An ADCP calibration system

Abstract

The application discloses an ADCP calibration system. The ADCP sends a measurement signal or an analog echo through a signal transceiving module. A mode switching judgment module switches a measurement signal sending mode to an analog echo module according to a mode switching instruction. The analog echo module forwards the measurement signal to an echo simulation module or receives a mode switching instruction to send an analog echo. The echo simulation module generates an analog echo according to the received measurement signal and sends the analog echo to the analog echo module. The land calibration system can calibrate the ADCP on land and in a laboratory, greatly reducing the expenditure of manpower and material resources and being convenient and fast. In addition, the flow environment and acoustic characteristics obtained during calibration in an actual water area are relatively single, and the calibration system can simulate target echoes with different flow rate parameters according to needs, so that more comprehensive calibration of the ADCP is realized.

Description

Technical Field

[0001] This invention relates to the field of calibration system technology, and more particularly to an ADCP calibration system. Background Technology

[0002] The marine environment is complex and ever-changing, especially underwater currents, which directly affect the underwater maneuverability of submarines. Accurate prediction and understanding of the current field structure in specific sea areas are of great significance. Self-contained acoustic Doppler current profilers (ADCPs), as an important component of underwater buoy systems, utilize the Doppler frequency shift and delay of echoes from scattered bodies in the water. They can not only measure the velocity of water layers at different depths in a current profile but also effectively calculate water depth, and are widely used in marine engineering fields such as underwater navigation, hydraulic monitoring, and ocean observation. However, ADCPs often operate in harsh underwater environments; changing pressure, temperature, water infiltration, and corrosion all affect their performance. Therefore, calibrating the ADCP system is crucial to ensuring it remains in optimal condition.

[0003] Currently, ADCP calibration is performed in deep waters using actual vessels. The advantage of this method is that the testing environment is closer to reality, and the ADCP can obtain realistic echo signals. However, its disadvantages are obvious: measurements in deep waters are costly, requiring significant manpower and resources, and a single measurement can only calibrate the ADCP's performance for a short period, making it impossible to perform continuous calibration and debugging of the system. Summary of the Invention

[0004] This invention provides an ADCP calibration system that solves the technical problems of high measurement costs, large manpower and material resources consumption, and the inability to calibrate and debug the system at any time by providing an ADCP calibration system. It achieves the technical effect of reducing calibration costs and improving calibration efficiency.

[0005] This invention provides an ADCP calibration system, comprising:

[0006] The signal transceiver module is used to receive measurement signals sent by the ADCP or to send analog echoes.

[0007] The mode switching judgment module is used to send a mode switching command to the analog echo module according to the measurement signal;

[0008] The simulated echo module is used to forward the measurement signal to the echo simulation module or receive the mode switching command and send a simulated echo.

[0009] The echo simulation module is used to generate the simulated echo based on the received measurement signal and send it to the simulated echo module.

[0010] Specifically, the signal transceiver module includes: a transmitter SMA connector, a receiver SMA connector, a first resistor, a second resistor, a third resistor, an operational amplifier, a first diode, a second diode, a third diode, a fourth diode, and a single-pole double-throw switch; the first interface of the transmitter SMA connector is connected to the echo transmission interface of the analog echo module, and the second interface of the transmitter SMA connector is connected to the first end of the first resistor; the second end of the first resistor is connected to the positive terminal of the operational amplifier; the first end of the second resistor is grounded, and the second end of the second resistor is connected to the negative terminal of the operational amplifier; the first diode and the second diode are connected in reverse parallel to form a transmission protection circuit; the first diode and the second diode are connected in reverse parallel to form a transmission protection circuit; the first diode and the second diode are connected in reverse parallel to form a single-pole double-throw switch. The first end of the three resistors is connected to the negative terminal of the operational amplifier, and the second end of the third resistor is connected to the output terminal of the operational amplifier. The first end of the transmit protection circuit is connected to the output terminal of the operational amplifier, and the second end of the transmit protection circuit is connected to the first terminal of the single-pole double-throw switch. The switching terminal of the single-pole double-throw switch is connected to the signal output terminal of the transducer. The switching control terminal of the single-pole double-throw switch is also connected to the switching signal output terminal of the control terminal. The third diode and the fourth diode are connected in reverse parallel to form a receive protection circuit. The second terminal of the single-pole double-throw switch is connected to the first end of the receive protection circuit, and the second end of the receive protection circuit is connected to the signal interface of the receiver SMA connector.

[0011] Specifically, the switching signal output terminal of the analog echo module is connected to the switching control terminal of the single-pole double-throw switch via a relay switch.

[0012] Specifically, the mode switching determination module includes:

[0013] A low-noise amplifier unit is used to amplify the measurement signal;

[0014] The envelope detection unit is used to detect the amplified signal to obtain the envelope signal.

[0015] The hysteresis comparison unit is used to compare the envelope signal with the comparison threshold, generate the mode switching command, and send it to the analog echo module.

[0016] Specifically, the hysteresis comparison unit includes:

[0017] A comparison subunit is used to compare the envelope signal with a comparison threshold.

[0018] The mode switching instruction generation subunit is used to generate the mode switching instruction and send it to the analog echo module if the envelope signal is greater than or equal to the comparison threshold.

[0019] Specifically, the simulated echo module includes:

[0020] A measurement signal forwarding unit is used to forward the measurement signal to the echo simulation module;

[0021] The echo storage unit is used to receive and store the simulated echo generated by the echo simulation module.

[0022] The analog echo transmission unit is used to receive the mode switching command, obtain the analog echo from the echo storage unit, and send it to the signal transceiver module.

[0023] One or more technical solutions provided in this invention have at least the following technical effects or advantages:

[0024] The land-based calibration system provided by this invention receives measurement signals from the ADCP or sends simulated echoes via a signal transceiver module. A mode switching judgment module sends a mode switching command to the simulated echo module based on the measurement signal. The simulated echo module then forwards the measurement signal to the echo simulation module or receives the mode switching command and sends a simulated echo. The echo simulation module then generates a simulated echo based on the received measurement signal and sends it to the simulated echo module. This allows for ADCP calibration on land and in laboratories, significantly reducing manpower and material costs while offering convenience and speed. Furthermore, calibration in actual water bodies yields relatively simple water flow environments and acoustic characteristics, while the calibration system can simulate target echoes with different flow velocity parameters as needed, achieving a more comprehensive calibration of the ADCP. Therefore, the land-based calibration system is of great significance in the practical production applications of ADCPs.

[0025] Furthermore, the present invention also has the following advantages:

[0026] 1. By generating reflected echoes from the measurement signals emitted by the ADCP in real time, instead of generating encoded signals, it is possible to avoid knowing the encoding method of the ADCP and measuring its actual frequency offset. This not only avoids the calibration error caused by the fixed frequency offset of the ADCP device itself, but also greatly saves workload. At the same time, this method is more stable and has stronger applicability, and theoretically it can be adapted to a variety of ADCPs.

[0027] 2. This invention proposes a novel hardware architecture and designs a transceiver conversion module based on a Zynq development board. This module utilizes a high-performance FPGA chip plus ARM structure to realize the real-time conversion between receiving simulated echo data, Zynq configuration files, and ADCP measurement signals downloaded via the network port and transmitting current measurement echo simulation signals. Attached Figure Description

[0028] Figure 1 This is a block diagram of the ADCP calibration system provided in an embodiment of the present invention;

[0029] Figure 2 A flowchart illustrating the generation of simulated echoes by the echo simulation module in the ADCP calibration system provided in this embodiment of the invention;

[0030] Figure 3 The circuit diagram of the signal transceiver module in the ADCP calibration system provided in the embodiment of the present invention;

[0031] Figure 4 This is a schematic diagram of the working principle of the mode switching judgment module in the ADCP calibration system provided in this embodiment of the invention;

[0032] Figure 5 This is a flowchart illustrating the process of the analog echo transmission unit transmitting analog echo signals in the ADCP calibration system provided in this embodiment of the invention.

[0033] Figure 6 These are the experimental conditions for calibrating the flow rate values ​​in this embodiment of the invention;

[0034] Figure 7 This is a comparison chart of calibration effects in an embodiment of the present invention. Detailed Implementation

[0035] This invention provides an ADCP calibration system that solves the technical problems of high measurement costs, large manpower and material resources consumption, and the inability to calibrate and debug the system at any time by means of a single measurement. This achieves the technical effect of reducing calibration costs and improving calibration efficiency.

[0036] The technical solutions in the embodiments of the present invention are intended to solve the above-mentioned technical problems, and the overall approach is as follows:

[0037] Before describing the embodiments of the present invention, the ADCP calibration principle will be explained in detail:

[0038] The purpose of the ADCP calibration system is to calibrate ADCPs in the laboratory or on land, saving ADCP development and testing resources. The calibration principle is to simulate echoes from real water conditions, using these simulated echoes to replace actual echo signals in the water for ADCP measurement. Its core lies in simulating the generation of water echoes containing Doppler frequency shift and bottom depth information, and the hardware system that interfaces with the ADCP. During calibration, the velocity profile and bottom depth information of the water echo are first set. Then, a water echo signal with this information is generated and sent to the ADCP. The ADCP receives the echo, processes it to obtain the velocity profile and bottom depth, and finally compares the parameters (velocity and bottom depth) obtained from the processed echo with the parameters set in the calibration system's echo signal. This allows the ADCP to assess its performance in measuring velocity and depth, and more comprehensive calibration can be achieved by changing different parameters in the echo.

[0039] This invention provides a land-based calibration system (ADCPTE) for ADCP300k. This system mainly performs tests on the transmitting and receiving systems of the ADCP300k system, thereby enabling the analysis of the overall performance of the ADCP300k and providing an evaluation basis for the equipment's operational effectiveness.

[0040] Specifically, based on a thorough understanding of the ADCP300k's ​​performance parameters, the approximate distribution of scatterers in the water and the spatial structure of scattering from the transducer are understood. Considering both scattering intensity and acoustic propagation loss, the coding method, flow velocity and direction, scatterer density, and number of measurement layers are pre-set to provide single-scatterer echo simulation results. Finally, all scattering results are superimposed to construct the current measurement echo simulation signal. During calibration, the system undergoes connection establishment, instrument parameter setting, echo parameter setting, echo data generation and download, and simulated echo output. To synchronize the ADCP, a synchronization signal is sent to trigger the calibration system during signal output. Finally, the ADCP receives the simulated acoustic echo signal and analyzes it to calibrate the ADCP. This entire calibration process is completed through the coordinated use of the calibration system's hardware and software.

[0041] Seawater and rivers contain numerous planktonic organisms and impurities, which act as scatterers of sound waves. The stationary random process is the basis for underwater acoustic Doppler velocity measurement, assuming that floating impurities and planktonic organisms are integrated with the water flow; the velocity of these scatterers represents the water flow velocity, and their direction of flow is the direction of the current. Based on this, an ADCP (Advanced Diffusion Probe) first emits sound waves into the water area to be measured. When the sound waves propagate through the water and encounter scatterers, some of the scatterers pass through and continue along the propagation direction, while the remaining energy is scattered in all directions. A portion of this scattered energy is then received again by the ADCP's transducer, and the signal transceiver module performs frequency selection, amplification, and AD conversion. GPS is used for ship positioning, a compass provides ship attitude information such as heading and roll / pitch, and a pressure-stabilized salt sensor is used to calibrate the sound velocity in the water. The central processing module combines this information and uses a frequency measurement algorithm to calculate the Doppler frequency shift of the echo signal. Based on the obtained Doppler frequency shift, the spatial velocity of the water flow can be obtained using a current measurement formula.

[0042] Specifically, in this embodiment of the invention, after the mode switching judgment module generates a trigger signal, the trigger signal is connected to the analog echo module. The analog echo module then performs digital-to-analog conversion on the stored analog echo signal and transmits the signal through the transceiver module. Further, during the system startup phase, the ADCPTE transducer sends the acquired ADCP300k transducer transmission signal to the mode switching judgment module. Since the ADCP300k is not transmitting a current measurement signal at this time, the trigger level of the mode switching judgment module is low, and the signal transceiver module is in a passive acquisition state. Simultaneously, after the system powers on and completes the loading of data from the SD card to the SDRAM card, the analog echo module receives the trigger level from the mode switching judgment module. If the level is low, the analog echo module does not transmit an analog echo signal. When the ADCP300k transmits a current measurement signal, the trigger level sent by the mode switching judgment module is high, the signal transceiver module is in an active transmission state, and the analog echo module starts working, transmitting the analog echo from the SDRAM back to the ADCP300k through the signal transceiver module and the ADCPTE transducer.

[0043] In this embodiment, the core of the analog echo module is the Zynq module. The main functions of the Zynq module are: (1) to download the analog echo data and Zynq configuration file through the network port; (2) to output the analog echo data according to the trigger signal, with a data output sampling rate of 6MHz; and (3) to realize the digital-to-analog conversion of four channels of analog echo data by combining two dual-channel DA modules.

[0044] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0045] See Figure 1The ADCP calibration system provided in this embodiment of the invention includes:

[0046] The signal transceiver module is used to receive measurement signals sent by the ADCP or to send analog echoes.

[0047] The mode switching judgment module is used to send mode switching commands to the analog echo module based on the measurement signal;

[0048] The analog echo module is used to forward the measurement signal to the echo simulation module or send the analog echo via the receiving mode switching command;

[0049] The echo simulation module is used to generate a simulated echo based on the received measurement signal and send it to the simulated echo module.

[0050] See Figure 2 This paper details the process of generating simulated echoes using the echo simulation module. First, various modeling parameters are acquired, including the echo signal generation mode, the velocity distribution, depth, and scatterer density. The layer thickness, total number of water layers, and total length of the emitted echo signal are calculated. Combining the number of water layers and the velocity distribution, the Doppler frequency offset corresponding to each water layer's echo can be obtained. Based on the principle of echo frustum modeling, the echo signal is layered, and the volume of each frustum is calculated. Multiplying the volume by the scatterer density yields the number of scatterers covered by the nth layer's echo beam. The amplitude of each scatterer echo follows a random distribution, exhibiting spherical attenuation with increasing water depth. The phase of each scatterer echo follows a random distribution of magnitude 2π. After determining the amplitude and phase of a scatterer, the scatterer echo data corresponding to that scattering point is obtained by combining it with the frequency offset of the current water layer. The scatterer echo of a certain layer is the superposition of the scatterer echoes corresponding to all scattering points, while the total water layer echo is the superposition of the scatterer echoes of each layer, resulting in the simulated echo signal.

[0051] See Figure 3The structure of the signal transceiver module is described in detail below. The signal transceiver module includes: a transmitter SMA connector SMA1, a receiver SMA connector SMA2, a first resistor R1, a second resistor R2, a third resistor R3, an operational amplifier U1, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, and a single-pole double-throw switch SW1. The first interface of the transmitter SMA connector SMA1 is connected to the echo transmission interface of the analog echo module, and the second interface of the transmitter SMA connector SMA1 is connected to the first end of the first resistor R1. The second end of the first resistor R1 is connected to the positive terminal of the operational amplifier U1. The first end of the second resistor R2 is grounded, and the second end of the second resistor R2 is connected to the negative terminal of the operational amplifier U1. The first diode D1 and the second diode D2 are connected in reverse parallel to form a transmit protection circuit. The first end of the third resistor R3 is connected to the negative terminal of the operational amplifier U1, and the second end of the third resistor R3 is connected to the output terminal of the operational amplifier U1, forming a forward amplification circuit for the operational amplifier U1. The amplification factor can be adjusted by the resistance value of the third resistor R3. The first terminal of the transmit protection circuit is connected to the output terminal of the operational amplifier U1, and the second terminal of the transmit protection circuit is connected to the first terminal of the single-pole double-throw switch SW1. The switching terminal of the single-pole double-throw switch SW1 is connected to the signal output terminal of the transducer. The switching control terminal of the single-pole double-throw switch SW1 is also connected to the switching signal output terminal of the control terminal. The third diode D3 and the fourth diode D4 are connected in reverse parallel to form the receive protection circuit. The second terminal of the single-pole double-throw switch SW1 is connected to the first terminal of the receive protection circuit, and the second terminal of the receive protection circuit is connected to the signal interface of the receiver SMA connector SMA2.

[0052] The structure of the signal transceiver module is further explained. The switching signal output terminal of the analog echo module is connected to the switching control terminal of the single-pole double-throw switch SW1 via a relay switch. The first terminal of the fourth resistor R4 is connected to the second terminal of the transmit protection circuit, and the second terminal of the fourth resistor R4 is connected to the first terminal of the single-pole double-throw switch SW1.

[0053] The working principle of the signal transceiver module is explained in detail. When transmitting the analog echo signal, there is a small power amplification. When the system is powered on, the entire system is in receiving mode. The single-pole double-throw switch SW1 is connected to the right-end receiving circuit J5. When the transducer receives the transmitted signal from the ADCP, the receiving circuit processes it, and ZYNQ will give a trigger signal. This triggers the external relay to switch the state of the single-pole double-throw switch SW1, disconnecting the transducer from the receiving circuit and connecting it to the left-end transmitting circuit. J3 in the circuit is connected to the ZYNQ module DAC section. The DAC transmits the analog echo signal stored in memory in real time. Before transmission, the echo signal passes through a low-power amplification operational amplifier. The operational amplifier selected is OPA552. Based on the inverse amplification principle of the operational amplifier, a voltage follower circuit with a 1.2x amplification is designed to give the echo signal a driving force, allowing it to drive the transducer with low power.

[0054] See Figure 4 The structure of the mode switching judgment module is described in detail below. The mode switching judgment module includes:

[0055] The low-noise amplifier unit is used to amplify the measurement signal.

[0056] The envelope detection unit is used to detect the amplified signal to obtain the envelope signal.

[0057] The hysteresis comparison unit is used to compare the envelope signal with the comparison threshold, generate a mode switching command, and send it to the analog echo module.

[0058] The structure of the hysteresis comparator is described in detail. The hysteresis comparator includes:

[0059] The comparison subunit is used to compare the envelope signal with a comparison threshold.

[0060] The mode switching instruction generation subunit is used to generate a mode switching instruction and send it to the analog echo module if the envelope signal is greater than or equal to the comparison threshold.

[0061] The working principle of the mode switching judgment module is explained in detail. During system operation, the low-noise amplifier unit receives the output signal from one ADCPTE transducer. The low-noise amplifier unit manually adjusts its amplification gain to ensure the signal entering the envelope detector is greater than 2Vpp. After detecting the low-noise amplifier signal, the envelope detector obtains a clear envelope signal. This signal level is unstable and insufficient as a trigger signal; therefore, a hysteresis comparator is added. After the detector provides a signal envelope, it is compared with a comparison threshold (set to 0.5V). If the signal envelope is equal to or higher than the threshold, the comparator outputs a stable high level for approximately 5ms. It ensures that within one transmission cycle, the comparator will only output one external trigger pulse to trigger the analog echo transmission function of the analog echo module. Upon receiving the external trigger pulse, the Zynq first switches the system state from receiving trigger signals to transmitting signals, and then outputs the echo signal stored in memory through four DA converters.

[0062] It should be noted that during the operation of the system, the signal received by the receiver includes the carrier signal and noise. If the energy of the noise is higher than the energy of the signal, the receiver will no longer be able to identify the signal. Therefore, the equivalent input noise of the receiver must be strictly limited. When the maximum output of the receiver is 0.5V and the maximum gain of the receiver is 100dB, the signal size referred to the input terminal is 5μV, and the lowest signal-to-noise ratio that can be detected is 0dB. In order to ensure the quality of the receiver output signal, in this embodiment, the equivalent input noise is not higher than 5μV. Based on the above performance considerations, the technical specifications of the mode switching judgment module are set as follows: (1) Receiving channels: 4 channels; (2) Gain control range: 0~80dB; (3) Preprocessing bandwidth: 350kHz~450kHz; (4) Equivalent input noise: 5μV; (5) Power supply voltage: 5V; (6) Power consumption: 0.5W; (7) Maximum DC bias: 1.5V; (8) Amplitude consistency: ≤1mV.

[0063] The structure of the analog echo module is described in detail. The analog echo module includes:

[0064] The measurement signal forwarding unit is used to forward the measurement signal to the echo simulation module;

[0065] The echo storage unit is used to receive and store the simulated echoes generated by the echo simulation module.

[0066] The analog echo transmission unit receives mode switching commands, retrieves analog echoes from the echo storage unit, and transmits them to the signal transceiver module. Specifically, the process of the analog echo transmission unit transmitting analog echo signals is as follows: Figure 5 As shown.

[0067] Before system operation, the ADCP300k output waveform is acquired, or based on the ADCP300k transmit waveform design parameters, the corresponding simulated echo signal is generated using the echo simulation module and loaded into the SD card via the Zynq module through the network port. The ADCP300k supports a maximum depth of 100m and a sampling rate of 5MHz. Considering the Kalman filtering requirements, 128 echo frames are stored at a time. Therefore, the SD card storage capacity is 2 * 100m (operating distance) / 1500 (speed of sound) * 5MHz (sampling rate) * 4 (channels) * 128 (number of echoes) = 86MB. After system power-on, the simulated echo data is read from the SD card into the SDRAM. Since the DA playback speed is 5MHz (sampling rate) * 4 (channels) = 20MB / s, the echoes can be stored in the SDRAM (512MB, read / write speed much greater than 100MB), without being limited by the low-speed SD card.

[0068] The main function of the calibration system provided in this embodiment of the invention is to measure flow velocity and depth, and to provide the direction and profile distribution of the flow velocity (number of layers and layer thickness). For these functions, the test examples of this embodiment of the invention are divided into two parts: velocity simulation and depth simulation. The calibration experiment of velocity simulation is further subdivided into two aspects: flow velocity value and flow velocity direction.

[0069] ADCP is called Doppler velocity profile because it can accurately provide a profile distribution of water flow velocity, including the magnitude of the flow velocity, its distribution in the vertical direction, and the direction of flow. Therefore, the main calibration functions of the calibration system provided in this embodiment of the invention include three aspects: velocity value, vertical distribution of flow velocity, and direction of flow velocity.

[0070] The data for flow velocity in these three aspects during the calibration experiment are given below. Before conducting the flow velocity calibration experiment, some common experimental conditions need to be provided. Figure 6 The experimental conditions for flow velocity calibration are given. The ADCP settings are parameters related to the transmitted signal, including the transmission frequency and the form of the transmitted signal. The parameters related to the simulated echo signal are not given in the calibration system conditions. It is assumed that the basic parameters of the echo signal are consistent with those of ADCP, because the simulated echo is generated based on the signal transmitted by ADCP.

[0071] To evaluate the calibration effect of the calibration system provided in this embodiment of the invention, the calibration effect is evaluated using comparison software. By downloading the velocity measurement results (TXT file) from the ADCP and importing it into the software, the difference between the set flow rate and the measured flow rate can be displayed intuitively. The comparison effect is as follows: Figure 7 As shown, from Figure 7It can be seen that the speed measurement results are very stable. Therefore, the calibration system provided in this embodiment of the invention can generate acoustic echoes containing four Doppler frequency offset information and depth information for ADCP calibration, verifying the feasibility of the calibration system provided in this embodiment of the invention.

[0072] This invention provides a land-based calibration system for the ADCP300K device. The system is highly integrated and modular, capable of simulating and generating ADCP emission signal echoes and calibrating the ADCP via acoustic docking in a waterless environment. Furthermore, this invention offers advantages such as small size, simple operation, and low cost.

[0073] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0074] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0075] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0076] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0077] Any aspects of this invention not described in detail in the embodiments are well-known techniques to those skilled in the art. Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this invention and not to limit it. Although this invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this invention without departing from the spirit and scope of this invention, and all such modifications and substitutions should be covered within the scope of the claims of this invention.

Claims

1. An ADCP calibration system, characterized in that, include: The signal transceiver module is used to receive measurement signals sent by the ADCP or to send analog echoes. The signal transceiver module includes: a transmitter SMA connector, a receiver SMA connector, a first resistor, a second resistor, a third resistor, an operational amplifier, a first diode, a second diode, a third diode, a fourth diode, and a single-pole double-throw switch; the first interface of the transmitter SMA connector is connected to the echo transmission interface of the analog echo module, and the second interface of the transmitter SMA connector is connected to the first end of the first resistor; the second end of the first resistor is connected to the positive terminal of the operational amplifier; the first end of the second resistor is grounded, and the second end of the second resistor is connected to the negative terminal of the operational amplifier; the first diode and the second diode are connected in anti-parallel to form a transmission protection circuit; the third diode... The first terminal of the resistor is connected to the negative terminal of the operational amplifier, and the second terminal of the third resistor is connected to the output terminal of the operational amplifier; the first terminal of the transmit protection circuit is connected to the output terminal of the operational amplifier, and the second terminal of the transmit protection circuit is connected to the first terminal of the single-pole double-throw switch; the switching terminal of the single-pole double-throw switch is connected to the signal output terminal of the transducer; the switching control terminal of the single-pole double-throw switch is also connected to the switching signal output terminal of the control terminal; the third diode and the fourth diode are connected in reverse parallel to form a receive protection circuit; the second terminal of the single-pole double-throw switch is connected to the first terminal of the receive protection circuit, and the second terminal of the receive protection circuit is connected to the signal interface of the receiver SMA connector; The mode switching judgment module is used to send a mode switching command to the analog echo module according to the measurement signal; The simulated echo module is used to forward the measurement signal to the echo simulation module or receive the mode switching command and send a simulated echo. The echo simulation module is used to generate the simulated echo based on the received measurement signal and send it to the simulated echo module.

2. The ADCP calibration system as described in claim 1, characterized in that, The switching signal output terminal of the analog echo module is connected to the switching control terminal of the single-pole double-throw switch via a relay switch.

3. The ADCP calibration system as described in claim 1, characterized in that, The mode switching determination module includes: A low-noise amplifier unit is used to amplify the measurement signal; The envelope detection unit is used to detect the amplified signal to obtain the envelope signal. The hysteresis comparison unit is used to compare the envelope signal with the comparison threshold, generate the mode switching command, and send it to the analog echo module.

4. The ADCP calibration system as described in claim 3, characterized in that, The hysteresis comparison unit includes: A comparison subunit is used to compare the envelope signal with a comparison threshold. The mode switching instruction generation subunit is used to generate the mode switching instruction and send it to the analog echo module if the envelope signal is greater than or equal to the comparison threshold.

5. The ADCP calibration system as described in any one of claims 1-4, characterized in that, The simulated echo module includes: A measurement signal forwarding unit is used to forward the measurement signal to the echo simulation module; The echo storage unit is used to receive and store the simulated echo generated by the echo simulation module. The analog echo transmission unit is used to receive the mode switching command, obtain the analog echo from the echo storage unit, and send it to the signal transceiver module.

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