title: Evaluation of the echolocation model for range estimation of multiple closely spaced objects.
abstract: Experimental evidence indicates that bats can use frequency-modulated echolocation to identify objects with an accuracy of less than 1 μs. However, when modeling this process, it is difficult to estimate the delay times of multiple closely spaced objects by analyzing the echo spectrum, because the sequence of delay separations cannot be determined without information on the temporal changes in the interference patterns of the echoes. To extract the temporal changes, Gaussian chirplets with a carrier frequency compatible with bat emission sweep rates are introduced. The delay time for object 1 (T(1)) is estimated from the echo spectrum around the onset time. The T(2) is obtained by adding the T(1) to the delay separation between objects 1 and 2. Further objects are located in sequence by this procedure. Here echoes were measured from single and multiple objects at a low signal-to-noise ratio. It was confirmed that the delay time for a single object could be estimated with an accuracy of about 1.3 μs. The range accuracy was less than 6 μs when the frequency bandwidth was less than 10 kHz. The delay time for multiple closely spaced objects could be estimated with a high range resolution by extracting the interference pattern.
authors: Department of Information Science, Tohoku Gakuin University, Sendai, Japan. matsuo@cs.tohoku-gakuin.ac.jp
authors: Ikuo
authors: I
authors: Matsuo
mesh_terms: D000162:Acoustics / Q000295:instrumentation; D000818:Animals; D002685:Chiroptera / Q000502:physiology* / Q000523:psychology; D004192:Discrimination, Psychological; D004455:Echolocation; D008954:Models, Biological; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted; D013018:Sound Spectrography; D013997:Time Factors