequency

LFM

linear frequency modulation

LPM

linear period modulation

Q

F.reson./BW (quality factor of a resonator)

T-6dB

signal duration between amplitude points of -6dB

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References

  1. Halls, J.A.T. (1980): An analogue device for the generation of sonar ambiguity diagrams. Animal Sonar Systems (eds. Busnel, R.G. and J.F. Fish), Plenum Press, N.Y. pp. 909–911.Google Scholar
  2. Johnson, R.A. and E.L. Titlebaum (1972): Range—Doppler uncoupling in the Doppler tolerant bat signal. Proc. 1972 I.E.E.E. Ultrasonics symposium.Google Scholar
  3. Pye, J.D. (1985): Signals as clues to system performance. Systemes Sonars Aeriens Animaux: Colloque International C.N.R.S., Lyon France.Google Scholar
  4. Simmons,J.A. and R.A. Stein (1980): Acoustic Imaging in Bat Sonar: Echolocation Signals and the Evolution of Echolocation. J.Comp.Physiol. 35, 61–84.CrossRefGoogle Scholar
  5. Zbinden, K. and P.E. Zingg (1985): Search and Hunting Signals of Echolocating Free—tailed Bats, Tadarida teniotis in Southern Switzerland. Mammalia 50 (1), 9–25.CrossRefGoogle Scholar

Copyright information

© Plenum Press, New York 1988

Authors and Affiliations

  • Karl Zbinden
    • 1
  1. 1.Institute of ZoologyUniversity of BerneBerneSwitzerland

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