CN102043091A - Digitized high-precision phase detector - Google Patents

Abstract

The invention discloses a digitized high-precision phase detector. The digitized high-precision phase detector comprises an analogue-to-digital conversion module (10), a filter module (20), a phase difference computation module (30), a phase correction module (40), and a phase detection result storage and display module (50). The digitized high-precision phase detector provided by the invention has the advantages that: the precision is high, the measuring range is wide, the frequency range is wide, and the digitized high-precision phase detector is convenient to operate and the like; and the digitized high-precision phase detector can work in a harmonic environment.

Description

The digital high precision phase detectors

Technical field

The present invention relates to the signal phase field of measuring technique, be specifically related to a kind of digital high precision phase detectors with accurate measurement two-way measured signal phase differential.

Background technology

Phase measurement is widely used for fields such as power industry, mechanical engineering, space flight and aviation, resource exploration, communication system, radar and sonar.Along with the swift and violent raising of contemporary science and technology level, each application has proposed new requirement to phase measurement, makes phase detectors develop towards wide-range, broadband, high precision, digitizing, intelligentized direction.

Traditional phase detectors have multiple, according to its implementation, can be divided into analog-and digital-two big classes.Wherein, analogue phase detector mainly contains: pulse pad count formula, and measured signal is shaped to square-wave signal and forms the pulse width signal of output pulse sequence, obtain the phase differential between the counting number reflection measured signal of high-frequency impulse with this control gate circuit; Phase discriminator type, measured signal is shaped to square-wave signal and makes phase discrimination processing through NOR gate circuit, obtains the amplitude of the DC component that is directly proportional with phase differential again through smothing filtering.Analogue phase detector is realized by mimic channel, needs special-purpose device, and the hardware cost height generally is difficult to the phase accuracy that reaches very high.

And the digital phase detecting device mainly contains: the zero passage detection formula, the coherent detection formula is based on fast fourier transform (FFT) formula.Zero passage detection formula phase detectors are very low for the phase measurement accuracy of high-frequency signal, can not satisfy the needed precision of phase measurement in the modern industry; Though traditional coherent detection formula phase detectors precision height can only measure the phase differential between 0 to 180 degree, and measurement result is vulnerable to the interference of harmonic wave; Based on the phase detectors of FFT, there is the spectrum leakage phenomenon, the phase test precision is lower under the harmonic wave environment.

Summary of the invention

(1) technical matters that will solve

In order to overcome the shortcoming of above-mentioned prior art, the object of the present invention is to provide a kind of digital high precision phase detectors, have high precision, wide-range, wideband section, easy to operate, the advantage that can work in the harmonic wave environment.

(2) technical scheme

For achieving the above object, the invention provides a kind of digital high precision phase detectors, comprising:

Analog-to-digital conversion module 10 is used for the first measured signal a1 and the second measured signal a2 of input are carried out analog digital conversion, realizes digital collection to measured signal, first digital sample as a result b1 and second digital sample as a result b2 export to filter module 20;

Filter module 20, be used for to first digital sample of analog-to-digital conversion module 10 output as a result b1 and second digital sample as a result b2 carry out bandpass filtering, suppress harmonic interference, phase difference calculating module 30 and phase place correcting module 40 are exported in first filtering c1 and second filtering as a result c2 as a result;

C1 and second filtering as a result of phase difference calculating module 30, first filtering that is used for calculating filter module 20 output is the phase differential between the c2 as a result, adopts cross-correlation method to carry out phase difference calculating, and phase difference calculating d is as a result exported to phase place correcting module 40;

Phase place correcting module 40, first filtering that is used to judge filter module 20 outputs c1 and second filtering as a result is phase differential symbol positive and negative between the c2 as a result, then to the phase difference calculating of phase difference calculating module 30 output as a result d carry out the symbol correction, the phase detection result e that obtains, and phase detection result e is exported to phase detection result store and display module 50;

Phase detection result storage and display module 50 are used for the phase detection result e of phase place correcting module 40 outputs is carried out digitizing storage and demonstration.

In the such scheme, described analog-to-digital conversion module 10 comprises:

First signal condition 101 is used for the first measured signal a1 of input is carried out signal condition, makes its amplitude in first high-speed AD is sampled 103 desired scopes;

Secondary signal conditioning 102 is used for the second measured signal a2 of input is carried out signal condition, makes its amplitude in second high-speed AD is sampled 104 desired scopes;

First high-speed AD sampling 103 is used for digital collection is carried out in the output of first signal condition 101, finishes the analog digital conversion, and sampling process is carried out controlling of sampling by computing machine;

Second high-speed AD sampling 104 is used for digital collection is carried out in the output of secondary signal conditioning 102, finishes the analog digital conversion, and sampling process is carried out controlling of sampling by computing machine, and sampling rate and first high-speed AD sampling 103 keep synchronously.

In the such scheme, described filter module 20 comprises:

Frequency detecting 201, first digital sample that is used to detect analog-to-digital conversion module 10 outputs is the frequency of b1 as a result, and export to first bandpass filter 202 and second bandpass filter 203, finish passband setting to first bandpass filter 202 and second bandpass filter 203;

First bandpass filter 202, be used for to first digital sample as a result b1 carry out bandpass filtering, filter bandwidht is controlled by frequency detecting 201 output results;

Second bandpass filter 203, be used for to second digital sample as a result b2 carry out bandpass filtering, filter bandwidht is controlled by frequency detecting 201 output results, the wave filter setting of second bandpass filter 203 is identical with 202 maintenances of first bandpass filter.

In the such scheme, described phase difference calculating module 30 comprises first cross-correlation calculation 301, first auto-correlation calculating, 302, second auto-correlation calculating, 303, first square root extractor 304, second square root extractor 305, multiplier 306, divider 307 and arc cosine calculating 308, wherein:

C1 and second filtering as a result of first cross-correlation calculation 301, first filtering that is used for calculating filter module 20 output is the cross correlation value between the c2 as a result, and result of calculation is exported to divider 307;

First auto-correlation is calculated 302 and second auto-correlation and is calculated 303 and be respectively applied for and calculate first filtering c1 and the second filtering as a result autocorrelation value of c2 as a result, and result of calculation is exported to first square root extractor 304 and second square root extractor 305 respectively;

First square root extractor 304 is used for the output result of first auto-correlation computation 302 is carried out extracting operation, and operation result is exported to multiplier 306;

Second square root extractor 305 is used for the output result of second auto-correlation computation 303 is carried out extracting operation, and operation result is exported to multiplier 306;

Multiplier 306 is used for the output result of first square root extractor 304 and second square root extractor 305 is carried out multiplication mutually, and operation result is exported to divider 307;

Divider 307 is used for the output result of first cross-correlation calculation 301 and multiplier 306 is carried out division operation mutually, and operation result is exported to arc cosine calculate 308;

Arc cosine calculates 308, is used for the output result of divider 307 is carried out arc cosine calculating.

In the such scheme, described phase place correcting module 40 comprises:

First shift unit 401, be used for to first filtering as a result c1 to carry out length be 1 displacement;

Second shift unit 402, be used for to second filtering as a result c2 to carry out length be 1 displacement;

Second cross-correlation calculation 403 is used to calculate first filtering c1 and the second filtering as a result cross correlation value between the shift value of c2 as a result;

The 3rd cross-correlation calculation 404 is used to calculate second filtering c2 and the first filtering as a result cross correlation value between the shift value of c1 as a result;

Subtracter 405 is used for the output result of second cross-correlation calculation 403 and the 3rd cross-correlation calculation 404 is carried out additive operation;

Symbol decision 406, output result by subtracter 405, be used to judge first filtering c1 and second filtering as a result phase differential symbol positive and negative between the c2 as a result, if the output result of subtracter 405 is greater than zero, then first filtering c1 and second filtering as a result as a result between the c2 phase differential symbol for just, if the output result of subtracter 405 is less than zero, then first filtering c1 and second filtering as a result as a result between the c2 phase differential symbol for negative;

Symbol correction 407, be used for to the phase difference calculating of phase difference calculating module 30 output as a result d carry out the symbol correction.

(3) beneficial effect

Digital high precision phase detectors provided by the invention are compared with existing phase detectors, have following advantage:

1), high precision: phase accuracy can reach 0.01 degree, and prior art generally can only reach 0.1 degree.

2), wide-range: can measure from-180 and spend to all phase differential 180 degree.

3), wideband section: from 1Hz to 50kHz.

4), easy to operate: Digital Realization, be convenient to adjust.

5), can work in the harmonic wave environment.

Description of drawings

Fig. 1 is the structural representation of digital high precision phase detectors provided by the invention.

Embodiment

For making the purpose, technical solutions and advantages of the present invention clearer, below in conjunction with specific embodiment, and with reference to accompanying drawing, the present invention is described in more detail.

In conjunction with the drawings most preferred embodiment according to the present invention is described in detail, the advantage of other aspects of the present invention will become clear and be more readily understood.

The ultimate principle of test phase difference of the present invention is as follows:

If two measured signals are as shown in the formula shown in (1), (2):

x(t)＝Asin?2πft+N _x(t)(1)

Wherein, A, B are the amplitude of x (t), y (t) signal, N _x(t), N _y(t) be respectively noise on x (t), y (t) signal, f is a signal frequency,

Be the phase differential between the two-way measured signal.

To x (t), y (t) carries out computing cross-correlation, has:

$R_{\mathrm{xy}}\left(\mathrm{\τ}\right)={\frac{1}{T}}^T\underset{0}{\∫}x\left(t\right)y(t+\mathrm{\τ})\mathrm{dt}---\left(3\right)$

When τ=0,

Because noise is uncorrelated with signal, and also uncorrelated between the noise, obtains behind the integration:

Therefore, phase differential can obtain by following formula:

The amplitude of two signals can be determined by autocorrelation function.

$R_x\left(\mathrm{\τ}\right)={\frac{1}{T}}^T\underset{0}{\∫}x\left(t\right)x(t+\mathrm{\τ})\mathrm{dt}=\frac{A^2}{2}\cos 2\mathrm{\πf\τ}---\left(7\right)$

When τ=0, can obtain:

$R_x\left(0\right)=\frac{A^2}{2}---\left(8\right)$

Therefore have:

$A=\sqrt{2R_x\left(0\right)}---\left(9\right)$

In like manner, can obtain,

$B=\sqrt{2R_y\left(0\right)}---\left(10\right)$

For the signal after the digitizing, corresponding discrete formula is:

$R_{\mathrm{xy}}\left(0\right)=\frac{1}{N}\underset{i=0}{\overset{N-1}{\mathrm{\Σ}}}x\left(i\right)y\left(i\right)---\left(11\right)$

$R_x\left(0\right)={\frac{1}{N}\underset{i=0}{\overset{N-1}{\mathrm{\Σ}}}x\left(i\right)}^2---\left(12\right)$

$R_y\left(0\right)={\frac{1}{N}\underset{i=0}{\overset{N-1}{\mathrm{\Σ}}}y\left(i\right)}^2---\left(13\right)$

Wherein, N is the sampling length of a frame.

More than measure

Value, scope is spent between 180 degree 0, spends between 180 degree for test specification being expanded to-180, also needs to judge

Positive and negative.

To y (t), x (t) carries out computing cross-correlation, has:

$R_{\mathrm{yx}}\left(\mathrm{\τ}\right)={\frac{1}{T}}^T\underset{0}{\∫}y\left(t\right)x(t+\mathrm{\τ})\mathrm{dt}---\left(15\right)$

For digitized signal, discrete formula is:

Both is poor

When m=1, can obtain:

Usually have

Therefore, if S (1)＞0, then

Symbol is for just;

Otherwise, if S (1)＜0, then

Symbol is for negative.

And then on the phase differential numerical value of (14) calculating gained, carry out the symbol correction, finally obtain

Its test specification-180 spend to 180 between.

Based on above-mentioned realization principle, Fig. 1 shows the structural representation of digital high precision phase detectors provided by the invention, these digital high precision phase detectors comprise analog-to-digital conversion module 10, filter module 20, phase difference calculating module 30, phase place correcting module 40 and phase detection result storage and display module 50, wherein:

Analog-to-digital conversion module 10 is used for the first measured signal a1 and the second measured signal a2 of input are carried out analog digital conversion, realizes digital collection to measured signal, first digital sample as a result b1 and second digital sample as a result b2 export to filter module 20;

Filter module 20, be used for to first digital sample of analog-to-digital conversion module 10 output as a result b1 and second digital sample as a result b2 carry out bandpass filtering, suppress harmonic interference, phase difference calculating module 30 and phase place correcting module 40 are exported in first filtering c1 and second filtering as a result c2 as a result;

C1 and second filtering as a result of phase difference calculating module 30, first filtering that is used for calculating filter module 20 output is the phase differential between the c2 as a result, adopts cross-correlation method to carry out phase difference calculating, and phase difference calculating d is as a result exported to phase place correcting module 40;

Phase place correcting module 40, first filtering that is used to judge filter module 20 outputs c1 and second filtering as a result is phase differential symbol positive and negative between the c2 as a result, then to the phase difference calculating of phase difference calculating module 30 output as a result d carry out the symbol correction, the phase detection result e that obtains, and phase detection result e is exported to phase detection result store and display module 50;

Phase detection result storage and display module 50 are used for the phase detection result e of phase place correcting module 40 outputs is carried out digitizing storage and demonstration.

Described analog-to-digital conversion module 10 comprises first signal condition 101, secondary signal conditioning 102, first high-speed AD sampling 103 and second high-speed AD sampling 104, wherein:

First signal condition 101 is used for the first measured signal a1 of input is carried out signal condition, makes its amplitude in first high-speed AD is sampled 103 desired scopes;

Secondary signal conditioning 102 is used for the second measured signal a2 of input is carried out signal condition, makes its amplitude in second high-speed AD is sampled 104 desired scopes;

First high-speed AD sampling 103 is used for digital collection is carried out in the output of first signal condition 101, finishes the analog digital conversion, and sampling process is carried out controlling of sampling by computing machine;

Second high-speed AD sampling 104 is used for digital collection is carried out in the output of secondary signal conditioning 102, finishes the analog digital conversion, and sampling process is carried out controlling of sampling by computing machine, and sampling rate and first high-speed AD sampling 103 keep synchronously.

Described filter module 20 comprises frequency detecting 201, first bandpass filter 202 and second bandpass filter 203, wherein:

Frequency detecting 201, first digital sample that is used to detect analog-to-digital conversion module 10 outputs is the frequency of b1 as a result, and export to first bandpass filter 202 and second bandpass filter 203, finish passband setting to first bandpass filter 202 and second bandpass filter 203;

First bandpass filter 202, be used for to first digital sample as a result b1 carry out bandpass filtering, filter bandwidht is controlled by frequency detecting 201 output results;

Second bandpass filter 203, be used for to second digital sample as a result b2 carry out bandpass filtering, filter bandwidht is controlled by frequency detecting 201 output results, the wave filter setting of second bandpass filter 203 is identical with 202 maintenances of first bandpass filter.

Described phase difference calculating module 30 comprises first cross-correlation calculation 301, first auto-correlation calculating, 302, second auto-correlation calculating, 303, first square root extractor 304, second square root extractor 305, multiplier 306, divider 307 and arc cosine calculating 308, wherein:

C1 and second filtering as a result of first cross-correlation calculation 301, first filtering that is used for calculating filter module 20 output is the cross correlation value between the c2 as a result, and result of calculation is exported to divider 307;

First auto-correlation is calculated 302 and second auto-correlation and is calculated 303 and be respectively applied for and calculate first filtering c1 and the second filtering as a result autocorrelation value of c2 as a result, and result of calculation is exported to first square root extractor 304 and second square root extractor 305 respectively;

First square root extractor 304 is used for the output result of first auto-correlation computation 302 is carried out extracting operation, and operation result is exported to multiplier 306;

Second square root extractor 305 is used for the output result of second auto-correlation computation 303 is carried out extracting operation, and operation result is exported to multiplier 306;

Multiplier 306 is used for the output result of first square root extractor 304 and second square root extractor 305 is carried out multiplication mutually, and operation result is exported to divider 307;

Divider 307 is used for the output result of first cross-correlation calculation 301 and multiplier 306 is carried out division operation mutually, and operation result is exported to arc cosine calculate 308;

Arc cosine calculates 308, is used for the output result of divider 307 is carried out arc cosine calculating.

Described phase place correcting module 40 comprises first shift unit 401, second shift unit 402, second cross-correlation calculation 403, the 3rd cross-correlation calculation 404, subtracter 405, symbol decision 406 and symbol correction 407, wherein:

First shift unit 401, be used for to first filtering as a result c1 to carry out length be 1 displacement;

Second shift unit 402, be used for to second filtering as a result c2 to carry out length be 1 displacement;

Second cross-correlation calculation 403 is used to calculate first filtering c1 and the second filtering as a result cross correlation value between the shift value of c2 as a result;

The 3rd cross-correlation calculation 404 is used to calculate second filtering c2 and the first filtering as a result cross correlation value between the shift value of c1 as a result;

Subtracter 405 is used for the output result of second cross-correlation calculation 403 and the 3rd cross-correlation calculation 404 is carried out additive operation;

Symbol decision 406, output result by subtracter 405, be used to judge first filtering c1 and second filtering as a result phase differential symbol positive and negative between the c2 as a result, if the output result of subtracter 405 is greater than zero, then first filtering c1 and second filtering as a result as a result between the c2 phase differential symbol for just, if the output result of subtracter 405 is less than zero, then first filtering c1 and second filtering as a result as a result between the c2 phase differential symbol for negative;

Symbol correction 407, be used for to the phase difference calculating of phase difference calculating module 30 output as a result d carry out the symbol correction.

The data collecting card USB-9215 that the embodiment of the invention adopts American National instrument company (NI) to produce has made up the digital high precision phase detectors in conjunction with software LabVIEW 8.5.USB-9215 is a 4 passage synchronous data collection cards, realizes the function of high-speed a/d sampling, and its precision is 16, and sampling rate is 100kS/s, and sampling is controlled by computing machine.Coding in LabVIEW8.5, the function of each module shown in realization Fig. 1.The same frequency sine-wave of two-way that utilizes phase difference signal generator generation phase differential and frequency to be provided with, input digit high precision phase detectors, the minimum phase differential that can be provided with of phase difference signal generator is 0.001 degree.

Test result shows: this digital high precision phase detectors index is as follows:

Phase resolution: 0.01 degree;

Measurement range :-180 spend to 180 degree;

Frequency range: from 1Hz to 50kHz;

These digital high precision phase detectors also have in the environment that can work in the harmonic wave environment and have noise, easy to operate, the characteristics being convenient to adjust.

Above-described specific embodiment; purpose of the present invention, technical scheme and beneficial effect are further described; institute is understood that; the above only is specific embodiments of the invention; be not limited to the present invention; within the spirit and principles in the present invention all, any modification of being made, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (5)

1. A digital high-precision phase detector, characterized in that, comprising: An analog-to-digital conversion module (10), configured to perform analog-to-digital conversion on the input first signal to be tested a1 and the second signal to be tested a2, to realize digital acquisition of the signal to be tested, and the first digital sampling result b1 and the second digital sampling The result b2 is output to the filter module (20); A filter module (20), configured to perform band-pass filtering on the first digital sampling result b1 and the second digital sampling result b2 output by the analog-to-digital conversion module (10) to suppress harmonic interference, the first filtering result c1 and the second The filtering result c2 is output to the phase difference calculation module (30) and the phase correction module (40); The phase difference calculation module (30) is used to calculate the phase difference between the first filtering result c1 and the second filtering result c2 output by the filter module (20), and the phase difference calculation is carried out by using the cross-correlation method, and the phase difference calculation result d is output to the phase correction module (40); The phase correction module (40) is used to judge whether the sign of the phase difference between the first filter result c1 and the second filter result c2 output by the filter module (20) is positive or negative, and then the phase difference output by the phase difference calculation module (30) Sign correction is carried out on difference calculation result d, obtained phase detection result e, and phase detection result e is output to phase detection result storage and display module (50); The phase detection result storage and display module (50) is used for digitally storing and displaying the phase detection result e output by the phase correction module (40). 2. digitization high precision phase detector according to claim 1, is characterized in that, wherein said analog-to-digital conversion module (10), comprises: The first signal conditioning (101) is used to perform signal conditioning on the input first signal to be tested a1, so that its amplitude is within the range required by the first high-speed AD sampling (103); The second signal conditioning (102), is used for carrying out signal conditioning to the second input signal a2 to be tested, so that its amplitude is within the required range of the second high-speed AD sampling (104); The first high-speed AD sampling (103) is used to digitally collect the output of the first signal conditioning (101), and complete the analog-to-digital conversion, and the sampling process is controlled by a computer; The second high-speed AD sampling (104), is used for digitally collecting the output of the second signal conditioning (102), and completes the analog-to-digital conversion. The sampling process is controlled by a computer, and the sampling rate is maintained with the first high-speed AD sampling (103). Synchronize. 3. digitization high precision phase detector according to claim 1, is characterized in that, wherein said filter module (20), comprises: Frequency detection (201), used to detect the frequency of the first digital sampling result b1 output by the analog-to-digital conversion module (10), and output to the first band-pass filter (202) and the second band-pass filter (203), Complete the passband setting to the first bandpass filter (202) and the second bandpass filter (203); The first band-pass filter (202), used for band-pass filtering the first digital sampling result b1, the filter bandwidth is controlled by the output result of the frequency detection (201); The second band-pass filter (203) is used to carry out band-pass filtering to the second digital sampling result b2, and the filter bandwidth is controlled by the output result of frequency detection (201), and the filter of the second band-pass filter (203) The settings remain the same as for the first bandpass filter (202). 4. The digital high-precision phase detector according to claim 1, wherein said phase difference calculation module (30) includes the first cross-correlation calculation (301), the first autocorrelation calculation (302), The second autocorrelation calculation (303), the first square root (304), the second square root (305), the multiplier (306), the divider (307) and the arccosine calculation (308), wherein: The first cross-correlation calculation (301) is used to calculate the cross-correlation value between the first filter result c1 output by the filter module (20) and the second filter result c2, and output the calculation result to the divider (307); The first autocorrelation calculation (302) and the second autocorrelation calculation (303) are used to calculate the autocorrelation values of the first filtering result c1 and the second filtering result c2 respectively, and output the calculation results to the first square extractor ( 304) and the second square extractor (305); The first square extractor (304), for carrying out the square root operation to the output result of the first autocorrelation operation (302), and output the operation result to the multiplier (306); The second square extraction device (305), is used for carrying out the square extraction operation to the output result of the second autocorrelation operation (303), and outputs the operation result to the multiplier (306); A multiplier (306), for multiplying the output results of the first square root (304) and the second square root (305), and outputting the result to the divider (307); The divider (307) is used to divide the output results of the first cross-correlation calculation (301) and the multiplier (306), and output the calculation result to the arccosine calculation (308); Inverse cosine calculation (308), used for performing an inverse cosine calculation on the output result of the divider (307). 5. digital high-precision phase detector according to claim 1, is characterized in that, wherein said phase correction module (40), comprises: A first shifter (401), configured to shift the first filtering result c1 with a length of 1; A second shifter (402), configured to shift the second filtering result c2 with a length of 1; The second cross-correlation calculation (403), used to calculate the cross-correlation value between the shift value of the first filtering result c1 and the second filtering result c2; The third cross-correlation calculation (404), for calculating the cross-correlation value between the shift value of the second filtering result c2 and the first filtering result c1; A subtractor (405), configured to subtract the output results of the second cross-correlation calculation (403) and the third cross-correlation calculation (404); Sign judgment (406), through the output result of the subtractor (405), is used for judging whether the sign of the phase difference between the first filter result c1 and the second filter result c2 is positive or negative, if the output result of the subtractor (405) is greater than zero , then the phase difference sign between the first filtering result c1 and the second filtering result c2 is positive, if the output result of the subtractor (405) is less than zero, then the phase difference sign between the first filtering result c1 and the second filtering result c2 is negative; sign correction (407), for performing sign correction on the phase difference calculation result d output by the phase difference calculation module (30).

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