CN103630706A - Method for acquiring radial direction water velocity in acoustic Doppler current profiler - Google Patents
Method for acquiring radial direction water velocity in acoustic Doppler current profiler Download PDFInfo
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- CN103630706A CN103630706A CN201310561947.5A CN201310561947A CN103630706A CN 103630706 A CN103630706 A CN 103630706A CN 201310561947 A CN201310561947 A CN 201310561947A CN 103630706 A CN103630706 A CN 103630706A
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Abstract
The invention relates to a method for acquiring radial direction water velocity in an acoustic Doppler current profiler. The acoustic Doppler current profiler adopts an acoustic wave transducer as a sensor, an emitted acoustic impulse generates a scatter echo through an irregular scatterer in a water body, the acoustic wave transducer receives the scatter echo, and the radial direction water velocity is acquired through analysis. The method is characterized by comprising the following steps: firstly, setting a search scope and a count of radial direction water velocity according to the direction and degree of urgency of water flow in measurement environment; and secondly, designing a matching signal corresponding to radial direction velocity of each search point, carrying out matched filtering operation on the matching signal corresponding to each radial direction velocity and an echo signal received by the acoustic wave transducer, and searching a matched filtering result, wherein the radial direction velocity corresponding to a maximum value of the matched filtering result is the radial direction velocity to be measured.
Description
Technical field
The present invention relates to a kind of method of obtaining radial water Flow Velocity in acoustic Doppler fluid velocity profile instrument (ADCP), belong to underwater sound signal field of measuring technique.
Background technology
Different from the current meter of rotary propeller type and electromagnetic type, acoustic Doppler fluid velocity profile instrument (Acoustic Doppler Current Profiler, ADCP) use acoustic wave transducer as sensor, the scatterers such as the sand grain of the sound pulse of its transmitting by uneven distribution in water body, planktonic organism produce scatter echo, by acoustic wave transducer, received, through Doppler frequency estimation, calculate radially flow velocity, the parallel water velocity part of acoustic wave beam of launching with acoustic wave transducer, then according to the angle calculation Water discharge flow speed degree between acoustic wave beam and water (flow) direction.ADCP can directly measure the fluid velocity profile of section, have not disturbance flow field, test last short, the features such as scope is large test the speed.
The accuracy that radially flow velocity is estimated directly has influence on the accuracy of water flow speed measurement result, therefore becomes one of gordian technique of ADCP.A lot of algorithms can be used for estimating Doppler frequency displacement, and then calculate radially flow velocity, and wherein major part is based on maximum likelihood (ML) method.The calculating of these algorithms is comparatively complicated, at present and be not suitable for the measurement requirement of ADCP fast and flexible.Reducing the conventional method of frequency domain estimator calculated amount is the estimation thought based on time domain phase place.Kay has provided phase difference estimator (the Steven Kay.A fast and accurate single frequency estimator at delay sampling interval, IEEE transactions on acoustics, speech and signal processing.1989, Vol37 (12): pp.1987-1990).Based on this; different postpone and the time domain frequency estimator of different weights in succession occur (M.P.Fitz. " Further results in the fast estimation of a single frequency; " IEEE Trans.Commun.; vol.42; no.2 – 4, Feb. – Apr.1994:pp.862-864; S.S.Abeysekera. " Performance of pulse-pair method of Doppler estimation, " IEEE Trans.Aerosp.Electron.Syst., vol.34, no.2, Apr.1998:pp.520-531).These estimators estimator than Kay in performance increases, but take limit frequency estimation range or to increase calculated amount be prerequisite.Brown and Wang (T.Brown, M.Wang.An iterative algorithm for singlefrequency estimation, IEEE Trans.Signal Process.50 (11) (2002): pp.2671-2682), bright (the Y.C.Xiao. of Xiao Yang, et al.Autocorrelation-based algorithm for single-frequency estimation, Signal Processing87 (2007): pp.1224 – 1233) provide respectively cycle frequency estimator separately, but also take, the raising of these frequency estimator performances increases computational complexity as cost.
The typical algorithm of other Frequency Estimation comprises zero passage detection method (V.A.Friendman, Zero crossing algorithm for the estimation of the frequency of a single sinusoid in white noise.IEEE Trans.On Signal Processing, 1994,43 (6): pp.1565-1569), adaptive method (D.G.Manolakis work, straight translating. statistics and Adaptive Signal Processing. Beijing: Electronic Industry Press .2003) etc.The operand of zero passage detection method is little and to realize logic simple; The narrow band frequency estimation that adaptive method can be realized high precision and regulate continuously.Above two kinds of algorithms all cannot be applied to the Doppler frequency estimation of wideband echoes.Complex autocorrelation technology (B.H.Brumley; R.G.Cabrera; K.L.Deines; and E.A.Terray. " Performance of a broad-band acoustic Doppler current profiler; " IEEE J.Oceanic Eng.; vol.16, Oct.1991:pp.402-407; B.H.Brumley, R.G.Cabrera, K.L.Deines, and E.A.Terray.broad-band acoustic Doppler current profiler, US Patent, NO.5615173.Mar, 1997; Zhu Hao, Liu Wenyao etc. application and the Implementation on Fixed Point DSP thereof of complex autocorrelation technology in acoustic Doppler fluid velocity profile instrument, war industry's journal, 2006,27 (3): pp.451-457) be applicable to the processing of broadband signal, be widely used in ADCP; On this basis, Liu Dezhu (Liu Dezhu. the research of acoustic Doppler fluid-velocity survey gordian technique. Harbin Engineering University, Doctor of engineering academic dissertation .2010) discussed three kinds of Doppler's flow measurement modes in detail: incoherent, relevant and wide band system, but its range of application is subject to the restriction of some conditions.
Because traditional ADCP carries out Doppler frequency estimation and then calculates radially flow velocity the scatter echo of irregular scattering body in water body, therefore the accuracy of detection under faint echo condition will directly affect the measurement performance of ADCP.Wish improves the detectability to feeble signal, obtains higher frequency resolution simultaneously, and the most direct method is to increase the length transmitting.To narrow band signal, the increase of the length that transmits will reduce its range capability, and the therefore normal broadband signal that adopts, as linear FM signal, phase-coded signal etc., transmits to improve distance accuracy as acoustic wave transducer.But while adopting conventional method to detect broadband signal, conventionally only for centre frequency or some Frequency points, process, the Doppler shift rule that does not reflect whole broader frequency spectrum, the broadband signal of usining in this case often can not be taken into account rate accuracy as transmitting.
Summary of the invention
The object of this invention is to provide a kind of radially method of flow velocity of obtaining in acoustic Doppler fluid velocity profile instrument (ADCP), the method is calculated radial water Flow Velocity without Doppler frequency estimation, and the technical scheme of employing is as follows:
A kind of method of obtaining radial water Flow Velocity in acoustic Doppler fluid velocity profile instrument, acoustic Doppler fluid velocity profile instrument adopts acoustic wave transducer as sensor, the sound pulse of its transmitting produces scatter echo by irregular scattering body in water body, after being received by acoustic wave transducer, process and obtain radial water Flow Velocity by analysis, it is characterized in that: first, direction and emergency situation according to current in measurement environment, set the hunting zone of radial water Flow Velocity and count, then the radially flow velocity of corresponding each search point designs matched signal, the correspondence echoed signal that respectively radially the matched signal of flow velocity and acoustic wave transducer receive is carried out to matched filtering operation, and matched filtering result is searched for, the corresponding radially flow velocity of maximal value of matched filtering result is the radially flow velocity of required measurement, comprise the following steps:
(1) set the radially hunting zone v of flow velocity
l～v
hwith search point N, pre-search each radially flow velocity be v
i=v
l+ i* (v
h-v
l)/(N-1), i=0,1 ..., N-1, wherein, the lower boundary v of flow velocity hunting zone radially
lwith coboundary v
hit is foundation that the radially flow velocity to be measured of take can not surpass this hunting zone, and radially to take required radially flow velocity measuring accuracy be foundation to the search point N of flow velocity, and N is larger, and radially flow velocity measuring accuracy is higher;
(2) transmitting of acoustic wave transducer being carried out to sample frequency is f
sc/ (c-2v
i) sampling, obtain corresponding to each flow velocity v radially
imatched signal h
i(n), f wherein
sfor the sample frequency of acoustic wave transducer reception signal, c is the velocity of sound in water;
(3) the echoed signal x (n) acoustic wave transducer being received and the matched signal h in (2)
i(n) carry out matched filtering operation, complete
by max (y
i) and v (m)
icorresponding one by one, result the maximum means between the echoed signal that this matched signal that radially flow velocity is corresponding receives with acoustic wave transducer and obtained completely and mated, and the corresponding radially flow velocity of this matched signal is radially flow velocity to be measured, i.e. max (the y of maximum
i(m)) corresponding v
ibe required radially flow velocity, wherein, max (y
i(m)) represent amount of orientation y
i(m) maximal value.
Advantage of the present invention and beneficial effect are: the present invention designs matched signal in the radially flow rates of pre-search, through matched filtering processing and the subsequent searches of the echoed signal with acoustic wave transducer reception, obtain radially flow velocity to be measured.Carry out Doppler frequency estimation with the scatter echo to irregular scattering body in water body of routine and then the radially method of flow velocity of calculating is compared, performing step of the present invention is simple, measurement result is accurate, be applicable to the measurement requirement of ADCP fast and flexible, especially for detection faint, wideband echoes signal, can take into account range finding, rate accuracy simultaneously.
Accompanying drawing explanation
Fig. 1 generates matched signal for improving sample frequency, realizes the schematic diagram mating completely with the echoed signal (frequency reduction) of acoustic wave transducer reception;
Fig. 2 generates matched signal for reducing sample frequency, realizes the schematic diagram mating completely with the echoed signal (frequency rising) of acoustic wave transducer reception;
Fig. 3 is the specific implementation process of the embodiment of the present invention;
Fig. 4 is the measurement result that the radially flow velocity of the embodiment of the present invention is 7.5m/s.
Embodiment
Below in conjunction with specific embodiment, further illustrate principle of the present invention and implementation process.Should understand this embodiment is only not used in and limits the scope of the invention for the present invention is described.
As shown in Figure 1, representative improves sample frequency and generates matched signal, thereby realizes mating completely between the echoed signal of matched signal and frequency reduction, i.e. matched filtering result reaches maximal value.Fig. 1 (a) is the waveform of s emission signal s (n), by scatterer in water body, produces scatter echo, by acoustic wave transducer, is received.Flow velocity v be radially on the occasion of in the situation that, Doppler shift
for negative value (f wherein
0the frequency that representative transmits), so the reduction of the frequency of echoed signal, waveform changes, as shown in Fig. 1 (b).Press f
sthe sample frequency of c/ (c-2v) is carried out resampling to s emission signal s (n), and as shown in Fig. 1 (c), the matched signal h of gained (n) can realize completely and mating (f wherein with echoed signal
ssample frequency for acoustic wave transducer reception signal), as shown in Fig. 1 (d), now matched filtering result obtains maximal value.
As shown in Figure 2, representative reduces sample frequency and generates matched signal, thereby realizes mating completely between the echoed signal of matched signal and frequency rising, i.e. matched filtering result reaches maximal value.Fig. 2 (a) is the waveform of s emission signal s (n), by scatterer in water body, produces scatter echo, by acoustic wave transducer, is received.In the situation that radially flow velocity v is negative value, Doppler shift
for on the occasion of, so the frequency of echoed signal raises, waveform changes, as shown in Fig. 2 (b).Press f
sthe sample frequency of c/ (c-2v) is carried out resampling to s emission signal s (n), as shown in Fig. 2 (c), the matched signal h of gained (n) can realize completely and mating with echoed signal, and as shown in Fig. 2 (d), now matched filtering result obtains maximal value.
Based on above principle, in measuring the process of flow velocity radially, first set the radially flow rates of pre-search and count, and designing corresponding matched signal; Matched filtering result to the echoed signal of each matched signal and acoustic wave transducer reception is searched for, result maximum means between the echoed signal that this matched signal and acoustic wave transducer receive and obtained completely and mated, and the corresponding radially flow velocity of this matched signal is radially flow velocity to be measured.Fig. 3 obtains the radially specific implementation process of flow velocity.
Fig. 4 is a specific embodiment according to Fig. 3.If radially flow velocity is 7.5m/s, velocity of sound c=1500m/s in water; Transmit as the linear FM signal of 18kHz～22kHz, pulsewidth is 0.001s; The sample frequency f of acoustic wave transducer
s=200kHz, the echoed signal x of its reception (n) is as shown in Fig. 4 (a).The concrete grammar of measuring flow velocity is radially as follows:
A) direction of current and emergency situation in measurement environment, setting radially flow velocity hunting zone is 0m/s～10m/s, to guarantee that radially flow velocity to be measured is included in this hunting zone; Setting search points N=21, radially flow velocity measuring accuracy is 0.5m/s, each of pre-search radially flow velocity is v
0=0m/s, v
1=0.5m/s ..., v
20=10m/s.Corresponding each v
i, to transmitting, carrying out sample frequency is f
sc/ (c-2v
i) sampling, obtain matched signal h
i(n), i=0 wherein, 1 ..., 20.
B) by each matched signal h
i(n) carry out matched filtering operation with the echoed signal x (n) of acoustic wave transducer reception
obtain altogether 20 groups of matched filtering results, Fig. 4 (b) is one of them matched signal h
20(n) the result y that the echoed signal x (n) receiving with acoustic wave transducer carries out matched filtering
20(m).
C) Fig. 4 (c) is each y
i(m) maximal value and v
iresult one to one.The maximal value of curve in figure, the corresponding 7.5m/s of round dot on curve, is measured radially flow velocity.
Claims (1)
1. a method of obtaining radial water Flow Velocity in acoustic Doppler fluid velocity profile instrument, acoustic Doppler fluid velocity profile instrument adopts acoustic wave transducer as sensor, the sound pulse of its transmitting produces scatter echo by irregular scattering body in water body, after being received by acoustic wave transducer, process and obtain radial water Flow Velocity by analysis, it is characterized in that: first, direction and emergency situation according to current in measurement environment, set the hunting zone of radial water Flow Velocity and count, then the radially flow velocity of corresponding each search point designs matched signal, the correspondence echoed signal that respectively radially the matched signal of flow velocity and acoustic wave transducer receive is carried out to matched filtering operation, and matched filtering result is searched for, the corresponding radially flow velocity of maximal value of matched filtering result is the radially flow velocity of required measurement, comprise the following steps:
(1) set the radially hunting zone v of flow velocity
l～v
hwith search point N, pre-search each radially flow velocity be v
i=v
l+ i* (v
h-v
l)/(N-1), i=0,1 ..., N-1, wherein, the lower boundary v of flow velocity hunting zone radially
lwith coboundary v
hit is foundation that the radially flow velocity to be measured of take can not surpass this hunting zone, and radially to take required radially flow velocity measuring accuracy be foundation to the search point N of flow velocity, and N is larger, and radially flow velocity measuring accuracy is higher;
(2) transmitting of acoustic wave transducer being carried out to sample frequency is f
sc/ (c-2v
i) sampling, obtain corresponding to each flow velocity v radially
imatched signal h
i(n), f wherein
sfor the sample frequency of acoustic wave transducer reception signal, c is the velocity of sound in water;
(3) the echoed signal x (n) acoustic wave transducer being received and the matched signal h in (2)
i(n) carry out matched filtering operation, complete
by max (y
i) and v (m)
icorresponding one by one, result the maximum means between the echoed signal that this matched signal that radially flow velocity is corresponding receives with acoustic wave transducer and obtained completely and mated, and the corresponding radially flow velocity of this matched signal is radially flow velocity to be measured, i.e. max (the y of maximum
i(m)) corresponding v
ibe required radially flow velocity, wherein, max (y
i(m)) represent amount of orientation y
i(m) maximal value.
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104502633A (en) * | 2014-12-29 | 2015-04-08 | 南京世海声学科技有限公司 | Flow field data correction method for acoustic Doppler flow velocity profiler |
| CN104502627A (en) * | 2014-12-29 | 2015-04-08 | 南京世海声学科技有限公司 | ADCP (acoustic Doppler current profiler) phase ambiguity solving method based on emission signal designing and processing |
| CN106124800A (en) * | 2016-07-25 | 2016-11-16 | 南京世海声学科技有限公司 | A kind of new ADCP moving average process of refinement method |
| CN108226911A (en) * | 2017-12-27 | 2018-06-29 | 南京世海声学科技有限公司 | A kind of ADCP tranmitting frequency optimum option methods with environmental suitability |
| CN110018323A (en) * | 2019-04-24 | 2019-07-16 | 杭州开闳流体科技有限公司 | A kind of flow field intelligence computation method and system based on acoustic Doppler measurement instrument |
| CN110763869A (en) * | 2019-10-12 | 2020-02-07 | 天健创新（北京）监测仪表股份有限公司 | Doppler current meter data processing method, system, medium and computer equipment |
| CN110824193A (en) * | 2019-11-11 | 2020-02-21 | 南京世海声学科技有限公司 | Non-uniform water velocity estimation method based on multi-beam radial flow velocity measurement |
| CN112986618A (en) * | 2021-05-12 | 2021-06-18 | 杭州开闳流体科技有限公司 | Broadband ADCP flow measurement method with large flow velocity measurement range |
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| CN101644716A (en) * | 2009-04-30 | 2010-02-10 | 中国科学院声学研究所 | Lowered acoustic Doppler current profiler with acoustic telemonitoring function |
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| CN104502627A (en) * | 2014-12-29 | 2015-04-08 | 南京世海声学科技有限公司 | ADCP (acoustic Doppler current profiler) phase ambiguity solving method based on emission signal designing and processing |
| CN104502633A (en) * | 2014-12-29 | 2015-04-08 | 南京世海声学科技有限公司 | Flow field data correction method for acoustic Doppler flow velocity profiler |
| CN104502633B (en) * | 2014-12-29 | 2018-04-13 | 南京世海声学科技有限公司 | A kind of flow field data correcting method for acoustic Doppler fluid velocity profile instrument |
| CN106124800B (en) * | 2016-07-25 | 2019-03-15 | 南京世海声学科技有限公司 | A kind of new ADCP sliding average process of refinement method |
| CN106124800A (en) * | 2016-07-25 | 2016-11-16 | 南京世海声学科技有限公司 | A kind of new ADCP moving average process of refinement method |
| CN108226911A (en) * | 2017-12-27 | 2018-06-29 | 南京世海声学科技有限公司 | A kind of ADCP tranmitting frequency optimum option methods with environmental suitability |
| CN108226911B (en) * | 2017-12-27 | 2021-09-28 | 南京世海声学科技有限公司 | ADCP (adaptive Doppler current profiler) transmitting frequency optimization selection method with environmental adaptability |
| CN110018323A (en) * | 2019-04-24 | 2019-07-16 | 杭州开闳流体科技有限公司 | A kind of flow field intelligence computation method and system based on acoustic Doppler measurement instrument |
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| CN110763869A (en) * | 2019-10-12 | 2020-02-07 | 天健创新（北京）监测仪表股份有限公司 | Doppler current meter data processing method, system, medium and computer equipment |
| CN110763869B (en) * | 2019-10-12 | 2021-09-28 | 天健创新（北京）监测仪表股份有限公司 | Doppler current meter data processing method, system, medium and computer equipment |
| CN110824193A (en) * | 2019-11-11 | 2020-02-21 | 南京世海声学科技有限公司 | Non-uniform water velocity estimation method based on multi-beam radial flow velocity measurement |
| CN112986618A (en) * | 2021-05-12 | 2021-06-18 | 杭州开闳流体科技有限公司 | Broadband ADCP flow measurement method with large flow velocity measurement range |
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Effective date of registration: 20160612 Address after: Jiangning District of Nanjing City, Jiangsu province Tong Road 211112 No. 101 000 401 Patentee after: NANJING SHIHAI ACOUSTIC TECHNOLOGY CO., LTD. Address before: 210018, room 8, building 28, 503 Portland Park, Xuanwu District, Jiangsu, Nanjing Patentee before: Fang Shiliang |