RU1772632C - Method of measuring propagation time of acoustic oscillations - Google Patents

Abstract

The invention relates to methods of physical measurements and can be used for acoustic measurements, to record the reverberation characteristics of rooms when working with audio signals. The aim of the invention is to increase accuracy by eliminating the Doppler effect. Frequency-modulated oscillations are emitted into the test medium, and frequency modulation is carried out according to the law of exponential function. The delayed signal removed from the object’s output is subjected to analog-to-digital conversion by clocking according to the law of exponential function, each sample of the signal is stored in a storage device, from where it is then selected uniformly in time, after which the code samples are spectrometered according to the principle of discrete Fourier transform. 1 ill.

Description

The invention relates to physical measurement methods and can be used for acoustic measurements to record the reverberation characteristics of rooms when working with audio signals.

A known method for measuring the time of propagation of ultrasound in materials by time between the moments of emission and reception of pulses of ultrasonic vibrations, fixed at two threshold levels.

Closest to the invention is a known method for measuring the propagation time of acoustic vibrations, which consists in. that a medium under study is emitted by frequency-modulated oscillations, and the propagation time of oscillations in the medium is judged by the position

spectral components of the received signal.

The disadvantage of this method is the low accuracy of the measurement, due to the shift and smearing of the spectrum due to the Doppler effect.

The aim of the invention is to increase the accuracy of measurements by eliminating the Doppler effect.

The goal is achieved in that in the method of measuring the propagation time of acoustic vibrations, namely, that frequency-modulated vibrations are emitted into the test medium, the propagation time of the vibrations in the medium is judged by the position of the spectral components of the received signal, the frequency modulation of the emitted signal carried out by law | XI ND ABOUT

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of the real function, and the vibrations passing through the medium are recorded in time with dispersion according to the law of modulation of the emitted vibrations.

The drawing shows a block diagram of an apparatus for implementing a method for measuring the propagation time of acoustic vibrations.

A device for measuring the propagation time of acoustic vibrations comprises a signal generator 1 of frequency-modulated according to the law of exponential function, a frequency divider 2, a test object 3. analog-to-digital converter 4, a code sample storage 5, a code selection reading clock 6, a spectrum analyzer 7.

The method is carried out as follows.

Oscillator 1 generates a frequency modulated signal according to the law of an exponential function. Thanks to the frequency divider 2, a signal of the same shape, but of a lower frequency, is supplied to the input of the test object 3. At the output of the object under study, signals appear that are close in form to the input but have different time delays. The combination of these signals undergoes analog-to-digital conversion. In this case, the resulting codes are selected and written to the accumulator 5 not uniformly in time, but with dispersion according to the law of the exponential function due to clocking the recording from the generator 1. The samples are read out from the accumulator uniformly using the clock generator b. The analyzer 7 ow0

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the completeness of the output signals of the test object with different delays is represented as a set of monochromatic signals with different frequencies, with each propagation time in the test object corresponding to a certain frequency at the input of the analyzer 7. In this way, the propagation times of the signals in the form of frequency components are realized.

Using the method ensures that the spectrum is not smeared due to the Doppler effect; moreover, the relative speed of the source-receiver can be estimated from the magnitude of the shift of the spectral components.

When implementing the method there is no mirror channel effect.

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Claims (1)

The claims A method for measuring the propagation time of acoustic vibrations, namely, that frequency-modulated vibrations are emitted into the test medium, and the propagation time in the medium is judged by the position of the spectral components of the received signal, characterized in that that in order to increase accuracy by eliminating the Doppler effect, the frequency modulation of the emitted signal is carried out according to the law of the exponential function, and the vibrations transmitted through the medium are recorded in time with dispersion according to the law of modulation of the emitted oscillations.