Ocean profile observation sensor and sound velocity measurement method thereof

Abstract

The invention relates to the technical field of marine environment observation, and discloses a marine profile observation sensor which comprises a fixing device and a measurement control circuit, an underwater ultrasonic flight time probe module is installed on the outer side of the fixing device, the underwater ultrasonic flight time probe module comprises an ultrasonic transducer and a metal reflector plate, and the metal reflector plate is installed on the fixing device. A shell is fixedly connected to one side of the fixing device, and a measuring probe module is installed on the periphery of the shell. High-precision sound velocity measurement and profile construction are realized by combining dynamic compensation, multiple sampling average processing and modular measurement control circuit design through a sound velocity measurement technology based on a time flight principle. The fixing device with a low thermal expansion coefficient and the pressure-resistant metal reflector plate are adopted, the path stability in the deep sea environment is ensured, the problems that in the prior art, errors are large due to dependence on indirect calculation, the path is influenced by deformation, and the equipment cruising ability is insufficient are solved, and the device is particularly suitable for complex hydrological environments and long-term observation requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of marine environment observation, and in particular to an ocean profile observation sensor and a sound velocity measurement method thereof. Background Art

[0002] At present, the measurement of ocean sound velocity profile mainly relies on two methods: indirect calculation and direct measurement. Indirect calculation uses temperature, salinity and depth data combined with empirical formulas to obtain the sound velocity value, but this method is highly dependent on the accuracy of temperature, salinity and depth measurements and is limited by the applicability of the formula. In the case of drastic changes in temperature and salinity gradients or special hydrological environments, the accuracy of sound velocity calculation is difficult to guarantee and is prone to large errors.

[0003] Direct measurement methods can avoid formula errors, but existing equipment is expensive, and in deep-sea high pressure and temperature difference environments, the sound wave propagation path is unstable due to thermal expansion and contraction or mechanical deformation of structural materials, which significantly affects the measurement accuracy. In addition, traditional sensors usually cannot guarantee the provision of continuous and stable profile data in water disturbances or fast-flowing sea areas, and single sampling or simple interpolation methods cannot truly reflect the complex distribution characteristics of the sound velocity profile.

[0004] The endurance of existing sound velocity measurement equipment is also relatively limited. In deep-sea deployment, the high energy consumption of the equipment leads to short working time, easy interruption during observation, and insufficient data integrity. At the same time, the real-time data transmission capability is weak, making it difficult to adapt to scenarios that require real-time analysis. These technical limitations restrict the application of existing equipment in complex hydrological environments. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides an ocean profile observation sensor and a sound velocity measurement method thereof, which solves the problems in the prior art of insufficient accuracy of ocean sound velocity measurement, poor environmental adaptability, and inability of data continuity and real-time performance to meet the requirements of complex hydrological environments.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions: an ocean profile observation sensor, comprising a fixing device and a measurement control circuit, an underwater ultrasonic time-of-flight probe module is installed on the outside of the fixing device, the underwater ultrasonic time-of-flight probe module comprises an ultrasonic transducer and a metal reflector, a housing is fixedly connected to one side of the fixing device, a measurement probe module is installed on the outer periphery of the housing, a support rod is installed between the acoustic transducer and the metal reflector, and the measurement control circuit is encapsulated inside the fixing device;

[0007] The measurement control circuit includes a main control module, a time-to-digital converter and a signal conditioning unit. The signal conditioning unit is connected to the ultrasonic transducer and is used to send a high-frequency electrical signal to the ultrasonic transducer and process the echo signal received by the ultrasonic transducer. The time-to-digital converter is used to record the time interval between the emission and reception of the ultrasonic signal. The main control module is used to calculate the sound velocity value.

[0008] Preferably, a jettison block is installed at one end of the underwater ultrasonic time-of-flight probe module away from the fixing device through a release mechanism, and a communication antenna is installed at the rear end of the shell.

[0009] Preferably, the support rod is made of epoxy resin material with a low thermal expansion coefficient, and is used to fix the distance between the ultrasonic transducer and the metal reflector and adapt to usage requirements in different temperature environments.

[0010] Preferably, the time interval recording accuracy of the time-to-digital converter reaches nanosecond level, so as to ensure the measurement accuracy of the time difference between the transmission and reception of the ultrasonic signal.

[0011] A method for measuring an ocean sound velocity profile comprises the following steps:

[0012] S1. Sending a high-frequency electrical signal pulse to the ultrasonic transducer through the measurement control circuit, the ultrasonic transducer converts the high-frequency electrical signal pulse into an ultrasonic signal and transmits it into the water;

[0013] S2. The ultrasonic signal propagates to the metal reflector and is reflected, and the reflected echo signal is received by the ultrasonic transducer again, and is processed by the signal conditioning unit and input into the time-to-digital converter;

[0014] S3. The time digital converter records the time interval between the emission and reception of the ultrasonic signal, the main control module reads the time data of the time digital converter, and calculates the sound velocity value according to the time interval and the distance between the ultrasonic transducer and the metal reflector;

[0015] S4. The main control module constructs a sound velocity profile according to the sound velocity values ​​measured at multiple depths.

[0016] Preferably, the calculation process of the sound velocity value is based on the end face distance of the fixing device and the time interval recorded by the time digital converter, and the sound velocity value is obtained by dividing twice the fixed distance by the time interval.

[0017] Preferably, the process of constructing the sound velocity profile includes measuring the sound velocity values ​​at different depths in real time by a depth measurement probe, and pairing the sound velocity values ​​with corresponding depth values ​​to form a data point set.

[0018] Preferably, the method further includes collecting water temperature data in real time through a temperature measurement probe, and dynamically correcting the sound velocity value based on the temperature to improve the accuracy of the sound velocity profile data.

[0019] Preferably, the jettison block is released by a release mechanism after the sensor reaches a predetermined depth, so that the sensor's buoyancy is restored and quickly floats to the water surface, and then the constructed sound velocity profile data is uploaded to the ground station via a communication antenna.

[0020] Preferably, the measurement process uses high-precision time recording of a time-to-digital converter, and the time interval measurement accuracy reaches nanosecond level to reduce the impact of time errors on sound speed calculation.

[0021] The present invention provides an ocean profile observation sensor and a sound velocity measurement method thereof. The present invention has the following beneficial effects:

[0022] 1. The present invention adopts the ocean sound speed measurement technology based on the time flight principle, through the emission, reflection and echo reception of ultrasonic signals, combined with the high-precision time digital converter to record the time interval, to achieve accurate calculation of the sound speed. Compared with the solution of relying on the temperature-salinity-depth formula to indirectly calculate the sound speed in the prior art, the present invention avoids the accumulation of errors in the formula calculation, solves the problem of high dependence on temperature-salinity-depth data and insufficient measurement accuracy in the prior art, and has more advantages in complex hydrological environments.

[0023] 2. The present invention adopts dynamic compensation and multiple sampling average processing technology to correct the temperature and depth of the sound velocity measurement value and eliminate abnormal data, and finally constructs a high-precision sound velocity profile. Compared with the solution of only single sampling or direct measurement of sound velocity value in the prior art, the present invention significantly improves the stability of data and the accuracy of profile construction, and effectively solves the problem of incomplete and discontinuous profile data caused by water disturbance or single sampling error in the prior art.

[0024] 3. The present invention ensures the structural stability of the sensor in deep-sea high-pressure and temperature-difference environments by combining a fixture material with a low thermal expansion coefficient and a pressure-resistant metal reflector design, thereby ensuring the constancy of the length of the sound velocity measurement path. Compared with the prior art design in which the path is unstable due to thermal expansion and mechanical deformation of the fixture, the present invention solves the problems of inaccurate measurement paths and poor data reliability in deep-sea environments, and is particularly suitable for application requirements in deep sea and extreme environments.

[0025] 4. The present invention adopts modular measurement control circuit design, the main control module, signal conditioning unit and time digital converter work together, and realizes high-precision measurement and long-term independent operation through multi-frequency signal adjustment and low-power optimization technology. Compared with the existing solution of high energy consumption of electronic modules and easy failure of long-term measurement, the present invention effectively solves the problems of insufficient endurance and short deployment cycle of measurement equipment, and can meet the needs of long-term ocean observation and real-time data transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A perspective view of the present invention;

[0027] Figure 2 It is a schematic diagram of the sound velocity measurement principle in the present invention;

[0028] Figure 3 Schematic diagram of the steps of the measurement method of the present invention.

[0029] Among them, 1. fixing device; 2. shell; 3. measuring probe module; 4. support rod; 5. throwing block; 6. ultrasonic transducer; 7. communication antenna; 8. metal reflector. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the specification of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Example:

[0032] Please refer to the attached Figure 1 -Attached Figure 2 The embodiment of the present invention provides an ocean profile observation sensor, including a fixing device 1 and a measurement control circuit. An underwater ultrasonic time-of-flight probe module is installed on the outside of the fixing device 1. The underwater ultrasonic time-of-flight probe module includes an ultrasonic transducer 6 and a metal reflector 8. A housing 2 is fixedly connected to one side of the fixing device 1. A measuring probe module 3 is installed on the outer periphery of the housing 2. The measuring probe module 3 is composed of a temperature measuring probe and a depth measuring probe, which are respectively used to measure the temperature of the current position and the depth from the sea level. A support rod 4 is installed between the ultrasonic transducer 6 and the metal reflector 8. The support rod 4 is made of epoxy resin material with a low thermal expansion coefficient, which is used to fix the distance between the ultrasonic transducer 6 and the metal reflector 8 and adapt to the use requirements under different temperature environments. The time interval recording accuracy of the time digital converter reaches nanosecond level, which is used to ensure the measurement accuracy of the time difference between the transmission and reception of the ultrasonic signal.

[0033] The measurement control circuit is encapsulated inside the fixture 1 ; a load-releasing block 5 is installed at one end of the support rod 4 away from the fixture 1 through a release mechanism, and a communication antenna 7 is installed at the rear end of the housing 2 .

[0034] In the present invention, the ocean profile observation sensor and the measurement control circuit are the key parts to achieve sound velocity measurement and profile construction. The sensor as a whole is composed of a housing 2, an underwater ultrasonic time-of-flight probe and a measurement control circuit. The modules cooperate with each other and can operate stably for a long time in a complex marine environment. In general, the housing 2 provides physical protection and buoyancy support, the underwater ultrasonic time-of-flight probe realizes the sending and receiving of ultrasonic signals, and the measurement control circuit completes signal acquisition, processing and sound velocity calculation.

[0035] In the present invention, the measurement control circuit mainly realizes measurement accuracy and stability through the coordinated work of the main control module, the time digital converter (TDC) and the signal conditioning unit. The technical details of the ocean profile observation sensor and the measurement control circuit are disclosed below.

[0036] In this embodiment, the ocean profile observation sensor is composed of a lightweight buoyancy shell 2, a fixing device 1, an underwater ultrasonic time-of-flight probe and a jettisoning system.

[0037] Generally, the shell 2 is made of buoyancy material with high pressure resistance and corrosion resistance. Specifically, the shell 2 can not only provide deep-sea pressure resistance, but also can achieve dynamic buoyancy adjustment through the design of the dumping block 5 when the buoyancy is insufficient.

[0038] The outer periphery of the housing 2 is equipped with a measuring probe module 3, which includes a temperature probe and a depth probe. The temperature probe is used to record the ambient temperature in real time and provide basic data for sound velocity correction; the depth probe records the water depth of the current sensor to ensure the accuracy of the data corresponding to the depth. The head of the fixture 1 is equipped with an underwater ultrasonic time-of-flight probe, and the receiving and transmitting direction of the probe is strictly aligned with the axis of the sensor to avoid interference from the water flow.

[0039] As an option, a communication antenna 7 is designed at the rear of the housing 2. Specifically, when the sensor surfaces after completing data collection, the communication antenna establishes a stable communication link with the ground station to upload measurement data or profile results. The communication antenna 7 is made of flexible material and can maintain a stable connection in harsh environments.

[0040] The underwater ultrasonic time-of-flight probe includes an ultrasonic transducer 6, a metal reflector 8, and a support frame 4 for fixing the two. Generally, the ultrasonic transducer 6 is responsible for converting high-frequency electrical signals into ultrasonic waves and converting echo signals into electrical signals. Specifically, the receiving and transmitting directions of the ultrasonic transducer 6 are vertically aligned with the metal reflector 8, thereby reducing the deviation in the sound wave reflection path. The metal reflector 8 is processed with high precision, and its surface reflection efficiency exceeds 98%. The reflector is fixed to the opposite side of the ultrasonic transducer 6 by an epoxy resin support rod 4 with a low thermal expansion coefficient, ensuring that the distance between the two remains unchanged in deep-sea high pressure or extreme temperature environments.

[0041] In order to achieve dynamic buoyancy adjustment, a jettisoning block 5 is installed at the tail of the underwater ultrasonic time-of-flight probe. The jettisoning block 5 is connected to the underwater ultrasonic time-of-flight probe through a mechanical locking mechanism. Generally, the sensor quickly dives to the target depth by relying on the weight of the jettisoning block 5. After reaching the target depth, the locking mechanism releases the jettisoning block 5, allowing the housing 2 to quickly float up due to the buoyancy. The jettisoning block 5 can be made of corrosion-resistant metal or high-density material, and its weight is precisely designed to balance buoyancy and motion stability.

[0042] In this embodiment, the measurement control circuit includes a main control module, a time-to-digital converter (TDC) and a signal conditioning unit, and each module works in coordination to complete signal acquisition, processing and calculation.

[0043] The main control module is the core of the entire measurement control circuit and is used to coordinate the workflow of the sensor. Generally, the main control module receives external measurement instructions through the serial port and triggers the signal conditioning unit and the time-to-digital converter.

[0044] Specifically, the main control module realizes signal control and data processing through a low-power microprocessor. As an option, an embedded processor with high integration, such as the Cortex-M series chip based on the ARM architecture, can be used. In standby mode, the main control module enters a low-power mode to reduce energy consumption.

[0045] The main control module is responsible for averaging multiple measurements. For example, for the measurement data of a certain depth point, the main control module will collect multiple time interval data and calculate its average value to reduce accidental errors. The main control module can also filter out abnormal data through thresholds to ensure data reliability.

[0046] The time-to-digital converter is used to record the time interval from the transmission of the ultrasonic signal to the return of the echo, with an accuracy of nanoseconds. TDC provides a timing reference through an internal high-stability clock, and its recording results directly affect the accuracy of sound velocity calculation.

[0047] The working range of TDC can be adjusted dynamically. For example, for shallow water measurements, a shorter time measurement range can be set; while in deep sea measurements, the time range can be expanded to accommodate longer sound wave propagation times. As an option, a high-performance TDC chip that supports dynamic range adjustment can be selected, such as the TDC-GP series.

[0048] The signal conditioning unit is located between the ultrasonic transducer 6 and the time-to-digital converter, and is mainly responsible for amplifying, filtering and shaping the signal. Generally, the signal conditioning unit includes a high-frequency amplifier and a low-pass filter.

[0049] Specifically, the conditioning unit can amplify the weak echo signal received by the ultrasonic transducer 6 and filter out the background noise. The filter cutoff frequency can be adjusted to adapt to different noise environments. For example, in the case of large high-frequency noise interference in shallow water, the filter cutoff frequency can be increased to enhance the signal quality.

[0050] In this embodiment, the main control module controls the working order of the signal conditioning unit and the time digital converter through the serial port. Generally, the main control module first triggers the signal conditioning unit to send a high-frequency electrical signal to the ultrasonic transducer 6, and the ultrasonic transducer 6 converts the electrical signal into an ultrasonic signal and transmits it. The ultrasonic wave is reflected by the metal reflector 8 and returns to the ultrasonic transducer 6, and the ultrasonic transducer 6 converts the received echo signal into an electrical signal and transmits it to the signal conditioning unit.

[0051] After the signal conditioning unit processes the echo signal, it sends it to the time digital converter. The TDC records the time interval data from the transmission to the reception of the signal and stores the data in the internal register. After the main control module reads the time data from the register, it calculates the sound speed value based on the fixed path length and time interval.

[0052] After completing the measurement of a certain depth point, the main control module will trigger the next measurement according to the preset depth increment to build a complete sound velocity profile point by point.

[0053] Please refer to the attached Figure 3 The present invention also provides a method for measuring an ocean sound velocity profile, comprising the following steps:

[0054] The high-frequency electrical signal pulse is sent to the ultrasonic transducer 6 through the measurement control circuit, and the ultrasonic transducer 6 converts the high-frequency electrical signal pulse into an ultrasonic signal and transmits it into the water;

[0055] The ultrasonic signal propagates to the metal reflector 8 and is reflected, and the reflected echo signal is received by the ultrasonic transducer 6 again, and is processed by the signal conditioning unit and input into the time-to-digital converter;

[0056] The time digital converter records the time interval between the emission and reception of the ultrasonic signal, the main control module reads the time data of the time digital converter, and calculates the sound velocity value according to the time interval and the distance between the ultrasonic transducer 6 and the metal reflector 8;

[0057] The main control module constructs a sound velocity profile based on the sound velocity values ​​measured at multiple depths.

[0058] The sound velocity value is calculated based on the end-to-end distance of the fixture and the time interval recorded by the time digitizer. The sound velocity value is obtained by dividing twice the fixture distance by the time interval.

[0059] The process of constructing the sound velocity profile includes measuring the sound velocity values ​​at different depths in real time through a depth measurement probe, and pairing the sound velocity values ​​with the corresponding depth values ​​to form a set of data points.

[0060] It also includes real-time collection of water temperature data through a temperature measurement probe, and dynamic correction of the sound velocity value based on the temperature to improve the accuracy of the sound velocity profile data.

[0061] The dump block 5 is released by the release mechanism after the sensor reaches a predetermined depth, so that the sensor's buoyancy is restored and it quickly floats to the water surface, and then the constructed sound velocity profile data is uploaded to the ground station through the communication antenna 7.

[0062] During the measurement process, high-precision time recording is adopted by the time-to-digital converter, and the time interval measurement accuracy reaches the nanosecond level to reduce the influence of time error on the sound speed calculation.

[0063] In order to ensure that the measurement process of the present invention has good continuity and logic, the measurement process based on the time flight principle needs to fully consider the connection with the aforementioned modules and steps. In the above content, it has been mentioned that the sensor is composed of an underwater ultrasonic time-of-flight probe and a measurement control circuit, wherein the time-of-flight probe is used to transmit and receive ultrasonic signals, and the measurement control circuit completes time recording and sound speed calculation. In this embodiment, the measurement process based on the time-of-flight principle is further disclosed, including the emission, reflection and time interval recording of the echo signal of the ultrasonic signal, and the process of calculating the sound speed value in combination with the path distance.

[0064] In this embodiment, the measurement process is mainly completed by the ultrasonic transducer 6, the metal reflector 8, the time-to-digital converter and the main control module.

[0065] Generally, the measurement process is started by the main control module. The main control module triggers the signal conditioning unit through the control signal, so that it sends a high-frequency electrical signal pulse to the ultrasonic transducer 6. The ultrasonic transducer 6 converts the high-frequency electrical signal into an ultrasonic signal and transmits it into the water. The signal propagates along a stable path until it reaches the metal reflector 8. Specifically, the metal reflector 8 reflects the ultrasonic signal, and the echo signal returns to the ultrasonic transducer 6. The ultrasonic transducer 6 converts the echo signal into an electrical signal and inputs it into the time digital converter through the signal conditioning unit. The time digital converter is responsible for accurately recording the time interval from the emission of the ultrasonic signal to the reception of the echo.

[0066] In some embodiments, the recording accuracy of the time interval needs to meet the nanosecond requirement to ensure high accuracy of the sound speed calculation. The time measurement reference of the time digital converter is provided by an internal high-stability clock. As an option, a clock chip with higher frequency stability can be selected, such as a temperature compensated crystal oscillator (TCXO) or an oven controlled crystal oscillator (OCXO) to further improve the timing accuracy. In scenarios where the temperature or pressure environment changes drastically, the accuracy requirement is particularly important.

[0067] In this embodiment, the calculation formula of the speed of sound is as follows:

[0068]

[0069] in:

[0070] c is the calculated sound speed in water;

[0071] L is the path length between the ultrasonic transducer 6 and the metal reflector 8;

[0072] Δt is the time interval between the transmission of the ultrasonic signal and the reception of the echo signal.

[0073] As an option, the design of the fixed path length L requires strict control of manufacturing errors. In one possible implementation, a material with a low thermal expansion coefficient (such as epoxy resin or ceramic material) is used to construct the fixture to ensure that the path length remains constant under different temperature conditions. In some embodiments, the path length can be further accurately calibrated, for example, by testing the path length value L through a water tank experiment and storing it in the main control module.

[0074] Generally, when calculating the speed of sound, the main control module reads the time interval data from the time-to-digital converter and calls the stored path length L. In a possible implementation, the values ​​of the path length L and the time interval Δt can be sampled multiple times, and the speed of sound is calculated by the average value to reduce accidental errors. Specifically, the main control module can perform sampling calculations according to the following formula:

[0075]

[0076] in It is the average value of the measured values ​​at multiple time intervals. In this way, the influence of high-frequency noise can be effectively reduced and the stability of the sound velocity measurement results can be improved.

[0077] In some specific scenarios, such as deep-sea high-pressure environments, since the ultrasonic signal propagation path may be slightly affected by water flow interference or pressure effects, a dynamic compensation model can be introduced to further correct the calculation results. Dynamic compensation includes the correction of temperature and pressure to the speed of sound. For example, the real-time temperature data T recorded by the temperature measurement probe can be used to correct the speed of sound using the following formula:

[0078] c 修正 =c+k T ·T

[0079] in:

[0080] c 修正 is the corrected sound velocity value;

[0081] k T is the temperature correction coefficient, obtained through experimental calibration.

[0082] As an extension method, the influence of water pressure on sound velocity can also be corrected by the water depth data recorded by the depth probe. In this case, the main control module introduces the pressure correction term k according to the real-time depth value D. P D, the specific formula is:

[0083] c 修正 =c+k T ·T+k P ·D

[0084] where k P is the pressure correction factor.

[0085] In some embodiments, the propagation path and time interval of the ultrasonic signal can be synchronously verified. For example, in an environment with poor signal quality or high noise, repeated measurements can be used to determine the signal reliability. The main control module can set a threshold range. For example, when the measured value of the time interval Δt deviates too much from the mean, the system will automatically re-trigger the measurement process to avoid abnormal data interfering with the results.

[0086] In general, the measurement process in this embodiment has high accuracy and repeatability, and can adapt to a variety of complex marine environmental conditions. Through the application of the time-of-flight principle and the dynamic correction of relevant data, stable and reliable sound speed measurement is finally achieved.

[0087] In the above-mentioned sound velocity measurement process based on the time-of-flight principle, the sound velocity value obtained is a preliminary calculation result. In order to improve the measurement accuracy, the sound velocity value needs to be dynamically corrected and compensated. In general, the sound velocity of seawater is affected by factors such as temperature, depth and pressure, and the calculation directly relying on the time-of-flight principle may have deviations. Therefore, it is necessary to correct the sound velocity in combination with real-time measurement data and environmental parameters.

[0088] In this embodiment, the data correction and compensation steps include temperature correction, depth correction and averaging of multiple measurements.

[0089] Specifically, the effect of temperature on the speed of sound is the primary compensation factor to be considered. The temperature measurement probe collects water temperature data T in real time, and the main control module uses the pre-calibrated temperature correction coefficient k T The initial sound velocity value c0 is corrected. The corrected sound velocity value c T The calculation formula is:

[0090] c T =c0+k T ·T

[0091] in:

[0092] c T Indicates the sound velocity value after temperature compensation;

[0093] c0 is the sound velocity value obtained by preliminary calculation;

[0094] T is the real-time water temperature value collected by the temperature measurement probe;

[0095] k T is the temperature correction coefficient, usually obtained through experimental calibration.

[0096] In some embodiments, the temperature correction factor k T The historical data of a specific water area can be dynamically adjusted to suit the particularities of the local hydrological environment. As an option, temperature correction coefficients for different water areas can be pre-stored, and the main control module selects the appropriate correction coefficient based on the positioning information at the beginning of the measurement.

[0097] Generally speaking, the effect of water depth on sound velocity is mainly reflected by pressure changes. The depth value D recorded by the depth measurement probe is directly related to the pressure change. The main control module further uses the depth correction factor k D Correct the sound speed. The corrected sound speed value c D It can be expressed as:

[0098] c D =c T +k D ·D

[0099] in:

[0100] c D is the sound velocity value after depth compensation;

[0101] k D It is the depth correction factor, usually obtained based on seawater density and pressure gradient experiments.

[0102] In one possible implementation, depth correction not only relies on the real-time measured water depth value, but can also be combined with a deep-sea specific pressure distribution model for correction. For example, for scenes with a depth of more than 1,000 meters, a segmented correction model can be used, that is, correction coefficients are set according to different depth intervals.

[0103] In addition, in order to reduce the impact of accidental errors on the results, this embodiment also introduces an averaging process of multiple measurements. In some embodiments, the main control module will perform multiple sound velocity measurements at each depth point and take the average of the multiple measurement results. The specific formula is:

[0104]

[0105] in:

[0106] c avg is the average sound velocity at a certain depth;

[0107] n is the number of measurements;

[0108] c i is the sound velocity value measured for the i-th time.

[0109] As an option, the main control module can set a measurement error range. If a certain measurement value deviates from the set range of the average value, it can be regarded as an abnormal value and removed. Specifically, the deviation range can be set by empirical data. For example, when a certain measurement value deviates from the average value by more than 5%, the main control module can automatically re-trigger the measurement.

[0110] In some embodiments, multi-parameter coupling correction is also considered. Specifically, the main control module will correct the sound velocity value according to temperature and depth at the same time. The final correction formula can be expressed as:

[0111] c final =c0+k T ·T+k D ·D

[0112] where c final is the final corrected sound velocity value.

[0113] In one possible implementation, for complex hydrological environments, such as areas where ocean currents converge, the main control module can dynamically adjust the weights of correction parameters. For example, when the temperature gradient is large, the temperature correction coefficient is applied first; when the depth changes significantly, the depth correction coefficient is applied first. The weight adjustment logic can be optimized through historical data.

[0114] The correction and compensation process not only relies on real-time measurement data, but can also be combined with historical data and empirical models to further improve accuracy. For example, in some embodiments, the main control module can also call a pre-stored hydrological model to perform a global correction on the sound speed. Specifically, the corresponding correction parameters can be read from the pre-stored model according to the geographical location and time period of the sensor and introduced into the correction formula.

[0115] In general, this embodiment further improves the accuracy of sound velocity measurement through temperature correction, depth correction and averaging of multiple measurements. At the same time, the introduction of multi-parameter coupling correction and historical data compensation enables the measurement results to adapt to complex marine environments. The corrected sound velocity data provides a reliable basis for subsequent profile construction.

[0116] Based on the aforementioned measurement of sound velocity values ​​and data correction and compensation, the sound velocity profile construction step of the present invention realizes a comprehensive expression of the sound velocity distribution at different depths. The construction of the sound velocity profile relies on the multi-point sound velocity data obtained by the measurement control circuit, combined with the depth information recorded in real time by the depth measurement probe. In general, the construction of the sound velocity profile needs to be completed continuously during the dive or ascent of the sensor. By pairing the depth data with the corrected sound velocity value, a complete profile can be formed, providing a basis for subsequent acoustic research or ocean observations.

[0117] In this embodiment, the main process of constructing the sound velocity profile includes the collection of sound velocity data, the pairing of multiple depth measurement points, and the organization and storage of profile data.

[0118] Specifically, when the sensor is diving or surfacing, the main control module triggers the sound velocity measurement according to a preset time interval or depth increment. As an option, the depth increment can be set according to the resolution requirement of the target profile. For example, in some embodiments, the depth increment can be 1 meter to ensure the density of the profile data; in another possible implementation, the increment can be 5 meters to cover a larger range of profile changes.

[0119] In each measurement, the main control module calculates the sound velocity value c at the current depth through the aforementioned time flight principle. i , and after combining temperature and depth correction, the final sound velocity value c is obtained final,i The depth probe also records the depth z corresponding to the sound velocity value. i The main control module will (zi ,c final,i ) is stored in the sensor memory as a set of profile data points.

[0120] In general, the main control module will continue to collect profile data until the sensor completes the dive or rise of the entire profile range. In some embodiments, the main control module will smooth the continuous data points to eliminate abnormal fluctuations caused by local disturbances in the water body or measurement errors. Specifically, the sliding average method can be used to smooth the profile data, and the formula is:

[0121]

[0122] in:

[0123] c smooth,i is the sound velocity value after smoothing;

[0124] c final,j is the original sound speed value;

[0125] n is the size of the sliding window, which can be adjusted according to the density of the data.

[0126] In one possible implementation, the main control module marks each set of data points. If the depth or sound velocity value of a certain measurement deviates significantly from the expected range, the data point can be marked as an outlier and removed in the subsequent profile construction. Specifically, the determination of outliers can be based on the gradient change of the profile data. For example, when the sound velocity gradient of a point exceeds twice the average gradient of the adjacent points before and after, it can be regarded as an outlier.

[0127] As an option, the main control module can also generate a preliminary sound velocity profile curve based on the real-time measured profile data and store it as a curve equation or a segmented data table. For example, for the profile data in the shallow sea area, the segmented linear interpolation method can be used to generate the curve equation:

[0128]

[0129] in:

[0130] c(z) is the sound velocity value corresponding to the depth z;

[0131] z i ,z i+1 is the depth of adjacent data points;

[0132] c i ,c i+1 is the sound velocity value of adjacent data points.

[0133] In some embodiments, in order to reduce the storage space occupied by the sensor, the profile data can be compressed. For example, the main control module can perform piecewise fitting on the measurement points and use polynomial fitting or piecewise function to represent the sound velocity profile. The fitted profile data can be stored in a limited parameter form to facilitate subsequent data uploading and processing.

[0134] Specifically, when the sensor surfaces, the main control module will upload the complete profile data to the ground station through the communication antenna. The profile data may include the original data of the measurement point, the smoothed data, and the fitted curve equation or segmented data table. In a possible implementation, the sensor can also generate a visualization result of the profile in real time and transmit it directly to the display device of the ground station through the communication module.

[0135] In some embodiments, the construction of profile data can also be corrected in combination with historical data. For example, the main control module can call a pre-stored reference profile, compare the real-time data with the historical data, and perform secondary corrections on data points with large deviations. This can further improve the accuracy of the profile, especially in complex marine environments.

[0136] In general, in this embodiment, the construction of the sound velocity profile realizes the dynamic acquisition of multi-depth sound velocity values, the smoothing of data points and the fitting expression of the profile curve, providing high-quality basic data for subsequent marine acoustic applications. By combining real-time measurement with subsequent data processing, this step can adapt to a variety of different application scenarios.

[0137] The measurement control circuit includes a main control module, a time-to-digital converter and a signal conditioning unit. The signal conditioning unit is connected to the ultrasonic transducer and is used to send high-frequency electrical signals to the ultrasonic transducer and process the echo signals received by the ultrasonic transducer. The time-to-digital converter is used to record the time interval between the emission and reception of the ultrasonic signal. The main control module is used to calculate the sound velocity value.

[0138] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An ocean profile observation sensor, comprising a fixing device (1) and a measurement control circuit, characterized in that: An underwater ultrasonic time-of-flight probe module is installed on the outside of the fixing device (1), and the underwater ultrasonic time-of-flight probe module comprises an ultrasonic transducer (6) and a metal reflector (8); a housing (2) is fixedly connected to one side of the fixing device (1), a measuring probe module (3) is installed on the outer periphery of the housing (2), a supporting rod (4) is installed between the acoustic transducer (6) and the metal reflector (8), and the measuring control circuit is encapsulated inside the fixing device (1); The measurement control circuit comprises a main control module, a time-to-digital converter and a signal conditioning unit. The signal conditioning unit is connected to the ultrasonic transducer (6) and is used to send a high-frequency electrical signal to the ultrasonic transducer (6) and process an echo signal received by the ultrasonic transducer (6). The time-to-digital converter is used to record the time interval between the emission and reception of the ultrasonic signal. The main control module is used to calculate the sound velocity value.

2. The ocean profile observation sensor according to claim 1, characterized in that: One end of the underwater ultrasonic time-of-flight probe module away from the fixing device (1) is installed with a jettison block (5) via a release mechanism, and a communication antenna (7) is installed at the rear end of the housing (2).

3. The ocean profile observation sensor according to claim 2, characterized in that: The support rod (4) is made of epoxy resin material with a low thermal expansion coefficient and is used to fix the distance between the ultrasonic transducer (6) and the metal reflector (8) and to adapt to usage requirements in different temperature environments.

4. The ocean profile observation sensor according to claim 1, characterized in that: The time interval recording accuracy of the time digital converter reaches nanosecond level, which is used to ensure the measurement accuracy of the time difference between the transmission and reception of the ultrasonic signal.

5. A method for measuring ocean sound velocity profile, characterized in that: The use of the ocean profile observation sensor according to any one of claims 1 to 4 comprises the following steps: S1. Sending a high-frequency electrical signal pulse to the ultrasonic transducer (6) through the measurement control circuit, and the ultrasonic transducer (6) converts the high-frequency electrical signal pulse into an ultrasonic signal and transmits it into the water; S2. The ultrasonic signal propagates to the metal reflector (8) and is reflected, and the reflected echo signal is received again by the ultrasonic transducer (6), and is processed by the signal conditioning unit and input into the time-to-digital converter; S3. The time digital converter records the time interval between the emission and reception of the ultrasonic signal, the main control module reads the time data of the time digital converter, and calculates the sound velocity value according to the time interval and the distance between the ultrasonic transducer (6) and the metal reflector (8); S4. The main control module constructs a sound velocity profile according to the sound velocity values ​​measured at multiple depths.

6. The method for measuring ocean sound velocity profile according to claim 5, characterized in that: The calculation process of the sound velocity value is based on the end surface distance of the fixing device and the time interval recorded by the time digital converter, and the sound velocity value is obtained by dividing twice the fixed distance by the time interval.

7. The method for measuring ocean sound velocity profile according to claim 5, characterized in that: The process of constructing the sound velocity profile includes measuring the sound velocity values ​​at different depths in real time by a depth measurement probe, and pairing the sound velocity values ​​with corresponding depth values ​​to form a data point set.

8. The method for measuring ocean sound velocity profile according to claim 5, characterized in that: It also includes real-time collection of water temperature data through a temperature measurement probe, and dynamic correction of the sound velocity value based on the temperature to improve the accuracy of the sound velocity profile data.

9. The method for measuring ocean sound velocity profile according to claim 5, characterized in that: The jettison block (5) is released by a release mechanism after the sensor reaches a predetermined depth, so that the sensor's buoyancy is restored and the sensor quickly floats to the water surface, and then the constructed sound velocity profile data is uploaded to a ground station via a communication antenna (7).

10. The method for measuring ocean sound velocity profile according to claim 5, characterized in that: The measurement process uses a time-to-digital converter to record time with high precision, and the time interval measurement precision reaches nanosecond level, so as to reduce the influence of time error on the sound speed calculation.

Images