Bottom-supported acoustic wave meter

Abstract

The invention discloses a bottom-supported acoustic wave meter, and relates to the field of ocean observation. In the bottom-supported acoustic wave meter, a transducer is fixed on a gimbal through a limiting hoop; the transducer is connected with one end of the signal cable; the other end of the signal cable is connected with the bottom of the instrument cabin; the host unit, the timing unit and the rechargeable lithium battery are positioned in the instrument cabin; the top of the instrument cabin is also connected with a wireless communication antenna through a watertight connector; the instrument cabin and the solar panel are fixed on a stainless steel bracket in the floater; one end of the fixing anchor is connected with the gimbal through a Kevlar rope, and the other end is connected with the bottom of the instrument cabin through an anti-oscillation rope; two ends of the recovery rope are respectively connected with the gimbal and the anchor. A data analysis control module in the host unit can calculate the wave height according to the echo data and transmit the wave height back to an upper computer in real time through a wireless communication antenna, so that the real-time performance of wave observation is improved; and the working time is prolonged through the arrangement of the timing unit, and the device has the characteristic of being convenient to lay and recycle.

Description

Technical Field

[0001] The present application relates to the field of ocean observation technology, and in particular to a bottom-mounted acoustic wave meter. Background Art

[0002] Ocean wave observation and tide level observation are routine observations in marine environmental dynamic monitoring and have been incorporated into the operational operation of marine observation. At present, the main wave observation technologies include underwater acoustic wave measurement, coastal radar wave measurement, and remote sensing wave measurement. For underwater wave measurement, the most commonly used is the Acoustic Doppler Current Profiler (ADCP), which uses the method of acoustic signal vector synthesis to measure waves. This technology can also be used to measure ocean currents. The ADCP wave measurement is self-contained, with poor real-time performance and short continuous working time. Due to the difficulty of offshore operations, it is not convenient to salvage and deploy it frequently. Summary of the invention

[0003] In view of the above problems existing in the prior art, the purpose of this application is to provide a bottom-mounted acoustic wave meter to improve the real-time performance of wave observation, extend the working time, and be easy to deploy and recover.

[0004] To achieve the above objectives, this application provides the following solutions.

[0005] The present application provides a bottom-mounted acoustic wave meter, comprising: a wireless communication antenna, a solar panel, a float, an instrument cabin, a signal cable, a transducer, a gimbal, a fixed anchor, an anti-sway rope, a recovery rope, a host unit, a timing unit, and a rechargeable lithium battery; wherein the host unit, the timing unit, and the rechargeable lithium battery are located in the instrument cabin; The transducer is fixed on the gimbal by a limiting hoop; the transducer is connected to one end of the signal cable through a watertight connector; the other end of the signal cable is connected to the bottom of the instrument cabin through a watertight connector; the top of the instrument cabin is also connected to the wireless communication antenna through a watertight connector; the upper part of the instrument cabin is connected to the stainless steel bracket inside the float by a limiting ring; the solar panel is fixed to the stainless steel bracket inside the float; one end of the fixed anchor is connected to the gimbal through a Kevlar rope, and the other end is connected to the bottom of the instrument cabin through an anti-swing rope; the two ends of the recovery rope are respectively connected to the gimbal and the fixed anchor; The gimbal comprises a top cover, a fairing, a chassis, a counterweight and a prying point; the fairing is hollow inside, the top of the fairing is connected to the top cover by screws, and the bottom of the fairing is connected to the chassis by screws; the transducer is mounted on the surface of the top cover, and is kept vertically facing the sea surface when deployed; the counterweight is located inside the fairing, and is connected to the top cover by welding; a plurality of prying points are welded on the edge of the chassis; the prying points are provided with prying rings; and the prying rings are connected with a recovery rope; The host unit includes a data analysis control module, a data acquisition module, a storage module, a signal generator, a transmitter and a receiver; the data analysis control module is respectively connected to the timing unit, the data acquisition module, the storage module, the signal generator and the wireless communication antenna; the rechargeable lithium battery is respectively connected to the solar panel, the timing unit and the host unit; the transmitter is respectively connected to the signal generator and the transducer; the receiver is respectively connected to the transducer and the data acquisition module; The signal generator is used to generate the signal source required for transmission under the control of the data analysis control module; the transmitter is used to amplify the power of the signal source and convert it into an electrical signal; the transducer is used to convert the electrical signal into an acoustic signal, send it vertically to the sea surface as a transmission signal, and receive the sea surface echo; the receiver is used to amplify and filter the echo signal, and then transmit the corresponding analog signal to the data acquisition module; the data acquisition module is used to convert the analog signal into a digital signal, and transmit it as echo data to the data analysis control module; the timing unit is used to wake up the data analysis control module at a fixed time, and control the data acquisition module to collect echo data; the data analysis control module is also used to calculate the wave height according to the echo data, and transmit the wave height calculation result to the storage module and the wireless communication antenna at the same time, and transmit it back to the host computer via the wireless communication antenna; the storage module is used to store the wave height calculation result.

[0006] Optionally, the solar panel is designed as an isosceles trapezoid and is fixed on a stainless steel bracket inside the float at an upward angle of 45°; the solar panel is used to convert solar energy into electrical energy and output it to a rechargeable lithium battery in the instrument cabin; the rechargeable lithium battery is used to provide electrical energy for each module in the instrument cabin.

[0007] Optionally, a plurality of water holes are provided on the deflector cover and the chassis.

[0008] Optionally, the counterweight block is a horseshoe-shaped solid stainless steel body with a signal cable channel in the middle.

[0009] Optionally, the deflector adopts a streamlined design with a smooth surface without protrusions.

[0010] Optionally, the chassis diameter is greater than 10 times the transducer diameter.

[0011] Optionally, the prying point is at an angle of 15° to the seabed plane.

[0012] Optionally, the data analysis control module is further used to calculate the wave height according to the echo data, specifically including: The cross-correlation algorithm is used to calculate the correlation peak value between the transmission signal and the echo signal, and the arrival time of the echo signal is determined according to the correlation peak value; Calculate the time from the transmission to the reception of the acoustic signal according to the arrival time of the echo signal ; Calculate the sound velocity in real time based on the preset water temperature and salinity values ; Using formula Calculate instantaneous wave height ;in is the distance between the transducer and the sea level.

[0013] Optionally, the rechargeable lithium batteries are divided into two groups; one group is a single-cell lithium battery mode with a voltage range of 3V-4.2V, which is used to power the timing unit, data analysis control module, data acquisition module, storage module and signal generator; the other group is a 4-cell lithium battery series mode with a voltage range of 12V-16.8V, which is used to power the transmitter and receiver.

[0014] Optionally, the data analysis control module is also used to implement a power-off protection function.

[0015] According to the specific embodiments provided in this application, this application discloses the following technical effects: The present application provides a bottom-mounted acoustic wave meter, which transmits the acoustic signal vertically from the seabed to the sea surface through a transducer, and the reflected echo signal returns according to the law of underwater sound propagation and is received by the transducer. The transducer transmits the received echo signal to the instrument cabin through a signal cable; the data analysis control module in the instrument cabin calculates the wave height according to the echo data collected by the data acquisition module, and transmits the wave height calculation result to the storage module and the wireless communication antenna at the same time, and transmits it back to the host computer via the wireless communication antenna, which has the characteristics of strong real-time data and flexible receiving location. On the other hand, the present application sets a timing unit for timed wake-up of the data analysis control module, controls the data acquisition module to collect echo data, and adopts a timed power supply method to reduce system power consumption and extend the working time of the equipment. On the other hand, the present application also designs a gimbal, and connects the recovery rope to the pry point of the gimbal chassis to facilitate deployment and recovery. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 The figure is a schematic diagram of the overall structure of a bottom-mounted acoustic wave meter; Figure 2 This is a connection diagram of the circuit part of the bottom-mounted acoustic wave meter; Figure 3 It is a structural schematic diagram of the gimbal; Figure 4 This is the principle block diagram of the transmitter; Figure 5 is an exemplary circuit diagram of a transmitter; Figure 6 is the equivalent circuit diagram of the transmitting transformer; Figure 7 This is the principle block diagram of the receiver; Figure 8 is an exemplary circuit diagram of a receiver; Fig. 9 This is a schematic diagram of the principle of acoustic wave measurement; Fig.10 Schematic diagram of the main control chip IC100C used in the power-off protection circuit; Fig.11 The schematic diagram of the transistor Q800 and its supporting circuit used in the power-off protection circuit; Fig.12 Schematic diagram of the power chip U600 and its supporting circuit used in the power-off protection circuit. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0019] In view of the defects existing in the prior art, the present application proposes a bottom-mounted acoustic wave meter to improve the real-time performance of wave observation, extend the working time, and be easy to deploy and recover.

[0020] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0021] In an exemplary embodiment, the present application provides a bottom-mounted acoustic wave meter, combined with Figure 1 and Figure 2As shown, the bottom-mounted acoustic wave meter includes: a wireless communication antenna 1, a solar panel 2, a float 3, an instrument cabin 4, a signal cable 5, a transducer 6, a gimbal 7, a fixed anchor 8, an anti-sway rope 9, a recovery rope 10, a host unit, a timing unit and a rechargeable lithium battery. The host unit, the timing unit and the rechargeable lithium battery are all located in the instrument cabin 4. The host unit includes a data analysis control module, a data acquisition module, a storage module, a signal generator, a transmitter and a receiver.

[0022] See also Figure 1 , the transducer 6 is fixed on the gimbal 7 by a limit hoop. The transducer 6 is connected to one end of the signal cable 5 through a watertight connector, and the other end of the signal cable 5 is connected to the bottom of the instrument cabin 4 through a watertight connector, so that the transducer 6 can communicate with the transmitter and receiver in the instrument cabin 4. The top of the instrument cabin 4 is also connected to the wireless communication antenna 1 through a watertight connector, so that the data analysis control module in the instrument cabin 4 can communicate with the wireless communication antenna 1. The float 3 contains a stainless steel bracket. The upper part of the instrument cabin 4 is connected to the stainless steel bracket inside the float 3 by a limit ring. The solar panel 2 is fixed to the stainless steel bracket inside the float 3. One end of the fixed anchor 8 is connected to the gimbal 7 through a Kevlar rope, and the other end is connected to the bottom of the instrument cabin 4 through an anti-swing rope 9. The two ends of the recovery rope 10 are respectively connected to the gimbal 7 and the fixed anchor 8.

[0023] Among them, the main function of the fixed anchor 8 is to fix the gimbal 7 and the instrument cabin 4 to prevent them from drifting or being washed away in the wind and waves. The two ends of the anti-sway rope 9 are respectively connected to the bottom of the instrument cabin 4 and the fixed anchor 8. The anti-sway rope 9 is used to restrain the instrument cabin 4, alleviate the impact of water flow, and prevent the instrument cabin 4 from shifting in the water. The two ends of the recovery rope 10 are respectively connected to the gimbal 7 and the fixed anchor 8. When recovering, the equipment can be easily recovered by pulling the recovery rope 10.

[0024] The solar panel 2 is designed as an isosceles trapezoid and is fixed on the stainless steel bracket inside the float 3 at an angle of 45° upward. The solar panel 2 is used to convert solar energy into electrical energy and output it to the rechargeable lithium battery in the instrument cabin 4. The rechargeable lithium battery is used to power each module in the instrument cabin 4.

[0025] When observing ocean waves, the base for installing the transducer needs to keep the transducer facing the sea surface vertically upward at all times, but the commonly used bottom-mounted bracket is a quadrilateral steel frame structure with edges and corners, which leads to it being often dragged down by fishermen's trawls on the one hand, and easily buried by silt on the other hand, causing the equipment to sink. In response to the above problems, the present application designs a gimbal 7 as the base of the bottom-mounted acoustic wave meter, on which the transducer 6 is installed and kept vertically facing the sea surface when deployed.

[0026] The structure of the gimbal 7 of this application is as follows Figure 3As shown, the gimbal 7 includes a top cover 701, a fairing hood 702, a chassis 703, a counterweight 704 and a prying point 705. The fairing hood 702 is hollow inside and is a cover body with a trapezoidal cross section. The top of the fairing hood 702 is connected to the top cover 701 by screws, and the bottom of the fairing hood 702 is connected to the chassis 703 by screws. The transducer 6 is mounted on the surface of the top cover 701 and is kept vertically facing the sea surface when deployed. The counterweight 704 is located inside the fairing hood 702, and the counterweight 704 is connected to the top cover 701 by welding. A plurality of prying points 705 are welded on the edge of the chassis 703; the prying point 705 is provided with a prying ring 706 for connecting the recovery rope 10. A plurality of water holes are provided on the fairing hood 702 and the chassis 703, respectively referred to as the fairing hood water hole 707 and the chassis water hole 708.

[0027] Among them, the counterweight block 704 is a solid stainless steel body, and the overall design is horseshoe-shaped. A channel is left in the middle for the signal cable 5 of the transducer 6, and it is connected to the top cover 701 of the gimbal 7 by welding. The horseshoe shape of the counterweight block 704 lowers the center of gravity of the gimbal 7. The deflector 702 is streamlined as a whole, with a smooth surface and no protrusions, ensuring that the gimbal 7 is not easily dragged down by the fishing net. A circle of deflector water holes 707 is set at the lower part of the deflector 702, which plays a role in diverting and buffering the impact of water flow. The diameter of the chassis 703 is designed to be more than 10 times the diameter of the transducer 6, which increases the contact area with the seabed and solves the problem of the equipment itself sinking, so that it is not easy to be buried by silt. The pry point 705 is connected to the chassis 703 by welding, and is at an angle of 15° to the seabed, ensuring that the signal cable 5 of the transducer 6 can pass through from under the chassis 703. The prying point 705 is provided with a prying ring 706, which is connected to the prying point 705 by welding. When deployed, the prying ring 706 is connected to a recovery rope 10, and the other end of the recovery rope 10 is connected to a fixed anchor 8. When recovered, the equipment can be easily recovered by pulling the recovery rope 10. The gimbal 7 of the present application adopts a recovery design with a preset prying point, which solves the problem that the chassis is sucked by silt and is difficult to recover.

[0028] See also Figure 2 The data analysis control module is respectively connected to the timing unit, the data acquisition module, the storage module, the signal generator and the wireless communication antenna. The rechargeable lithium battery is respectively connected to the solar panel, the timing unit and the host unit. The transmitter is respectively connected to the signal generator and the transducer. The receiver is respectively connected to the transducer and the data acquisition module.

[0029] The timing unit is used to regularly wake up the data analysis control module of the host unit and control the data acquisition module to collect 18 minutes of echo data every hour. The CPU of the timing unit can achieve ultra-low power consumption in active mode, with a working current consumption of ≤2mA and a power consumption of ≤0.1mA in sleep mode.

[0030] The signal generator is used to generate a signal source required for transmission under the control of the data analysis control module. The transmitter is used to amplify the power of the signal source and convert it into an electrical signal. The transducer is used to convert the electrical signal into an acoustic signal, which is sent vertically to the sea surface as a transmission signal, and receives the sea surface echo. The receiver is used to amplify and filter the echo signal, and then transmit the corresponding analog signal to the data acquisition module. The data acquisition module is used to convert the analog signal into a digital signal, and transmit it to the data analysis control module as echo data. The timing unit is used to wake up the data analysis control module at a fixed time, and control the data acquisition module to collect echo data. The data analysis control module is also used to calculate the wave height according to the echo data, and transmit the wave height calculation result to the storage module and the wireless communication antenna at the same time, and transmit it back to the host computer via the wireless communication antenna. The storage module is used to store the wave height calculation result. Specifically, the storage module uses an SD card to facilitate data reading.

[0031] The principle block diagram of the transmitter is as follows: Figure 4 As shown, it mainly includes a gain regulator, a preamplifier, a current amplifier stage, a power amplifier, a power supply, a transmitting transformer, a signal matching circuit and a filtering and shaping circuit. Figure 5 An exemplary circuit diagram of a transmitter is shown. Figure 5 The gain regulator is mainly composed of potentiometers W1, W2, and W3. The main components of the preamplifier U4 are high-speed operational amplifiers. The gain regulator adjusts the gain of the preamplifier U4 through potentiometers W1, W2, and W3, thereby changing the output power. In this application, the preamplifier U4 uses the OPA211 chip of AD Company. The input stage of the chip uses two pairs of differential amplifiers, which ensures that the static voltage of the input end and the feedback end of the main amplifier is 0, which is convenient for using DC feedback. Amplifiers U5A, U5B, U5C, U5D, U5E, and U5F constitute the current amplifier stage. The preamplifier U4 cooperates with the current amplifier stages U5A, U5B, U5C, U5D, U5E, and U5F to improve the low-frequency response of the amplifier and play an isolation role. The power amplifier uses high-speed dual MOS transistors Q1 and Q2 to drive the field effect tube Q3, and the operating speed can reach 100MHz. Under the condition of a capacitive load of 1000pF, a driving rise and fall edge of 6ns and a driving current of 2A can be obtained. The FET Q3 model can be RF150. Transmitter transformer T2 is one of the most important auxiliary components of the power amplifier, and its performance directly determines the performance of the power amplifier. The power supply mainly includes CE10, CE11, E3, etc., which are used to power the components in the transmitter. The signal matching circuit is mainly composed of and The diodes D5 and D6 form a filter shaping circuit. Among them, the signal matching circuit , Together with the inductor coil of the transmitting transformer T2, it forms an LC circuit to achieve the signal matching function. It further cooperates with the filter shaping circuit formed by diodes D5 and D6 to play the role of filtering and shaping. Of course, in order to meet the needs of the circuit, the transmitter circuit also includes some other components, such as the terminal D / AIN and PZ, capacitors C11, CE9, E1, E2, resistors RE, R19~R23, inductor L1, etc., all of which realize their conventional functions and will not be repeated here.

[0032] Among them, the most important indicator of the transmitting transformer T2 is the working frequency bandwidth, which is mainly determined by the distributed capacitance and leakage inductance of the transformer. The equivalent circuit of the transmitting transformer T2 is shown in Figure 6 . Figure 6 La is the primary inductance, Lb is the secondary inductance, Ca is the primary distributed capacitance, and Cb is the secondary distributed capacitance. La determines the low-end frequency of the transformer. The low-end frequency can be reduced by using a core material with high magnetic flux density and increasing the number of coil turns. However, when the frequency is lower than 100Hz, the volume of the transformer will increase rapidly, which will bring difficulties to the project implementation. The high-end frequency of the transformer is determined by Lb and Cb. Lb and Cb are determined by the distance, voltage difference, and area between the coil layers. The leakage inductance and distributed capacitance can be effectively reduced by special winding methods such as layering and segmentation. After a carefully designed transformer structure, its operating bandwidth can reach three times the frequency band. The bandwidth of the transformer is also affected by the output voltage and the number of output windings (taps). The higher the output voltage, the more coil turns, and the greater the leakage inductance of the transformer; similarly, the more output windings, the thicker the coil, and the greater the leakage inductance, which will reduce the frequency band of the output transformer. The frequency range of the transmitting transformer T2 developed in this application is 180kHz~220kHz, and the operating bandwidth is between the 30KHz frequency band.

[0033] The task of the receiver is to truly and completely receive the echo signal with channel information, and it is necessary to amplify, filter, detect and process the echo signal. The principle block diagram of the receiver is shown in the figure. Figure 7 As shown, the circuit diagram is as Figure 8As shown, the receiver mainly includes a receiving transformer T1, a receiving gain regulator W5, an operational amplifier OP37, and a receiving filter circuit composed of operational amplifiers U7 and U8. Among them, the receiving transformer T1, the receiving gain regulator W5 and the operational amplifier OP37 are used together to power amplify the received signal. In addition, since there are noise and ripples in the analog circuit, in order to reduce the influence of noise and ripples on the collected signal, the present application adopts receiving filter circuits U7 and U8, and U7 and U8 form a bandpass filter to filter the received signal. Specifically, U7 and U8 select the operational amplifier ADA4898-1 with high speed, ultra-low power consumption, dual-channel wide voltage range to form a bandpass filter, with a gain of 20dB, a -3dB bandwidth of 40kHz, and a center frequency of 200kHz. To meet the circuit requirements, the receiver circuit also includes some other components, such as terminal blocks LK1, LK2, LK3, TOA / D, capacitors C15, C2, C14, K3, K4, resistors R28, R29, R16, R1~R5, etc., all of which realize their conventional functions and will not be repeated here.

[0034] Figure 1 In the bottom-mounted acoustic wave meter, the timing unit, data analysis control module, signal generator, data acquisition module, and storage module are all composed of digital circuits. When entering the measurement cycle, the CPU of the data analysis control module is awakened from the sleep mode, the signal generator is initialized, the self-test program of the signal generator is completed, and the pulse signal is started to be transmitted. The data acquisition module enters the stage of waiting for receiving signals. After completing the transmission and reception measurement, the data analysis control module calculates the sound velocity value in real time according to the preset water temperature and salinity values, and performs real-time analysis and processing on the raw data according to the preset sampling period to calculate the wave height. Finally, the wave height calculation result is transmitted back to the host computer and written to the SD card in the storage module through the wireless communication antenna at the same time.

[0035] The principle of acoustic wave measurement is as follows Fig. 9 As shown in the figure, the acoustic wave meter calculates the wave height and corresponding period based on the recorded propagation time. Assume that the speed of sound in seawater is a constant The time from the transmission to the reception of the acoustic signal is , is the distance between the transducer and the wave surface, is the instantaneous wave height, is the distance between the transducer and the sea level, then: (1) The bottom-mounted acoustic wave meter with transducer is installed on the seabed. In actual calculation, the height of the bottom-mounted acoustic wave meter itself can be ignored. Usually the distance from the seafloor to the sea level is taken, such as Fig. 9 The data analysis control module calculates the time , we can get the instantaneous wave height: (2) According to the measurement principle, it is necessary to obtain the time from the transmission to the reception of the acoustic signal. , which requires determining the arrival time of the echo signal returned by the ultrasonic wave from the sea surface. Usually, the time when the amplitude of the front edge of the echo reaches a certain threshold is used as the arrival time of the echo signal, but such judgment has some difficult-to-solve problems. The first is the problem of echo distortion, and the second is the problem of false triggering and missed triggering of the threshold judgment circuit. Therefore, improving the processing method of the echo signal is an inevitable idea to solve the problem. One of the main tasks of the data analysis control module of this application is to extract the arrival time of the echo signal as accurately as possible from the echo signal. This application uses a cross-correlation algorithm to calculate the arrival time of the echo signal. The cross-correlation algorithm can accurately determine the delay length of the two signals by calculating and comparing the similarity of the two signals. Specifically, the transmitting signal and the echo signal are selected for cross-correlation calculation, and the corresponding time of the calculated correlation peak is the arrival time of the echo signal. A great advantage of using the cross-correlation algorithm to measure the delay time is its immunity to noise. This is mainly because there is no correlation between the noise signals, so the result of the correlation operation is basically not affected by noise. The formula of the cross-correlation algorithm is as follows: (3) is the relevant calculation result, is the number of sampling points, Indicates the transmission signal. represents the echo signal, independent variable The value range is 0~ The specific calculation method is and Multiply (or AND), then add their products and divide by , that is .actual The value range of the independent variable is 0~ , but the formula requires that of value, then it needs to be filled with zeros, but before filling with zeros, , First weight them, that is, subtract their respective averages to get new data , The data obtained by zero padding is: (4) Such a correlation operation needs to be performed times multiplication and When the echo signal data is long, the amount of calculation is very large, which will reduce the real-time measurement of the system and the system refresh frequency. To solve this problem, Fourier transform can be used to convert the time domain correlation into frequency domain correlation for solution.

[0036] The Wiener-Khinchin theorem provides a fast algorithm for the cross-correlation function, which is based on the cross-power spectral density function The cross-correlation function is obtained indirectly. The cross-power spectrum density function is: (5) in, To transmit the signal The spectrum of for The conjugate function of ; Echo signal Spectrum of for and The cross power spectral density function of By performing an inverse fast Fourier transform (IFFT), the cross-correlation function can be obtained from the cross-power spectrum density function: (6) In this way, the time domain correlation operation is converted into the Fourier transform of the two signals and the inverse Fourier transform after multiplication. In the correlation operation result, the time corresponding to the correlation peak is determined, which is the time difference between the two signals. It requires only a few multiplication operations, which is faster than directly calculating the cross-correlation function algorithm in the time domain.

[0037] Therefore, the data analysis control module calculates the wave height according to the echo data, specifically including: using the cross-correlation algorithm to calculate the correlation peak value between the transmission signal and the echo signal, and determining the arrival time of the echo signal according to the correlation peak value; calculating the time from the transmission to the reception of the acoustic signal according to the arrival time of the echo signal ; Calculate the sound velocity value in real time according to the preset water temperature and salinity value ; Using the formula Calculate instantaneous wave height .

[0038] The bottom-mounted acoustic wave meter of this application can work continuously for 90 days in self-contained mode. The system fully considers the control of power consumption during circuit design and component selection. At the same time, in order to reduce the size of the equipment, achieve miniaturization, and reduce the size of the rechargeable lithium battery, it is necessary to strictly control the working timing and power consumption of each module. At the hour, turn on the main switch of the rechargeable lithium battery to power the system. After the system is powered on, start the data analysis control module, initialize the system, read the setting parameters, including acquisition rate, sampling period, signal waveform, current temperature, salinity, pressure and other parameters, and start measurement.

[0039] The system is designed with two groups of lithium batteries to power the digital circuit and analog circuit respectively. The digital circuit includes the timing unit, data acquisition module, storage module, data analysis control module, and signal generator, and the analog circuit includes the transmitter and receiver. This design can reduce the noise and ripple caused by the power supply. One group is a single-cell lithium battery mode with a voltage range of 3V-4.2V, which powers digital circuits such as the timing unit, data analysis control module, data acquisition module, storage module, and signal generator; the other group is a 4-cell lithium battery series mode with a voltage range of 12V-16.8V, which powers analog circuits such as transmitters and receivers. The battery capacity of the two groups of lithium batteries is calculated as follows.

[0040] The working current of the data acquisition module is <100mA. It works once per hour, collects 8192 points each time, and collects 8 points per second. It needs to work for 1024 / 60=17.06 minutes. Therefore, this application designs the data acquisition module to work for 18 minutes per hour, and the required battery capacity is: 100mA×10 -3 ×18 / 60×24h×90≈65Ah. The capacity of each lithium battery is 5Ah. The battery pack consists of 16 lithium batteries connected in parallel. The battery capacity after parallel connection is 80Ah.

[0041] Receiver operating current <20mA, working for 18 minutes per hour, required battery capacity: 20mA×10 -3 ×18 / 60×24h×90≈13Ah, the transmitter emits an instantaneous current of 0.5A, the pulse length is 3.3ms, and the required battery capacity is: 0.5×3.3×10 -3 ×18 / 60×24h×90≈0.65Ah. To ensure that the battery does not reach the overcurrent protection current at the moment of transmission, the transmitting circuit needs a battery capacity of 1Ah and the battery redundancy is designed to be 1.5 times. Therefore, the battery capacity is 14×1.5=21Ah. Finally, the lithium battery capacity for the analog circuit is determined to be 25Ah.

[0042] In addition, the data analysis control module of the present application can also realize the power-off protection function. The data analysis control module monitors the output voltage of the rechargeable lithium battery, the static DC voltage at the output end of the power amplifier, the output current of the rechargeable lithium battery, the output current of the power amplifier, and the temperature in the instrument cabin. If a problem occurs, it will immediately protect and cut off the power supply to avoid accidents. In order to realize the power-off protection function, a power-off protection circuit is also provided in the data analysis control module, and the power-off protection circuit mainly includes Fig.10 The main control chip IC100C shown, Fig.11 The transistor Q800 shown, Fig.12 The power chip U600 and its supporting circuit shown in the figure. The model of the main control chip IC100C can be STM32F207VGT-LOFP100. The model of the transistor Q800 can be 2N9013. The model of the power chip U600 can be LT1963AEQ. Among them, the transistor Q800 is used to design the cut-off circuit, and its CPUON / OFF pin is connected to the pin PC13 of the main control chip IC100C, and the CPUON / OFF_H pin is connected to the enable pin PCTR_2 of the power chip U600 through the transistor Q600 and other components. Fig.12 Vin indicates the output of the rechargeable lithium battery, and V2O indicates the power input of the digital circuit. When the circuit needs to be cut off, the main control chip IC100C gives a high level to the CPUON / OFF pin, and the CPUON / OFF_H pin can output a low level, control the power chip U600 to stop working, and complete the function of cutting off the circuit. Within a few seconds after the fault disappears, the main control chip IC100C controls the CPUON / OFF pin to output a low level, the CPUON / OFF_H pin outputs a high level, the power chip U600 starts working, and the system resumes power supply. Due to the adoption of perfect protection measures, the power amplifier can basically avoid damage in the case of misoperation, so it has high reliability.

[0043] The bottom-mounted acoustic wave meter proposed in this application measures waves using the principle of hydroacoustic ranging. The acoustic transducer is installed on the seabed, and acoustic pulses of a certain frequency are emitted vertically upward to calculate the vertical distance from the transducer to the sea surface. Ocean waves are composed of many component waves of different periods and amplitudes. After collecting a certain amount of echo data samples, wave information such as wave height and wave period can be calculated based on the echo data, and a specification document can be formed according to the seashore observation specification. The main technical parameters of the bottom-mounted acoustic wave meter of this application are shown in Table 1.

[0044] Table 1 Main technical parameters of the bottom-mounted acoustic wave meter

[0045] Among them, according to the provisions of the national standard "GB / T 14914.2-2019 Ocean Observation Specification Part 2: Seashore Observation", in wave observation, one-tenth of the wave height of level 1 wave (micro wave) is less than 0.1m, so this application determines the minimum measured wave height to be 0.1m. One-tenth of the wave height of level 9 wave (raging wave) is less than 18 meters, so this application determines the maximum measured wave height to be less than 20 meters. The wave height measurement range is 0.1m to 20.0m.

[0046] In wave observation, the wave height measurement accuracy is specified in two levels, the maximum allowable error of the first level is ±10% of the observed value, and the maximum allowable error of the second level is ±15% of the observed value. This application determines that the wave height measurement accuracy is ±0.05m when the wave height is less than or equal to 1m; when the wave height is greater than 1m, the wave height measurement accuracy is the maximum allowable error of the first level, that is, ±10% of the observed value.

[0047] The maximum allowable error of wave period measurement accuracy is ±0.5s. The wave period measurement range is 2s to 20s.

[0048] In addition, according to the national standard "GB / T 14914.2-2019 Marine Observation Specification Part 2: Seashore Observation", the number of waves recorded continuously is not less than 100 waves, and the recording time length is generally 17min-20min. Therefore, this application sets three sampling periods, namely 0.5s, 0.25s and 0.125s. Among them, the sampling period is 0.5s, and 2048 points are collected each time; the sampling period is 0.25s, and 4096 points are collected each time; the sampling period is 0.125s, and 8192 points are collected each time. In order to improve the measurement accuracy of wave height and wave period, a sampling period of 0.125s is generally used.

[0049] The bottom-mounted acoustic wave meter developed by the present application is a self-contained real-time data analysis device. The bottom-mounted acoustic wave meter transmits ultrasonic waves vertically from the seabed to the sea surface through a transducer, and the reflected echo signal returns according to the law of underwater sound propagation and is received by the transducer. The transducer transmits the received echo signal to the instrument cabin through a signal cable. The instrument cabin transmits the wave height calculation result back to the host computer through a wireless communication antenna. Therefore, the bottom-mounted acoustic wave meter of the present application has the characteristics of strong real-time data and flexible receiving location. On the other hand, the bottom-mounted acoustic wave meter of the present application adopts a timed power supply method, which reduces system power consumption, reduces battery capacity, and extends the working time of the equipment. All modules of the host unit are arranged in the instrument cabin, so that the equipment is miniaturized and lightweight. The bottom-mounted acoustic wave meter of the present application is also designed with a gimbal, and the recovery rope 10 is connected to the pry point of the gimbal chassis to facilitate the deployment and recovery of the instrument.

[0050] In addition, the gimbal of the present application also adopts a design of increasing the chassis diameter, lowering the center of gravity, and smoothing the surface of the fairing without protrusions, which can prevent the equipment from sinking and being buried in mud, and is not easily dragged down by fishing nets. The bottom-mounted acoustic wave meter is powered by two sets of lithium batteries, and the power supply of the analog circuit and the digital circuit are designed separately, which improves the reliability of the hardware circuit. The bottom-mounted acoustic wave meter of the present application is also designed with a complete power-off protection circuit to improve the safety and stability of the work.

[0051] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0052] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A bottom-mounted acoustic wave meter, characterized in that: include: Wireless communication antenna, solar panel, float, instrument cabin, signal cable, transducer, gimbal, fixed anchor, anti-sway rope, recovery rope, host unit, timing unit and rechargeable lithium battery; wherein, the host unit, timing unit and rechargeable lithium battery are located in the instrument cabin; The transducer is fixed on the gimbal by a limiting hoop; the transducer is connected to one end of the signal cable through a watertight connector; the other end of the signal cable is connected to the bottom of the instrument cabin through a watertight connector; the top of the instrument cabin is also connected to the wireless communication antenna through a watertight connector; the upper part of the instrument cabin is connected to the stainless steel bracket inside the float by a limiting ring; the solar panel is fixed to the stainless steel bracket inside the float; one end of the fixed anchor is connected to the gimbal through a Kevlar rope, and the other end is connected to the bottom of the instrument cabin through an anti-swing rope; the two ends of the recovery rope are respectively connected to the gimbal and the fixed anchor; The gimbal comprises a top cover, a fairing, a chassis, a counterweight and a prying point; the fairing is hollow inside, the top of the fairing is connected to the top cover by screws, and the bottom of the fairing is connected to the chassis by screws; the transducer is mounted on the surface of the top cover, and is kept vertically facing the sea surface when deployed; the counterweight is located inside the fairing, and is connected to the top cover by welding; a plurality of prying points are welded on the edge of the chassis; the prying points are provided with prying rings; and the prying rings are connected with a recovery rope; The host unit includes a data analysis control module, a data acquisition module, a storage module, a signal generator, a transmitter and a receiver; the data analysis control module is respectively connected to the timing unit, the data acquisition module, the storage module, the signal generator and the wireless communication antenna; the rechargeable lithium battery is respectively connected to the solar panel, the timing unit and the host unit; the transmitter is respectively connected to the signal generator and the transducer; the receiver is respectively connected to the transducer and the data acquisition module; The signal generator is used to generate the signal source required for transmission under the control of the data analysis control module; the transmitter is used to amplify the power of the signal source and convert it into an electrical signal; the transducer is used to convert the electrical signal into an acoustic signal, send it vertically to the sea surface as a transmission signal, and receive the sea surface echo; the receiver is used to amplify and filter the echo signal, and then transmit the corresponding analog signal to the data acquisition module; the data acquisition module is used to convert the analog signal into a digital signal, and transmit it as echo data to the data analysis control module; the timing unit is used to wake up the data analysis control module at a fixed time, and control the data acquisition module to collect echo data; the data analysis control module is also used to calculate the wave height according to the echo data, and transmit the wave height calculation result to the storage module and the wireless communication antenna at the same time, and transmit it back to the host computer via the wireless communication antenna; the storage module is used to store the wave height calculation result.

2. The bottom-mounted acoustic wave meter according to claim 1, characterized in that: The solar panel is designed as an isosceles trapezoid and is fixed on the stainless steel bracket inside the float at an upward angle of 45°; the solar panel is used to convert solar energy into electrical energy and output it to the rechargeable lithium battery in the instrument cabin; the rechargeable lithium battery is used to provide electrical energy for each module in the instrument cabin.

3. The bottom-mounted acoustic wave meter according to claim 1, characterized in that: The deflector cover and the chassis are both provided with a plurality of water holes.

4. The bottom-mounted acoustic wave meter according to claim 1, characterized in that: The counterweight block is a horseshoe-shaped solid stainless steel body with a signal cable channel in the middle.

5. The bottom-mounted acoustic wave meter according to claim 1, characterized in that: The deflector adopts a streamlined design and has a smooth surface without protrusions.

6. The bottom-mounted acoustic wave meter according to claim 1, characterized in that: The base plate diameter is greater than 10 times the transducer diameter.

7. The bottom-mounted acoustic wave meter according to claim 1, characterized in that: The prying point is at an angle of 15° to the seabed plane.

8. The bottom-mounted acoustic wave meter according to claim 1, characterized in that: The data analysis control module is also used to calculate the wave height according to the echo data, specifically including: The cross-correlation algorithm is used to calculate the correlation peak value between the transmission signal and the echo signal, and the arrival time of the echo signal is determined according to the correlation peak value; Calculate the time from the transmission to the reception of the acoustic signal according to the arrival time of the echo signal ; Calculate the sound velocity in real time based on the preset water temperature and salinity values ; Using formula Calculate instantaneous wave height ;in is the distance between the transducer and the sea level.

9. The bottom-mounted acoustic wave meter according to claim 1, characterized in that: The rechargeable lithium batteries are divided into two groups; one group is a single-cell lithium battery mode with a voltage range of 3V-4.2V, which is used to power the timing unit, data analysis control module, data acquisition module, storage module and signal generator; the other group is a 4-cell lithium battery series mode with a voltage range of 12V-16.8V, which is used to power the transmitter and receiver.

10. The bottom-mounted acoustic wave meter according to claim 1, characterized in that: The data analysis control module is also used to implement a power-off protection function.

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