CN104034937B - A kind of multichannel nV grades of alternating voltage testing equipment and detection method - Google Patents
A kind of multichannel nV grades of alternating voltage testing equipment and detection method Download PDFInfo
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Abstract
The invention discloses a kind of multichannel nV grades of alternating voltage testing equipment and detection method, the testing equipment includes amplifying filter unit, multi-channel synchronous data acquisition card and control unit；Amplify and be connected by shielded cable between filter unit and multi-channel synchronous data acquisition card, amplifying filter unit is used to by amplifying export measured signal to multi-channel synchronous data acquisition card with after filtering process；Amplifying filter unit includes at least one-level filtering and amplifying circuit, and amplifier and the wave filter being connected by shielded cable with amplifier are included per one-level filtering and amplifying circuit；If amplifying filter unit includes two grades or more than two grades filtering and amplifying circuits, it is connected by shielded cable between filtering and amplifying circuits at different levels；The signal that multi-channel synchronous data acquisition card will be received is sent to control unit.The present invention have be difficult by external interference, measuring accuracy it is high, test flexibility is high the features such as, research of the present invention to testing weak signals technology has more directive significance.
Description
Technical field
The present invention relates to Technique of Weak Signal Detection field, and in particular to a kind of multichannel nV grades of alternating voltage testing equipment
And detection method.
Background technology
In the various activities of engineering technology, scientific research and production practices, nV grades of ac voltage signal detection is in oil
Well logging, light analysis, superconductor evaluation, metal material tension test, Auger electron spectroscopy, metal detection, eddy current inspection, electronics
The fields such as beam measurement suffer from being widely applied.Because the ambient noise in these fields is very strong, and measured signal is very faint,
Therefore therefrom detect that useful signal is extremely difficult.Studied for nV grades of ac voltage signal detection, explored new detection
Method, develops a focus and difficult point that new testing equipment is current Technique of Weak Signal Detection field.
In the prior art, lock-in amplifier is the Main Means of Detection of Weak Signals, and it is substantially similar to one and carries
The high q-factor wave filter of enlarging function, but in the absence of the central frequency deviation problem of general wave filter.It utilizes coherent detection skill
Art, is greatly enhanced signal to noise ratio, can be the signal extraction being submerged in noise out.But current extracting method error compared with
Greatly, precision is relatively low, and is highly prone to the interference of outside noise, influences the extraction quality of signal.Lock-in amplifier is generally single-pass
Road or binary channels are input into, it is difficult to the need for meeting some multi-channel synchronous concurrent testings, and test result and data cannot be entered
Row subsequent analysis, application flexibility is poor.
In traditional measurement method, the detection method about small-signal is a lot, such as joins from Power estimation method, signal model
Number identification method, noise model subjunctive, higher order cumulants measuring method etc..These methods be mainly by remove and suppress noise come
Signal detection is realized, loss is also result in itself to signal while noise is removed, simultaneously because by various factors
Limitation, the reduction of its work signal to noise ratio lower limit is difficult, it is impossible to measure nV grades of signal.For nV grades of signal, due to measuring system
The various noises and external interference for introducing make noise be higher by tens times of useful signal, and some traditional voltage measurement methods are for this
Plant the nV step voltages measurement being submerged in very noisy helpless.Up to now, the measurement to this nV grades of alternating voltage is a large amount of
Using the phase lock amplifying technology based on computing cross-correlation.
Using phase lock amplifying technology measurement signal, particularly when nV grades of alternating voltage is measured, multiplier output voltage is very
It is small, make the dc amplifier drift being followed by serious, it is unfavorable for the measurement of nV voltages.Numeral is commonly used in existing lock-in amplifier
The detection algorithm of phase-sensitive detector (DPSD), the extraction of line amplitude and phase, current extracting method error are entered to input signal
Larger, precision is relatively low, and is highly prone to the interference of outside noise, influences the extraction quality of signal.Lock-in amplifier is generally list
Passage or binary channels are input into, it is difficult to the need for meeting some multi-channel synchronous concurrent testings, and cannot be to test result and data
Subsequent analysis are carried out, application flexibility is poor.
The content of the invention
Easily influenceed by external interference for existing lock-in amplifier, measuring accuracy is low, cannot multi-channel parallel test, test
The deficiency of very flexible, the present invention provides a kind of multichannel nV grades of alternating voltage testing equipment and detection method.
The first technical solution of the invention：
A kind of multichannel nV grades of alternating voltage testing equipment, its special character：
Including amplifying filter unit, multi-channel synchronous data acquisition card and control unit；
It is connected by shielded cable between the amplification filter unit and multi-channel synchronous data acquisition card, amplifies filtering single
Unit is used to by amplifying export measured signal to multi-channel synchronous data acquisition card with after filtering process；
Amplifying filter unit includes at least one-level filtering and amplifying circuit, include per one-level filtering and amplifying circuit amplifier and
The wave filter being connected by shielded cable with amplifier；If amplify filter unit amplifies filtered electrical including two grades or more than two grades
Road, then be connected between filtering and amplifying circuits at different levels by shielded cable；
The amplifier is the adjustable multichannel low noise amplifier of multiplication factor, the equivalent input noise voltage of amplifier
It is less thanWave filter is the adjustable multichannel bandpass filter of cut-off frequency；Amplifier is equal with the port number of wave filter
It is n, wherein n is not less than 2, and the port number of multi-channel synchronous data acquisition card is m, m=n+1；
Multi-channel synchronous data acquisition card is to be not less than the multi-channel synchronous data acquisition card of 24, multi-channel synchronous data
Capture card is provided with antialiasing filter；
Described control unit is in communication with each other with amplifier and wave filter is connected respectively；
Multi-channel synchronous data acquisition card is in communication with each other with control unit by external hanging type controller without groove and is connected；
One of passage of multi-channel synchronous data acquisition card is used to receive reference signal, reference signal and measured signal
Frequency it is identical, the measured signal and reference signal that multi-channel synchronous data acquisition card will be received are sent to control unit.
Second technical solution of the invention：
A kind of multichannel nV grades of alternating voltage testing equipment, it is characterized in that：
Including amplifying filter unit, multi-channel synchronous data acquisition card and control unit；
It is connected by shielded cable between the amplification filter unit and multi-channel synchronous data acquisition card, amplifies filtering single
Unit is used to by amplifying export measured signal to multi-channel synchronous data acquisition card with after filtering process；
Amplifying filter unit includes at least one-level filtering and amplifying circuit, and filtering and amplifying circuit includes amplifier and and amplifier
The wave filter being connected by shielded cable；If amplifying filter unit includes two grades or more than two grades filtering and amplifying circuits, at different levels
It is connected by shielded cable between filtering and amplifying circuit；
The amplifier is the adjustable multichannel low noise amplifier of multiplication factor, the equivalent input noise voltage of amplifier
It is less thanWave filter is the adjustable multichannel bandpass filter of cut-off frequency；The port number of amplifier and wave filter
N is, wherein n is not less than 2, and the port number of multi-channel synchronous data acquisition card is m, m=n+1；
Multi-channel synchronous data acquisition card is to be not less than the multi-channel synchronous data acquisition card of 24, multi-channel synchronous data
Capture card is provided with antialiasing filter；
Control unit is Embedded Zero greeve controller, control unit respectively with amplifier, wave filter and multi-channel synchronous number
Connection is in communication with each other according to collection cartoon；
One of passage of multi-channel synchronous data acquisition card is used to receive reference signal, reference signal and measured signal
Frequency it is identical, the measured signal and reference signal that multi-channel synchronous data acquisition card will be received are sent to control unit.
Based on above-mentioned technical proposal, the present invention also makes following optimization and restriction：
Amplifying filter unit includes two grades of filtering and amplifying circuits.
Above-mentioned amplifier includes signal amplification board, and wave filter includes LPF plate and high-pass filtering plate；
The input of the output termination LPF plate of signal amplification board, the output termination high-pass filtering plate of LPF plate
Input.
Above-mentioned LPF plate includes that the be sequentially connected the 1st selects 1 analog switch, 16 road low-pass filter circuits and second
16 select 1 analog switch, and high-pass filtering plate includes that the be sequentially connected the 3rd 16 selects 1 analog switch, 16 road high-pass filtering circuits and the
4 16 select 1 analog switch；
LPF plate is multichannel LPF plate, and high-pass filtering plate is multichannel high-pass filtering plate, LPF plate
Port number with high-pass filtering plate is equal.
Above-mentioned testing equipment also includes cabinet, and the multi-channel synchronous data acquisition card is 24 multi-channel synchronous PXI numbers
According to capture card, multi-channel synchronous data acquisition card is arranged on cabinet.
Wherein, the equivalent input noise voltage of amplifier of the present invention is less thanIt refer to the frequency in measured signal
When rate is 1kHz, the equivalent input noise voltage of amplifier is less than
The third technical solution of the invention：
A kind of multichannel nV grades of alternating voltage detection method, comprises the following steps,
1) measured signal is accessed into one-level filtering and amplifying circuit, by the amplifier of one-level filtering and amplifying circuit to measured signal
It is amplified, the wave filter that the measured signal after amplification accesses to one-level filtering and amplifying circuit is filtered；
2) filtered measured signal is accessed into multi-channel synchronous data acquisition card；Reference signal is accessed into multi-channel synchronous
One passage of data collecting card；
3) it is input into by control unit Real-time Collection to the signal of each input channel of multi-channel synchronous data acquisition card, and will
Test data is preserved；
4) amplitude and phase of measured signal are calculated.
Above-mentioned steps 1) it is further comprising the steps of,
1.1) using two grades of amplifiers of filtering and amplifying circuit to by the filtered tested letter of one-level filtering and amplifying circuit
Number it is amplified again；
1.2) using the wave filters of two grades of filtering and amplifying circuits to by step 1.1) amplify after measured signal enter again
Row filtering.
Amplitude A, the angular frequency of the measured signal after being processed through two grades of filtering and amplifying circuits0, phase meet formula：s
(t)=Asin (ω0T+ φ), the frequency of the measured signal after being processed through two grades of filtering and amplifying circuits is f0；
If the sample frequency of multi-channel synchronous data acquisition card is fs, sampling length is N, then multi-channel synchronous data acquisition
Blocking the periodicity sampled isWherein, T0=2 π/ω0, it is the week of the measured signal after being processed through two grades of filtering and amplifying circuits
Phase；Ts=1/fs, it is the sampling interval of multi-channel synchronous data acquisition card；
The step 4) according to the amplitude and phase of procedure below calculating measured signal, each in following calculating process is public
In formula, n=0,1 ... N-1；
The sample rate and sampling length of multi-channel synchronous data acquisition card select the integer-period sampled of measured signal, then sample
Measured signal afterwards is：
According to the frequency of reference signal, following two reference waveform sequences are produced by software：
Can then be obtained according to (1), (2)：
Similarly, can be obtained according to (1), (3)：
Can then be obtained by (4), (5)：
According to (6), (7), the amplitude and phase that can obtain measured signal are respectively：
Beneficial effects of the present invention：
1st, external interference is easily received instant invention overcomes existing equipment, measuring accuracy is low, cannot carry out data analysis, test spirit
The deficiency of poor activity；
2nd, the present invention can realize the more multichannel nV grades parallel measurement of ac voltage signal, amplified using software phlase locking and calculated
Method, can suppress, because of the noise jamming that hardware phase lock high precision amplifying circuit is introduced, to improve measuring accuracy, improve the anti-interference energy of equipment
Power.
3rd, the present invention is more transparent to the processing procedure of signal, and parameter configuration is more convenient, flexible, and test data is preserved more
Add whole, be more beneficial for the shared of data, be that the treatment of experimental data brings and greatly facilitates.
4th, the present invention as a kind of detection of nV grade ac voltage signal equipment, to the research of testing weak signals technology more
With directive significance.
Brief description of the drawings
Fig. 1 is equipment composition frame chart of the invention；
Fig. 2 is the theory diagram of filtering and amplifying circuit of the present invention；
Fig. 3 is the theory diagram of single channel program control filtering circuit of the present invention；
Fig. 4 is test software functional block diagram of the present invention；
Fig. 5 is software phlase locking interpolator arithmetic schematic diagram of the invention；
Fig. 6 is the test philosophy block diagram of the inventive method；
Fig. 7 is the inventive method testing signal process flow chart.
Specific embodiment
The present invention provides a kind of multichannel nV grades of alternating voltage testing equipment, as shown in Figure 1 and Figure 7, including amplifies filtering
Unit, multi-channel synchronous data acquisition card and control unit；Multi-channel synchronous data acquisition card can complete the numeral of analog signal
Change, control unit can use computer, realize storage and the Treatment Analysis of data.
Amplify and be connected by shielded cable between filter unit and multi-channel synchronous data acquisition card, amplify filter unit and use
Exported to multi-channel synchronous data acquisition card with after filtering process by amplifying in by measured signal.
Amplifying filter unit includes at least one-level filtering and amplifying circuit, include per one-level filtering and amplifying circuit amplifier and
The wave filter being connected by shielded cable with amplifier；If amplify filter unit amplifies filtered electrical including two grades or more than two grades
Road, then be connected between filtering and amplifying circuits at different levels by shielded cable；As shown in fig. 7, amplification filter unit of the invention can be with
Including two grades of filtering and amplifying circuits, can further amplify measured signal so that the amplitude of measured signal reaches and leads to more after amplification
Within the dynamic range of road simultaneous data-acquisition；Also the signal to noise ratio of measured signal can further be improved.It is of the invention to amplify filter
Wave circuit can make the amplitude of measured signal reach within the dynamic range of capture card and effectively suppress and filter part interference noise,
So as to improve signal to noise ratio, expand the dynamic range of instrument.
Amplifier is the adjustable multichannel low noise amplifier of multiplication factor, can be 1 preamplifier of multichannel,
Multichannel preamplifier can also be constituted by many single pass preamplifiers, its port number and measured signal port number
Unanimously；The gain of preamplifier at least 60dB, less noise is introduced while nV grades of signal is effectively amplified, amplifier
Programmable gain is adjustable.The equivalent input noise voltage of amplifier is less than
Wave filter is the adjustable multichannel bandpass filter of cut-off frequency, and the wave filter has program-controlled interface, can pass through
Computer software programming is filtered parameter setting；And wave filter is adjustable by frequency step；
Amplifier is n with the port number of wave filter, and wherein n is not less than 2, the passage of multi-channel synchronous data acquisition card
Number is m, m=n+1；
Multi-channel synchronous data acquisition card is to be not less than the multi-channel synchronous data acquisition card of 24；With larger dynamic
Scope, sample rate higher and good synchronizing characteristics, and input has antialiasing filter；Low noise can specifically be used
High-precision 24 multi-channel synchronous PXI data collecting cards；
Control unit is in communication with each other with amplifier and wave filter is connected respectively；Multi-channel synchronous data acquisition card is by plug-in
Formula Zero greeve controller is in communication with each other with control unit and is connected；Multi-channel synchronous data acquisition card and external hanging type controller without groove
Using standard PXI modules, in PXI cabinets, control unit controls multi-channel synchronous number by external hanging type controller without groove
Collection and storage according to capture card to measured signal.
One of passage of multi-channel synchronous data acquisition card is used to receive reference signal, reference signal and measured signal
Frequency it is identical, the measured signal and reference signal that multi-channel synchronous data acquisition card will be received are sent to control unit.
Control unit can use Embedded Zero greeve controller, if control unit uses Embedded Zero greeve controller, control
Be in communication with each other logical with amplifier, wave filter and multi-channel synchronous data acquisition card is connected unit respectively.
As shown in Fig. 2 amplifier of the invention includes signal amplification board, wave filter includes LPF plate and high-pass filtering
Plate；LPF plate and high-pass filtering plate composition signal filter circuit.The output of signal amplification board terminates the defeated of LPF plate
Enter end, the input of the output termination high-pass filtering plate of LPF plate.
Power panel is powered to signal amplification board and signal filter circuit, and signal amplification board is passed after being amplified to measured signal
Signal filter circuit is given, amplification, filtered signal are sent to multichannel by signal filter circuit after being filtered to signal
Simultaneous data-acquisition.
Wherein, power panel is used to power signal amplification board and signal filter circuit, is obtained the most using linear power supply
Preferable noise characteristic.The ripple frequency of linear power supply is 100Hz, and on this frequency, the PSR (PSRR) of amplifier can
To reach more than 100dB, it is assumed that power supply ripple is 1mVRMS, the influence to amplifier is only below lnV, and power supply noise can be neglected
Slightly.The power supply uses rectification, filtering, the processing method of LDO mu balanced circuits, and wherein mu balanced circuit is done to feed back using amplifier and reduced
Ripple and noise, obtain excellent circuit performance.Power panel is powered for polylith printed board, is to reduce each printed board as far as possible
The crosstalk of noise, the power supply to each printed board adds π types to filter using single LDO voltage stabilizings, after LDO voltage stabilizings
Device, using common mode magnet ring and differential mode magnet ring, reduces common-mode noise and differential mode noise so that ripple noise peak when power panel works
Value is less than 3mV.
Signal amplification board realizes the enlarging function of measured signal, can be carried out by RS485 interfaces it is program control, it is parallel with 4
Passage, per bandwidth chahnel 3MHz, the stepping of gain 1~10000 is program-controlled, 10 times of stepping.Amplifying circuit is used without gain resistor
Integrated magnifier, use AD8429 chips.The chip relies onVoltage noise level, with excellent
Noise characteristic.Optional 20kHz low-pass filter circuits are added in amplifying circuit rear end, when low-frequency test is carried out, by drop
Low bandwidth reduces noise；To avoid being grounded the noise of improper introducing, single board design is floating ground circuit, and RS485 communications are connect
Mouth is isolated.
Signal filter circuit is used for the filtering to amplified signal, improves signal to noise ratio.The filter circuit has 4 independent filters
Ripple passage, is made up of 4 LPF plates and 4 blocks of high-pass filtering plates, can be carried out by RS485 interfaces program control.LPF and
High-pass filtering is separated, and both be can be used alone, it is also possible to be combined into a bandpass filtering, easy to use, flexible.
LPF plate includes that the be sequentially connected the 1st selects 1 analog switch, 16 road low-pass filter circuits and the 2nd 16 to select 1
Analog switch, high-pass filtering plate includes that the be sequentially connected the 3rd 16 selects 1 analog switch, 16 road high-pass filtering circuits and the 4th 16 choosing
1 analog switch；LPF plate is multichannel LPF plate, and high-pass filtering plate is multichannel high-pass filtering plate, LPF
The port number of plate and high-pass filtering plate is equal.
The specific annexation of LPF plate and high-pass filtering plate is as shown in figure 3, be single channel filter circuit function knot
Composition, comprising 1 block of LPF plate and 1 block of high-pass filtering plate, two pieces of circuit boards are composed in series 1 bandpass filtering electricity of passage
Road.The filter circuit of LPF plate therein and high-pass filtering plate uses 4 rank Butterworth filter circuits, is put down in passband
Smooth, attenuation characteristic is ideal in stopband.Filter bandwidht is 3MHz, and 64 frequency ranges are divided into bandwidth range, and each is frequently
The wave filter of section is separate.Filter circuit front and back end respectively adds 4 16 to select 1 analog switch to constitute 64 switches for selecting 1, and it is right to come
The wave filter of 64 frequency ranges is selected.Such as Fig. 3,16 select 1 analog switch to be respectively the 1st selects 1 analog switch, the 2nd 16
Select 1 analog switch, the 3rd 16 to select 1 analog switch and the 4th 16 to select 1 analog switch, can enter according to following condition during wave filter setting
Stroke control is set：
A) during frequency range DC~1kHz, 100Hz steppings；
B) during frequency range 1kHz~20kHz, 1kHz steppings；
C) during frequency range 20kHz~100kHz, 5kHz steppings；
D) during frequency range 100kHz~1MHz, 100kHz steppings；
E) during frequency range 1MHz~3MHz, 200kHz steppings.
Testing equipment of the invention also includes cabinet, and multi-channel synchronous data acquisition card is that multi-channel synchronous PXI data are adopted
Truck, multi-channel synchronous data acquisition card is arranged on cabinet.
Filtering and amplifying circuit of the invention can be arranged in cabinet, and cabinet panel installs BNC insulating barriers socket to be used to believe
Number input, between panel and internal circuit board be connected by BNC-SMB screened coaxial cables connection, between internal circuit board
Connected using SMB-SMB coaxial shielded cables, the method can be effectively reduced the noise that electrostatic coupling and electromagnetic interference are produced, solution
The interference that certainly connection cable is produced.Shielding processing is carried out using metal screen case to crucial signal amplification board, is prevented effectively from
The radiation interference of surrounding environment influences the performance of equipment.
PXI cabinets in the present embodiment using Haitai electronics HTPXI1008 standard PXI cabinets, Zero greeve controller makes
With the HTPXI4900 external hanging type controller without groove of Haitai electronics, computer uses the 2U industrial computers IPC-2320 for grinding China.24 high
Accuracy data capture card selects the PXI-4472 data collecting cards of NI companies, dynamic range 110dB, 102.4kS/S sample rate, 8
Channel Synchronous are gathered, and there is antialiasing filter inside.
Control unit of the invention can use computer, and test software is installed on computers, and such as Fig. 4 is wrapped in software
Containing data acquisition module, lock phase interpolator arithmetic module, data management module, data readback module, equipment test and management module, set
Standby selftest module, equipment Alignment module, equipment configuration module, testing analysis module, report generation module and equipment help module
Deng.
The drive software of data acquisition module cooperation capture card carries out Real-time Collection to the input signal of each passage of capture card,
And preserved the data of collection；Lock phase interpolator arithmetic module resolves the amplitude of measured signal according to test data by algorithm
And phase parameter；Data management module is managed to the test data of each time, including data such as browse, search, deleting at the behaviour
Make, every time the single data of experiment generation and configuration file；Data readback module completes the reproduction afterwards of test data.
Equipment test and management module is the support section of whole software, completes the scheduling and management of whole equipment resource.If
Standby test and management module realizes the function of most of man-machine interaction, including primary control program, each application program graphical user
Interface, realizes the setting of various operational factors and operating figure shows, and provide spirit by different window and dialog box
Man-machine interaction mode living, friendly.When equipment is run, operational outfit test and management module calls each functional module first, respectively
Next functional module is performed automatically after individual functional module operation is finished or by equipment test and management module schedules or is directly returned
Main interface, interacts formula and operates by user.
Equipment self-inspection module completes the self-inspection of equipment each several part and provides self-detection result.Before equipment starts each test assignment
Self-inspection is carried out to the circuit module in front end signal conditioning case and the module in PXI data collecting systems, before ensureing test
Module is in normal condition.
Equipment Alignment module is mainly responsible for the signal calibration to test equipment input channel.With environment, the change of temperature,
These measuring accuracies for all influenceing test equipment and the degree of accuracy, equipment Alignment module cooperation external perimysium reference instrument can be realized to equipment
Calibration, it is ensured that test equipment measuring accuracy under any circumstance and the degree of accuracy.
Equipment configuration module is configured to the various operational factors of equipment, mainly includes that data acquisition parameters set, adjust
Reason circuit parameter setting etc..Acquisition parameter mainly sets sample rate and sampling number etc., on triggering mode, can set passage
Triggering, external trigger are freely gathered, and when signal is triggered, the trigger parameters such as triggering level, triggering edge can be set.Modulate circuit is joined
Number sets gain and the filtering parameter of wave filter of the featured configuration amplifier mainly according to measured signal.
Testing analysis module is realized by calling the control of the complete paired data capture card of driving function and front end modulate circuit
Data acquisition, is then analyzed, to the signal for gathering using software phlase locking interpolator arithmetic so as to obtain the amplitude of measured signal
And phase information.The module using various data analysing methods, can be analyzed to test data according to actual needs, from
And obtain interested and valuable information.The module can also be entered according to the data for collecting according to the playback parameter of setting
The playback afterwards of row data, reproduces situation during test.
Report generation module generates the custom formats test report that both pictures and texts are excellent according to test data and method of testing.
Equipment help module has provided the user help information, and it includes that the arrange parameter in test process is helped and operated
Step, guide for use of operating method etc., quickly familiar and configuration uses equipment to help user.
Lock phase interpolator arithmetic module is realized using being the principle based on quarter-phase lock-in amplifier, in test signal amplitude
When the phase of signal and reference signal need not be adjusted, the software phlase locking algorithm is by same reference signal frequency and phase
Position identical input signal carries out Fourier transformation to eliminate noise, equivalent to an arrowband centered on reference signal frequency
Bandpass filter；Using software phlase locking interpolator arithmetic, can suppress, because of the noise jamming that hardware phase lock high precision amplifying circuit is introduced, to improve and survey
Examination precision, and it is more transparent to the processing procedure of signal, parameter configuration is more convenient, flexible, and test data preserves more complete,
The shared of data is more beneficial for, is that the treatment of experimental data brings and greatly facilitates.
Reference picture 1~3, describes the present invention in detail.
The inventive method test philosophy block diagram is as shown in figure 1, front end is in the form of the cascade of two grades of filtering and amplifying circuits pair
Measured signal is nursed one's health, and signal to noise ratio is improved while being amplified to signal, and the conditioning part is using hardware circuit come real
Existing, rear end is entered using 24 high-precision multi-channel synchronous data acquisition cards of low noise to the output signal of each passage modulate circuit
Then the data of each passage are calculated by row Real-time Collection in real time by software phlase locking interpolator arithmetic in a computer, are extracted
The amplitude and phase parameter of measured signal.In addition, data storage, data point can also be realized by software in a computer
Various functions such as analysis, data readback and generation test report.
Based on monitoring device of the invention, present invention also offers a kind of multichannel nV grades of alternating voltage detection method,
NV grades of alternating voltage is detected using software phlase locking interpolator arithmetic on the basis of testing equipment of the present invention, as shown in Figure 6 and Figure 7, bag
Include following steps：
1) measured signal is accessed into one-level filtering and amplifying circuit, by the amplifier of one-level filtering and amplifying circuit to measured signal
It is amplified, the wave filter that the measured signal after amplification accesses to one-level filtering and amplifying circuit is filtered；
1.1) using two grades of amplifiers of filtering and amplifying circuit to by the filtered tested letter of one-level filtering and amplifying circuit
Number it is amplified again；
1.2) using the wave filters of two grades of filtering and amplifying circuits to by step 1.1) amplify after measured signal enter again
Row filtering, further improves signal to noise ratio；
2) filtered measured signal is accessed into multi-channel synchronous data acquisition card；Reference signal is accessed into multi-channel synchronous
One passage of data collecting card；
3) it is input into by control unit Real-time Collection to the signal of each input channel of multi-channel synchronous data acquisition card, and will
Test data is preserved on computers；
4) amplitude and phase of measured signal are calculated.If desired, number that can be by the test software on computer to preserving
According to being managed, including the operation such as browse, search, deleting, it is also possible to test data is played back by data readback software.
This method uses 24 multi-channel synchronous data acquisition modules, achievable more multichannel nV grades ac voltage signal
Parallel measurement.
Amplitude A, the angular frequency of the measured signal after being processed through two grades of filtering and amplifying circuits0, phase meet formula：s
(t)=Asin (ω0T+ φ), the frequency of the measured signal after being processed through two grades of filtering and amplifying circuits is f0；
If the sample frequency of multi-channel synchronous data acquisition card is fs, sampling length is N, then multi-channel synchronous data acquisition
Blocking the periodicity sampled isWherein, T0=2 π/ω0, it is the week of the measured signal after being processed through two grades of filtering and amplifying circuits
Phase；Ts=1/fs, it is the sampling interval of multi-channel synchronous data acquisition card；
Step 4) according to the amplitude and phase of procedure below calculating measured signal, in the separate equations of following calculating process
In, n=0,1 ... N-1；Following calculating can be realized by the application software comprising lock phase interpolator arithmetic；
The sample rate and sampling length of multi-channel synchronous data acquisition card select the integer-period sampled of measured signal, then sample
Measured signal afterwards is：
According to the frequency of reference signal, following two reference waveform sequences are produced by software, specifically can be with passage such as lower section
Formula is realized：Reference signal enters internal reference signal maker, and (reference signal generator is a software module, is specially measured
The frequency and phase of reference signal, produce the reference waveform calculated for algorithm.) frequency of reference signal is extracted by the maker
Rate and phase information, and two kinds of generation does not have noisy reference waveform sequence：
Can then be obtained according to (1), (2)：
Similarly, can be obtained according to (1), (3)：
Can then be obtained by (4), (5)：
According to (6), (7), the amplitude and phase that can obtain measured signal are respectively：
The measured signal of testing equipment of the present invention is nV grades of signal, is easily interfered in test process, including electricity is made an uproar
Sound and the conduction from emission system and radiation interference etc., equipment complex are simultaneous to electromagnetism with measures such as ground connection, shielding and filtering
Capacitive has carried out special consideration, mainly there is the following aspects：
A) test signal is transmitted from coaxial cable to signal, reduces the introducing of outside noise；
B) front end conditioning has used the amplifier of low input noise, and is filtered outside band by setting flexible bandpass filter
Noise, employs digital filtering algorithm, and use the software phlase locking interpolator arithmetic of strong antijamming capability to signal in software
Amplitude and phase are analyzed；
C) AC power input sets alternating current filter, weakens Conduction Interference of the external electrical to equipment；Wave filter is installed
In power supply unit AC power cord porch, do not allow input ac power line detoured in cabinet very over long distances after connect filtering again
Device, in case the line produces radiated noise in cabinet；The input/output line of wave filter is arranged apart, uneven walking line or ties up
Together, it is to avoid the noise in input line is directly coupled on output line without wave filter；The output line of wave filter is using double
Twisted wire, strengthens diamagnetic field interference performance.
Claims (6)
1. a kind of multichannel nV grades of alternating voltage testing equipment, it is characterised in that：
Including amplifying filter unit, multi-channel synchronous data acquisition card and control unit；
It is connected by shielded cable between the amplification filter unit and multi-channel synchronous data acquisition card, amplifies filter unit and use
Exported to multi-channel synchronous data acquisition card with after filtering process by amplifying in by measured signal；
Amplifying filter unit includes at least one-level filtering and amplifying circuit, include per one-level filtering and amplifying circuit amplifier and with put
The wave filter that big device is connected by shielded cable；If amplifying filter unit includes two grades or more than two grades filtering and amplifying circuits,
It is connected by shielded cable between filtering and amplifying circuits at different levels；
The amplifier is the adjustable multichannel low noise amplifier of multiplication factor, and the equivalent input noise voltage of amplifier is less thanWave filter is the adjustable multichannel bandpass filter of cut-off frequency；Amplifier is n with the port number of wave filter,
Wherein n is not less than 2, and the port number of multi-channel synchronous data acquisition card is m, m=n+1；
Multi-channel synchronous data acquisition card is to be not less than the multi-channel synchronous data acquisition card of 24, multi-channel synchronous data acquisition
Card is provided with antialiasing filter；
Described control unit is in communication with each other with amplifier and wave filter is connected respectively；
Multi-channel synchronous data acquisition card is in communication with each other with control unit by external hanging type controller without groove and is connected；
One of passage of multi-channel synchronous data acquisition card is used to receive the frequency of reference signal, reference signal and measured signal
Rate is identical, and the measured signal and reference signal that multi-channel synchronous data acquisition card will be received are sent to control unit.
2. a kind of multichannel nV grades of alternating voltage testing equipment, it is characterised in that：
Including amplifying filter unit, multi-channel synchronous data acquisition card and control unit；
It is connected by shielded cable between the amplification filter unit and multi-channel synchronous data acquisition card, amplifies filter unit and use
Exported to multi-channel synchronous data acquisition card with after filtering process by amplifying in by measured signal；
Amplifying filter unit includes at least one-level filtering and amplifying circuit, and filtering and amplifying circuit includes amplifier and passes through with amplifier
The connected wave filter of shielded cable；If amplifying filter unit includes two grades or more than two grades filtering and amplifying circuits, amplifications at different levels
It is connected by shielded cable between filter circuit；
The amplifier is the adjustable multichannel low noise amplifier of multiplication factor, and the equivalent input noise voltage of amplifier is less thanWave filter is the adjustable multichannel bandpass filter of cut-off frequency；Amplifier is n with the port number of wave filter,
Wherein n is not less than 2, and the port number of multi-channel synchronous data acquisition card is m, m=n+1；
Multi-channel synchronous data acquisition card is to be not less than the multi-channel synchronous data acquisition card of 24, multi-channel synchronous data acquisition
Card is provided with antialiasing filter；
Control unit is Embedded Zero greeve controller, and control unit is adopted with amplifier, wave filter and multi-channel synchronous data respectively
Collection cartoon is in communication with each other connection；
One of passage of multi-channel synchronous data acquisition card is used to receive the frequency of reference signal, reference signal and measured signal
Rate is identical, and the measured signal and reference signal that multi-channel synchronous data acquisition card will be received are sent to control unit.
3. multichannel nV grades of alternating voltage testing equipment according to claim 1 and 2, it is characterised in that：Amplify filtering single
Unit includes two grades of filtering and amplifying circuits.
4. multichannel nV grades of alternating voltage testing equipment according to claim 3, it is characterised in that：The amplifier includes
Signal amplification board, wave filter includes LPF plate and high-pass filtering plate；
The input of the output termination LPF plate of signal amplification board, the output of LPF plate terminates the defeated of high-pass filtering plate
Enter end.
5. multichannel nV grades of alternating voltage testing equipment according to claim 4, it is characterised in that：The LPF plate
Including being sequentially connected the 1st selects 1 analog switch, 16 road low-pass filter circuits and the 2nd 16 to select 1 analog switch, high-pass filtering
Plate includes that the be sequentially connected the 3rd 16 selects 1 analog switch, 16 road high-pass filtering circuits and the 4th 16 to select 1 analog switch；
LPF plate is multichannel LPF plate, and high-pass filtering plate is multichannel high-pass filtering plate, LPF plate and height
The port number of pass filter plate is equal.
6. multichannel nV grades of alternating voltage testing equipment according to claim 5, it is characterised in that：The testing equipment is also
Including cabinet, the multi-channel synchronous data acquisition card is 24 multi-channel synchronous PXI data collecting cards, multi-channel synchronous data
Capture card is arranged on cabinet.
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| CN105572655B (en) * | 2015-12-22 | 2019-01-01 | 中国船舶重工集团公司第七一五研究所 | A kind of faint underwater sound signal simulation and test device |
| CN110940416A (en) * | 2019-11-18 | 2020-03-31 | 武汉光谷信息光电子创新中心有限公司 | Multichannel parallel photoelectric detection circuit structure |
| CN112485697A (en) * | 2020-11-11 | 2021-03-12 | 中山大学 | High-voltage power supply ripple measurement and analysis system based on phase-locked amplification algorithm |
| CN112735310B (en) * | 2020-12-22 | 2022-08-02 | 北京市轨道交通运营管理有限公司 | Testing system and high-precision testing method for ceiling guide display panel |
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