CN201435826Y - Vibrating sound pick-up parameter analyzing and testing device - Google Patents

Abstract

The utility model discloses a vibrating sound pick-up parameter analyzing and testing device, which mainly comprises an interface device, a testing module and an electromagnetic vibrating table equipped with a standard accelerator. An operator only need to measure the amplitude-frequency curve parameter of the output curve of the vibrating table through the standard accelerator to be used as a relative reference standard and then compares and calculates the curve parameter of the sound pick-up under testing with the relative reference standard. In this way, the amplitude-frequency characteristic and the sensitivity parameter of the sound pick-up under testing can be tested. The frequency resolution of the vibrating sound pick-up parameter analyzing and testing device is only limited by theprocessing capacity and the memory capacity of the testing module, and the vibrating sound pick-up parameter analyzing and testing device can satisfy the basic testing condition without requiring theassembly of a plurality of special testing instruments. The vibrating sound pick-up parameter analyzing and testing device is low in cost, simple in debugging process and high in testing efficiency and can satisfy the requirement of batch production.

Description

Vibration type pickup parameter analysis test apparatus

Technical field

The utility model relates to a kind of vibration type pickup parameter analysis test method and device.

Background technology

Vibration type pickup is a kind of vibration audio frequency sensing element that utilizes the acceleration transducer test philosophy to design, and is mainly used in the usefulness of carrying out the antinoise communication under military battlefield, fire-fighting scene and all strong noise particular surroundingss.In development, production and the testing process of vibration type pickup, because detection principle according to the acceleration device, necessarily require to possess a kind of vibrating device that in measured scope, can keep the constant acceleration parameter, utilize the permanent character of this system to test the key parameter of the sensitivity and the frequency response of device under test.

Vibration audition device before adopts the analog vibration detection system substantially, this system testing principle as shown in Figure 1, mainly form by vibration machine A, the vibration measurement instrument B, recorder C and the preamplifier D that are provided with monitoring accelerometer and tested vibration pickup, under this test pattern, because electromagnetic vibration generator system A is inductive load, by following formula its output impedance as can be known:

R ₀＝ωL

Along with its input impedance meeting of increase of driving signal frequency progressively strengthens, its power output can be successively decreased gradually with the increase of driving signal frequency under the situation of constant drive voltage, is difficult to keep the desired constant acceleration output of test.In order to address this problem, when adopting above-mentioned test macro, all in system, increase real-time feedback control system (being also referred to as compressibility), form the compressed feedback closed loop by the monitoring accelerometer of vibration machine A table top installation and the compression amplifier E of feedback control system, when the monitoring accelerometer senses the constant acceleration that can adjust the output voltage of compression amplifier E voluntarily when the table vibration acceleration reduces and keep table top.Can see that by Fig. 1 this test macro needs can reach the basic test condition after many special test equipment combinations, the cost height, the testing and measuring technology complexity, testing efficiency is low, is difficult to satisfy the demand of producing in batches.

In recent years, along with computer science and technology develops rapidly, a kind of new analytical technology occurred, be called " FFT spectrum analysis technique ", this kind analytical method is simulation thousands of parallel filters and carry out the complex mathematical computing.

The utility model content

The purpose of this utility model is to use the FFT spectrum analysis technique, and a kind of quick test that can finish vibration pickup is provided, and satisfies the method for testing and the device of a large amount of production demands.

A kind of vibration type pickup parameter analysis test apparatus mainly comprises the electromagnetic vibration generator system of interface arrangement, test module and installing standard accelerometer;

Described interface arrangement comprise preamplifier, this A/D converter to tested pick-up output through the direct sample of preamplifier amplifying signal, send this signal to test module by the audio digital signals processing module; This test module output noise signal is converted to analog signal by audio digital signals processing module and D/A converter, is carried in the input of electromagnetic vibration generator system through power amplifier;

Described test module mainly comprises FFT spectrum analysis module, energy calculator, parameter memory module, the level and smooth module of numerical value, noise generator module, coordinate generation module and Output Display Unit;

Described accelerometer comprises acceleration transducer and acceleration analysis module;

Described acceleration transducer is fixed in the electromagnetic vibration generator system table top, output inserts the acceleration analysis module, this acceleration analysis module AC signal exports the FFT spectrum analysis module of test module to, the white noise spectrum signal of straight frequency characteristic arranged to encourage tested pick-up to the input input of electromagnetic vibration generator system at the logarithmic coordinates cording by the noise generator module, the frequency width of cloth supplemental characteristic that this acceleration analysis module testing goes out deposits parameter memory module in, the reference curve during as test;

The described tested pick-up that is fixed in the electromagnetic vibration generator system table top outputs signal to interface arrangement, the FFT spectrum analysis module of transporting to test module after interface arrangement buffering is amplified compares computing with the reference curve that deposits parameter memory module in, and its difference is converted to voltage width of cloth signal and draw out the frequency characteristics of the product of surveying after level and smooth module of numerical value and coordinate generation module are calibrated on Output Display Unit frequently through energy calculator.

The frequency resolution degree of the utility model only is subject to the disposal ability and the memory capacity of test module, does not need many special test equipment combinations just can reach the basic test condition, and cost is low, and testing and measuring technology is simple, and the testing efficiency height can satisfy the demand of producing in batches.

Description of drawings

Fig. 1 is for practising the test philosophy schematic diagram of the analog vibration detection system that has;

Fig. 2 is a system of the present utility model connection diagram;

Fig. 3 is a test philosophy schematic diagram of the present utility model;

Fig. 4 is the principle schematic of interface arrangement in the utility model;

Fig. 5 is an interface arrangement integrated circuit board connection layout in the utility model;

Fig. 6 carries out spectrum analysis for FFT spectrum analysis module in the utility model to analog signal block diagram;

Fig. 7 obtains frequency spectrum profile after FFT handles in the utility model;

The utility model is described in further detail below in conjunction with drawings and Examples.

Embodiment

To shown in Figure 5, the utility model mainly comprises the electromagnetic vibration generator system 3 of interface arrangement 1, test module 2 and installing standard accelerometer 5 as Fig. 2.

Described accelerometer 5 comprises acceleration transducer 51 and acceleration analysis module 52.

The function that the input conversion of described interface arrangement 1 burden test signal and electromagnetic vibration generator system 3 pumping signals are amplified output, comprise 12 pairs of tested pick-ups 4 outputs of preamplifier 11, this A/D converter through preamplifier 11 amplifying signal direct samples, send this signal to test module 2 by audio digital signals processing module 13; These test module 2 output noise signals are converted to analog signal by audio digital signals processing module 13 and D/A converter 14, are carried in the input of electromagnetic vibration generator system 3 through power amplifier 15.

Described test module 2 mainly comprises FFT spectrum analysis module 21, energy calculator 22, parameter memory module 23, the level and smooth module 24 of numerical value, noise generator module 25, coordinate generation module 26 and Output Display Unit 27.In the test, tested pick-up 4 is fixed in the table top of electromagnetic vibration generator system 3, the FFT spectrum analysis module 21 of transporting to test module 2 after its output access interface device 1 buffering amplification is compared computing with the reference curve that deposits parameter memory module 23 in, its difference is passed through the frequency characteristics that energy calculator 22 is converted to voltage frequency width of cloth signal and draws out the product of surveying after level and smooth module 24 of numerical value and coordinate generation module 26 are calibrated on Output Display Unit 27, just can test out the frequency response curve and the sensitivity of tested pick-up 4.

Described acceleration transducer 51 usefulness bolt are in electromagnetic vibration generator system 3 table tops, its output is inserted acceleration analysis module 52, these acceleration analysis module 52 AC signal outputs directly are connected to FFT spectrum analysis module 21, the white noise spectrum signal of straight frequency characteristic arranged to encourage tested pick-up 4 to the input input of electromagnetic vibration generator system 3 at the logarithmic coordinates cording by noise generator module 25, the frequency width of cloth supplemental characteristic that this acceleration analysis module testing goes out deposits parameter memory module in, the reference curve during as test.

Vibration type pickup parameter analysis test method of the present utility model mainly comprises calibration electromagnetic vibration generator system 3 and two steps of tested pick-up 4 parameter testings:

Calibrate electromagnetic vibration generator system 3 before step 1, the test earlier

At first, degree of will speed up transducer 51 usefulness bolt insert acceleration analysis module 52 in electromagnetic vibration generator system 3 table tops with its output, again these acceleration analysis module 52 AC signal outputs directly are connected to FFT spectrum analysis module 21; The white noise spectrum signal that straight frequency characteristic is arranged at the logarithmic coordinates cording to the input input of electromagnetic vibration generator system 3 by noise generator module 25, these acceleration transducer 51 acquired signal are sent to acceleration analysis module 52, by acceleration analysis module 52 output AC signals to FFT spectrum analysis module 21, until the acceleration value of electromagnetic vibration generator system 3 being adjusted to 1g; Because this standard accelerometer 5 has more accurate falt characteristic in working frequency range, the frequency width of cloth signal that acceleration analysis this moment module 52 tests out just can be represented the frequency response of electromagnetic vibration generator system 3, simultaneously with this frequently width of cloth supplemental characteristic deposit parameter memory module 23 in, the reference curve when tested pick-up 4 parameters will be analyzed from now on; Then, will acceleration transducer 51 usefulness bolt in electromagnetic vibration generator system 3 table tops, its output is inserted acceleration analysis module 52, and the AC signal output of degree of will speed up measurement module 52 is connected to interface arrangement 1 and cushions amplification, compare with the frequency width of cloth parameter of curve that deposits the electromagnetic vibration generator system 3 of parameter memory module 23 in after FFT spectrum analysis module 21 is analyzed through exporting to again, with the virtual frequency width of cloth characteristic curve of its difference as electromagnetic vibration generator system 3; If the parameter of curve basically identical that tests out for twice, then its difference can be considered electromagnetic vibration generator system 3 corresponding virtual frequency width of cloth curve when the 1g acceleration, and this virtual frequency width of cloth curve has satisfactory falt characteristic in the particular job frequency range, and electromagnetic vibration generator system 3 calibrations are so far finished;

Step 2, tested pick-up 4 parameters are tested

After the correction through 5 pairs of electromagnetic vibration generator systems 3 of standard accelerometer, remove acceleration transducer 51 from electromagnetic vibration generator system 3, tested pick-up 4 is fixed in the table top of electromagnetic vibration generator system 3, with its output access interface device 1, the FFT spectrum analysis module 21 that exports test module 2 after interface arrangement 1 buffering is amplified to compares computing with the reference curve that deposits parameter memory module 23 in, its difference is passed through the frequency characteristics that energy calculator 22 is converted to voltage frequency width of cloth signal and draws out the product of surveying after level and smooth module 24 of numerical value and coordinate generation module 26 are calibrated on Output Display Unit 27, just can test out the frequency response curve and the sensitivity of tested pick-up 4.

The test of the utility model frequency response is similar with filtering analyzer in parallel, is input and the output signal component of estimating tested object equally.In theory, if use [periodic noise signal], as long as might measure [output spectrum], get final product the calculated rate response, the frequency response value of standard accelerometer 5 outputs in this value and the electromagnetic vibration generator system 3 is compared computing, can obtain the sensitivity and the frequency response curve of tested vibration pickup 4.

The frequency resolution degree of the utility model only is subject to the disposal ability and the memory capacity of test module 2.

Below use the basic principle that Fourier transform (FFT) carries out spectrum analysis in summary the utility model.

1, the basic principle of Fourier transform (FFT)

Length is that the discrete Fourier transform (DFT) X (k) of the sequence x (n) of N is:

$X\left(k\right)=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}x\left(n\right)W_N^{\mathrm{nk}},k=0,....,N-1$

Wherein, the DFT that N is ordered can be decomposed into the DFT that two N/2 are ordered, and the DFT that each N/2 is ordered can be decomposed into the DFT that two N/4 are ordered again.The rest may be inferred, (N=2 when N is 2 integral number power ^M), because separating, per minute once reduces single order power, so pass through M time decomposition, all become a series of 2 DFT computings at last.

It more than is exactly the fast Fourier transform (FFT) algorithm of decimation in time.When the length of carrying out the sequence of conversion when needs is not 2 integer power,, can make its length extend to 2 integer power with the method for end zero padding in order to use 2 to be the FFT of base.

The difference of above-mentioned inverse discrete fourier transform and direct transform is W _NBecome W _N ^-1, and many computings of a 1/N.Because W _NAnd W _N ^-1Fast fourier transformation algorithm for the derivation decimation in time there is no essential distinction, therefore FFT and inverse fast fourier transform (IFFT) algorithm can be incorporated in the same program.

2. utilize FFT spectrum analysis module 21 to carry out spectrum analysis

If signal itself is time-limited sequence, the frequency spectrum of the sequence of calculation is exactly directly sequence to be carried out the FFT computing to try to achieve X (k), and X (k) has just represented the spectrum value of sequence between [0,2 π].

Amplitude spectrum $\left|X\left(k\right)\right|=\sqrt{X_R^2\left(k\right)+X_I^2\left(k\right)}$

Phase spectrum

If signal is an analog signal, when carrying out spectrum analysis with FFT spectrum analysis module 21, at first must sample, make it to become discrete signal, just can come continuous signal is carried out spectrum analysis with FFT spectrum analysis module 21 then according to the method for front to this signal.By sampling thheorem, sample frequency f _sShould in order to satisfy sampling thheorem, generally before sampling, an anti-aliasing low pass filter to be set greater than the highest frequency of 2 times of signals.The block diagram that carries out spectrum analysis with 21 pairs of analog signals of FFT spectrum analysis module as shown in Figure 6.

Based on the first-harmonic of specifying waveform, by discreteness Fourier transform (DiscreteFourier Transform-DFT) being applied to the periodic waveform that transient analysis produces, Fourier analysis signal calculated frequency spectrum.

Described FFT spectrum analysis module 21 resolves into discrete frequency component by Fourier's computing with measured signal exactly, reaches the effect same with traditional spectrum analyzer.

This FFT spectrum analysis module 21 is directly taken a sample to the input signal of tested vibration type pickup 4 by A/D converter 12, obtains the frequency spectrum profile (see figure 7) again after FFT handles.

Can regard this discrete Fourier transform (DFT) X (k) the equidistant sampled value of z conversion on unit circle as, same, X (k) also can regard the sampling of sequence Fourier transform X (ej ω) as, and the sampling interval is ω N=2 π/N.Therefore, discrete Fourier transform (DFT) comes down to the discrete frequency domain sampling of its frequency spectrum, and frequency is had selectivity (ω k=2 π k/N), has reflected the frequency spectrum of signal on these aspects.

According to the sampling law, the signal of a band limiting can carry out time-domain sampling and not lose any information it, and the FFT conversion then illustrates also can carry out frequency domain sample to time-limited signal (finite length sequence), and does not lose any information.So as long as time series long enough, sampling are enough close, frequency domain sample is the frequency spectrum trend of reflected signal preferably just, so FFT can be in order to carry out signal Spectrum Analysis.

The utility model is for obtaining good linearty and high-resolution, when signal is carried out data acquisition, the minimum twice that equals the input signal highest frequency of the sampling rate of A/D converter 12, that is upper frequency limit is that the real-time spectrum analyzer of 100MHz needs A/D converter 12 that the sampling rate of 200mS/S is arranged.

The performance of this FFT spectrum analysis module 21 characterizes with number of sampling and sampling rate, for example with the sampling rate of 100kS/S to input signal 1024 points of taking a sample, then the highest incoming frequency is 50kHz, resolution is 50Hz.If number of sampling is 2048 points, then resolution is brought up to 25Hz.Hence one can see that, and the highest incoming frequency depends on sampling rate, and resolution depends on number of sampling.This FFT spectrum analysis module becomes logarithmic relationship with number of sampling 21 operation times.When the utility model needs high-frequency, high-resolution and high-speed computation, must select FFT spectrum analysis module 21 at a high speed for use, perhaps digital signal corresponding processing module 13 (DSP) chip.

The used signal source of the utility model adopts the random white noise signal, and white noise is meant power spectral density equally distributed noise in whole frequency domain.That is to say that white noise has the equal-wattage energy in all frequencies.Utilize this characteristic of white noise to have good sound source performance in the acoustical testing field.This random white noise signal is after FFT spectrum analysis module 21 is extracted spectrum component, and it has desirable straight frequency characteristic to its frequency domain distribution in the frequency range of required measurement.

When the utility model is carried in the input of electromagnetic vibration generator system 3 with above-mentioned random white noise signal through power amplifier 15, because the inductance characteristic of electromagnetic vibration generator system 3, the signal of its vibration acceleration and input can be non-linear relation between the width of cloth characteristic frequently, the analog vibration pick-up test macro that habit has is to solve non-linear relation between input one output by real-time compression system, the utility model then only needs to measure with a standard accelerometer 5 the frequency width of cloth parameter of curve of electromagnetic vibration generator system 3 curves of output, and with this frequently width of cloth parameter of curve deposit in the parameter memory module 23 of test module 2 as the relative reference standard, the parameter of curve and the relative reference standard of each tested pick-up 4 are compared calculating, can draw the frequency width of cloth characteristic and the sensitivity parameter of tested pick-up 4.Because standard accelerometer 5 has straight response in required frequency range, so can be used as the calibration reference curve of electromagnetic vibration generator system 4.Therefore, after the calibration through 5 pairs of electromagnetic vibration generator systems 3 of standard accelerometer, remove acceleration transducer 51 from electromagnetic vibration generator system 3, tested pick-up 4 is fixed in the table top of electromagnetic vibration generator system 3, the FFT spectrum analysis module 21 of transporting to test module 2 after its output access interface device 1 buffering amplification is compared computing with the reference curve that deposits parameter memory module 23 in, its difference is passed through the frequency characteristics that energy calculator 22 is converted to voltage frequency width of cloth signal and draws out the product of surveying after level and smooth module 24 of numerical value and coordinate generation module 26 are calibrated on Output Display Unit 27, just can test out the frequency response curve and the sensitivity of tested pick-up 4.

Claims (1)

1, a kind of vibration type pickup parameter analysis test apparatus is characterized in that: the electromagnetic vibration generator system that mainly comprises interface arrangement, test module and installing standard accelerometer;

Described interface arrangement comprise preamplifier, this A/D converter to tested pick-up output through the direct sample of preamplifier amplifying signal, send this signal to test module by the audio digital signals processing module; This test module output noise signal is converted to analog signal by audio digital signals processing module and D/A converter, is carried in the input of electromagnetic vibration generator system through power amplifier;

Described test module mainly comprises FFT spectrum analysis module, energy calculator, parameter memory module, the level and smooth module of numerical value, noise generator module, coordinate generation module and Output Display Unit;

Described accelerometer comprises acceleration transducer and acceleration analysis module;

Described acceleration transducer is fixed in the electromagnetic vibration generator system table top, output inserts the acceleration analysis module, this acceleration analysis module AC signal exports the FFT spectrum analysis module of test module to, the white noise spectrum signal of straight frequency characteristic arranged to encourage tested pick-up to the input input of electromagnetic vibration generator system at the logarithmic coordinates cording by the noise generator module, the frequency width of cloth supplemental characteristic that this acceleration analysis module testing goes out deposits parameter memory module in, the reference curve during as test;

The described tested pick-up that is fixed in the electromagnetic vibration generator system table top outputs signal to interface arrangement, the FFT spectrum analysis module of transporting to test module after interface arrangement buffering is amplified compares computing with the reference curve that deposits parameter memory module in, and its difference is converted to voltage width of cloth signal and draw out the frequency characteristics of the product of surveying after level and smooth module of numerical value and coordinate generation module are calibrated on Output Display Unit frequently through energy calculator.

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