CN116183011A

CN116183011A - Autonomous lifting underwater sound velocity measuring instrument, measuring system and measuring method

Info

Publication number: CN116183011A
Application number: CN202310450155.4A
Authority: CN
Inventors: 高伟; 王良; 高明宇; 徐铭
Original assignee: Ocean University of China
Current assignee: Ocean University of China
Priority date: 2023-04-25
Filing date: 2023-04-25
Publication date: 2023-05-30

Abstract

The invention belongs to the technical field of underwater sound velocity data measurement, and discloses an autonomous lifting underwater sound velocity measuring instrument, a measuring system and a measuring method. The autonomous lifting underwater sound velocity measuring method comprises the following steps: and measuring the reflected echo time delay at a fixed distance by using an underwater sound velocity measuring device, and calculating real-time underwater sound velocity data by using a pulse time method from the measured reflected echo time delay by a CPU of the main control core. The data transmission mode of the invention abandons high-cost and low-efficiency enameled wire transmission, and instead uses Wi-Fi wireless communication technology, after data acquisition, the system automatically floats to the water surface to carry out wireless data transmission with receiver equipment such as unmanned aerial vehicles, deck units and the like, thereby completing low-cost accurate measurement of ocean sound velocity profile in a specific area. The invention can accurately customize the circuit board according to the required functions, select components with reasonable size and proper power for device assembly and arrangement, and realize miniaturization and low power consumption.

Description

Autonomous lifting underwater sound velocity measuring instrument, measuring system and measuring method

Technical Field

The invention belongs to the technical field of underwater sound velocity data measurement, and particularly relates to an autonomous lifting underwater sound velocity measuring instrument, a measuring system and a measuring method.

Background

The ocean sound speed is one of the important acoustic properties of an ocean body of water, which is typically 1430-1550m/s. In the process of exploring the ocean, most marine instruments rely on sound waves for detection, and sound velocity has direct influence on detection accuracy, and is an important parameter for describing an underwater sound field, and sound velocities at different depths form sound velocity profiles (Sound Velocity Profile, SVP). The sound velocity profile refers to a water layer tangent plane of which the sound velocity at a certain position changes along with the depth, shows the function relation of the sound velocity along with the depth, reflects the rule of the sound velocity in the sea water along with the depth, and has very important significance for target detection, underwater acoustic communication, sonar countermeasure and the like. The underwater sound velocity is affected by the temperature of the sea water, is closely related to factors such as time, atmospheric temperature, ocean current and the like, is related to the salinity and depth (static pressure) of the sea water, and is a parameter which is not easy to measure and estimate. The current common measuring principle of instruments is to use pulse time method and pulse cycle method, and also Doppler method.

The common underwater sound velocity acquisition has the following schemes:

in the first, the sound velocity inversion is carried out according to a model based on water body data such as temperature, salt depth and the like by an indirect measurement method. The method comprises the steps of obtaining water body information such as temperature, salinity and depth by using common instruments and methods such as a thermal salt depth meter (Conductivity Temperature Depth, CTD), ocean microwave remote sensing, visible light remote sensing and the like, and inverting sound velocity under corresponding conditions according to an existing empirical model by combining a Wilson sound velocity empirical formula. The prior products are widely used with SBE 911plus CTD and warm salt depth series instruments;

The second type, the disposable sound velocity measuring instrument (Expendable Sound Velocimeter, XSV) is mainly used on board, and is mainly used for rapidly measuring a ship in sailing, and comprises a probe, a transmitter, a deck processing unit and a data display recording instrument. After the probe body enters water, the measuring circuit starts to work and returns to the deck unit through the data transmission line, and the circuit is automatically disconnected after the set depth is reached to finish the measurement, and the probe body is automatically discarded. In the 30 s of the 20 th century, the prior art began on-board disposable marine instrumentation development, with the earliest successful development of disposable temperature and depth gauges (Expendable Bathythermograph, XBT), on the basis of which pedigree on-board, on-board and off-board series of equipment was developed. In the prior art, as the buoy dynamic data transmission technology, the winding technology and the signal processing technology of the jettisoningmarine instrument are complex, the equipment cost is high, and the application is easy to be limited to a certain extent in the actual scene;

thirdly, the hanging sound velocity measuring instrument is similar to a hanging sonar, a helicopter or an unmanned plane is adopted to hover above a corresponding water area, the measuring instrument is lowered to the water body to carry out sound velocity measurement, a cable is used for carrying out data return, and compared with the ship navigation measuring cost, the hanging sound velocity measuring instrument is lower and the positioning is more accurate;

Fourth, the direct sound velocity measuring instrument, the most naive measuring mode of direct sound velocity measurement, directly put the measuring instrument into the water, divide into from appearance formula and towing rope formula measuring instrument again. The water data processing equipment and the underwater detection acquisition equipment of the towing rope type acoustic velocity meter are connected together, and real-time communication can be carried out through a serial port; the water data processing equipment and the underwater detection acquisition equipment of the self-contained acoustic velocity meter are separated, data are stored in the internal memory, equipment recovery is carried out after primary acoustic velocity detection is completed, and then data processing is carried out.

Through the above analysis, the problems and defects existing in the prior art are as follows:

(1) The sound velocity measurement accuracy of the indirect measurement method is difficult to guarantee, and the accuracy of the data cannot be verified after measurement. According to the existing research, the sound velocity accuracy obtained by carrying out sound velocity inversion on water body data such as temperature and salt depth according to a model by an indirect measurement method is lower than that obtained by a direct measurement method by a few schemes;

(2) The transmission cables in the shipborne disposable measuring instrument are mostly enameled wires, and are not commonly used RS232 transmission wires, the depth range which can be measured by the transmission cables is limited due to the limitation of the length of the enameled wires, the service life and the quality of the enameled wires are also considered in the cost and the factors influencing the test result, the measuring instrument does not carry a pressure measuring element, and the falling depth of the measuring instrument is calculated by an empirical formula, namely a falling rate formula (Falling Rate Equation, FRE). The formula of the descent rate of the probe is related to the nature of the probe and is also affected by the launch environment. Whether the calculation formula directly influences the reliability of sound velocity profile measurement or not is accurate, but the problem of the formula is still undetermined, and no accurate theorem exists;

(3) When the suspended sound velocity measuring instrument is used for measuring, the original characteristics of the water surface can be changed due to the water wave generated by the propeller of the aircraft, so that the measurement and calculation of the sound velocity are affected, and meanwhile, the measuring depth is limited by the cable length;

(4) For a towing-cable type direct sound velocity measuring instrument, the cable length is limited, so that the measuring depth is limited, and the quality of the cable is also an influencing factor; for self-contained direct sound velocity measuring instruments, it is not possible to transmit real-time measurement data.

Disclosure of Invention

In order to overcome the problems in the related art, the invention discloses an autonomous lifting underwater sound velocity measuring instrument, a measuring system and a measuring method. The invention aims to provide a novel instrument for measuring underwater sound velocity and sound velocity profile, which has the advantages of miniaturization, low cost, low power consumption, high accuracy and the like.

The technical scheme is as follows: an autonomous lifting underwater sound velocity measurement method comprises the following steps: and measuring the reflected echo time delay at a fixed distance by using an underwater sound velocity measuring device, and calculating real-time underwater sound velocity data by using a pulse time method from the measured reflected echo time delay by a CPU of the main control core.

In one embodiment, the pulse time method comprises: when the sound velocity measuring device measures, the underwater sound transducer emits a high-frequency pulse, a reflector baffle is arranged at a position far away from the underwater sound transducer L, and the high-frequency pulse is received by the underwater sound transducer after being reflected by the reflector; the CPU of the main control core directly calculates the sound velocity by measuring the reflection echo time delay of the underwater sound transducer at a fixed distance, and the calculation formula is as follows:

（1）

wherein ,

the time difference from pulse transmission to reception is in seconds, L is in meters, and c is the underwater sound velocity of the underwater sound transducer at a fixed distance in meters per second.

In one embodiment, in calculating real-time underwater sound velocity data by using a pulse time method for measured reflected echo time delay by a CPU of a master control core, the CPU cooperates with a DMA controller to process the sound velocity data, including: dividing RAM carried by the DMA controller into two data storage areas buffer_1 and buffer_2 with the same size, when the buffer_1 reaches the upper limit of the DMA transmission data quantity, sending an interrupt to the CPU by the DMA, and judging which data storage area is about to overflow in the corresponding interrupt service function;

the CPU directs the target Buffer of the DMA to buffer_2 and completes the real-time processing of the data in buffer_1; when the DMA reaches the upper limit of storage for the data transmitted by the buffer_2, a new interrupt is sent to the CPU, and the data is circularly and alternately collected, stored and processed to realize real-time processing of the data; in the peak threshold detection of echo signals, the CPU extracts fifty sampling points at the peak value, which are larger than a set threshold value to judge whether the signals are to be taken or not, finally selects accurate sampling points to determine the accurate time difference between the transmitted signals and the received signals, transmits time data in a circuit board of a main control core, processes digital signals and calculates real-time underwater sound velocity data by using a formula.

In one embodiment, after the CPU of the main control core calculates real-time underwater sound velocity data by using a pulse time method on measured reflection echo time delay, the weight is released at a preset depth through the control release device, the buoyancy is larger than the gravity, the water surface is floated, the data communication transmission is carried out with a water surface platform or an unmanned plane through the antenna wireless communication, and the underwater sound velocity profile measurement of the preset depth is completed.

Another object of the present invention is to provide an autonomous elevating underwater sound velocity measurement system comprising: the system comprises a power supply module, a wireless communication module, a main control core, a lifting control module, a transmitting module, a receiving module and a transducer module;

the power supply module is used for providing power supply;

the transducer module is used for measuring the reflection echo time delay of a certain fixed distance under water;

the receiving module is used for receiving the reflected echo time delay data;

the main control core is used for calculating the reflected echo time delay and calculating real-time underwater sound velocity data; sending the floating instruction to a wireless communication module and a lifting control module;

the transmitting module is used for solving the real-time underwater sound velocity data by the main control core and transmitting the real-time underwater sound velocity data to the transducer module;

the wireless communication module is used for communicating the measurement data of the main control core with external equipment;

The lifting control module is used for executing the floating instruction of the main control core.

In one embodiment, the transmitting module is configured with TIM2 of STM32F4, and drives and transmits PWM pulse signals with specific frequency, specific duty cycle and specific signal peak-to-peak value, and the PWM pulse signals are converted into forward pulse after being processed by the inverting module, and finally, the forward PWM pulse is coupled and amplified by the transformer, and drives the underwater sound transducer of the sound velocity measuring device to complete signal transmission;

the receiving module performs indifferent amplification on signals sent by the underwater acoustic transducer by utilizing a triode amplifying circuit, the amplified signals are filtered out by a second-order active band-pass filtering amplifying circuit, the signals are shaped by a shaping amplifying circuit and are subjected to heightening treatment, the signals are finally input to the band-pass filtering circuit by pins of the triode amplifying circuit, an analog-digital converter is synchronously started to acquire the signals, a DMA function is enabled to assist in completing signal transmission, and the DMA transmission copies data from the output of the ADC to a storage address space.

In one embodiment, the triode amplifying circuit amplifies the forward PWM pulse signal into a high-power shock wave signal through transformer coupling, and drives the underwater sound transducer to complete signal transmission; when the secondary coil is conducted with current, clamping circuits consisting of two anti-parallel diodes D2 and D3 are added at the two ends of the underwater sound transducer to limit the voltage amplitude of the backflow signal to protect the transformer.

In one embodiment, the band-pass filter circuit is configured to filter noise components in an irrelevant frequency band to obtain a clean target frequency signal; the band-pass filter circuit is provided with resistance values of a resistor R1, a resistor R2 and a resistor R3 and capacitance values of a capacitor C1 and a capacitor C2, and performance indexes are calculated according to the following formula to design the band-pass filter circuit;

（2）

（3）

（4）

the center frequency is calculated to be

The passband width is B, and the passband voltage amplification is +.>

。

Another object of the present invention is to provide an autonomous elevating underwater sound velocity measuring apparatus comprising: the device comprises an antenna, a floater, a connecting rod, an electronic cabin, a sound velocity measuring device, a releasing device and a weight;

the floating weight ratio of the floater to the counterweight is adjusted to enable the system to sink and float automatically after the measurement is finished; the antenna is arranged on the upper part of the floater and used for communicating with the outside; the floater is connected with the electronic cabin through a connecting rod; the sound velocity measuring device is arranged at the lower end of the electronic cabin; the sound velocity measuring device is connected with the weight through the releasing device.

In one embodiment, the electronic cabin is designed as a metal cabin body for installing the autonomous elevating underwater sound velocity measurement system.

By combining all the technical schemes, the invention has the advantages and positive effects that: on autonomous lifting, the invention is different from the measurement modes of cable connection such as throwing type, hanging type and the like, uses a trigger mechanical device to release, puts the device into an environment to be measured through the mechanical device to enable the device to descend at a constant speed, uses an electric control mechanical device to release a weight after a certain time and a certain depth of measurement are finished to enable the buoyancy of an object to be greater than gravity, and enables the device to float automatically and begin wireless data transmission communication after the device reaches the water surface.

In the data transmission communication mode, the data transmission mode is different from the cable data transmission communication of a common sound velocity meter, and is based on a wireless Wi-Fi mode. In the aspects of overall structure and hardware overall design of the system, the system has the advantages of low cost, low power consumption and high precision due to miniaturization, accurate plate making of the circuit board, proper component selection, no cable traction and wireless transmission. The invention can be matched with unmanned aerial vehicle to carry out rapid release in wide sea area, and can carry out rapid sound velocity measurement in large sea area in short time. The invention provides an autonomous lifting underwater sound velocity measuring instrument which is oriented to a new period ocean strategy, integrates factors such as measuring precision, power consumption, cost, miniaturization and the like of a system, and provides a key technology for measuring a sound velocity profile, and comprises sound velocity measurement, data communication transmission and an autonomous lifting device. The data transmission mode of the invention abandons high-cost and low-efficiency enameled wire transmission, and instead uses Wi-Fi wireless communication technology (with satellite communication reconstruction interface and SD card slot storage function), after data acquisition, the system automatically floats to the water surface to carry out wireless data transmission with receiver equipment such as unmanned aerial vehicle, deck unit and the like, thereby completing low-cost accurate measurement of ocean sound velocity profile in a specific area.

The invention uses high sampling rate ADC and high calculation force STM32F4 series chip as the guarantee of accuracy, reduces the systematic error and can realize the improvement of measurement accuracy. The invention can accurately customize the circuit board according to the required functions, select components with reasonable size and proper power for device assembly and arrangement, and realize miniaturization and low power consumption. The invention abandons a cable transmission mode with high cost and easy damage, reduces the cost and consumable materials of the system for the accurate selection of components meeting calculation force and the miniaturization of the system, and can realize low cost. Due to the low-cost characteristic of the invention, the unmanned aerial vehicle can be used for carrying out fixed point throwing in a large range and rapidly in the sea area to be measured, so that the sound velocity data of the large range sea area can be rapidly obtained, and the wide measuring range and high speed can be realized. The invention has low manufacturing cost and excellent and accurate measuring and calculating result, so that the scheme is widely applied to the fields of sound velocity measurement, observation of sound velocity profile, marine scientific research, marine environment monitoring, underwater navigation positioning and underwater target detection.

The invention solves the problem of single data transmission mode after sound velocity measurement, and can introduce wireless transmission into the system of the invention; meanwhile, the invention solves the problems of high cable cost and inconvenient throwing equipment in sound velocity measurement. The invention solves the technical problem of using cables in the traditional sound velocity measurement, and provides a new thought for the research and development of sound velocity measuring devices.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the disclosure and together with the description, serve to explain the principles of the disclosure.

FIG. 1 is a schematic view of an autonomous elevating underwater sound velocity meter provided by an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a sound velocity measurement device according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of an autonomous elevating underwater sound velocity measurement system provided by an embodiment of the present invention;

FIG. 4 is a diagram of a minimum system architecture of a main control chip system according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of an inverting circuit provided by an embodiment of the present invention;

FIG. 6 is a circuit diagram of a signal transmission circuit for driving an underwater acoustic transducer by coupling and amplifying a forward PWM pulse signal into a high-power oscillating wave signal by a transformer by the power amplifier provided by the embodiment of the invention;

FIG. 7 is a diagram of a clamping circuit for receiving a larger voltage across the transducer when the secondary winding is turned on in accordance with an embodiment of the present invention;

FIG. 8 is a diagram of an equivalent circuit for impedance matching of a transducer provided by an embodiment of the present invention;

fig. 9 is an amplifying circuit diagram of a triode according to an embodiment of the present invention;

FIG. 10 is a diagram of a bandpass filter circuit provided by an embodiment of the invention;

FIG. 11 is a schematic diagram of second order bandpass filtering provided by an embodiment of the invention;

FIG. 12 is a shaping and amplifying circuit diagram provided by an embodiment of the present invention;

FIG. 13 is a graph showing the effect of an oscillatory wave signal in an experiment according to an embodiment of the present invention;

FIG. 14 is a graph of the signal effect after shaping in an experiment provided by an embodiment of the present invention;

in the figure: 1. an antenna; 2. a float; 3. a connecting rod; 4. an electronic cabin; 5. a sound velocity measuring device; 5-1, an underwater acoustic transducer; 5-2, a reflector; 6. a release device; 7. a weight; 8. a power module; 9. a wireless communication module; 10. a master control core; 11. a lifting control module; 12. a transmitting module; 13. a receiving module; 14. a transducer module.

Detailed Description

In order that the above objects, features and advantages of the invention will be readily understood, a more particular description of the invention will be rendered by reference to the appended drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The invention may be embodied in many other forms than described herein and similarly modified by those skilled in the art without departing from the spirit or scope of the invention, which is therefore not limited to the specific embodiments disclosed below.

The embodiment of the invention provides an autonomous lifting underwater sound velocity measuring method, which comprises the following steps: and measuring the reflected echo time delay at a fixed distance by using an underwater sound velocity measuring device, and calculating real-time underwater sound velocity data by using a pulse time method from the measured reflected echo time delay by a CPU of the main control core.

The pulse time method comprises the following steps: when the sound velocity measuring device measures, the underwater sound transducer emits a high-frequency pulse, a reflector baffle is arranged at a position far away from the underwater sound transducer L, and the high-frequency pulse is received by the underwater sound transducer after being reflected by the reflector; the CPU of the main control core directly calculates the sound velocity by measuring the reflection echo time delay of the underwater sound transducer 5-1 at a fixed distance, and the calculation formula is as follows:

（1）

wherein ,

the time difference from pulse transmission to reception is in seconds, L is in meters, and c is the underwater sound velocity of the underwater sound transducer 5-1 at a fixed distance, in meters/second.

Example 1 as shown in fig. 1, the whole system is composed of an antenna 1, a float 2, a connecting rod 3, an electronic cabin 4, a sound velocity measuring device 5, a releasing device 6, and a weight 7. The system is made to sink and float up independently after the measurement is finished by adjusting the floating weight ratio of the floater 2 and the counterweight 7. An antenna 1 is installed at an upper portion of the float 2 for communication with the outside; the floater 2 is connected with the electronic cabin 4 through a connecting rod 3; the sound velocity measuring device 5 is arranged at the lower end of the electronic cabin 4; the sound speed measuring device 5 is connected to a weight 7 via a release device 6.

The system is initially put into water and descends at a certain speed, sound velocity measurement is carried out while data are stored, the weight 7 is released at a preset depth through the mechanical depth-fixing release device 6 or the electric control electromagnetic release device, the buoyancy of the system is larger than gravity at the moment, the system rapidly floats out of the water, data communication transmission is carried out between the system and a water surface platform or an unmanned plane through wireless communication of the antenna 1, and sound velocity profile measurement of the node is completed.

As shown in the schematic structural diagram of the sound velocity measuring device 5 provided by the embodiment of the invention in fig. 2, the invention adopts a pulse time method to measure, when in measurement, the transmitting-receiving integrated underwater acoustic transducer 5-1 transmits a high-frequency pulse, a reflector baffle is arranged at a position away from the transducer L, and the high-frequency acoustic pulse is received by the underwater acoustic transducer 5-1 after being reflected by the reflector 5-2. The sound velocity is directly calculated by measuring the time delay of the reflected echo of the transmitting transducer at a fixed distance, and the calculation formula of the scheme is as follows:

（1）

wherein ,

the time difference from pulse transmission to reception is in seconds, L is in meters, and c is the underwater sound velocity of the underwater sound transducer 5-1 at a fixed distance, in meters/second. The method is an absolute calibration method for acquiring sound velocity, and factors influencing sound velocity results mainly comprise a distance value and a time value of sound pulse advancing. In order to obtain an accurate sound velocity value, it is first necessary to obtain an accurate distance +. >

And corresponding acoustic propagation time difference +.>

. This distance and time may be from transmission to reception or some small fraction in between.

As shown in the overall architecture of the autonomous lifting underwater sound velocity measurement system provided by the embodiment of the present invention in fig. 3, the autonomous lifting underwater sound velocity measurement system realizes corresponding functions based on an STM32F4 processor, and includes: the sound velocity measuring device comprises a power module 8, a wireless communication module 9, a main control core 10, a lifting control module 11, a transmitting module 12, a receiving module 13 and a transducer module 14, wherein the transducer module 14 can adopt the sound velocity measuring device 5. The power module 8 converts a part of 24V DC power supply into DC 5V to supply power to the wireless communication module 9 and the receiving module 13, DC 3.3V to supply power to the main control core 10 and DC 24V to supply power to the transducer module 14. The main control core controls the working logic of the transmitting module 12, the receiving module 13 and the lifting control module 11, and after a certain instruction is obtained, the transmitting module 12 and the receiving module 13 perform transmitting/receiving processing on the signals of the transducer module 14.

(1) STM32F4 is a high performance family of microcontrollers. The method adopts a Non-Volatile Memory (NVM) process of 90nm and an Adaptive Real-time Memory Accelerator (ART) technology, is compatible with STM32F2 series products, is convenient for users to expand or upgrade products, and maintains the compatibility of hardware; multiple advanced high performance bus (Advanced High performance Bus, AHB) matrix and multi-channel direct memory read: the program execution and the parallel data transmission processing are supported, and the data transmission rate is very fast; the pulse width modulation technology (Pulse Width Modulation, PWM) high-speed timer reaches 168MHz, and meets the requirements of high-frequency sound pulses.

In terms of system architecture, a single-core embedded design scheme taking an advanced simplified instruction set machine (Advanced RISC Machine, ARM) as a core processor is determined, a Cortex-M4 core is selected as a core for system control and operation processing, so that the calculation force requirement of real-time signal processing is met, the purpose of system miniaturization design is achieved, and the cost performance is high.

In terms of the selection of the chip and other components of the master control core 10, on the premise of meeting the system performance requirements, the packaging and the size of the chip and the complexity of the corresponding peripheral circuit are mainly analyzed. For example, STM32F4 series meeting the design requirement of a main control chip of a system comprises a plurality of sub-series and different packaging forms, so that the sub-series with redundant I/O output interfaces and unnecessary advanced peripheral functions can be eliminated on the premise of guaranteeing the basic function of the chip, and STM32F405RGT6 with fewer output pins and small packaging is selected; selecting a low-noise double operational amplifier integrated operational amplifier AD8052 to design a second-order band-pass filter; the Wi-Fi module selects a common ESP8266 module. Thanks to the compact peripheral circuits of the modules, the power consumption and the circuit design of the system are optimized as a whole.

And in the aspects of designing and drawing the circuit board, the layout is reasonably planned, the wiring density is improved by adopting a multi-layer board design, and the shape of the circuit board is optimized to further save the board-level space of the system.

(2) For the transmitting module 12 and the transducer module 14, by configuring the TIM2 of STM32F4, the PWM pulse signal of a specific frequency, a specific duty ratio and a specific signal peak-peak value is driven to be transmitted, and is converted into a forward pulse after being processed by the inverting module, finally, the forward PWM pulse is coupled and amplified by the transformer, so as to drive the underwater acoustic transducer 5-1 of the acoustic velocity measuring device 5 to complete signal transmission, and considering the miniaturization design principle of the system, the underwater acoustic transducer with the model DYW-500-E corresponding to a high working frequency is selected (the higher the working frequency is, the smaller the transducer size is, which is determined by the physical characteristics of the underwater acoustic transducer 5-1 itself, and the underwater acoustic transducers with different models can be selected according to the working frequency setting).

(3) For the receiving module 13, the underwater echo sound signal and noise generated by the background are converted into weak electric signals by the underwater echo sound transducer 5-1, the signals are amplified indiscriminately by the triode amplifying circuit, the amplified signals are filtered out of signals with required frequency bands by the second-order active band-pass filtering amplifying circuit, the signals are shaped by the shaping circuit and are subjected to certain-degree pulling-up processing, the signals are finally input into the system through pins of the circuit, the analog-digital converter (Analog to Digital Converter, ADC) is synchronously started for signal acquisition, the DMA function is enabled to assist in completing signal transmission, and the DMA transmission copies data from the output of the ADC to a storage address space.

When the CPU of the master core 10 initiates this transfer action, the transfer action itself is carried out and completed by the DMA controller. Here a double buffering (ping-pong) scheme in DMA mode is employed. Firstly, a RAM is opened up, the RAM is divided into two data storage areas buffer_1 and buffer_2 with the same size, when the buffer_1 reaches the upper limit of the DMA transmission data quantity, the DMA can send an interrupt to the CPU, and the corresponding interrupt service function judges which data storage area is about to overflow. At this time, the CPU directs the target Buffer of the DMA to buffer_2 (where the CPU reconfigures a part of parameters of the DMA, i.e. a start address of the newly directed Buffer 2, a transmission data length, etc.), and completes the real-time processing of the data in buffer_1. The signal processing must be completed before the data in buffer_2 overflows (i.e., before the data in a newly acquired memory area is transferred). When the DMA reaches the upper limit of the storage, the DMA sends a new interrupt to the CPU, and the data is circularly and alternately collected, stored and processed, so that the real-time processing of the data is realized. Such as moving blocks of external memory to faster memory areas within the chip. Operations such as this do not hold the processor work off, but may be rearranged Cheng Quchu to handle other work. DMA transfer is important for high performance embedded system algorithms and networks. The acquisition mode does not occupy CPU function, so that a single-core CPU can detect the peak value threshold value of the echo signal, fifty sampling points are extracted at the peak value and are larger than a set threshold value to judge whether the signal is to be acquired or not, and finally, an accurate sampling point is selected to determine the accurate time difference between the transmitted signal and the received signal, and time data are transmitted in a circuit board. And finally, carrying out digital signal processing on the main chip, and calculating real-time underwater sound velocity data according to speed calculation shown in a formula (1).

In the embodiment of the invention, the STM32F405RGT6 microprocessor is used as a speed measuring system and a main control chip and a signal processing platform, so that the access from 8 main control buses (connected with main control equipment) to 7 controlled buses (connected with slave equipment) can be realized, and the system can be accessed in parallel under the condition that a plurality of high-speed peripherals work simultaneously, thereby realizing the high-efficiency operation of the system.

Through the AD module of the advanced peripheral bus connection equipment of the APB1 (Advanced Peripheral Bus), the Contex_M4 main chip wakes up the GP DMA1 through the bus matrix, and the DMA starts to continuously work, and receives and stores the transmitted data under the condition of not affecting the Contex_M4 main chip to select and operate the data.

In order to realize the design principle of miniaturization and low power consumption of the system, the STM32F405RGT6 (with LQFP64 packages and 64 pins) with the smallest package in the STM32F4 series is finally selected as the main control chip of the main control core 10, the schematic diagram of the minimum system circuit matched with the main control chip is shown in fig. 4, and the upper parts are marked with VDD, VSS, VDDAVERF + and VSSAVERF-which are respectively connected with the corresponding chip power supply voltage and ground; the PA1 pin is responsible for outputting PWM1 waveforms of corresponding frequencies of the excitation transducer, and the PA2 pin is responsible for driving the AD2 to perform data acquisition so that the main chip performs data analysis and processing; the PA4-PA7 pins are 4 pins required by SPI communication, namely NSS chip selection signals, SCK clock signals, MISO master-slave transmission and MOSI master-slave transmission and reception respectively, and the four pins are connected with an external Memory FLASH1 (FLASH Memory) Memory for sound velocity data storage; the PA9 and the PA10 are used for transmitting and receiving information of the serial port 1 and are responsible for 232 communication; PA13, PA14 are program download debug ports, connect JTMS/SWDIO, JTCK/SWCLK separately, insert J-Link downloader carry on the erasure of the system program; the PC6 and the PC7 are used for transmitting and receiving information of the serial port 6 and are responsible for wireless communication; PB0-PB2 is a wireless transceiver module control port, and the module mode is regulated and controlled by outputting corresponding high and low levels; PB8 and PB9 are IIC communication protocol ports, and are in data communication with the temperature and pressure sensor, so that data of registers in the temperature and pressure sensor are transmitted to the main chip; PB12-PB15 are also four pins of SPI communication, which are connected to FLASH2 for temperature and pressure data storage.

The general timer TIM2 inside STM32F4 is configured, the register tim2_ccr1 is modified to achieve Pulse width control, and tim2_ch1 is remapped to pin PA1 (here the frequency is adjusted by setting the value of the register, the duty cycle is adjusted by tim_pulse), and PWM square wave pulses (here 8 pulses are set to be generated once) with a frequency of 500KHZ and a duty cycle of 50% are generated as initial transmission signals. The generated PWM level information is led out from a chip PA1 pin, and can be measured and observed by using an oscilloscope, wherein VDD is a power supply pin.

In the embodiment of the present invention, the transmitting module 12 of the system is responsible for the function of signal inversion and transformer amplification of the generated transmitting signal. PWM pulse signals generated by a microprocessor (Micro programmed Control Unit, MCU) are coupled and amplified by a Schmidt inverter and a transformer in sequence to finally drive the underwater acoustic transducer 5-1 to finish signal transmission.

In the embodiment of the invention, the power module 8 of the system adopts a single power supply mode, and the ADC inside the STM32F4 is used for completing signal acquisition, so that only signals with positive voltage amplitude can be acquired. The MCU generates a negative PWM pulse signal, so that an inverting module is required to be designed for converting negative pulse into positive pulse signal in order to facilitate the subsequent AD sampling and signal processing.

As shown in the schematic diagram of the reverse circuit of FIG. 5, the reverse circuit is made of NC7SZ14P5X chip as a single-channel inverter with Schmitt trigger input, and is manufactured by adopting a CMOS process, can finish high-output driving at an ultra-fast speed, and can keep lower static power consumption in a normal working voltage range. The rated working voltage range of the device is 1.65V to 5.5V, the single power supply VCC=5V is adopted for power supply, and the input end of the chip can bear 6V voltage at maximum. PWM wave is input into the chip by the A pin, and is output by the Y pin after the chip is reversed, so that signals become positive values. The PWM waveform output by the PA1 pin of the main control chip is firstly reversed and triggered by the NC7SZ14P5X chip, and the PWM waveform is output to the signal transmission element from the No. 4 pin after being pulled up.

The underwater acoustic transducer 5-1 needs to be driven with up to several tens to several hundreds volts to normally complete signal transmission, and thus a power amplification function needs to be introduced. The transformer is used as an electromagnetic element, and changes voltage output by utilizing the principle of electromagnetic induction, so that the transformer is widely applied to aspects of impedance transformation, matching, isolation and the like of a circuit. The system adopts 24V direct current to supply power to the transformer, and the transformer is opened and closed by controlling a field effect transistor (MOSFET) which is used as a switch of the transformer, wherein the MOSFET is a semiconductor device working by utilizing a field effect principle, and compared with a transistor, the system has the characteristics of high input impedance, small driving power, high switching speed, no secondary breakdown, pure resistance of the conduction characteristic, low power consumption, easiness in integration and the like. When the MOSFET is applied to a switching circuit, the MOSFET can completely replace a common transistor, so that the MOSFET is selected as a switch of the transformer coupling amplifying module.

In the principle of the power amplification circuit shown in fig. 6, the power amplifier couples and amplifies the forward PWM pulse signal into a high-power oscillating wave signal through a transformer, so as to drive the underwater acoustic transducer to complete signal transmission. P2 is the primary coil side of the transformer, 24V power supply is controlled by a Q1 field effect transistor UMW7N65, when a signal passes through a trigger and reaches the source stage of the field effect transistor, the source is connected with the field effect transistor when the signal exists, 24V direct current voltage is connected with the ground after RC filtering, and the transformer is output. When the secondary coil is conducted with current, the two ends of the transducer bear larger voltage, a clamping circuit (as shown in fig. 7, which consists of two anti-parallel diodes D2 and D3) is added, and the voltage amplitude of the reflux signal is limited to protect the transformer; the figure shows a circuit on the right side of the transformer, and a transmitting signal is output in high voltage after being transformed by the transformer, so that a self-transmitting and self-receiving transducer used in the system can reasonably transmit and receive ultrasonic signals.

(4) In the embodiment of the invention, the model DYW-500-E of the underwater acoustic transducer 5-1 which is temporarily used by the transducer module 14 of the system belongs to a piezoelectric ceramic transducer. As can be seen from the maximum output power theorem, when the input power source is matched with the load, the maximum output power can be obtained; when the impedance difference between the load and the power amplification module is large, the large output power cannot be obtained, so that the output efficiency is low, and circuit elements are seriously burnt. The load of the underwater acoustic transducer as a power amplification module, whether a magnetostrictive transducer or a piezoelectric transducer used in the invention, is not a purely resistive load. The purpose of impedance matching is therefore to transform the reactance of the load into a resistance to increase the power factor across the load. The invention adopts the series-parallel matching inductance to change the impedance characteristic of the load, as shown in the equivalent circuit of the impedance matching of the transducer in fig. 8, the resistance value of the transducer is very high and belongs to a capacitive load, and the direct driving of the power amplifier cannot be performed, so that the impedance matching is required. The impedance matching mainly uses tuning matching, which converts the capacitive load of the power amplifier into a resistive load, so that the effective power on the load is maximized, and the impedance matching is often completed by using a resonance method.

(5) In the embodiment of the present invention, the receiving module 13 of the system needs to perform functions such as triode amplification, band-pass filter amplification, waveform shaping, etc. Because of adopting the design of receiving and transmitting combination, in order to prevent the sending signal with larger voltage amplitude from directly damaging the amplifying circuit module, a clamping protection circuit (consisting of two anti-parallel diodes) is added at the front stage of the module, so that the signal amplitude received by the underwater sound transducer is limited within 1V. First, the received signal is amplified, and a triode amplifying circuit is shown in fig. 9, and the part of the circuit is a receiving amplifying part. When the self-receiving transducer transmits the received signal to the circuit (trans+), the received signal is processed IN the next step after passing through a common emission amplifying circuit consisting of MMBT9018H triode, and the processed signal is SIG_IN.

And a transistor MMBT9018H is selected to build a resistance-capacitance coupling co-emission amplifying circuit. As shown in fig. 9, a signal is applied between the base (B pole) and the emitter (E pole) of the transistor in the form of a voltage through a coupling capacitor C91, and passes through the B pole and the E pole in the form of a current, and electrons (negative charges) are transferred in the direction of the E pole to the B pole. VCC5 and R15 are used to provide proper forward bias at the junctions of the B and E poles and current that can drive the transistor into a linear operating region. VCC5 and R14 are used to provide proper reverse bias of the base and collector (C-pole) junctions, and the electron (negative charge) transfer direction is B-pole to C-pole. The C-pole collects a large number of electrons (negative charges), and a few holes (positive charges) drift to the B-pole and recombine with the holes of the B-pole to partially recombine electrons (negative charges) from the E-pole to the C-pole. Since the electron concentration of the E-pole is greater than that of the B-pole, the power supply brings a large number of electrons from the E-pole to the B-pole and then to the C-pole while supplementing holes. The triode completes the amplifying current function, the amplified signal current generates voltage drop on the C electrode through the R14, the voltage drop is the signal voltage of the output end, and finally, the signal output is completed through the coupling of the capacitor C20.

The background noise of the underwater acoustic channel is strong, the multi-path effect is complex, and other factors influence, the echo signals received by the transducer can be superimposed with other frequency components or noise, and after the echo signals are amplified indiscriminately by the triode, the noise of irrelevant frequency bands is correspondingly amplified. In order to facilitate subsequent sampling and signal processing, the part filters out noise components of irrelevant frequency bands by designing an analog filter, so that a pure target frequency signal is obtained. The AD8052 is selected as an integrated operational amplifier chip, is a low-cost, high-speed and voltage feedback type amplifier, and has the characteristics of low distortion and high speed and stability, so that the design requirement of an active filter can be well met. The band-pass filter circuit is shown IN fig. 10, and the sig_in signal is output by a pin 6-IN 2 and a pin 1 OUT1 through a dual-core integrated operational amplifier chip consisting of an AD8052 chip, so that the sig_out signal is finally obtained. The chip and its designed peripheral circuit constitute the band-pass filter of the system, and the design makes the active filter have low cost, high speed, reasonable gain bandwidth product and slew rate. For ease of analysis, fig. 10 is simplified to fig. 11, and fig. 11 is a schematic diagram of a bandpass filter design, according to which we have designed a negative feedback infinite gain bandpass filter based on an op-amp chip in this example. Setting resistance values of a resistor R111, a resistor R112 and a resistor R113 and capacitance values of a capacitor C111 and a capacitor C112 in a circuit diagram shown in a second-order band-pass filtering principle diagram, and calculating performance indexes according to the following formula to design a filter;

（2）

（3）

（4）

The center frequency is calculated to be

The passband width is B, and the passband voltage amplification is +.>

。

Since the system's transmit signal frequency is 500KHZ, the target frequency for receiving the echo signal is also 500KHZ. The theoretical parameters of the filter obtained by calculating the resistor R11 and the resistor R13 in fig. 10 to be equal to the resistor R10 and the resistor r12=5.6kΩ, the resistor R20 and the resistor R21 in fig. 10 to be equal to 51kΩ, and the capacitor c111=capacitor c112=27 pF in fig. 11 are as follows: center frequencyf ₀ =493.28KHZ passband widthB= 231.16KHZ, passband voltage amplificationA _uo =4.55。

In order to improve the accuracy of the subsequent A/D sampling precision and the accuracy of a threshold detection algorithm, the signals passing through the band-pass filtering and amplifying module are further processed, shaped into signals with prominent peaks and subjected to a certain degree of pull-up processing. As shown in fig. 12, the logarithmic amplification module selects a logarithmic amplifier AD8310 with high-speed voltage output. The chip has good stability and wide dynamic range, is suitable for pulse modulation and power control in various directions, and has low power consumption, small volume and low cost. In addition, the response time of the AD8310 is fast, the driving load capacity is strong, the circuit is very suitable for circuits requiring the attenuation of signals to decibel level, the operational amplifier module selects a low-power operational amplifier MCP6001 which has a gain bandwidth of 1MHz and a phase margin of 90 degrees, single power supply can be adopted for power supply, the power supply voltage range is 1.8V to 5.5V, the minimum power supply current is only 100 mu A, the signals are input from an INHI pin of the AD8310, and the signals are amplified again through the operational amplifier MCP6001 powered by the power supply after being output by the high-speed voltage of the chip, so that the effective signals with prominent peak values are finally obtained. The collected signals are input into an AD8310 logarithmic amplification module through a SIG OUT after passing through a band-pass filter circuit, and the signals output by the module are continuously input into an operational amplifier MCP6001 and amplified again to achieve the shaping purpose. The shaping amplifying circuit is shown in fig. 12, and in order to improve the accuracy of the subsequent a/D sampling precision and the accuracy of the threshold detection algorithm, the signal after the band-pass filtering is shaped to be pulled up to a certain extent. The partial circuit is mainly input by the INHI pin and the VOUT pin of the integrated chip AD8310, and is used as logarithmic amplification and the operational amplifier MCP6001 as an operational amplifier. And finally, outputting SIG_AD signals, carrying out A/D conversion on the signals entering the PA2 pin of the main chip, and then calculating.

In the embodiment of the invention, in order to solve the anti-interference problem, the electronic cabin 4 is designed as a hardware circuit system inside the metal cabin protection system, and the metal cabin has better shielding capability and can reduce electromagnetic interference in an external working environment. In order to further improve the anti-interference capability of the system, the following measures are adopted for circuit design:

(1) the filtering and amplifying module adopts the modes of hierarchical filtering, virtual grounding and the like to reduce the interference of external noise sources, and utilizes passive low-pass RC filtering to eliminate the aliasing noise of a high frequency band, so that the anti-interference capability is further improved;

(2) for the wiring design of the key module, the power line should be widened as much as possible, and a bypass capacitor is added at the power supply input end of the chip (the bypass capacitor should be placed as close to the chip as possible), so as to filter out ripple noise and create a good and pure power supply environment. Meanwhile, the key signal wires are kept at a certain distance from other nodes, the 3W principle is strictly followed (when the wire center distance is more than or equal to 3 times of the wire width, the mutual noninterference of 70% of the wire electric fields is ensured) so as to reduce the possibility of crosstalk and coupling between wires and improve the reliability of the system;

(3) for the adjacent plane routing of the PCB to form an orthogonal structure, the routing is prevented from forming acute angles or right angles, the turning is as smooth as possible, and the routing principle of short, smooth and flat is followed. In order to ensure the stability of the system, the power line and the power ground line are both thickened, and the minimum rule of the loop is required to be followed, so that the influence of external electromagnetic interference on the signal loop is reduced.

In embodiment 2, the data transmission mode of the system provided by the embodiment of the invention reserves two data transmission modes of SD card storage and satellite communication forwarding besides wireless data transmission communication, and can realize data transmission in different modes by simple modification according to requirements.

In the embodiment of the invention, the program can be correspondingly modified according to the conditions of different water areas, different pulse transmitting frequencies are determined, and then the transducers with different parameters are replaced, so that the modification is convenient.

It should be noted that, because the content of information interaction and execution process between the above devices/units is based on the same concept as the method embodiment of the present invention, specific functions and technical effects thereof may be referred to in the method embodiment section, and will not be described herein.

It will be apparent to those skilled in the art that, for convenience and brevity of description, only the above-described division of the functional units and modules is illustrated, and in practical application, the above-described functional distribution may be performed by different functional units and modules according to needs, i.e. the internal structure of the apparatus is divided into different functional units or modules to perform all or part of the above-described functions. The functional units and modules in the embodiment may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit, where the integrated units may be implemented in a form of hardware or a form of a software functional unit. In addition, the specific names of the functional units and modules are only for distinguishing from each other, and are not used for limiting the protection scope of the present invention. The specific working process of the units and modules in the above system may refer to the corresponding process in the foregoing method embodiment, which is not described herein again.

In the foregoing embodiments, the descriptions of the embodiments are emphasized, and in part, not described or illustrated in any particular embodiment, reference is made to the related descriptions of other embodiments.

Based on the above-described embodiments, the present invention further provides a computer apparatus, including: at least one processor, a memory, and a computer program stored in the memory and executable on the at least one processor, which when executed by the processor performs the steps of any of the various method embodiments described above.

Based on the above-described embodiments, the present invention also provides a computer-readable storage medium storing a computer program, which when executed by a processor, can implement the steps in the above-described method embodiments.

Based on the above-described embodiments, the present invention further provides an information data processing terminal, where the information data processing terminal is configured to provide a user input interface to implement the steps in the above-described method embodiments when implemented on an electronic device, and the information data processing terminal is not limited to a mobile phone, a computer, and a switch.

Based on the above-described embodiments, the present invention further provides a server for providing a user input interface to implement the steps in the above-described method embodiments when implemented for execution on an electronic device.

Based on the above-described embodiments, the present invention also provides a computer program product, which, when run on an electronic device, causes the electronic device to perform the steps of the respective method embodiments described above.

The integrated units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer readable storage medium. Based on such understanding, the present invention may implement all or part of the flow of the method of the above embodiments, and may be implemented by a computer program to instruct related hardware, where the computer program may be stored in a computer readable storage medium, and when the computer program is executed by a processor, the computer program may implement the steps of each of the method embodiments described above. Wherein the computer program comprises computer program code which may be in source code form, object code form, executable file or some intermediate form etc. The computer readable medium may include at least: any entity or device capable of carrying computer program code to a photographing device/terminal apparatus, recording medium, computer Memory, read-Only Memory (ROM), random access Memory (Random Access Memory, RAM), electrical carrier signals, telecommunications signals, and software distribution media. Such as a U-disk, removable hard disk, magnetic or optical disk, etc.

Based on the examples described above, the present invention conducted the following experiments, including: feasibility test is carried out on the equipment which is not packaged and is water-tightness processed, the main body of the system is not filled with water, only the underwater acoustic transducer is filled with water, and the test is carried out in a water tank with the height of 150 mm and the length of 450 mm. After the driving program is downloaded to the main control chip, the underwater sound transducer is vertically immersed in water.

An oscilloscope is used for sending a reverse polarity PWM pulse signal with the frequency of 500KHZ, the duty ratio of 50% and the cycle number of 8 to a PA1 pin of STM32F4, the reverse polarity PWM pulse signal is amplified into a high-power oscillating wave signal through a transformer module after passing through an inverter, and the output effect of the oscilloscope is shown in figure 13.

And after the acoustic signals emitted by the transducer collide with the reflecting wall, the acoustic signals are reflected to generate echo signals and are received by the transducer, and the acoustic signals are converted into electric signals and then transmitted to the receiving module. The sound velocity is calculated through the steps of sampling after amplification, filtering and shaping treatment of a receiving module, obtaining a time difference through threshold monitoring, and finally solving the sound velocity.

As can be seen in fig. 14, the amplitudes of the three shaped signal waveforms decrease in sequence, which is consistent with theory. The three signal peaks (from left to right) in fig. 14 are the results of the shaping and amplifying treatment of the transmitted signal, the primary echo and the secondary echo, respectively, and it can be seen that the peak heights of the three signals are also gradually reduced to reach the expected result.

According to the echo waveform in fig. 14, the program of using the threshold detection method and the averaging of multiple measurements is programmed inside the chip, and the calculated data is read out directly on the computer through the RS485 interface port.

While the invention has been described with respect to what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Claims

1. An autonomous elevating underwater sound velocity measurement method, characterized in that the autonomous elevating underwater sound velocity measurement method comprises: the method comprises the steps that a sound velocity measuring device (5) positioned under water is used for measuring the reflected echo time delay at a fixed distance, and a CPU (central processing unit) of a main control core (10) processes the measured reflected echo time delay through a pulse time method to calculate real-time underwater sound velocity data.

2. The autonomous elevating underwater sound velocity measurement process of claim 1, wherein the pulse time method comprises: when the sound velocity measuring device (5) measures, the underwater acoustic transducer (5-1) emits a high-frequency pulse, a reflector baffle is arranged at the L position far from the underwater acoustic transducer (5-1), and the high-frequency pulse is received by the underwater acoustic transducer (5-1) after being reflected by the reflector (5-2); the CPU of the main control core (10) directly calculates the sound velocity by measuring the reflection echo time delay of the underwater sound transducer (5-1) at a fixed distance, and the calculation formula is as follows:

（1）

wherein ,

3. The autonomous lifting underwater sound velocity measurement method according to claim 2, wherein in the real-time underwater sound velocity data calculated by the CPU of the master control core (10) using the pulse time method for the measured reflected echo time delay, the CPU cooperates with the DMA (Direct Memory Access) direct memory access controller to process the sound velocity data, comprising: dividing a RAM (Random Access Memory) random access memory carried by a DMA controller into two data storage areas buffer_1 and buffer_2 with the same size, and when the buffer_1 reaches the upper limit of the DMA transmission data quantity, sending an interrupt to a CPU by the DMA, and judging which data storage area is about to overflow in a corresponding interrupt service function;

the CPU directs the target Buffer of the DMA to buffer_2 and simultaneously completes the real-time processing of the data in the buffer_1; when the DMA reaches the upper limit of storage for the data transmitted by the buffer_2, a new interrupt signal is sent to the CPU, and the data is circularly and alternately collected, stored and processed to realize real-time processing of the data; in the peak threshold detection of echo signals by a CPU, fifty sampling points are extracted at the peak and are larger than a set threshold to judge whether the signals are to be taken or not, and finally, the accurate sampling points are selected to determine the accurate time difference between the transmitted signals and the received signals, the time data are transmitted in a circuit board of a main control core (10), digital signal processing is carried out, and real-time underwater sound velocity data are calculated by using a formula (1).

4. The autonomous lifting underwater sound velocity measurement method according to claim 1, wherein after the CPU of the master control core (10) calculates real-time underwater sound velocity data from the measured reflected echo time delay by using a pulse time method, the weight (7) is released at a predetermined depth by the control release device (6), the buoyancy is greater than the gravity, and the water surface is floated; and carrying out data wireless communication transmission with a water surface platform or an unmanned aerial vehicle through an antenna (1) to finish acoustic velocity profile measurement of a preset depth under water.

5. An autonomous elevating underwater sound velocity measurement system, wherein the autonomous elevating underwater sound velocity measurement method of any of claims 1 to 4 is implemented, the autonomous elevating underwater sound velocity measurement system comprising: the device comprises a power supply module (8), a wireless communication module (9), a main control core (10), a lifting control module (11), a transmitting module (12), a receiving module (13) and a transducer module (14);

the power supply module (8) is used for providing power supply for each power utilization module;

the transducer module (14) is used for measuring the reflection echo time delay at a certain fixed distance under water;

the receiving module (13) is used for receiving the reflected echo time delay data;

The main control core (10) is used for calculating the reflected echo time delay and calculating real-time underwater sound velocity data; and sends the floating instruction to a wireless communication module (9) and a lifting control module (11);

the transmitting module (12) is used for solving the real-time underwater sound velocity data by the main control core (10) and transmitting the real-time underwater sound velocity data to the transducer module (14);

the wireless communication module (9) is used for communicating the measurement data of the main control core (10) with external equipment;

the lifting control module (11) is used for executing the floating instruction of the main control core (10).

6. The autonomous elevating underwater sound velocity measurement system according to claim 5, wherein the transmitting module (12) is configured with a TIM2 counter of STM32F4, drives and transmits PWM pulse signals of set frequency, duty cycle and signal peak-peak value, converts the PWM pulse signals into forward pulse after processing by the inverting module, and finally, the forward PWM pulse signals are coupled and amplified by the transformer, and drives the underwater sound transducer (5-1) of the sound velocity measurement device (5) to complete signal transmission;

the receiving module (13) uses the triode amplifying circuit to carry out indifferently amplification on the signal sent by the underwater acoustic transducer (5-1), the amplified signal is filtered out by the second-order active band-pass filtering amplifying circuit, the signal is shaped by the shaping amplifying circuit and is pulled up, finally, the signal is input to the band-pass filtering circuit through the pin of the triode amplifying circuit, the analog-digital converter is synchronously started to carry out signal acquisition, the DMA function is enabled to assist in completing signal transmission, and the DMA transmission copies data from the output of the ADC to a storage address space.

7. The autonomous elevating underwater sound velocity measurement system according to claim 6, wherein the triode amplifying circuit amplifies the forward PWM pulse signal into a high-power oscillating wave signal through transformer coupling, and drives the underwater sound transducer to complete signal transmission; when the secondary coil is conducted with current, two ends of the underwater sound transducer are added with a clamping circuit consisting of two anti-parallel diodes P and a diode D3, and the voltage amplitude of the backflow signal is limited to protect the transformer.

8. The autonomous elevating underwater sound velocity measurement system of claim 6, wherein the bandpass filter circuit is configured to filter out noise components in irrelevant frequency bands to obtain a clean target frequency signal; the band-pass filter circuit is provided with resistance values of a resistor R1, a resistor R2 and a resistor R3 and capacitance values of a capacitor C1 and a capacitor C2, and performance indexes are calculated according to the following formula to design the band-pass filter circuit;

（2）

（3）

（4）

the center frequency is calculated to be

The passband width is B, and the passband voltage amplification is +.>

。

9. An autonomous elevating underwater sound velocity measurement apparatus, wherein the autonomous elevating underwater sound velocity measurement method according to any one of claims 1 to 4 is implemented, the autonomous elevating underwater sound velocity measurement apparatus comprising: the device comprises an antenna (1), a floater (2), a connecting rod (3), an electronic cabin (4), a sound velocity measuring device (5), a releasing device (6) and a weight (7);

The floating weight ratio of the floater (2) to the counterweight (7) is adjusted to enable the system to sink and float automatically after the measurement is finished; the antenna (1) is arranged at the upper part of the floater (2) and is used for communicating with the outside; the floater (2) is connected with the electronic cabin (4) through the connecting rod (3); the sound velocity measuring device (5) is arranged at the lower end of the electronic cabin (4); the sound velocity measuring device (5) is connected with the weight (7) through the releasing device (6).

10. Autonomous up-down underwater sound velocity measuring instrument according to claim 9, characterized in that the electronic cabin (4) is designed as a metal cabin for mounting the autonomous up-down underwater sound velocity measuring system according to claim 5.