CN111157098A

CN111157098A - Demodulation device for simultaneously obtaining amplitude and phase of vibration signal

Info

Publication number: CN111157098A
Application number: CN201911406952.2A
Authority: CN
Inventors: 舒风风; 王凯旋; 刘永顺; 迟明波; 王越; 吴一辉
Original assignee: Changchun Institute of Optics Fine Mechanics and Physics of CAS
Current assignee: Changchun Institute of Optics Fine Mechanics and Physics of CAS
Priority date: 2019-12-31
Filing date: 2019-12-31
Publication date: 2020-05-15
Anticipated expiration: 2039-12-31
Also published as: CN111157098B

Abstract

The invention provides a demodulation device for simultaneously acquiring the amplitude and phase of a vibration signal, which is characterized in that an interference signal containing the amplitude and phase information of a piezoelectric type measured object during vibration is acquired through a heterodyne Doppler interference optical module, and the amplitude and phase of the vibration signal are extracted through operations such as quadrature demodulation, Hilberg transform and the like; therefore, the amplitude and the phase of the vibration signal can be obtained simultaneously only by acquiring the excitation signal without acquiring the orthogonal signal of the excitation signal, and the method can be used for analyzing the sine excitation mode.

Description

Demodulation device for simultaneously obtaining amplitude and phase of vibration signal

Technical Field

The invention belongs to the technical field of laser detection, and particularly relates to a demodulation device for simultaneously obtaining the amplitude and the phase of a vibration signal.

Background

The laser heterodyne Doppler vibration measurement technology is more and more widely concerned due to the characteristics of non-contact, high precision and high signal-to-noise ratio, modal analysis is a method for researching the dynamic characteristics of a structure, the combination of the modal analysis and the structural design can be used for structural design, nondestructive testing, fault analysis and the like, and the laser heterodyne Doppler vibration measurement technology has wide application prospects in the fields of aerospace vehicles, industrial production, scientific research and the like. However, modal analysis needs to obtain the amplitude and phase of the vibration signal at the same time, and the laser heterodyne doppler vibration measurement technology can only obtain the amplitude of the vibration signal and cannot obtain phase information.

Disclosure of Invention

In order to solve the above problems, the present invention provides a demodulation apparatus for simultaneously obtaining the amplitude and phase of a vibration signal, which can simultaneously obtain the amplitude and phase of the vibration signal only by collecting an excitation signal without collecting an orthogonal signal of the excitation signal, and can be used for sinusoidal excitation modal analysis.

A demodulation device for simultaneously acquiring the amplitude and the phase of a vibration signal is applied to a piezoelectric measured object, and comprises a heterodyne Doppler interference optical module 1, an avalanche photodetector 2, an excitation signal source 4, a dual-channel data acquisition card 5 and a processing module 6;

the excitation signal source 4 is used for generating an excitation signal;

the piezoelectric type measured object 3 is used for vibrating under the action of an excitation signal;

the heterodyne Doppler interference optical module 1 is used for generating the same test light and reference light, wherein the test light is incident on a vibrating piezoelectric measured object 3 to obtain feedback light with frequency offset; the feedback light is reflected to the heterodyne Doppler interference optical module 1 to interfere with the reference light to obtain an interference signal;

the avalanche photodetector 2 is used for converting the interference signal into an interference electric signal;

the two-channel data acquisition card 5 is used for converting the excitation signal and the interference electric signal into an excitation digital signal and an interference digital signal respectively;

the processing module 6 is used for performing quadrature demodulation on the interference digital signal to obtain a vibration signal and an amplitude of the vibration signal; and the phase difference processing module is also used for multiplying the excitation digital signal by the vibration signal after Hilberg transformation is carried out on the excitation digital signal, and then obtaining the phase difference between the vibration signal and the excitation digital signal after low-pass filtering is carried out on the product.

Has the advantages that:

Drawings

FIG. 1 is a schematic block diagram of a demodulation apparatus for simultaneously obtaining amplitude and phase of a vibration signal according to the present invention;

the device comprises a 1-heterodyne Doppler interference optical module, a 2-avalanche photodetector, a 3-piezoelectric measured object, a 4-excitation signal source, a 5-double-channel data acquisition card and a 6-processing module.

Detailed Description

In order to make the technical solutions better understood by those skilled in the art, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application.

Referring to fig. 1, the schematic block diagram of a demodulation apparatus for simultaneously obtaining the amplitude and the phase of an oscillation signal according to this embodiment is shown. A demodulation device for simultaneously acquiring the amplitude and the phase of a vibration signal is applied to a piezoelectric measured object and specifically comprises a heterodyne Doppler interference optical module 1, an avalanche photodetector 2, an excitation signal source 4, a dual-channel data acquisition card 5 and a processing module 6;

the excitation signal source 4 is used for generating an excitation signal;

the heterodyne Doppler interference optical module 1 is used for generating two beams of same test light and reference light, wherein the test light is incident on a vibrating piezoelectric measured object 3 to obtain feedback light with frequency offset; the feedback light is reflected to the heterodyne Doppler interference optical module 1 to interfere with the reference light to obtain an interference signal;

The laser of the laser heterodyne interference module is a helium-neon laser with the wavelength of 633nm, the heterodyne signal is 40MHz, and the bandwidth of the avalanche photodetector is 100 MHz. The sampling frequency of the dual-channel data acquisition card is 200MHz, and the low-pass filtering frequency is 1 KHz.

The working principle of the device is as follows:

the heterodyne Doppler interference optical module 1 can generate two beams of same test light and reference light, wherein the test light is incident on a piezoelectric measured object 3, because the piezoelectric measured object 3 vibrates, the incident test light can generate frequency shift to form feedback light with the frequency shift, the feedback light is reflected back into the piezoelectric measured object 3 and interferes with the reference light, and finally, an interference signal output by the piezoelectric measured object 3 contains amplitude and phase information when the piezoelectric measured object 3 vibrates; the method comprises the following steps of simultaneously sampling an interference electric signal and an excitation signal by adopting a dual-channel data acquisition card 5, orthogonally demodulating the interference digital signal to obtain a vibration signal, carrying out Hilberg transformation on the excitation digital signal to obtain a complex signal, wherein the real part of the complex signal represents the excitation signal, the imaginary part of the complex signal represents the orthogonal signal of the excitation signal, multiplying the complex signal by the vibration signal, carrying out low-pass filtering to obtain a complex direct-current component, marking as A + iB, and then obtaining the amplitude of the vibration signal as: sqrt (A2 + B2)/A0, where A0 is the amplitude of the excitation signal, where the excitation signal is known, and the phase of the vibration signal is: arctan (A/B). Therefore, based on the device, the amplitude and the phase of the vibration signal can be obtained simultaneously only by acquiring the excitation signal without acquiring the orthogonal signal of the excitation signal, and the device can be used for analyzing the sine excitation mode.

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it will be understood by those skilled in the art that various changes and modifications may be made herein without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A demodulation device for simultaneously acquiring the amplitude and the phase of a vibration signal is applied to a piezoelectric measured object and is characterized by comprising a heterodyne Doppler interference optical module (1), an avalanche photodetector (2), an excitation signal source (4), a dual-channel data acquisition card (5) and a processing module (6);

the excitation signal source (4) is used for generating an excitation signal;

the piezoelectric type measured object (3) is used for vibrating under the action of the excitation signal;

the heterodyne Doppler interference optical module (1) is used for generating the same test light and reference light, wherein the test light is incident on a vibrating piezoelectric measured object (3) to obtain feedback light with frequency offset; the feedback light is reflected to the heterodyne Doppler interference optical module (1) to interfere with the reference light to obtain an interference signal;

the avalanche photodetector (2) is used for converting the interference signal into an interference electric signal;

the double-channel data acquisition card (5) is used for converting the excitation signal and the interference electric signal into an excitation digital signal and an interference digital signal respectively;

the processing module (6) is used for carrying out quadrature demodulation on the interference digital signal to obtain a vibration signal and the amplitude of the vibration signal; and the phase difference processing module is also used for multiplying the excitation digital signal by the vibration signal after Hilberg transformation is carried out on the excitation digital signal, and then obtaining the phase difference between the vibration signal and the excitation digital signal after low-pass filtering is carried out on the product.