Doublet Pulses Research Articles

Use of time separation pitch in equalizing the interpulse intervals of pulse triplets by method of adjustment

Previously we reported that pulse triplets with both interpulse intervals (IPI) equal to 2.0 ms could be discriminated from pulse triplets with each IPI differing from 2.0 ms by at least 0.14 ms (M. G. Ceruti, R. W. Floyd, and D. W. Martin, J. Acoust. Soc. Am. Suppl. 1 72, S92 (1982)]. Here we report a further experiment in which we presented subjects with a triple pulse stimulus with random differences in IPI's. The Objective of this experiment was to determine the accuracy with which subjects could manipulate the timing of a variable pulse, relative to a pulse doublet with a fixed 4.0-ms interval, in order to produce a triplet containing two IPI's equal to 2.0 ms. The time delay of the doublet, relative to the variable pulse, was randomized prior to each trial. All three identical broadband pulses had durations of 1.0 ms each. Triple pulse stimuli were repeated at 9 Hz during each trial. The subjects' task was to listen to the TSP generated by each stimulus, to adjust a potentiometer controlling the timing of the variable pulse, and finally, to respond when the pulse was centered in the 4.0-ms pulse doublet. The data indicate that subjects responded correctly (forming two IPI's of exactly 2.0 ms each) on 41% of the trials, and produce intervals which both differed from 2.0 ms by 0.1 ms on 33% of the trials. We will discuss both the subjects' performance strategies for pulse centering, as well as subjects' pitch perception of the stimuli.

Sonar for generalized target description and its similarity to animal echolocation systems

Range‐distributed targets are often characterized arrays of point scatterers. This conceptualization corresponds to a target impulse response that is a sequence of impulses. A physically meaningful generalization of this description is obtained by modeling an impulse response in terms of pulse doublets, impulses, step functions, ramp functions, etc., i.e., as a superposition of delayed impulses and differentiated or integrated impulses. The resulting impulse response model resembles a spline function without continuity conditions. A sonar system for generalized target characterization is described; signals and receivers are specified for (1) optimum estimation of reflector parameters and (2) detection of a known target in clutter. The derived signals correspond closely with some of the waveforms that are used by dolphins and bats for echolocation. The corresponding echo analyzers are similar to some psychoacoustic models of the mammalian hearing system.

Acoustic behaviour as a generic character in New Zealand cicadas (Hemiptera: Homoptera)

Abstract Pulse patterns of certain New Zealand Cicadidae (Subfamily Tibicininae) represent hitherto undescribed modes of increasing the repetition rate of clicks in tymbal song. Elaboration of tymbal song by addition of wing-clapping is characteristic of the genus Amphipsalta Fleming, but subdued wing-clapping is also observed in Kikihia Dugdale and Notopsalta Dugdale, not however as a regular element in the song. Rhodopsalta Dugdale and Maoricicada Dugdale differ from the other genera in lacking an alarm note. In Kikihia and Maoricicada, in-out doublet pulses result from the buckling of the two tymbals, generally in unison, but the click repetition rate is lower in Kikihia than in most Maoricicada. In most species of Maoricicada pulses are regularly repeated to generate long notes with regular intervals between clicks but in others the intervals between clicks may be gradually or abruptly altered; in one species the repetition rate is increased by alternation of doublets from right and left tymbals and i...

Doublet pulsed control systems

The doublet pulsed feedback system consists of a doublet pulse modulator and a linear position follow-up system. The pulse modulator generates two pulses, an acceleration pulse, and a retarding pulse. The characteristics of the pulses are chosen so that minimum response time and stable operation are achieved. The phase plane method is used to analyze the doublet pulsed system. It is shown that an optimum adaptive contactor servo can be realized using the doublet pulsed system. The validity of approximating higher order transfer functions by a second-order function and an equivalent transportation lag is demonstrated. This enhances the application of the phase plane method to higher order systems. The analytical stipulations are proved experimentally. An experimental procedure to obtain a specified optimization of a high-order pulsed system through the doublet pulser is developed. The switching pattern and the necessary equations to design a doublet pulser are derived.