CN107870034A - A kind of underwater sound sonic velocity measurement method based on phase difference - Google Patents
A kind of underwater sound sonic velocity measurement method based on phase difference Download PDFInfo
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- CN107870034A CN107870034A CN201711000856.9A CN201711000856A CN107870034A CN 107870034 A CN107870034 A CN 107870034A CN 201711000856 A CN201711000856 A CN 201711000856A CN 107870034 A CN107870034 A CN 107870034A
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- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
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Abstract
It is synchronous respectively to pre-sampling transmission signal x by using two-way AD sampling modules the invention discloses a kind of underwater sound sonic velocity measurement method based on phase difference1And pre-sampling reception signal x (t)2(t) it is acquired, obtains two-way discrete sampling sequence x1And x (n)2(n), then two-way discrete sampling sequence x1And x (n)2(n) cross-spectrum processing and cross-correlation calculation are done, by the phase difference and complete cycle issue sum in the monocycle are resolved into the measurement in propagation time in distance d to acoustic signals, the measurement accuracy in the computational accuracy can acoustic signals propagation time of phase difference in the monocycle is thus improved；Advantage is to obtain the acoustic signals propagation time by accurately calculating phase difference and complete cycle issue of the acoustic signals within the monocycle, and on the basis of measurement in real time is ensured, measurement process is simple, and measurement accuracy is high, and cost is relatively low.
Description
Technical field
The present invention relates to a kind of underwater sound sonic velocity measurement method, more particularly, to a kind of underwater sound acoustic velocity measutement based on phase difference
Method.
Background technology
At present, conventional underwater sound sonic velocity measurement method mainly has two kinds of experience equation and the direct method of measurement.Empirical equation
After method is by the temperature in Measuring Oceanic environment, salinity and depth, the parameter obtained based on these measurements is calculated, and obtains water
Several speed.Although the precision that the empirical formula method measures to the velocity of sound is higher, in this method, to be first respectively adopted corresponding
Instrument go to obtain temperature, salinity and the depth in marine environment, then obtain from these instruments ability after these parameters again
Calculated, measurement process is complicated, obtains that the time of the velocity of sound is also longer, and hysteresis quality is obvious, it is impossible to obtains current sea in real time
The underwater sound velocity of sound in domain.
The direct method of measurement mainly utilizes sound wave propagation characteristic in the seawater, and acoustic signals are collected by analog-digital converter
After be delivered directly in processor, the propagation time of sound wave is calculated by processor, then the underwater sound velocity of sound is calculated.This method
Measurement process is simple, obtains that the time of the velocity of sound is shorter, and hysteresis quality can be ignored, and can obtain the underwater sound sound in current marine site in real time
Speed.But in this method, the digital measurement precision in propagation time directly constrains the precision of the velocity of sound.Although improve analog-to-digital conversion
The frequency acquisition of device can improve the measurement accuracy in propagation time in a way, but the higher analog-digital converter of frequency acquisition into
This is higher, and the frequency acquisition of the analog-digital converter under the present art is than relatively limited, therefore improves in this way
The measurement accuracy of the velocity of sound is than relatively limited.
The content of the invention
The technical problems to be solved by the invention are to provide a kind of on the basis of measurement in real time is ensured, measurement process letter
Single, measurement accuracy is high, and the lower-cost underwater sound sonic velocity measurement method based on phase difference.
Technical scheme is used by the present invention solves above-mentioned technical problem：A kind of underwater sound acoustic velocity measutement based on phase difference
Method, it is characterised in that comprise the following steps：
1. transmitting transducer and receive transducer interval are placed in tested seawater, by described transmitting transducer and described
Spacing between receive transducer is designated as d, wherein 10cm≤d≤20cm；
2. it is f using signal generator generation frequency0Sine wave signal, f0=1MHz, the sine wave signal is designated as se
(t), wherein t is the time domain time；
3. by power amplifier drive signal will be obtained after 4~8 times of the power amplification of the sine wave signal, this is driven
Signal is designated as s (t)；
4. the drive signal s (t) is decayed by attenuator circuit, attenuation multiple is 8~16, obtains pre-sampling transmitting
Signal, the pre-sampling transmission signal is designated as x1(t)；And using the described transmitting transducer of the drive signal s (t) drivings, institute
The transmitting transducer stated launches acoustic signals, and described receive transducer receives the acoustic signals and changes the acoustic signals
To receive electric signal, obtain pre-sampling by filtering process again after described reception electric signal first is amplified into 4-8 times and receive letter
Number, pre-sampling reception signal is designated as x2(t)；
5. using two-way AD sampling modules respectively to pre-sampling transmission signal x1And pre-sampling reception signal x (t)2(t) carry out
Collection, the sample frequency of two-way AD sampling modules is fs,20MHz≤fs≤ 80MHz, will be to pre-sampling transmission signal x1(t) carry out
Sample obtained discrete sampling sequence and be designated as x1(n), to pre-sampling reception signal x2(t) obtained discrete sampling sequence is sampled
Row are designated as x2(n), n is discrete series number, and n=0,1,2,3 ..., N-1, N is whole more than or equal to 2000 and less than or equal to 2500
Number；
6. by discrete sampling sequence x1(n) with discrete sampling sequence x2(n) cross-spectrum processing is carried out, detailed process is：
6. -1 by discrete sampling sequence x1(n) frequency spectrum is designated as X1(k), by discrete sampling sequence x2(n) frequency spectrum is designated as X2
(k), discrete sampling sequence x1And discrete sampling sequence x (n)2(n) cross-spectrum is designated as Y (k), and k is discrete sampling sequence x1(n) and
Discrete sampling sequence x2(n) sequence number of frequency domain, k=0,1,2,3 ..., N ' -1, wherein N ' are adopted to participate in the discrete of FFT computings
The points of sample sequence, N ' value is 128 or 256；
6. -2, which are respectively adopted FFT computings, is calculated discrete sampling sequence x1(n) frequency spectrum X1And discrete sampling sequence (k)
x2(n) frequency spectrum X2(k)；
6. -3 use formulaX is calculated1And x (n)2(n) cross-spectrum Y (k), wherein
For X1(k) conjugate complex number sequence, symbol * accord with for conjugate operation, symbol × accorded with for inner product operation；
7. cross-spectrum Y (k) is calculated in frequency f0The phase angle at placeDetailed process is：
7. -1 one intermediate parameters of setting, are designated as k0, using formula k0=[f0/fs(N'-1)] calculate in cross-spectrum Y (k)
Frequency f0Corresponding k0, symbol " [] " be rounding operation symbol, symbol/for division operation accord with；
7. -2 solve angle phi using arctan function0, i.e.,Im(Y(k0)) it is Y (k0)
Imaginary part, Re (Y (k0)) it is Y (k0) real part；
8. calculating the complete cycle issue M that acoustic signals are propagated, detailed process is：
8. -1 by discrete sampling sequence x1And discrete sampling sequence x (n)2(n) cross-correlation function is designated as R (r), and uses
FormulaCorresponding cross-correlation function value is calculated, L is more than or equal to 100 and is less than or equal to
200 integer, r=0,1,2,3 ..., N-L；
8. the maximum cross-correlation function of the cross-correlation function value being calculated in step 8. -1 is designated as R (q) by -2, q is big
In the integer equal to 0 and less than or equal to N-L；
8. -3 according to formula M=[qf0/fs] M is calculated, symbol " [] " accords with for rounding operation, symbol/it is division operation
Symbol；
9. acoustic signals are designated as T by distance d time, using formulaT is calculated；
10. the underwater sound velocity of sound is designated as into c, velocity of sound c is calculated using formula c=d/T.
Compared with prior art, it is the advantage of the invention is that synchronous respectively to pre-sampling by using two-way AD sampling modules
Transmission signal x1And pre-sampling reception signal x (t)2(t) it is acquired, obtains two-way discrete sampling sequence x1And x (n)2(n), so
Two-way discrete sampling sequence x afterwards1And x (n)2(n) cross-spectrum processing and cross-correlation calculation are done, acoustic signals will be propagated in distance d
Phase difference and complete cycle issue sum in the monocycle are resolved into the measurement of time, thus improve the calculating of the phase difference in the monocycle
The measurement accuracy in precision can acoustic signals propagation time, method of the invention is by accurately calculating acoustic signals in the monocycle
Interior phase difference and complete cycle issue obtains the acoustic signals propagation time, and on the basis of measurement in real time is ensured, measurement process is simple,
Measurement accuracy is high, and cost is relatively low.
Brief description of the drawings
Fig. 1 is that the method for the present invention measures the error curve of propagation time absolute error under different signal to noise ratio snr；
Fig. 2 is that the method for invention measures the error curve of velocity of sound absolute error under different signal to noise ratio snr.
Embodiment
The present invention is described in further detail below in conjunction with accompanying drawing embodiment.
Embodiment：A kind of underwater sound sonic velocity measurement method based on phase difference, comprises the following steps：
1. transmitting transducer and receive transducer interval are placed in tested seawater, by transmitting transducer and receive transducer it
Between spacing be designated as d, wherein 10cm≤d≤20cm；
2. it is f using signal generator generation frequency0Sine wave signal, f0=1MHz, the sine wave signal is designated as se
(t), wherein t is the time domain time；
3. by power amplifier drive signal will be obtained after 4~8 times of the power amplification of the sine wave signal, this is driven
Signal is designated as s (t)；
4. the drive signal s (t) is decayed by attenuator circuit, attenuation multiple is 8~16, obtains pre-sampling transmitting
Signal, the pre-sampling transmission signal is designated as x1(t)；And using the described transmitting transducer of the drive signal s (t) drivings, institute
The transmitting transducer stated launches acoustic signals, and described receive transducer receives the acoustic signals and changes the acoustic signals
To receive electric signal, obtain pre-sampling by filtering process again after described reception electric signal first is amplified into 4-8 times and receive letter
Number, pre-sampling reception signal is designated as x2(t)；
5. using two-way AD sampling modules respectively to pre-sampling transmission signal x1And pre-sampling reception signal x (t)2(t) carry out
Collection, the sample frequency of two-way AD sampling modules is fs,20MHz≤fs≤ 80MHz, will be to pre-sampling transmission signal x1(t) carry out
Sample obtained discrete sampling sequence and be designated as x1(n), to pre-sampling reception signal x2(t) obtained discrete sampling sequence is sampled
Row are designated as x2(n), n is discrete series number, and n=0,1,2,3 ..., N-1, N is whole more than or equal to 2000 and less than or equal to 2500
Number；
6. by discrete sampling sequence x1(n) with discrete sampling sequence x2(n) cross-spectrum processing is carried out, detailed process is：
6. -1 by discrete sampling sequence x1(n) frequency spectrum is designated as X1(k), by discrete sampling sequence x2(n) frequency spectrum is designated as X2
(k), discrete sampling sequence x1And discrete sampling sequence x (n)2(n) cross-spectrum is designated as Y (k), and k is discrete sampling sequence x1(n) and
Discrete sampling sequence x2(n) sequence number of frequency domain, k=0,1,2,3 ..., N ' -1, wherein N ' are adopted to participate in the discrete of FFT computings
The points of sample sequence, N ' value is 128 or 256；
6. -2, which are respectively adopted FFT computings, is calculated discrete sampling sequence x1(n) frequency spectrum X1And discrete sampling sequence (k)
x2(n) frequency spectrum X2(k)；
6. -3 use formulaX is calculated1And x (n)2(n) cross-spectrum Y (k), wherein
For X1(k) conjugate complex number sequence, symbol * accord with for conjugate operation, symbol × accorded with for inner product operation；
7. cross-spectrum Y (k) is calculated in frequency f0The phase angle at placeDetailed process is：
7. -1 one intermediate parameters of setting, are designated as k0, using formula k0=[f0/fs(N'-1)] calculate in cross-spectrum Y (k)
Frequency f0Corresponding k0, symbol " [] " be rounding operation symbol, symbol/for division operation accord with；
7. -2 solve angle phi using arctan function0, i.e.,Im(Y(k0)) it is Y (k0)
Imaginary part, Re (Y (k0)) it is Y (k0) real part；
8. calculating the complete cycle issue M that acoustic signals are propagated, detailed process is：
8. -1 by discrete sampling sequence x1And discrete sampling sequence x (n)2(n) cross-correlation function is designated as R (r), and uses
FormulaCorresponding cross-correlation function value is calculated, L is more than or equal to 100 and is less than or equal to
200 integer, r=0,1,2,3 ..., N-L；
8. the maximum cross-correlation function of the cross-correlation function value being calculated in step 8. -1 is designated as R (q) by -2, q is big
In the integer equal to 0 and less than or equal to N-L；
8. -3 according to formula M=[qf0/fs] M is calculated, symbol " [] " accords with for rounding operation, symbol/it is division operation
Symbol；
9. acoustic signals are designated as T by distance d time, using formulaT is calculated；
10. the underwater sound velocity of sound is designated as into c, velocity of sound c is calculated using formula c=d/T.
The method of the present invention is emulated in Matlab platforms, it is assumed that condition is that the velocity of sound is 1500 meter per seconds, is existed respectively
Signal to noise ratio snr is measured in 20dB, 30dB and 40dB using this method, measures the obtained absolute error in propagation time such as
Shown in Fig. 1, the absolute error of the velocity of sound for measuring to obtain is as shown in Figure 2.
Analysis chart 1 and Fig. 2 it is concluded that：With the raising of signal to noise ratio snr, measurement error is reduced substantially, and precision carries
It is high.When signal to noise ratio snr is 40dB, the measurement absolute error in propagation time is less than 0.674 × 10-9Second, i.e. 0.674 nanosecond；And
Corresponding acoustic velocity measutement absolute error is less than 0.012 meter per second.During actual measurement, the propagation distance of acoustical signal only have 10cm~
20cm, the signal to noise ratio snr of local environment>40dB is easily met, and is measured by the method for the present invention, can be obtained high accuracy
Acoustic velocity measutement.
Claims (1)
1. a kind of underwater sound sonic velocity measurement method based on phase difference, it is characterised in that comprise the following steps：
1. transmitting transducer and receive transducer interval are placed in tested seawater, by described transmitting transducer and described reception
Spacing between transducer is designated as d, wherein 10cm≤d≤20cm；
2. it is f using signal generator generation frequency0Sine wave signal, f0=1MHz, the sine wave signal is designated as se (t),
Wherein t is the time domain time；
3. drive signal will be obtained after 4~8 times of the power amplification of the sine wave signal by power amplifier, by the drive signal
It is designated as s (t)；
4. the drive signal s (t) is decayed by attenuator circuit, attenuation multiple is 8~16, obtains pre-sampling transmitting letter
Number, the pre-sampling transmission signal is designated as x1(t)；And using the described transmitting transducer of the drive signal s (t) drivings, it is described
Transmitting transducer launch acoustic signals, described receive transducer receives the acoustic signals and is converted to the acoustic signals
Electric signal is received, pre-sampling reception signal is obtained by filtering process again after described reception electric signal first is amplified into 4-8 times,
Pre-sampling reception signal is designated as x2(t)；
5. using two-way AD sampling modules respectively to pre-sampling transmission signal x1And pre-sampling reception signal x (t)2(t) adopted
Collection, the sample frequency of two-way AD sampling modules is fs,20MHz≤fs≤ 80MHz, will be to pre-sampling transmission signal x1(t) adopted
The discrete sampling sequence that sample obtains is designated as x1(n), to pre-sampling reception signal x2(t) obtained discrete sampling sequence is sampled
It is designated as x2(n), n is discrete series number, and n=0,1,2,3 ..., N-1, N is whole more than or equal to 2000 and less than or equal to 2500
Number；
6. by discrete sampling sequence x1(n) with discrete sampling sequence x2(n) cross-spectrum processing is carried out, detailed process is：
6. -1 by discrete sampling sequence x1(n) frequency spectrum is designated as X1(k), by discrete sampling sequence x2(n) frequency spectrum is designated as X2(k),
Discrete sampling sequence x1And discrete sampling sequence x (n)2(n) cross-spectrum is designated as Y (k), and k is discrete sampling sequence x1(n) it is and discrete
Sample sequence x2(n) sequence number of frequency domain, k=0,1,2,3 ..., N ' -1, wherein N ' they are the discrete sampling sequence for participating in FFT computings
The points of row, N ' value is 128 or 256；
6. -2, which are respectively adopted FFT computings, is calculated discrete sampling sequence x1(n) frequency spectrum X1And discrete sampling sequence x (k)2(n)
Frequency spectrum X2(k)；
6. -3 use formulaX is calculated1And x (n)2(n) cross-spectrum Y (k), whereinFor X1
(k) conjugate complex number sequence, symbol * accord with for conjugate operation, symbol × accorded with for inner product operation；
7. cross-spectrum Y (k) is calculated in frequency f0The phase angle at placeDetailed process is：
7. -1 one intermediate parameters of setting, are designated as k0, using formula k0=[f0/fs(N'-1) cross-spectrum Y (k) intermediate-frequeney point f] is calculated0
Corresponding k0, symbol " [] " be rounding operation symbol, symbol/for division operation accord with；
7. -2 solve angle phi using arctan function0, i.e.,Im(Y(k0)) it is Y (k0) void
Portion, Re (Y (k0)) it is Y (k0) real part；
8. calculating the complete cycle issue M that acoustic signals are propagated, detailed process is：
8. -1 by discrete sampling sequence x1And discrete sampling sequence x (n)2(n) cross-correlation function is designated as R (r), and uses formulaCorresponding cross-correlation function value is calculated, L is more than or equal to 100 and less than or equal to 200
Integer, r=0,1,2,3 ..., N-L；
8. the maximum cross-correlation function of the cross-correlation function value being calculated in step 8. -1 is designated as R (q) by -2, q be more than etc.
In 0 and less than or equal to N-L integer；
8. -3 according to formula M=[qf0/fs] M is calculated, symbol " [] " accords with for rounding operation, symbol/accorded with for division operation；
9. acoustic signals are designated as T by distance d time, using formulaT is calculated；
10. the underwater sound velocity of sound is designated as into c, velocity of sound c is calculated using formula c=d/T.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111352099A (en) * | 2018-12-20 | 2020-06-30 | 宁波大学科学技术学院 | Time delay estimation method based on cross-correlation signal phase decomposition |
| CN112067301A (en) * | 2020-09-10 | 2020-12-11 | 宁波大学科学技术学院 | S-shaped water turbine combination mode comprehensive performance test experimental device |
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| US20100315284A1 (en) * | 2009-09-02 | 2010-12-16 | Trizna Dennis B | Method and apparatus for coherent marine radar measurements of properties of ocean waves and currents |
| CN104634878A (en) * | 2014-12-16 | 2015-05-20 | 北京林业大学 | Wood damage monitoring method based on acoustic emission technique |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111352099A (en) * | 2018-12-20 | 2020-06-30 | 宁波大学科学技术学院 | Time delay estimation method based on cross-correlation signal phase decomposition |
| CN112067301A (en) * | 2020-09-10 | 2020-12-11 | 宁波大学科学技术学院 | S-shaped water turbine combination mode comprehensive performance test experimental device |
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