CN101907656A - Method for measuring phase difference of common-frequency signal with fixed phase drift - Google Patents
Method for measuring phase difference of common-frequency signal with fixed phase drift Download PDFInfo
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Abstract
The invention provides a method for measuring the phase difference of a common-frequency signal with fixed phase drift, which comprises the following steps of: respectively performing the same phase drift to two common-frequency original signals which only contain homogeneous harmonic component to obtain two time-delayed signals, wherein the common-frequency original signals are respectively to be a reference signal and a measurement signal; comparing the amplitude value of the two time-delayed signals after the same phase drift with the reference signal and the measurement signal, leading a pair of a positive threshold value and a negative threshold value at the front and the back of each intersection point to obtain two time points, and obtaining an intersection point time by taking the center of the two time points; repeating the step 2, obtaining one or a series of the time intersection point(s) within half-wave periods, and taking the middlemost intersection point time to be approximate to the peak time of the original signals in the half-wave periods; shaping the reference signal and the measurement signal to be two rectangular wave signals according to the peak time obtained in each half-wave period, and diversifying or operating the obtained two rectangular wave signals to obtain a pulse signal, wherein the width of the pulse signal is the time difference from the peak of the reference signal and the peak of the measurement signal; and converting the time difference to obtain the difference value of the phase position to be measured.
Description
Technical field
The invention belongs to the signal processing technology field, particularly a kind of method of utilizing the stationary phase in-migration to measure same-frequency signal phase difference.
Background technology
The phase difference measurement of same frequency periodic signal all has a wide range of applications in many fields such as signal analysis, parametric test circuit, electrotechnics, industrial automation, Based Intelligent Control, communication and electronic technology, as determining etc. of power-factor angle in the calculating at alternating circuit middle impedance angle, the electric energy metrical.
Measurement of Phase difference is more: the method for traditional dependence analog device, and as vector method, diode phase demodulation method, pulse counting method etc., the measuring system complexity needs dedicated devices, the hardware cost height; In recent years, computing machine and Digital Signal Processing make great progress, and phase difference measurement develops to the digitizing direction gradually, and the advantage of digitized measurement is that hardware cost is low, adaptability is strong, only need the algorithm of reprogramming for different measuring objects, and precision generally is better than analog measurement.
The phase differential digital measuring method can be divided into hardware method and software method two big classes by the realization approach.The hardware method is measured the cycle of two signals and the mistiming of initial phase by hardware circuit, to be transformed to phase differential the mistiming by software shows, need sample simultaneously to the instantaneous value of two same frequency constant amplitude sinusoidal signals, as vector method, multiplier method and various phase demodulation method.The software method is classified according to the mode of signal Processing, and can be divided into two big classes: a class is the time domain disposal route, and promptly all processing of signal all are to carry out in time domain, as sampling integral method and cross-correlation method; Another kind of is frequency domain technique, is about to signal transformation to frequency domain, according to the spectral characteristic of signal signal is handled then, as the DFT method.
The essence of time domain disposal route is that the phase differential of the sinusoidal signal of two same frequencys can characterize with the mistiming of their corresponding zero passage points, its great advantage is that signal processing method is simple, directly perceived, physical significance is obvious, is easy to realize with hardware, shortcoming is that efficient is low, the degree of accuracy of estimated value depends on the length of observed reading, only can estimate single sinusoidal signal.When signal was subjected to harmonic wave or noise, the phase difference measurement error of zero-crossing method will be very big; Method for measuring phase difference based on the digital correlation principle has good noise inhibiting ability, but this method requirement is strict integer-period sampled to the periodic signal implementation, and is difficult to the harmonic carcellation interference; Though based on the method for measuring phase difference energy harmonic carcellation or the interference of noise partly of adaptive bandpass filter and measured channel switching technology, it only is suitable for the measurement of low frequency signal phase differential.
Based on the frequency domain evaluation method of DFT, made full use of the improvement effect of DFT to signal to noise ratio (S/N ratio), overcome the have relatively high expectations shortcoming of signal to noise ratio (S/N ratio) of time domain approach, can suppress noise effectively, improve measuring accuracy.When signal is carried out the DFT processing, owing to only limited time-domain signal sample value handled, be signal function in time domain by rectangular function windowing brachymemma, FFT and analysis of spectrum also can only carry out in finite interval, and this just exists because time domain is blocked the energy leakage of generation inevitably, and spectrum peak is diminished, frequency and phase angle shift actual value, measuring accuracy reduces, and produces bigger secondary lobe component in frequency domain, is the leakage effect of DFT.Generally speaking, because Fourier transform is actually a kind of mapping relations of time-domain and frequency-domain, do not have the phase difference measurement error in theory, measuring error is mainly derived from truncation effect, the frequency departure between actual signal of signal time domain and is subjected to harmonic wave or interference of noise and the error that produces.The DFT method it is generally acknowledged and also need strict integer-period sampledly that otherwise its precision is influenced by spectrum leakage and fence effect.In addition, this method also is subject to harmonic interference.
Summary of the invention
The purpose of this invention is to provide a kind of method of utilizing the stationary phase in-migration to measure same-frequency signal phase difference, in order to overcome the deficiency of existing measuring method, measure on the basis of method of same-frequency signal phase difference at the stationary phase in-migration that utilizes that zero-crossing method and forefathers propose, proposes a kind of new mode in time domain processing measure phase difference problem.Adopt method of the present invention, can get rid of the defective that zero passage is disturbed, avoid being generally and reduce noise and introduce the delay time error that hysteresis comparator brings into and realize high-acruracy survey, and need not consider the influence of signal amplitude measuring.
Technical scheme of the present invention is:
The invention provides a kind of method of utilizing the stationary phase in-migration to measure the phase differential of homogenous frequency signal, comprising:
Step 1: with the original signal that only contains homogeneous harmonic component of two same frequencys, promptly reference signal is passed through identical phase shift respectively with measuring-signal, obtains two signals after the time-delay;
Step 2: will try to achieve two time points at a pair of positive negative threshold value of the forward and backward introducing of each intersection point through the signal after two time-delays of identical phase shift and reference signal and measuring-signal comparison amplitude, the center of getting two time points obtains the time of intersection point;
Step 3: repeating step 2, in a half wave cycles, try to achieve the one or a series of intersection point time, get the middle intersection point time to be approximately the summit time of original signal in this half wave cycles;
Step 4: according to the summit time that in each half wave cycles, obtains, reference signal and measuring-signal shaping are become two square-wave signals, two square-wave signals that will obtain are then done xor operation and are obtained pulse signal, and the width of this pulse signal is the mistiming on the summit of the summit of reference signal and measuring-signal;
Step 5: will convert the mistiming is tested phase difference value.
Signal after two time-delays and reference signal and measuring-signal amplitude relatively wherein, process at a pair of positive negative threshold value of the forward and backward introducing of each intersection point is: the positive negative threshold value of introducing occurs in pairs and absolute value equates, and positive negative threshold value alternately occurs according to the situation that detects intersection point, that is to say at current intersection point place and use positive threshold value earlier, negative threshold value is used in the back, then use negative threshold value earlier at next intersection point place, positive threshold value is used in the back;
Wherein try to achieve in the process of two time points, in a period of time before an intersection point, use positive threshold value to obtain a time point, in the process with the corresponding another one time point of negative threshold value detection the situation of positive threshold test to new time point appearred again then again, should be with the record before the new time point correction, vice versa.
When wherein in a half wave cycles, trying to achieve one or a series of intersection point, determine a half wave cycles, reference signal and measuring-signal and its time-delay signal are later carried out windowing by hysteresis comparator.
When wherein getting middle intersection point and being approximately the summit of original signal, be similar to the limit of original signal by the intersection point of original signal and its time delayed signal, original signal has the odd number limit in a half wave cycles, and the phase differential of two signals is asked on the summit of the corresponding original signal of a middle limit as reference quantity.
Wherein according to the summit time that in each half wave cycles, obtains, the process that reference signal and measuring-signal shaping is become square-wave signal is, reference signal and measuring-signal respectively with its time-delay after signal compare, in each half wave cycles, obtain a summit, obtain a series of summits in a period of time, reference signal and measuring-signal are shaped as square wave respectively, the time of each summit corresponding square wave level saltus step.
Advantage of the present invention
1, the method for the present invention's employing is to carry out the detection of phase differential according to the limit situation of signal in half wave cycles, because it is far away from zero point to contain the signal limit of homogeneous harmonic wave, conveniently utilize the hysteresis comparator windowing on the one hand, can avoid the influence of " ringing " of signal on the other hand.
2, the present invention has introduced a pair of positive negative threshold value when seeking each limit, and the time point that finds by positive negative threshold value is got the mode at center and avoided introducing the delay time error that hysteresis comparator is brought into because of reducing noise usually.Simultaneously, the present invention has kept the advantage of hysteresis comparator, has noise removal function.
3, usable range of the present invention is wider, and to detect error lower to having signal phase difference that high-order multifrequency sinusoid and amplitude successively decrease, experimental results show that the highest signal phase error that comprises 19 rank multifrequency sinusoids is not more than 0.01 degree.
Description of drawings
For further specifying technology contents of the present invention, below in conjunction with accompanying drawing and case study on implementation to the detailed description of the invention as after, wherein:
Fig. 1 is a method flow diagram of the present invention;
Fig. 2 seeks signal half-wave center principle schematic;
Fig. 3 is the phase difference measurement overall schematic.
Embodiment
See also Fig. 1, Fig. 2 and shown in Figure 3, a kind of method of utilizing the stationary phase in-migration to measure the phase differential of homogenous frequency signal of the present invention comprises:
Step 1 (S10): with the original signal that only contains homogeneous harmonic component of two same frequencys, promptly reference signal is passed through identical phase shift respectively with measuring-signal, obtains two signals after the time-delay.As shown in Figure 3, reference signal 301 and measuring-signal 302 at first all by the delay unit in the module shown in Figure 2 202, obtain the time delayed signal of original signal through two paths as two objects of phase difference measurement.The present invention is similar to the limit of original signal by the intersection point of original signal and its time delayed signal, so that delay time is difficult for is long.Should choose suitable delay time, easily exceed the sensitivity of circuit if delay time is too short, cause to detect or to miss limit; If delay time is long, make that on the one hand the error of the approximate limit of intersection point is bigger, owing to the factor of circuit hardware, the delay time error of introducing is bigger on the other hand.
Step 2 (S20): will try to achieve two time points at the positive negative threshold value of the forward and backward introducing of each intersection point through the signal after two time-delays of identical phase shift and reference signal and measuring-signal comparison amplitude, the center of getting two time points obtains the time of intersection point.
Shown in 202 modules among Fig. 2, when reference signal and measuring-signal are faint, behind the time-delay subtractor circuit, to introduce an amplifying circuit usually.The present invention tries to achieve two time points before and after each intersection point by two comparers 204 and 205 of different threshold values.The positive negative threshold value of introducing occurs in pairs and absolute value equates, positive negative threshold value alternately occurs according to the situation that detects intersection point, that is to say at current intersection point place and uses positive threshold value earlier, and negative threshold value is used in the back, then uses negative threshold value earlier at next intersection point place, and positive threshold value is used in the back.Among the present invention, whenever trying to achieve an intersection point after the time, system can send threshold value negate the function to realize claim 2 pair threshold value require of a threshold value negate signal with comparer 204 and 205.
Two registers 206 shown in Figure 2 and 207 are used for storing two time points that two comparers 204 and 205 are tried to achieve.Keep communication between the register 206 and 207, promptly there is interface circuit, in a period of time before an intersection point, use positive threshold value to obtain a time point, in the process with the corresponding another one time point of negative threshold value detection the situation of positive threshold test to new time point appearred again then again, should be with the record before the new time point correction, vice versa.The process purpose of this correction time point record is the situation that may occur flex point at original signal in the part: if the result before not revising, our last threshold test to time point right in preceding very little a period of time of original signal flex point according to threshold value, up to the another one flex point occurring, perhaps just can detect corresponding another one time point in the very little a period of time after the limit, this moment resulting intersection point time of centering is wrong.The present invention can correctly judge the difference of limit and flex point and cast out flex point automatically, seeks two time points by positive negative threshold value near intersection point and asks average method to avoid the delay time error that uses the hysteresis comparator denoising to introduce.Measurement result of the present invention is particularly remarkable than additive method when the measuring-signal crest is smoother.
The present invention utilizes 203 pairs of original signals of hysteresis comparator to carry out shaping becomes square wave, and the arrival of determining a half wave cycles with the edge of square-wave signal whether.Herein, hysteresis comparator 203 has been introduced delay time error, does not seek the half-wave summit but do not influence.The square wave edge signal of trying to achieve also is the initializing signal of comparer 204 and 205 threshold values simultaneously, makes that the present invention can self-starting.Clock counter 208 as shown in Figure 2 is used for identifying the time that each time point occurs, whenever a half wave cycles finishes and will zero clearing restart counting.
Step 3 (S30): repeating step 2, in a half wave cycles, try to achieve the one or a series of intersection point time, get the middle intersection point time to be approximately the summit time of original signal in this half wave cycles.According to the symmetry of odd harmonic signal, the signal that only contains homogeneous harmonic sine component must have the odd number limit in a half wave cycles, and the summit of the middle corresponding standard signal of a limit, and the present invention asks the phase differential of two signals as reference quantity.Two comparers 204 of two registers 206 shown in Figure 2 and 207 storages and 205 two time points of trying to achieve install 209 as shown in Figure 2, summation, and the center of getting obtains the intersection point time and is stored in register.Register in the device 209 will be stored the one or a series of intersection point time in a half wave cycles; Experimental results show that for the sinusoidal signal that contains 19 subharmonic when the threshold voltage of comparer 204 and 205 was got 0.3 volt, the interior number of hits that detects of half-wave was not more than 20, illustrate that the present invention also has the less advantage of hardware spending.The output signal of hysteresis comparator 203 time-delay back is as the output enable signal of device 211, simultaneously also as 209 reset signal; Guaranteed that on the one hand device 211 is in each half-wave output and only export a summit time, install 211 output vertexs install 209 records after the time all zero clearings of intersection point time on the other hand, make the register in the device 209 to read and write repeatedly, saved the hardware spending.
Step 4 (S40): according to the summit time that in each half wave cycles, obtains, reference signal and measuring-signal shaping are become two square-wave signals, two square-wave signals that will obtain are then done xor operation and are obtained pulse signal, and the width of this pulse signal is the mistiming on the summit of the summit of reference signal and measuring-signal.As shown in Figure 3, reference signal 301 is passed through circuit 303 shown in Figure 2 and 304 respectively with measuring-signal 302, in each half wave cycles, obtain a summit, obtain a series of summits in a period of time, according to this a series of summit time reference signal 301 and measuring-signal 302 are shaped as square wave respectively by device 305 and 306, the time of each summit time corresponding square wave level saltus step.Then, two square-wave signals after reference signal 301 and measuring-signal 302 shapings are carried out xor operation through installing 307, obtain the pulse signal that a series of pulsewidths equate.
Step 5 (S50): will convert the mistiming is tested phase difference value.The pulsewidth time that the present invention calculates the pulse signal that is obtained by step 4 by counter, just this pulsewidth time conversion can have been become phase differential with the time ratio of original signal half-wave experience.
The above is preferred embodiment of the present invention only, is not in order to limit the right of applying for a patent of the present invention; Simultaneously above description should be understood and be implemented for the special personage who knows the present technique field, so other does not break away from the equivalence of being finished under the disclosed spirit and change or modification, all should be included in the claim scope of the present invention.
Claims (6)
1. method of utilizing the stationary phase in-migration to measure the phase differential of homogenous frequency signal comprises:
Step 1: with the original signal that only contains homogeneous harmonic component of two same frequencys, promptly reference signal is passed through identical phase shift respectively with measuring-signal, obtains two signals after the time-delay;
Step 2: will try to achieve two time points at a pair of positive negative threshold value of the forward and backward introducing of each intersection point through the signal after two time-delays of identical phase shift and reference signal and measuring-signal comparison amplitude, the center of getting two time points obtains the time of intersection point;
Step 3: repeating step 2, in a half wave cycles, try to achieve the one or a series of intersection point time, get the middle intersection point time to be approximately the summit time of original signal in this half wave cycles;
Step 4: according to the summit time that in each half wave cycles, obtains, reference signal and measuring-signal shaping are become two square-wave signals, two square-wave signals that will obtain are then done xor operation and are obtained pulse signal, and the width of this pulse signal is the mistiming on the summit of the summit of reference signal and measuring-signal;
Step 5: will convert the mistiming is tested phase difference value.
2. the method for utilizing the stationary phase in-migration to measure the phase differential of homogenous frequency signal as claimed in claim 1, signal after two time-delays and reference signal and measuring-signal amplitude relatively wherein, process at a pair of positive negative threshold value of the forward and backward introducing of each intersection point is: the positive negative threshold value of introducing occurs in pairs and absolute value equates, and positive negative threshold value alternately occurs according to the situation that detects intersection point, that is to say at current intersection point place and use positive threshold value earlier, negative threshold value is used in the back, then use negative threshold value earlier at next intersection point place, positive threshold value is used in the back;
3. the method for utilizing the stationary phase in-migration to measure the phase differential of homogenous frequency signal as claimed in claim 1, wherein try to achieve in the process of two time points, in a period of time before an intersection point, use positive threshold value to obtain a time point, in the process with the corresponding another one time point of negative threshold value detection the situation of positive threshold test to new time point appearred again then again, should be with the record before the new time point correction, vice versa.
4. the method for utilizing the stationary phase in-migration to measure the phase differential of homogenous frequency signal as claimed in claim 1, when wherein in a half wave cycles, trying to achieve one or a series of intersection point, determine a half wave cycles, reference signal and measuring-signal are carried out windowing with its time-delay signal later by hysteresis comparator.
5. the method for utilizing the stationary phase in-migration to measure the phase differential of homogenous frequency signal as claimed in claim 1, when wherein getting middle intersection point and being approximately the summit of original signal, be similar to the limit of original signal by the intersection point of original signal and its time delayed signal, original signal has the odd number limit in a half wave cycles, and the phase differential of two signals is asked on the summit of the corresponding original signal of a middle limit as reference quantity.
6. the method for utilizing the stationary phase in-migration to measure the phase differential of homogenous frequency signal as claimed in claim 1, wherein according to the summit time that in each half wave cycles, obtains, the process that reference signal and measuring-signal shaping is become square-wave signal is, reference signal and measuring-signal respectively with its time-delay after signal compare, in each half wave cycles, obtain a summit, obtain a series of summits in a period of time, reference signal and measuring-signal are shaped as square wave respectively, the time of each summit corresponding square wave level saltus step.
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