SU1128160A1 - Device for registering ultrasonic signals - Google Patents

Abstract

A DEVICE FOR REGISTRATION OF ULTRASONIC SIGNALS, containing a series-connected resonant electroacoustic transducer, amplifier, threshold unit, pulse counter and the first digital-to-analog converter, recorder, amplitude detector, which is connected to the output unit, and a delay line input, which input line, input amplitude detector, which is connected to the output unit, and delay line, input, and amplitude detector, which is connected to the output unit the second input of the first digital-to-analog converter, and the output is c. input Reset pulse counter, characterized in that, in order to improve noise immunity, it is equipped with a series-connected time meter, the input of which is connected to the output of the amplitude detector, a second digital-to-analog converter, a ratio meter, the second input of which is connected to the output of the first digital-analog converter, and a differential discriminator , trigger, the S-input of which is connected to the output of the amplitude detector, the R-input is connected to the input of the time meter and the output line back rzhki and Q-output of secondary connected to § rum input analog converter and to the input of the delay line, the electronic switch connected between the output of the first digital to analog input and npieobrazovatel recorder and the control input of the electronic key connected to the output of the differential discriminator.

Description

The invention relates to non-destructive quality control of products and materials by acoustic emission and ultrasonic methods in the case of using resonant receiving transducers, and can be used in mechanical engineering, metallurgy and other fields of industry. A device for measuring the amplitude of acoustic emission signals is known, comprising a series-connected electroacoustic transducer, amplifier, peak detector and C13 recorder. Closest to the invention. is a device for recording ultrasonic signals containing a series-connected resonant electroacoustic transducer, an amplifier, a threshold unit, a pulse counter and a first digital-to-analogue converter, an amplitude detector recorder, the input of which is connected to the output of the threshold unit, and a delay line whose input is connected to the second input of the first digital-to-analog converter, and the output - with the input Reset pulse counter C2. A disadvantage of the known devices is the low noise immunity from induced electromagnetic interference and high-power low-frequency acoustic interference due to. lack of special protection schemes. The purpose of the invention is to increase the noise immunity. The goal is achieved by the fact that a device for recording ultrasonic signals containing series-connected resonant electroacoustic transducer, amplifier, threshold unit, pulse counter and first digital-to-analogue converter, recorder, amplitude detector, whose input is connected to the output unit of the threshold unit, and the delay line , the input of which is connected to the second input of the first digital-to-audio converter, and the output with the input Reset of the impulse counter, is equipped with series-connected a time meter: the input of which is connected to the output of an amplitude detector, a second digital-to-analog converter, a ratio meter. the second input of which is connected to the output of the first digital-to-analog converter, and the differential discriminator, a trigger, the 5-input of which is connected to the output of the amplitude detector, the R-input is connected to the input of the time meter and the output of the delay line, and the O-output is connected to the second input of the second digital-analogue the converter and to the input of the delay line, an electronic key connected between the output of the first digital-to-analog converter and the recorder's input, and the control input, elec- tronic. A tron key is connected to the output of a differential discriminator. The drawing shows a block diagram of the device. The device contains a series-connected resonant-electroacoustic transducer 1, amplifier.2, threshold unit 3, pulse counter 4, first digital-to-analog converter 5, electronic key 6 and recorder 7 connected in series to an amplitude detector 8, the input of which is connected to the output of threshold unit 3 , a time meter 9, a second digital-to-analog converter 10, a meter 11 ratios and a differential discriminator 12, the OUT of which is connected to the control input of the electronic key 6, trigger 13.5-in d is connected to the output of the amplitude detector 8, and a line 14 delays input of which is coupled to second inputs of the first and second digital to analog transformations gels 5 and 10 and a Q-output of flip-flop 13, and an output - to the inputs Reset Counter 4 pulses and meter 9. time and R-input trigger 13. A device for recording ultrasonic signals works as follows. Discrete acoustic emission pulses or ultrasonic pulses, in the case of projection of materials with a large attenuation coefficient, received by the resonant elec- trographic transducer 1, are converted by the latter into oscillating electrical signals with a frequency equal to its resonant frequency. The resulting electrical signals are amplified by amplifier 2, converted by a threshold unit 3 into a series of pulses, and counted by 4 pulses. The amplitude detector 8 selects the envelope of the pulse train, the duration of which is determined by the time meter 9, clocked by frequency, equal to the resonant frequency of the electroacoustic transducer 1. On the falling edge of the pulse envelope, the trigger 13 is set to one, allowing the output of the number of pulses in the run and its duration digital-to-analog converter 14I 5 and 10. The latter, in the form of analog values, is fed to the inputs of the Divisible and divisor ratios meter 11, which calculates the ratios these quantities. The result is actually compared in the differential discriminator 12 with that established by means of the settings (reference voltages) and and. the value corresponding to the resonant frequency of the electroacoustic transducer 1 When the magnitude of the relationship coincides with a predetermined limit, the differential discriminator 12 turns on the electronic key 6 at the control input allowing the output of information to the recorder 7. The output time of the information is determined by the delay time of the delay line 14 after the which device is reset. Electromagnetic interference induced by the signal circuits or by the power supply circuits bypasses the resonant mechanical system of the electroacoustic transducer 1. Since the disturbances are random functions, the likelihood of their temporal characteristics and temporal characteristics coincide. The electrical signal of the electroacoustic converter 1 is very small. Therefore, the relationship meter 11 fixes a result, different from that established in the differential discriminator 12, which does not generate a control signal and does not open the electronic key o. Similarly, the registration of high-power acoustic low-frequency noise, is eliminated. . , When using an electroacoustic converter 1 with a different resonant frequency, the values of the settings 1) and, respectively, are changed accordingly. Thus, the device makes it possible to significantly increase the noise immunity of recording ultrasonic signals from electromagnetic interference of on-air and network nature, the frequency of which does not correspond to the resonant frequency of the electroacoustic transducer 1, and powerful acoustic low-frequency noise.

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Claims (1)

DEVICE FOR REGISTRATION OF ULTRASONIC SIGNALS, containing series-connected resonant electro-acoustic transducer, amplifier, threshold block, counting - a pulse counter and a first digital-to-analog converter, a recorder, an amplitude detector, the input of which is connected to the output of the threshold unit, and a delay line, the input of which is connected to the second input of the first digital-to-analog converter, and the output - with, the input Reset the pulse counter, characterized in , that, in order to increase the noise immunity; it is equipped with a series-connected time meter, the input of which is connected to the output of the amplitude detector, a second digital-to-analog converter, a ratio meter, the second input of which is connected to the output of the first digital-to-analog converter, and a differential discriminator, trigger, whose S-input is. It is connected to the output of the amplitude detector, the R-input is connected to the input of the time meter and the output of the delay line, and the Q-output is connected to the second input of the digital-to-analog converter and to the input of the delay line, K /) by an electronic key connected between | a “by the output of the first digital-analogue pre-1 ·· ™ transmitter and the recorder input, g and the control input of the electronic key is connected to the output of the differential discriminator.