CN205404489U - System for improving ultrasonic time reversal focusing detection by using linear frequency modulation pulse excitation technology - Google Patents

Abstract

A system for improving ultrasonic time-reversal focus detection with chirp excitation technology, including a computer, a signal generator, a power amplifier, an oscilloscope, a transmitting transducer and a receiving transducer; the computer is connected to the oscilloscope, and the oscilloscope is connected to the signal generator Connected by GPIB data line, the signal generator is used to output the chirp signal to the power amplifier, the power amplifier is connected to the transmitting transducer, the signal in the medium to be tested is detected by the receiving transducer and sent to the oscilloscope, and the oscilloscope is used to display the receiving The signal received by the transducer for the first time and the focused signal after time reversal. The utility model uses the linear frequency modulation pulse excitation technology to improve the ultrasonic time-reversal focusing detection, improves the effect of crack focusing, and improves the quality and accuracy of crack detection, which makes it effectively used in the detection of national large aircraft materials and automobile materials This is of great significance to ensure safe production and stable economic operation.

Description

A System for Improving Ultrasonic Time-Reversal Focus Detection Using Chirp Excitation Technique

technical field

The utility model belongs to the technical field of signal processing and ultrasonic detection, in particular to a system for improving ultrasonic time-reversal focus detection by using linear frequency modulation pulse excitation technology.

Background technique

At present, in the process of ultrasonic non-destructive testing, time reversal technology is more and more widely used. Time reversal is one of the applications of the principle of acoustic reciprocity, which can focus the acoustic energy in time and space, and realize the Signal reconstruction at the source location. In the process of time reversal, the traditional method generally selects a single pulse signal as the excitation signal. However, due to the low energy carried by the single pulse signal, the measured pulse response after transmission through the detection medium cannot provide a strong enough This will lead to a relatively poor signal-to-noise ratio, and affect the effect of focusing and imaging on cracks, reducing the quality and accuracy of crack detection.

Utility model content

The purpose of this utility model is to solve the problem that the signal-to-noise ratio of the focus signal is low when a single pulse signal is used as the excitation signal in the traditional ultrasonic detection. the quality of.

The technical scheme of the utility model is:

A system for improving ultrasonic time-reversal focus detection with chirp excitation technology, which includes a computer, a signal generator, a power amplifier, an oscilloscope, a transmitting transducer and a receiving transducer;

Described computer sets center frequency f, signal cycle T, scanning bandwidth B, amplitude A of the chirp signal that signal generator sends out by LabVIEW software and controls the display of oscilloscope, and computer communicates with signal generator, oscilloscope through data line connected;

Described signal generator is used for outputting chirp signal to power amplifier, and it is connected with computer by USB data line, and signal generator is connected with oscilloscope by GPIB data line;

The power amplifier is used to amplify the chirp signal, and its signal output terminal is connected with the transmitting transducer;

The transmitting transducer is used to output the amplified chirp signal to the medium to be tested, and the receiving transducer is used to detect the medium to be tested, which is connected to the oscilloscope through a data line, and sends the received signal in the medium to oscilloscope;

The oscilloscope is used to display the signal received by the receiving transducer and the focus signal after time reversal.

Both the transmitting transducer and the receiving transducer of the utility model are ultrasonic probes.

The model of the signal generator of the present utility model is AWG2021.

The beneficial effects of the utility model:

The utility model uses the linear frequency modulation pulse excitation technology to improve the ultrasonic time-reversal focusing detection, which can improve the crack focusing effect and improve the quality and precision of crack detection, which can be effectively applied in the national large aircraft materials and automobile industry In the detection of materials, this is of great significance to ensure safe production and stable economic operation.

Description of drawings

Fig. 1 is a structural representation of the utility model.

detailed description

Below in conjunction with accompanying drawing and embodiment the utility model is described further.

As shown in FIG. 1 , an application of the chirp excitation technology is realized based on an ultrasonic nondestructive testing experimental platform system. The hardware part of the experimental platform is composed of computer, signal generator, power amplifier, oscilloscope, ultrasonic transducer, etc. The system connection block diagram is shown in Figure 1. In terms of software, the control of the hardware system is realized through the development and design of the LabVIEW program, and the application of various time reversal technologies, such as time reversal (TimeReversal: TR), inverse filter (InverseFilter: IF) and 1-bit processing technology (1BitProcessing), etc., to realize the detection of the focus signal.

When implementing it:

S1, adopt the computer control signal generator to produce the linear frequency modulation pulse signal s (t), it is the frequency modulation pulse signal that the instantaneous frequency increases linearly, the expression is as follows:

$\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}\mathrm{<span\; class="notranslate">\; f</span>}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&pi;</span>}\frac{\mathrm{<span\; class="notranslate">\; B</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; t</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; \&le;</span>\frac{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}$

Among them, A is the amplitude of the signal source, f is the center frequency, T is the signal period, and B is the scanning bandwidth;

The chirp signal is generated by LabVIEW software programming on the computer, and the center frequency f, signal period T, scanning bandwidth B and amplitude A of the signal are set in the computer through LabVIEW programming;

S2. The aforementioned input signal s(t) is amplified by the power amplifier and transmitted to the medium to be measured by the transmitting transducer and excited to generate sound waves. The sound waves propagate in the medium to be measured and are received by the receiving transducer on the other side. take over;

S3. The signal received by the receiving transducer is sent to the oscilloscope and sent to the computer. After being processed by the time reversal technology in the computer, the transmitting transducer transmits the inverted signal to the medium to be tested. Focusing of the signal is realized in the measured medium, and the focusing signal is detected by the receiving transducer. During this process, the oscilloscope displays the signal received by the receiving transducer for the first time and the focusing signal after time reversal.

The parts not involved in the utility model are all the same as the prior art or can be realized by adopting the prior art.

Claims (3)

1. improve a system for ultrasonic time reversion focus detection with chirp excitation technique, it is characterized in that it includes computer, signal generator, power amplifier, oscillograph, transmitting transducer and reception transducer；

Described computer arranges the mid frequency f of the chirp pulse signal that signal generator sends, signal period T, sweep bandwidth B, amplitude A by LabVIEW software and controls oscillographic display, and computer is connected with signal generator, oscillograph by data wire；

Described signal generator is for output linearity chirp signal to power amplifier, and it is connected by USB data line with computer, and signal generator is connected by GPIB data wire with oscillograph；

Described power amplifier is used for amplifying chirp pulse signal, and its signal output part is connected with transmitting transducer；

Described transmitting transducer is for by the chirp pulse signal output after amplification to testing medium, and reception transducer is used for detecting testing medium, and it is connected with oscillograph by data wire, gives oscillograph by the signal in the medium received；

Described oscillograph is for showing the signal receiving transducer reception and the focus signal after time reversal.

2. chirp excitation technique according to claim 1 improves the system of ultrasonic time reversion focus detection, it is characterized in that described transmitting transducer and reception transducer are ultrasonic probe.

3. chirp excitation technique according to claim 1 improves the system of ultrasonic time reversion focus detection, it is characterized in that the model of described signal generator is AWG2021.