CN102353515A - Method and system for acoustically monitoring neritic non-linear internal waves - Google Patents

Abstract

The invention relates to a method and a system for acoustically monitoring neritic non-linear internal waves. The method comprises the following steps: the acoustic transmission direction of an acoustic emission monitoring station and an acoustic reception monitoring station is made to be parallel or vertical to the transmission direction of the non-linear internal waves, wherein the acoustic emission monitoring station is 2-10 km away from the acoustic reception monitoring station; the acoustic emission monitoring station emits acoustic signals; the acoustic reception monitoring station receives the signals, carries out filtering, decoding and sampling on the signals, and stores sampled acoustic transmission data; and the playback of the moving speed or amplitude of the non-linear internal waves is finally carried out. The system comprises a singlechip which is respectively connected with an emission unit, a reception unit, a clock-synchronization unit and an upper computer, wherein the emission unit is provided with an emission transducer, the reception unit is connected with a hydrophone array which comprises 2-16 hydrophones through a multiplexer switch, and the emission unit comprises a signal generator which can emit pseudo-random signals, frequency-sweeping signals and chaotic signals. The method provided by the invention has the advantages of simple steps, convenience in implement, high efficiency for measuring, and reliable and accurate measuring result; and the system provided by the invention has the advantages of simple structure, low cost and convenience for use, thus the system has a wide application value.

Description

A kind of shallow sea nonlinear internal wave acoustic monitoring method and system

Technical field

The invention belongs to the ocean environment parameter monitoring technical field, particularly relate to a kind of shallow sea nonlinear internal wave acoustic monitoring method and system.

Prior art

Internal wave of ocean is to occur in the inner a kind of fluctuation of seawater with stable stratification density; It causes strong sea water mixing in communication process, to revenue and expenditure and equilibrium process, submarine topography landforms, the sea bed material of energy in the whole ocean transport, the marine eco-environment changes the crucial effect that plays.Monitoring shallow sea nonlinear internal wave is built significant to sail, ocean research, ocean development and marine battlefield surroundings.

Yin Neibo appears at ocean interior, adopts the method for meter ground roll to be difficult to it is effectively monitored.The method that ripple in the shallow sea is monitored generally adopts buoy observation chain or anchor system observation chain at present; For parameters such as wave-wave length, amplitude in measuring exactly; Must on the observation chain, place a plurality of temperature sensors or velocimeter, obtain interior wave parameter through temperature or the fluid velocity profile that measures.(application number: 200710187340.X) then adopt anchor is that wave datum was measured in the liftable raft was realized in the water to people's such as Wu Jing patent.Also can adopt acoustic Doppler fluid velocity profile appearance (Acoustic Doppler Current Profiler) in addition, through wave parameter in the fluid velocity profile information acquisition that records.Also has the reverse acoustic scattering intensity that records through analysis of high frequency broadband acoustics backscattering appearance, wave parameter information in also can obtaining.

Ripple must pass through the observation instrument position in above measuring method all required, and can only measure the interior wave parameter of the three unities, if measure the change in time and space information of wave parameter in certain sea area, then needed to lay a plurality of observation erect-positions in the observation sea area.Though adopt seasat remote sensing technology or radar can obtain interior in a big way interior ripple space time information; But the collateral information that shows on extra large surface through interior ripple obtains, therefore be difficult to the interior wave parameter that is present in ocean interior carry out comprehensively, monitoring exactly.

Employing conductivity-temperature-depth system (CTD), temperature chain, velocimeter and the acoustics doppler flow speed section plotter internal ripples of classic method such as (ADCP) carry out on a large scale, the continuous monitoring difficulty is bigger synchronously; Cost is higher; And employing satellite-borne synthetic aperture radar or shipborne radar; Can only observe because the surface modulation effect that interior ripple causes; Difficult to the ubiquitous interior ripple observation in depths; Observing frequency is low, can't carry out Continuous Observation, and accuracy of observation receives the restriction of sea state.

The content of invention

The objective of the invention is to propose a kind of shallow sea nonlinear internal wave acoustic monitoring method and system, to overcome the above-mentioned deficiency of prior art.

Technical conceive of the present invention is following: at interior ripple---the sea area, shallow sea of nonlinear internal wave frequent activities especially; Adopt acoustic means; Promptly receive signal through the be separated by acoustics erect-position of certain level distance of analysis; Obtain large-scale ocean environment parameter in real time; Utilize the substantial connection between acoustic propagation fluctuating characteristic and interior wave characteristic in the spring layer; Ripple features relevant parameter in obtaining is like nonlinear internal wave translational speed or nonlinear internal wave amplitude.

To achieve these goals, the technical scheme taked of the present invention is following:

A kind of shallow sea nonlinear internal wave acoustic monitoring method comprises according to existing ocean environment parameter observational data and confirms the observation nonlinear internal wave direction of propagation, sea area; It is characterized in that further comprising the steps of:

(1) select acoustic emission monitor(ing) station and position, sound reception monitoring station, make the acoustic propagation direction parallel, and acoustic emission monitor(ing) station and sound reception are monitored distance between sites and be set to the 2-10 kilometer with the nonlinear internal wave direction of propagation;

(2) confirm to transmit the coding and frequency parameter;

(3) through the determined signal of above-mentioned acoustic emission monitor(ing) station step of transmitting (2), through a plurality of these signals of nautical receiving sets reception of sound reception monitoring station;

(4) acoustical signal that above-mentioned each nautical receiving set is received is carried out filtering, decoding and sampling, and the acoustic propagation data storage after will sampling;

(5) carry out the inverting of nonlinear internal wave translational speed:

Acoustic propagation The data normal mode filter method to after the sampling is handled, and obtains the time of arrival and the amplitude of each rank normal mode of place, sound reception monitor spots;

To each rank normal mode amplitude of gained, utilize the short-term spectrum analytical approach then, obtain spectrum peak frequency; Utilize the spectrum peak frequency of this acquisition again, inverting nonlinear internal wave translational speed u.

Above-mentioned steps (5) has been utilized normal mode filter method and short-term spectrum analytical approach, and this is owing to when having nonlinear internal wave between acoustic emission detection station and the sound reception measuring station, according to the normal mode coupled wave theory, receive sound field and can be expressed as each number normal mode sum:

$p(r,z)=\underset{m}{\mathrm{\Σ}}{\mathrm{\Ψ}}_m(z_s,r_N)e^{{\mathrm{ik}}_m(r-r_N)}\underset{n}{\mathrm{\Σ}}{P}_{\mathrm{mn}}{\left(k_{n}r\right)}^{-1/2}{a}_n{\mathrm{\Ψ}}_n\left(z_s\right)e^{{\mathrm{ik}}_{n}r}---\left(1\right)$

M rank normal wave amplitude is during moment t:

$A_m\left(t\right)=\exp ({\mathrm{ik}}_m^1(r-r_N)\underset{n}{\mathrm{\&Sigma;}}{P}_{\mathrm{mn}}{\left(k_n^{0}r\right)}^{-1/2}{a}_n{\mathrm{\&Psi;}}_n\left(z_s\right)\exp \left(i(k_n^0{\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="HDA0000070109130000031.png,HDA0000070109130000032.png"\; state="\{\{state\}\}">r</figure-callout>}}_1+{\mathrm{\&omega;}}_{\mathrm{mn}}t)\right)---\left(2\right)$

${\mathrm{\&omega;}}_{\mathrm{mn}}=(k_m^1-k_n^0)u---\left(3\right)$

Wherein

With

Be respectively the normal mode wave number of reception place and emission place, P _MnBe the normal mode coupling coefficient matrix of whole sound field waveguide, a _nΨ _n(z _s) be the excitation intensity of emission sound source place n rank normal mode, u is the translational speed of nonlinear internal wave, ω _MnBe spectrum peak frequency.

Therefore can be through each normal mode amplitude A to having got _m(t), utilize the short-term spectrum analytical approach to obtain spectrum peak frequency; Utilize the spectrum peak frequency of this acquisition to calculate nonlinear internal wave translational speed u again according to above-mentioned formula (3).

A kind of shallow sea nonlinear internal wave acoustic monitoring method comprises according to existing ocean environment parameter observational data and confirms the observation nonlinear internal wave direction of propagation, sea area; It is characterized in that further comprising the steps of:

(1) select acoustic emission monitor(ing) station and position, sound reception monitoring station, make the acoustic propagation direction vertical, and acoustic emission monitor(ing) station and sound reception are monitored distance between sites and be set to the 2-10 kilometer with the nonlinear internal wave direction of propagation;

(2) according to acoustic emission monitor(ing) station and the sound reception monitoring station spacing and the seawater depth of water, confirm to transmit coding and frequency parameter;

(3) through the determined signal of above-mentioned acoustic emission monitor(ing) station step of transmitting (2), through a plurality of these signals of nautical receiving sets reception of sound reception monitoring station;

(4) acoustical signal that above-mentioned each nautical receiving set is received is carried out filtering, decoding and sampling, and the acoustic propagation data storage after will sampling;

(5) carry out the inverting of nonlinear internal wave amplitude:

Acoustic propagation The data normal mode filter method to after the sampling is handled, and obtains the time of arrival and the amplitude of each rank normal mode of place, sound reception monitor spots;

Adopt the empirical orthogonal method then, obtain the corresponding intrinsic mode of observation sea area velocity of sound disturbance, utilize each rank normal mode of gained time of arrival again, calculate the time parameter of above-mentioned intrinsic mode, and then obtain velocity of sound disturbance, obtain the nonlinear internal wave amplitude at last.

Above-mentioned steps (5) has been utilized normal mode filter method and empirical orthogonal method, and this is because the existence of nonlinear internal wave can cause the disturbance of the velocity of sound, and this moment, the velocity of sound was expressed as

c(z)＝c ₀(z)+Δc(z) (4)

C wherein ₀(z) be the average section of the observation area velocity of sound, be time average.

According to historical observation data, utilize Empirical Orthogonal Function to obtain the corresponding intrinsic mode φ of observation sea area velocity of sound disturbance _l(z), then in the velocity of sound disturbance that causes of ripple:

$\mathrm{\&Delta;c}(z,t)=\underset{l=1}{\overset{N}{\mathrm{\&Sigma;}}}{b}_l\left(t\right){\mathrm{\&phi;}}_l\left(z\right)---\left(5\right)$

According to perturbation theory, the variation of normal mode wave number can be expressed as:

${\mathrm{\&Delta;k}}_m\left(t\right)=-\frac{{\mathrm{\&omega;}}^2}{k_m}\underset{l=1}{\overset{N}{\mathrm{\&Sigma;}}}{b}_l\left(t\right)\underset{0}{\overset{\&infin;}{\&Integral;}}\frac{{\mathrm{\&phi;}}_l\left(z\right){\mathrm{\&Psi;}}_m^2\left(z\right)\mathrm{dz}}{\mathrm{\&rho;}\left(z\right)c^3\left(z\right)}---\left(6\right)$

And $\frac{1}{V_n^g\left(t\right)}-\frac{1}{V_n^g\left(t_0\right)}\&ap;{\mathrm{\&Delta;k}}_m\left(t\right)\{\frac{2}{\mathrm{\&omega;}}-\frac{1}{k_n^0}\frac{1}{V_n^g\left(t_0\right)}\}---\left(7\right)$

Through acquired each number normal mode time of arrival, obtain the wave number changes delta k of normal mode by formula (7) _m(t), calculate the acquisition parameter b by formula (6) _l(t), further can obtain by the caused velocity of sound disturbance of interior ripple Δ c (z), thereby the velocity of sound profile information when being obtained nonlinear internal wave and existed by formula (4) obtains nonlinear internal wave amplitude (from the c (z) that obtains at last, directly obtaining) at last by formula (5).

Above-mentioned acoustic emission monitor(ing) station and sound reception monitoring station are that the mode of boat-carrying, buoy or anchor system is fixed in the seawater.

Above-mentioned confirm to transmit coding and frequency parameter are to select emission pseudo random signal, swept-frequency signal or chaotic signal and order or frequency.

A kind of shallow sea nonlinear internal wave acoustic monitoring system; Comprise the single-chip microcomputer that has the clock reference module that is connected with host computer and clock synchronization unit; The receiving element that links to each other with the clock synchronization unit with single-chip microcomputer, the transmitter unit that includes signal generator that links to each other with transmitting transducer mutually with single-chip microcomputer; And be the power supply unit of single-chip microcomputer and transmitter unit power supply, it is characterized in that above-mentioned receiving element also is provided with multiplexer switch, and connect a hydrophone array that comprises 2～16 nautical receiving sets through this multiplexer switch; Three kinds of signals of above-mentioned signal generator emission are respectively pseudo random signal, swept-frequency signal and chaotic signal.

Above-mentioned receiving element comprises multiplexer switch, bandpass filter, amplifier, signal correction detuner and the A/D converter that is connected with hydrophone array successively, and is connected with single-chip microcomputer via this A/D converter.

Above-mentioned transmitter unit comprises interior by monolithic processor controlled signal generator, and wideband power amplifer and the impedance matching box launched through transmitting transducer after the signal amplification with signal generator again.

Above-mentioned clock synchronization unit comprises the timing loop that links to each other with single-chip microcomputer and clock reference module thereof, the gps receiver that has gps antenna that links to each other with timing loop with single-chip microcomputer.

Step of the present invention is simple, enforcement is convenient, efficiency of measurement is high, monitoring result is reliably accurate; Monitoring system of the present invention has advantage simple in structure, with low cost, easy to use.

Shallow sea of the present invention nonlinear internal wave acoustic monitoring system; Through between two monitor spots, transmitting and receiving sound wave; Adopt broadband sound source; Launching code sequence modulation signal; Obtain accurate acoustic propagation data; And based on the shallow sea normal mode theory; Obtain marine environment information through receiving the nonlinear internal wave parameter of acoustical signal characteristic inverting campaign between two erect-positions along the acoustic propagation path; Translational speed, amplitude information that can the inverting nonlinear internal wave; And can be through monitoring in real time, regulating system controlled variable as required at any time.Compare with existing interior wave measurement method, can carry out long-time remote measurement to nonlinear internal wave, and need between two erect-positions, not increase recording geometry, thereby adopt less erect-position to monitor the interior wave parameter that ocean interior exists without monitor spots.System signal coding, transmission frequency, sampling interval all can be adjusted according to actual observation sea area situation.Observation data can be a self-tolerant, also can transmit through cable.Compare with classic method, efficiency of measurement is high, and it is convenient to implement, and it is less influenced by shipping and the activity of fishing at shallow sea area, has at aspects such as ocean research, ocean development and marine making full preparations in the battlefields extensively and significant using value.

Description of drawings

Fig. 1 is the general structure synoptic diagram of monitoring system of the present invention.

Fig. 2 is the flow process exemplary flow of monitoring method of the present invention.

Fig. 3 is the synoptic diagram (the acoustic propagation direction is parallel with the nonlinear internal wave direction of propagation) of inverting nonlinear internal wave translational speed.

Fig. 4 is the synoptic diagram (the acoustic propagation direction is vertical with the nonlinear internal wave direction of propagation) of inverting nonlinear internal wave amplitude.

Wherein, 1, transmitting transducer, 2, transmitter unit, 3, hydrophone array; 4, receiving element, 5, the clock synchronization unit, 6, single-chip microcomputer, 21, signal generator; 22, wideband power amplifer, 23, impedance matching box, 41, multiplexer switch; 42, bandpass filter, 43, amplifier, 44, the signal correction detuner; 45, A/D converter, 51, gps antenna, 52, gps receiver; 53, timing loop, 61, storer, 62, the clock reference module.

Embodiment

A kind of shallow sea nonlinear internal wave acoustic monitoring method comprises according to existing ocean environment parameter observational data and confirms the observation nonlinear internal wave direction of propagation, sea area; It is characterized in that further comprising the steps of:

(1) select acoustic emission monitor(ing) station and position, sound reception monitoring station, as shown in Figure 3, make the acoustic propagation direction parallel, and acoustic emission monitor(ing) station and sound reception are monitored distance between sites and be set to the 2-10 kilometer with the nonlinear internal wave direction of propagation;

(2) confirm to transmit the coding and frequency parameter;

(3) through the determined signal of above-mentioned acoustic emission monitor(ing) station step of transmitting (2), through a plurality of these signals of nautical receiving sets reception of sound reception monitoring station;

(4) acoustical signal that above-mentioned each nautical receiving set is received is carried out filtering, decoding and sampling, and the acoustic propagation data storage after will sampling;

(5) carry out the inverting of nonlinear internal wave translational speed:

Acoustic propagation The data normal mode filter method to after the sampling is handled, and obtains the time of arrival and the amplitude of each rank normal mode of place, sound reception monitor spots;

To each rank normal mode amplitude of gained, utilize the short-term spectrum analytical approach then, obtain spectrum peak frequency; Utilize the spectrum peak frequency of this acquisition again, inverting nonlinear internal wave translational speed u.

A kind of shallow sea nonlinear internal wave acoustic monitoring method comprises according to existing ocean environment parameter observational data and confirms the observation nonlinear internal wave direction of propagation, sea area; It is characterized in that further comprising the steps of:

(1) select acoustic emission monitor(ing) station and position, sound reception monitoring station, make the acoustic propagation direction vertical, and acoustic emission monitor(ing) station and sound reception are monitored distance between sites and be set to the 2-10 kilometer with the nonlinear internal wave direction of propagation;

(2) according to acoustic emission monitor(ing) station and the sound reception monitoring station spacing and the seawater depth of water, confirm to transmit coding and frequency parameter;

(3) through the determined signal of above-mentioned acoustic emission monitor(ing) station step of transmitting (2), through a plurality of these signals of nautical receiving sets reception of sound reception monitoring station;

(4) acoustical signal that above-mentioned each nautical receiving set is received is carried out filtering, decoding and sampling, and the acoustic propagation data storage after will sampling;

(5) carry out the inverting of nonlinear internal wave amplitude:

Acoustic propagation The data normal mode filter method to after the sampling is handled, and obtains the time of arrival and the amplitude of each rank normal mode of place, sound reception monitor spots;

Adopt the empirical orthogonal method then, obtain the corresponding intrinsic mode of observation sea area velocity of sound disturbance, utilize each rank normal mode of gained time of arrival again, calculate the time parameter of above-mentioned intrinsic mode, and then obtain velocity of sound disturbance, obtain the nonlinear internal wave amplitude at last.

As shown in Figure 1; Shallow sea of the present invention nonlinear internal wave acoustic monitoring system; Comprise the single-chip microcomputer that has clock reference module 62 6 that is connected with host computer 7 and clock synchronization unit 5; The receiving element 4 that links to each other with clock synchronization unit 5 with single-chip microcomputer 6 links to each other with single-chip microcomputer 6 and has the transmitter unit that includes signal generator 21 2 of transmitting transducer 1; And be the power supply unit 8 of single-chip microcomputer 6 and transmitter unit 2 power supplies, it is characterized in that above-mentioned receiving element 4 also is provided with multiplexer switch 41, and connect a hydrophone array 3 that comprises 2～16 nautical receiving sets through this multiplexer switch 41; Three kinds of signals of above-mentioned signal generator 21 emissions are respectively pseudo random signal, swept-frequency signal and chaotic signal.

As shown in Figure 1, above-mentioned receiving element 4 comprises multiplexer switch 41, bandpass filter 42, amplifier 43, signal correction detuner 44 and the A/D converter 45 that is connected with hydrophone array 3 successively, and is connected with single-chip microcomputer 6 via this A/D converter 45.The multiplexer switch 41 of receiving element 4 passes through bandpass filter 42, amplifier 43 and signal correction detuner 44 in proper order with each nautical receiving set in the receiving hydrophone battle array 3; Signal is carried out filtering, amplification, demodulation process; Link to each other with A/D converter 45 again, import single-chip microcomputer 6 at last.

As shown in Figure 1, the signal generator of controlling by single-chip microcomputer 6 in above-mentioned transmitter unit 2 comprises 21, and the wideband power amplifer 22 and impedance matching box 23 launched through transmitting transducer 1 again after the signal amplification with signal generator 21.The signal generator 21 of transmitter unit 2 can be chosen the signal of different coding as required; Like pseudorandomcode signal, swept-frequency signal or chaotic signal; The order of signal or optional frequency are selected this area order or frequency commonly used; Behind this signal process wideband power amplifer 22, the impedance matching box 23, through transmitting transducer 1 emission.

As shown in Figure 1, above-mentioned clock synchronization unit 5 comprises the timing loop 53 that links to each other with single-chip microcomputer 6 and clock reference module 62 thereof, the gps receiver that has gps antenna 51 52 that links to each other with timing loop 53 with single-chip microcomputer 6.Clock synchronization unit 5 provides the precise time signal for system, and the clock reference module 62 of single-chip microcomputer 6 is carried out clock alignment, for A/D converter 45 and signal correction detuner 44 clock signal is provided through timing loop 53 again.

As shown in Figure 1, single-chip microcomputer 6 obtains the clock signal that provides for total system through gps receiver 52, controls in real time in that system is in service, and can accomplish systematic parameter modification, data storage and data transmission; The signal that receives from receiving element 4 for the ease of storage, but this single-chip microcomputer 6 self-contained storing devices 61 also.

As shown in Figure 1, host computer 7 is connected with interior single-chip microcomputer 6 through cable, can monitor in real time, parameter modification and data transmission; Power supply unit 8 is respectively single-chip microcomputer 6 and with transmitter unit 2 energy is provided.

For the ease of producing, safeguard and use, shallow sea of the present invention nonlinear internal wave acoustic monitoring system is for can making full use of the design of prior art, so its each parts all can adopt existing equipment.

Nonlinear internal wave acoustic monitoring system work process in shallow sea of the present invention is following:

According to existing ocean environment parameter observational data; Confirm the observation nonlinear internal wave direction of propagation, sea area; Select the acoustic emission monitor(ing) station and receive the position, monitoring station, make the acoustic propagation direction parallel or vertical with the nonlinear internal wave direction of propagation, emission and receiving station's column pitch are from being set to the 2-10 kilometer; Utilize method of the present invention that nonlinear internal wave translational speed or amplitude are monitored, execution in step as shown in Figure 2,

Step 901 is beginning steps, and through host computer 7 and single-chip microcomputer 6, whether the check system duty is normal;

In the step 902, select the transmit coded signals parameter, can select to launch pseudo random signal, swept-frequency signal or chaotic signal and order or frequency, and storage format;

In the step 903, system initialization; Judge whether to receive gps signal, whether the clock synchronization unit is in proper working order;

In the step 904 and 905, a shallow sea nonlinear internal wave acoustic monitoring system emission predictive encoding signal, another shallow sea nonlinear internal wave acoustic monitoring system receives signal;

In the step 906, the receiving element 4 of being responsible for the monitoring system of reception signal carries out filtering, decoding and sampling to the acoustical signal that each nautical receiving set receives;

In the step 907, the acoustic propagation data that obtain in the storing step 906 are beneficial to follow-up inversion procedure;

In the step 908, judge whether observation process finishes,, get into step 910, carry out non-linear inner translational speed or amplitude inverting through the acoustic propagation data of having stored in host computer 7 obtaining steps 907 that link to each other with single-chip microcomputer 6 if finish; If observation does not finish, judge whether to carry out inversion procedure in step 909, if; Through the acoustic propagation data of having stored in host computer 7 obtaining steps 907 that link to each other with single-chip microcomputer 6; Carry out non-linear inner translational speed or amplitude inverting, if not, step 904 then returned;

In the step 910, the acoustic propagation The data normal mode filter method that extracts is handled, obtained to receive the time of arrival and the amplitude of erect-position each number of place normal mode;

Step 911 is monitoring of nonlinear internal wave translational speed and inversion step, to each number of step 910 gained normal mode amplitude A _m(t), utilize the short-term spectrum analytical approach, the spectrum peak frequency of acquisition is utilized the spectrum peak frequency of this acquisition, employing formula (3) inverting nonlinear internal wave translational speed u again;

In step 912, this inversion result is carried out diagrammatic representation or storage at last.

Step 913 is non-linear interior wave-amplitude monitoring and inversion step, adopts the empirical orthogonal method, obtains the intrinsic mode φ of observation sea area velocity of sound disturbance correspondence _l(z), utilize each number of step 910 gained normal mode amplitude time of arrival again, according to formula (6) calculating parameter b _l(t), and then according to the disturbance of formula (3) the acquisition velocity of sound, and then obtain the nonlinear internal wave amplitude.

In step 914, inversion result is carried out diagrammatic representation or storage at last.

Claims (9)

1. a shallow sea nonlinear internal wave acoustic monitoring method comprises according to existing ocean environment parameter observational data and confirms the observation nonlinear internal wave direction of propagation, sea area; It is characterized in that further comprising the steps of:

(1) select acoustic emission monitor(ing) station and position, sound reception monitoring station, make the acoustic propagation direction parallel, and acoustic emission monitor(ing) station and sound reception are monitored distance between sites and be set to the 2-10 kilometer with the nonlinear internal wave direction of propagation;

(2) confirm to transmit the coding and frequency parameter;

(3) through the determined signal of above-mentioned acoustic emission monitor(ing) station step of transmitting (2), through a plurality of these signals of nautical receiving sets reception of sound reception monitoring station;

(4) acoustical signal that above-mentioned each nautical receiving set is received is carried out filtering, decoding and sampling, and the acoustic propagation data storage after will sampling;

(5) carry out the inverting of nonlinear internal wave translational speed:

Acoustic propagation The data normal mode filter method to after the sampling is handled, and obtains the time of arrival and the amplitude of each rank normal mode of place, sound reception monitor spots;

To each rank normal mode amplitude of gained, utilize the short-term spectrum analytical approach then, obtain spectrum peak frequency; Utilize the spectrum peak frequency of this acquisition again, inverting nonlinear internal wave translational speed u.

2. a shallow sea nonlinear internal wave acoustic monitoring method comprises according to existing ocean environment parameter observational data and confirms the observation nonlinear internal wave direction of propagation, sea area; It is characterized in that further comprising the steps of:

(1) select acoustic emission monitor(ing) station and position, sound reception monitoring station, make the acoustic propagation direction vertical, and acoustic emission monitor(ing) station and sound reception are monitored distance between sites and be set to the 2-10 kilometer with the nonlinear internal wave direction of propagation;

(2) according to acoustic emission monitor(ing) station and the sound reception monitoring station spacing and the seawater depth of water, confirm to transmit coding and frequency parameter;

(3) through the determined signal of above-mentioned acoustic emission monitor(ing) station step of transmitting (2), through a plurality of these signals of nautical receiving sets reception of sound reception monitoring station;

(4) acoustical signal that above-mentioned each nautical receiving set is received is carried out filtering, decoding and sampling, and the acoustic propagation data storage after will sampling;

(5) carry out the inverting of nonlinear internal wave amplitude:

Acoustic propagation The data normal mode filter method to after the sampling is handled, and obtains the time of arrival and the amplitude of each rank normal mode of place, sound reception monitor spots;

Adopt the empirical orthogonal method then, obtain the corresponding intrinsic mode of observation sea area velocity of sound disturbance, utilize each rank normal mode of gained time of arrival again, calculate the time parameter of above-mentioned intrinsic mode, and then obtain velocity of sound disturbance, obtain the nonlinear internal wave amplitude at last.

3. monitoring method as claimed in claim 1 or 2 is characterized in that above-mentioned acoustic emission monitor(ing) station and sound reception monitoring station are that the mode that boat-carrying, buoy or anchor are is fixed in the seawater.

4. monitoring method as claimed in claim 1 or 2 is characterized in that above-mentioned confirm to transmit coding and frequency parameter, is to select emission pseudo random signal, swept-frequency signal or chaotic signal and order or frequency.

5. monitoring method as claimed in claim 1 is characterized in that the spectrum peak frequency inversion nonlinear internal wave translational speed u that above-mentioned utilization obtains, and is to calculate according to following formula

${\mathrm{\&omega;}}_{\mathrm{mn}}=(k_m^1-k_n^0)u$

ω wherein _MnBe spectrum peak frequency,

With

Be respectively the normal mode wave number at sound reception monitoring station and acoustic emission monitor(ing) station, u is the translational speed of interior ripple.

6. shallow sea nonlinear internal wave acoustic monitoring system; Comprise the single-chip microcomputer that has clock reference module (62) (6) that is connected with host computer (7) and clock synchronization unit (5); The receiving element (4) that links to each other with clock synchronization unit (5) with single-chip microcomputer (6), the transmitter unit that includes signal generator (21) (2) that links to each other with transmitting transducer (1) with single-chip microcomputer (6); And be the power supply unit (8) of single-chip microcomputer (6) and transmitter unit (2) power supply, it is characterized in that above-mentioned receiving element (4) also is provided with multiplexer switch (41), and connect a hydrophone array (3) that comprises 2～16 nautical receiving sets through this multiplexer switch (41); Three kinds of signals of above-mentioned signal generator (21) emission are respectively pseudo random signal, swept-frequency signal and chaotic signal.

7. monitoring system as claimed in claim 6; It is characterized in that above-mentioned receiving element (4) comprises multiplexer switch (41), bandpass filter (42), amplifier (43), signal correction detuner (44) and the A/D converter (45) that is connected with hydrophone array (3) successively, and be connected with single-chip microcomputer (6) via this A/D converter (45).

8. monitoring system as claimed in claim 6; It is characterized in that above-mentioned transmitter unit (2) comprises interior signal generator (21) by single-chip microcomputer (6) control, and wideband power amplifer (22) and the impedance matching box (23) launched through transmitting transducer (1) again after the signal amplification with signal generator (21).

9. monitoring system as claimed in claim 6; It is characterized in that above-mentioned clock synchronization unit (5) comprises the timing loop (53) that links to each other with single-chip microcomputer (6) and clock reference module (62) thereof, the gps receiver that has gps antenna (51) (52) that links to each other with timing loop (53) with single-chip microcomputer (6).

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