Automatic calibration device and method for sensitivity of air acoustic wave detector

Abstract

The invention belongs to the technical field of acoustic measurement and testing, and particularly discloses an automatic calibration device and method for the sensitivity of an air acoustic detector. The device comprises a sound tube calibration device, a control unit, a sound field detection unit and a signal sounding and detection unit, the control unit controls the signal sounding and collecting unit to generate a sound field in an inner cavity of the sound tube calibration device; the sound field detection unit obtains signals of different positions of a sound field in the sound tube calibration device through the signal generation and acquisition unit, transmits the obtained signals to the control unit, detects sound field distribution, and obtains sound pressures of different positions. The signal sounding and collecting unit collects output signals of the standard detector and the detector to be detected, transmits the collected signals to the control unit, and then calibrates the sensitivity of the detector to be detected through a comparison method. The geophone calibration device is used for calibrating the geophone of which the working frequency range is between 1Hz and 2000Hz, and can effectively calibrate the geophone to be tested in batches.

Description

Technical Field

[0001] The invention belongs to the technical field of acoustic measurement and testing, and in particular relates to an automatic calibration device and method for the sensitivity of an airborne acoustic detector. Background Art

[0002] The geophone is a hardware device that receives ground vibrations in seismic exploration. Its performance is directly related to the quality of the collected data and the geological effect. With the continuous development of acoustic technology, the frequency of acoustic applications is gradually moving towards low frequencies, which places higher and higher requirements on the accuracy and quality of seismic data acquisition. The unit performance measurement of the relevant low-frequency geophones has become particularly important.

[0003] In the prior art, the calibration method of low-frequency geophones varies according to the difference in the working frequency of the low-frequency geophones. In the development of seismic geophone technology, the working frequency of low-frequency geophones mostly ranges from a few hertz to several hundred hertz. Geophones with working frequencies above 2 kHz are usually calibrated using the free-field reciprocity method. Geophones working at low frequencies have a long wavelength in the low-frequency band, and laboratory conditions are difficult to meet free-field and far-field test conditions. Therefore, they are usually tested and calibrated in an acoustic tube. The test and calibration methods in the acoustic tube mainly include the vibrating liquid column method, the standing wave tube comparison method, the coupled cavity reciprocity method, and the traveling wave tube method. The coupled cavity reciprocity method can only calibrate one geophone at a time. Although the vibrating liquid column method, the standing wave tube comparison method, and the traveling wave tube method can calibrate multiple geophones at the same time, the calibration process needs to be carried out in water, the operation steps are cumbersome, and the work efficiency is low. Summary of the invention

[0004] In order to solve the above deficiencies existing in the known technology, the present invention aims to provide an automatic calibration device for the sensitivity of an airborne acoustic detector. The device uses a standard detector with known sensitivity to effectively calibrate the detector to be tested in the air, and is suitable for calibrating detectors with operating frequencies in the range of 1Hz-2000Hz.

[0005] Another object of the present invention is to provide a method for automatic calibration of the sensitivity of an airborne acoustic geophone. The method needs to be implemented by using the above-mentioned automatic calibration device for the sensitivity of an airborne acoustic geophone. The method can realize batch calibration of the geophones to be tested in the air.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] An automatic calibration device for the sensitivity of an airborne acoustic detector, comprising a sound tube calibration device, a control unit, a sound field detection unit and a signal sounding and collecting unit;

[0008] The signal input end of the signal sounding and collecting unit is connected to the signal output end of the control unit and the sound field detection unit; the signal output end of the signal sounding and collecting unit is connected to the signal input end of the control unit;

[0009] The control unit controls the signal sound generation and collection unit to generate a sound field in the inner cavity of the sound tube calibration device; the audio signal of the sound field is used as an input signal of the sound field detection unit, the standard detector and the detector to be tested;

[0010] The sound field detection unit obtains signals at different positions of the sound field in the sound tube calibration device, transmits the obtained signals to the control unit through the signal generation and acquisition unit to detect the sound field distribution, and obtains the sound pressure at different positions;

[0011] The signal sounding and collecting unit is provided with a signal input terminal connected to the standard detector and the detector to be tested. The signal sounding and collecting unit collects the output signals of the standard detector and the detector to be tested, transmits the collected signals to the control unit, and then calibrates the sensitivity of the detector to be tested by comparison method.

[0012] As a limitation, the signal sound generation and acquisition unit includes an acquisition card, a low-frequency power amplifier, a preamplifier and a low-frequency sound source; the control unit is connected to the signal input end of the acquisition card to control the acquisition card to output a sinusoidal swept frequency continuous signal, the acquisition card is connected to the low-frequency sound source through the low-frequency amplifier, the sinusoidal swept frequency continuous signal is amplified by the low-frequency power amplifier and then loaded to the low-frequency sound source, and the low-frequency sound source emits a sound wave signal to generate a sound field in the sound tube calibration device;

[0013] The standard detector and the detector to be tested are connected to the acquisition card through a preamplifier. The output signals of the standard detector and the detector to be tested are amplified by the preamplifier and then transmitted to the acquisition card, and then transmitted to the control unit through the acquisition card.

[0014] As a second limitation, the sound field detection unit includes a first microphone and a second microphone. The first microphone and the second microphone amplify the collected audio signals through a preamplifier and transmit them to an acquisition card. The acquisition card collects the amplified signals and transmits the signals to the control unit to detect the sound field distribution and obtain the sound pressure at different positions.

[0015] As a third limitation, the automatic calibration device for the sensitivity of the airborne acoustic detector also includes a data offline processing unit, which includes a printer and a display, and the signal input ends of the printer and the display are connected to the signal output end of the control unit; the printer prints the test report in real time, and the display displays the sensitivity calibration curve and the sound pressure distribution curve inside the calibration sound tube in real time.

[0016] As a fourth limitation, the control unit adopts an industrial control computer.

[0017] As a fifth limitation, the preamplifier is a four-channel acquisition amplifier; the acquisition card has four-channel signal acquisition and one-channel analog signal output functions.

[0018] As a sixth limitation, the automatic sensitivity calibration device for the airborne acoustic geophone further comprises an automatic sensitivity calibration platform, and the automatic sensitivity calibration platform is a box-type structure;

[0019] The sound tube calibration device adopts a calibration sound tube, the outer surface of which is provided with a sound-absorbing sponge, and the calibration sound tube is arranged inside the sensitivity automatic calibration platform and fixed to the bottom surface thereof; the first microphone and the second microphone are arranged in the inner cavity of the calibration sound tube and are arranged in sequence along the vertical direction close to the side wall;

[0020] The acquisition card, low-frequency power amplifier, low-frequency sound source and industrial control computer are all arranged inside the detector sensitivity calibration platform.

[0021] The present invention also discloses an automatic calibration method for the sensitivity of an airborne acoustic detector, the method comprising the following steps performed in sequence:

[0022] S1, the signal sound generation and collection unit generates a sound field in the inner cavity of the sound tube calibration device;

[0023] S2, the sound field detection unit collects audio signals in the inner cavity of the sound tube calibration device and transmits the collected audio signals to the control unit through the signal sound generation and collection unit, detects the sound field distribution, and obtains the sound pressure at different positions;

[0024] S3, the detector to be tested and the standard detector transmit the collected signals to the control unit, and the detector to be tested is calibrated by a comparison method.

[0025] As the second limitation, the method for the signal sounding and collecting unit to generate a sound field in the inner cavity of the calibration sound tube in step S1 is: the control unit controls the signal sounding and collecting unit to generate a sinusoidal swept frequency continuous signal with a frequency band of 1Hz-2000Hz, and the signal sounding and collecting unit amplifies the power and outputs it to generate a sound field in the inner cavity of the sound tube calibration device.

[0026] As a second limitation, while executing steps S1 and S2 or after executing step S2 and before executing step S3, the detector to be tested and the standard detector are connected to the input end of the signal sounding and collecting unit, while ensuring that the detector to be tested and the standard detector are at the same level in the inner cavity of the sound tube calibration device.

[0027] Due to the adoption of the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0028] (1) The device of the present invention makes the calibration of the detector more efficient and convenient. By simply connecting a standard detector with known sensitivity, the detectors to be tested can be calibrated in batches.

[0029] (2) The present invention reduces the noise of the received signals of the standard detector and the detector to be tested by providing a preamplifier, thereby improving the signal-to-noise ratio;

[0030] (3) The sound field detection unit of the present invention is provided with a first microphone and a second microphone. By placing the two microphones at different heights in the inner cavity of the calibration sound tube, the sound field at different positions can be obtained, and whether the sound field is stable can be judged based on the obtained sound field. At the same time, when calibrating the detector, placing the detector to be tested and the standard detector at a horizontal height between the first microphone and the second microphone can effectively control the decibel condition required for calibration.

[0031] (4) The present invention can obtain the test report in real time and have an intuitive understanding of the calibration process by setting a printer and a display in the offline processing unit, thereby improving work efficiency;

[0032] (5) The preamplifier used in the present invention is set to multi-channel acquisition and amplification, and the acquisition card adopts multi-channel signal acquisition and analog signal output functions, which can realize batch rapid calibration of the detectors to be tested;

[0033] (6) The present invention arranges a sound-absorbing sponge on the outer surface of the calibration sound tube, which can absorb vibration noise, background noise and sound generated by low-frequency sound sources, thereby weakening the sound intensity.

[0034] In summary, the present invention can realize batch effective calibration of detectors with an operating frequency range of 1 Hz-2000 Hz. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] Figure 1 This is a schematic diagram of a device for automating the calibration of the sensitivity of a geophone according to an embodiment of the present invention;

[0037] Figure 2 This is a schematic diagram of the internal structure of the automatic calibration device for geophone sensitivity according to an embodiment of the present invention;

[0038] Figure 3 This is a principle block diagram of the automatic calibration system for the sensitivity of the detector according to an embodiment of the present invention;

[0039] Figure 4 This is a diagram of the interface for the automatic calibration of the sensitivity of the detector according to the embodiment of the present invention;

[0040] In the figure, 101, signal sound generation and acquisition unit; 102, data offline processing unit; 1, detector sensitivity automatic calibration station; 2, calibration sound tube; 3, sound absorbing sponge; 4, detector to be tested; 5, standard detector; 6, low-frequency sound source; 7, first microphone; 8, second microphone; 9, preamplifier; 10, acquisition card; 11, printer; 12, low-frequency power amplifier; 13, industrial control computer. DETAILED DESCRIPTION

[0041] In order to better explain the present invention and facilitate understanding, the preferred embodiments of the present invention are described in detail below through specific implementation modes in conjunction with the accompanying drawings.

[0042] Embodiment 1 Automatic calibration device for airborne acoustic detector sensitivity

[0043] like Figures 1 to 3 As shown, in order to describe this embodiment more clearly, this embodiment is Figures 1 to 3 The detector to be tested 4 and the standard detector 5 are added. This embodiment includes a sound tube calibration device, a control unit, a sound field detection unit and a signal sound generation and collection unit 101, a data offline processing unit 102 and a detector sensitivity automatic calibration station 1.

[0044] The signal input end of the signal sound generation and collection unit 101 is connected to the signal output end of the control unit and the sound field detection unit; the signal output end of the signal sound generation and collection unit 101 is connected to the signal input end of the control unit; the signal input end of the data offline processing unit 102 is connected to the signal output end of the control unit.

[0045] The control unit includes an industrial control computer 13; the signal sound generation and acquisition unit 101 includes an acquisition card 10, a low-frequency power amplifier 12 and a preamplifier 9; the sound field detection unit includes a first microphone 7 and a second microphone 8; the data offline processing unit 102 includes a printer 11 and a display; the sound tube calibration device adopts a calibration sound tube 2, and the calibration sound tube 2 in this embodiment is a hollow cylinder.

[0046] Combination Figures 1 to 3 The control unit is connected to the signal input end of the acquisition card 10, and controls the acquisition card 10 to output a sine swept frequency continuous signal with a calibration frequency band of 1Hz-2000Hz. The acquisition card 10 is connected to the low-frequency sound source 6 through a low-frequency amplifier, and the sine swept frequency continuous signal is amplified by the low-frequency power amplifier 12 and then loaded to the low-frequency sound source 6. The low-frequency sound source 6 emits a sound wave signal to generate a sound field in the sound tube calibration device.

[0047] The standard detector 5 and the detector to be tested 4 are connected to the acquisition card 10 through the preamplifier 9. The output signals of the standard detector 5 and the detector to be tested 4 are amplified by the preamplifier 9 and then transmitted to the acquisition card 10, and then transmitted to the control unit through the acquisition card 10. The control unit calibrates the sensitivity of the detector to be tested 4 by a comparison method; the signal input end of the printer 11 and the display is connected to the signal output end of the control unit; the printer 11 prints the test report in real time, and the display displays the sensitivity calibration curve and the sound pressure distribution curve inside the calibration sound tube 2 in real time, which can express the data intuitively.

[0048] Figure 2 The figure shows a schematic diagram of the internal structure of the present embodiment. The automatic calibration platform 1 for the sensitivity of the detector is a box-type structure. The calibration sound tube 2 is arranged inside the automatic calibration platform 1 for the sensitivity of the detector and fixedly arranged on its lower bottom surface. The outer surface of the calibration sound tube is provided with a sound-absorbing sponge 3. The first microphone 7 and the second microphone 8 are arranged in the inner cavity of the calibration sound tube 2 and are arranged in sequence along the vertical direction close to the side wall. The acquisition card 10, the low-frequency power amplifier 12, the low-frequency sound source 6, and the industrial control computer 13 are all arranged inside the sensitivity calibration platform for the detector.

[0049] The acquisition card 10 of this embodiment adopts four-channel signal acquisition and one-channel analog signal output functions, and the preamplifier 9 is set to four-channel acquisition amplification, which can realize the simultaneous calibration of the sensitivity of four detectors 4 to be tested. In this embodiment, only one detector 4 to be tested is used as an example for calibration. It should be noted that the number of detectors to be calibrated simultaneously is determined by the number of analog input channels of the acquisition card.

[0050] The model of the acquisition card 10 in this embodiment is USB-4431, and the material of the calibration sound tube in this embodiment is organic glass.

[0051] Working principle of this embodiment: When using this embodiment to calibrate the detector 4 to be tested, it is necessary to prepare a standard detector 5 with known sensitivity and the detector 4 to be tested, and connect the standard detector 5 with known sensitivity and the detector 4 to be tested to the signal input end of the preamplifier 9. When calibrating, the detector 4 to be tested and the standard detector 5 need to be at the same level, and the height positions of the detector 4 to be tested and the standard detector 5 are between the first microphone 7 and the second microphone 8. The heights of the first microphone and the second microphone are adjustable. After confirming that the connection of this embodiment is correct, turn on the power supply, and this embodiment starts to work, that is, it starts to calibrate the detector 4 to be tested.

[0052] Example 2 Automatic calibration method for airborne acoustic detector sensitivity

[0053] This embodiment provides an automatic calibration method for the sensitivity of an airborne acoustic detector, which needs to be implemented using the device in Embodiment 1. This embodiment includes the following steps performed in sequence:

[0054] S1. The control unit controls the signal sound generation and acquisition unit 101 to generate a sine frequency sweep continuous signal with a frequency band of 1 Hz-2000 Hz, and the signal sound generation and acquisition unit 101 amplifies the power and outputs it to generate a sound field in the inner cavity of the sound tube calibration device.

[0055] S2. The sound field detection unit collects audio signals in the inner cavity of the sound tube calibration device and transmits the collected audio signals to the control unit through the signal sound generation and collection unit 101, detects the sound field distribution, and obtains the sound pressure at different positions.

[0056] S3, the detector to be tested 4 and the standard detector 5 transmit the collected signals to the control unit, and the detector to be tested 4 is calibrated by a comparison method.

[0057] In this embodiment, the step of connecting the detector to be tested 4 and the standard detector 5 to the input end of the signal sounding and collecting unit 101 is performed in step S1, and can also be performed at the same time as step S2 or after step S2 and before step S3, while ensuring that the detector to be tested 4 and the standard detector 5 are at the same horizontal height in the inner cavity of the sound tube calibration device.

[0058] The formula for calculating the sensitivity of the detector 4 to be tested by the comparison method is: Among them, M a is the sensitivity of the detector 4 to be tested, U a is the open circuit voltage at the output of the detector 4 to be tested, U j is the open circuit voltage at the output of the standard detector 5; M j is the sensitivity value of standard detector 5.

[0059] Figure 4 The figure shows the detector sensitivity automatic calibration inspector interface diagram of the embodiment of the present invention, which includes: sensitivity curve diagram, detector time domain waveform diagram, detector frequency domain diagram, multi-column list box, measurement results, channel selection and product name setting, and calibration completion button.

[0060] Among them, the sensitivity curve reflects the sensitivity trend of the detector 4 to be tested, and different curves represent the sensitivity of different transducers. BT is the sensitivity curve of the standard detector, and CH1 is the sensitivity curve of the detector 4 to be tested. The detector time domain waveform diagram is the original waveform of the received voltage collected by the acquisition card 10, BT is the waveform of the standard detector 5, and CH2 is the waveform of the detector 4 to be tested. The detector frequency domain diagram is the Fourier transform of the detector time domain waveform diagram signal, reflecting the frequency component of the current signal, where BT refers to the frequency component of the current signal of the standard detector 5, and CH1 is the frequency component of the current signal of the detector 4 to be tested. The multi-column list box contains the product name, serial number, and sensitivity data corresponding to different frequency bands, as well as whether it is qualified. The measurement result shows whether the sensitivity of the detector to be tested meets the qualified standard, and "PASS" is displayed if it is qualified, and "NO" is displayed if it is unqualified; the channel selection and product name setting buttons are used to select the channel corresponding to the detector to be tested and set its product name, model and other parameters. Pressing the calibration button indicates that calibration is in progress, and the display shows "calibrating in progress". After calibration is completed, the display shows "calibration completed".

Claims

1. An automatic calibration device for airborne acoustic detector sensitivity, characterized in that: It includes a sound tube calibration device, a control unit, a sound field detection unit and a signal sound generation and collection unit; The signal input end of the signal sounding and collecting unit is connected to the signal output end of the control unit and the sound field detection unit; the signal output end of the signal sounding and collecting unit is connected to the signal input end of the control unit; The control unit controls the signal sound generation and collection unit to generate a sound field in the inner cavity of the sound tube calibration device; the audio signal of the sound field is used as an input signal of the sound field detection unit, the standard detector and the detector to be tested; The sound field detection unit obtains signals at different positions of the sound field in the sound tube calibration device, transmits the obtained signals to the control unit through the signal generation and acquisition unit to detect the sound field distribution, and obtains the sound pressure at different positions; The signal sounding and collecting unit is provided with a signal input terminal connected to the standard detector and the detector to be tested. The signal sounding and collecting unit collects the output signals of the standard detector and the detector to be tested, transmits the collected signals to the control unit, and then calibrates the sensitivity of the detector to be tested by comparison method.

2. The automatic calibration device for airborne sound detection sensitivity according to claim 1, characterized in that: The signal sound generation and acquisition unit comprises an acquisition card, a low-frequency power amplifier, a preamplifier and a low-frequency sound source; the control unit is connected to the signal input end of the acquisition card to control the acquisition card to output a sine frequency sweep continuous signal; the acquisition card is connected to the low-frequency sound source via the low-frequency amplifier, the sine frequency sweep continuous signal is amplified by the low-frequency power amplifier and then loaded to the low-frequency sound source; the low-frequency sound source emits a sound wave signal to generate a sound field in the sound tube calibration device; The standard detector and the detector to be tested are connected to the acquisition card through a preamplifier. The output signals of the standard detector and the detector to be tested are amplified by the preamplifier and then transmitted to the acquisition card, and then transmitted to the control unit through the acquisition card.

3. The automatic calibration device for airborne acoustic detector sensitivity according to claim 2, characterized in that: The sound field detection unit includes a first microphone and a second microphone. The first microphone and the second microphone amplify the collected audio signals through a preamplifier and transmit them to an acquisition card. The acquisition card collects the amplified signals and transmits the signals to a control unit to detect the sound field distribution and obtain the sound pressure at different positions.

4. The automatic calibration device for airborne acoustic detector sensitivity according to claim 3, characterized in that: The automatic calibration device for the sensitivity of the airborne acoustic detector also includes a data offline processing unit, which includes a printer and a display. The signal input ends of the printer and the display are connected to the signal output end of the control unit; the printer prints the test report in real time, and the display displays the sensitivity calibration curve and the sound pressure distribution curve inside the calibration sound tube in real time.

5. The automatic calibration device for airborne acoustic detector sensitivity according to claim 4, characterized in that: The control unit adopts an industrial control computer.

6. The automatic calibration device for airborne acoustic detector sensitivity according to claim 2, characterized in that: The preamplifier is a four-channel acquisition amplifier; the acquisition card has four-channel signal acquisition and one-channel analog signal output functions.

7. The automatic calibration device for airborne acoustic detector sensitivity according to claim 5, characterized in that: The automatic sensitivity calibration device for airborne acoustic geophones also includes an automatic sensitivity calibration platform, which is a box-type structure; The sound tube calibration device adopts a calibration sound tube, the outer surface of which is provided with a sound-absorbing sponge, and the calibration sound tube is arranged inside the sensitivity automatic calibration platform and fixed to the bottom surface thereof; the first microphone and the second microphone are arranged in the inner cavity of the calibration sound tube and are arranged in sequence along the vertical direction close to the side wall; The acquisition card, low-frequency power amplifier, low-frequency sound source and industrial control computer are all arranged inside the detector sensitivity calibration platform.

8. A method for automatically calibrating the sensitivity of an airborne acoustic geophone, implemented by using the automatic calibration device for the sensitivity of an airborne acoustic geophone according to claim 1, characterized in that: The method comprises the following steps performed in sequence: S1, the signal sound generation and collection unit generates a sound field in the inner cavity of the sound tube calibration device; S2, the sound field detection unit collects audio signals in the inner cavity of the sound tube calibration device and transmits the collected audio signals to the control unit through the signal sound generation and collection unit, detects the sound field distribution, and obtains the sound pressure at different positions; S3, the detector to be tested and the standard detector transmit the collected signals to the control unit, and the detector to be tested is calibrated by a comparison method.

9. The automatic calibration device for airborne acoustic detector sensitivity according to claim 8, characterized in that: The method in step S1 for the signal sounding and collecting unit to generate a sound field in the inner cavity of the calibration sound tube is as follows: the control unit controls the signal sounding and collecting unit to generate a sinusoidal swept frequency continuous signal with a frequency band of 1 Hz-2000 Hz, and the signal sounding and collecting unit amplifies the power and outputs it to generate a sound field in the inner cavity of the sound tube calibration device.

10. The method for automatic calibration of airborne acoustic detector sensitivity according to claim 8, characterized in that: While executing steps S1 and S2 or after executing step S2 and before executing step S3, the detector to be tested and the standard detector are connected to the input end of the signal sounding and collecting unit, while ensuring that the detector to be tested and the standard detector are at the same level in the inner cavity of the sound tube calibration device.

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