Animal Sonar pp 803-807 | Cite as

Echoes from Insects Processed Using Time Delayed Spectrometry (TDS)

  • Lee A. Miller
  • Simon Boel Pedersen
Part of the NATO ASI Science book series (NSSA, volume 156)


TDS uses a linearly frequency modulated (FM) signal for system response analysis. The technique was first described by Heyser (1967) and has been applied to microwave and ultrasonic imaging systems (Heyser and LeCroissette 1974). Briefly, the technique utilized an FM probe signal where the instantaneous frequency of the signal received by the transducer is a function of the FM sweep rate and path length, or time delay, during transmission. Reflected signals (echoes) arriving at the transducer are delayed relative to the direct signal. Each time delay is associated with a frequency change hence the name, Time Delayed Spectrometry. TDS has several useful analytical aspects. For example, the nature of the probe signal allows for easy conversion between time and frequency domains. Also, one can show that, under certain restrictions, the echo is a (linear) FM signal modulated with the transfer function of the system (target). Hence the envelope of the echo is the numerical value of the transfer function for the target. If the phase information is available the impulse response can be obtained and the system can be uniquely described.


Frequency Modulate Instantaneous Frequency Frequency Filter Linear Frequency Modulate Linear Frequency Modulate Signal 
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.


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Copyright information

© Plenum Press, New York 1988

Authors and Affiliations

  • Lee A. Miller
    • 1
  • Simon Boel Pedersen
    • 2
  1. 1.Institute of BiologyOdense UniversityOdenseDenmark
  2. 2.Acoustics LaboratoryTechnical UniversityLyngbyDenmark

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