Single-transmitting and multi-receiving multi-channel system based on river acoustic tomography flow measurement and layout control method

Abstract

The invention discloses a single-transmitting and multi-receiving multi-channel system based on river acoustic tomography flow measurement and a layout control method. The method comprises the following steps: (1) adopting transmitting transducers and receiving transducers with independent functions, and arranging a plurality of receiving transducers in a row vertically downwards at certain intervals; (2) adjusting the receiving gain of a pre-amplifier to improve the transmission quality of a received signal; (3) according to the change of the sound velocity of the water body at different temperatures, the arrangement distance of each receiving transducer which is vertically arranged is adjusted, and the distance between every two adjacent receiving transducers enables the difference of the water temperature difference to be more than 1 DEG C; and (4) after a column of vertical receiving transducers receive the sound waves, deleting abnormal signals, and calculating average signal arrival time according to the weight ratio of the remaining signals to serve as the arrival time of the actually measured signals. The problem that an existing river acoustic tomography flow measurement system is affected by changes of environmental sound velocity in water is solved, interference is reduced, and the quality of received sound wave signals and measurement stability are improved.

Description

Technical Field

[0001] The invention relates to the field of intelligent analysis of river flow measurement data, and in particular to a single-transmitter-multiple-receiver multi-channel system and a layout control method based on river acoustic tomography flow measurement. Background Art

[0002] River acoustic tomography technology has the advantages of real-time, simplicity, and high resolution. It sends sound signals and analyzes the river environment information carried by the received signals to inversely measure the flow rate and volume of a large range of rivers. Existing systems mostly use transducers with integrated transceiver functions to transmit signals to the other side. The technology is convenient to deploy transducers and the signal consistency is strong, but it has high requirements for the performance bias of the transducer's reception and transmission. With current technology, it is difficult to make the transducer's reception and transmission performance consistent.

[0003] At present, in order to ensure the real-time and simplicity of the river acoustic tomography flow measurement system, its circuit drive is generally single-channel drive, and the transducer is an omnidirectional, integrated transceiver. The layout method adopts a horizontal layout of a transceiver with a certain distance, and there is no vertical layout of multiple transducers according to the depth, which brings certain mutual signal interference. In addition, since the speed of sound in water is greatly affected by the water body, such as temperature, water impurities, water pressure and other factors, the temperature difference in the four seasons in the north is large, and the river is deep. When the speed of sound in the water changes greatly, the path of the sound wave changes, so that the sound wave signal cannot reach the position of the receiving transducer on the other side. Therefore, in the river section with a relatively complex water environment, it is very difficult for a single transducer receiving system to be laid out to a layout point where both sending and receiving are ideal. It is also affected by the temperature changes brought about by the alternation of day and night, and the quality of transducer reception changes regularly between day and night.

[0004] The prior art uses an acoustic wave probe to measure water flow. Instead of using a vertical string of receiving transducers to receive the transmitted sound waves, the patent name is a water flow detection system based on acoustic tomography cross-section detection, and the application number is CN202410695337.2. The acoustic wave probe with transceiver function used receives the reflected signal through a data processing unit, pre-processes the reflected signal to obtain a pre-processed signal; evaluates the quality of the pre-processed signal to obtain an evaluation result, and dynamically adjusts the acoustic wave signal processing parameters according to the evaluation result to obtain the final pre-processed signal; extracts pure signals and noise signals from the pre-processed signal; calculates the variance of the noise signal, traverses all samples of the noise signal, and calculates the difference between adjacent samples to calculate the flow velocity distribution and flow rate. It is very difficult for this system and method to extract pure signals and noise signals. The acoustic wave probe with transceiver function used in the system is conventionally arranged at a certain lateral distance, without considering the influence of water depth and temperature on the sound velocity, which will eventually affect the calculation of the actual arrival time of the sound wave. Summary of the invention

[0005] In order to solve the problem that the existing river acoustic tomography flow measurement system is affected by the change of environmental sound velocity in the water, reduce interference, and improve the quality of received sound wave signals and measurement stability, the present invention provides a single-transmitter-multiple-receiver multi-channel system based on river acoustic tomography flow measurement and a layout control method.

[0006] First, the present invention provides a multi-channel system deployment control method based on river acoustic tomography flow measurement with single-transmitter and multiple-receiver, comprising the steps of:

[0007] (1) Using independent transmitting transducers and receiving transducers, multiple receiving transducers are arranged in a row vertically downward at a certain interval. In response to the change in water sound velocity, each receiving transducer performs single-channel frequency impedance matching to ensure matching in receiving sensitivity;

[0008] (2) adjusting the receiving gain of the pre-stage amplifier to improve the transmission quality of the received signal, and adjusting the amplification gain of the pre-stage amplifier according to the receiving sensitivity of each receiving transducer at the operating frequency;

[0009] (3) In terms of the layout of the receiving transducers, according to the change of water sound velocity at different temperatures, the layout spacing of each vertically arranged receiving transducer is adjusted, and the distance between adjacent receiving transducers is such that the water temperature difference is more than 1°C;

[0010] (4) After a row of vertical receiving transducers receives the sound waves transmitted by the transmitting transducer on the opposite side of the river, abnormal signals are eliminated and the average signal arrival time is calculated according to the weight ratio of the remaining signals as the actual measured signal arrival time.

[0011] Further, step (2) specifically includes:

[0012] The receiving gain of the pre-amplifier is adjusted to improve the transmission quality of the received signal, and the amplification gain of the pre-stage is adjusted according to the receiving sensitivity of each receiving transducer at the operating frequency, so that each receiving transducer can have a unified electrical signal on the electrical signal collected by the system AD after amplification.

[0013] Further, step (3) specifically includes:

[0014] The transmitting transducer and the receiving transducer are arranged on the same side of the river channel, and the distance between the transmitting transducer and the nearest receiving transducer is maintained at more than 2 times the wavelength;

[0015] Multiple receiving transducers are arranged on the same side of the river channel to collect the water temperature at the location of the vertically arranged transducer. According to the change of water sound velocity at different temperatures and the corresponding data table of water sound velocity and temperature, the layout spacing of each vertically arranged receiving transducer is calculated and adjusted. The distance between adjacent receiving transducers is such that the water temperature difference is more than 1°C.

[0016] Further, step (4) specifically includes:

[0017] After a row of vertical receiving transducers receives the sound waves transmitted by the transmitting transducer on the opposite side of the river, the abnormal signals are filtered and deleted, and the signal-to-noise ratio of the receiving signal of each receiving transducer is calculated to obtain the weight ratio of each receiving signal;

[0018] Then, according to the weight ratio of each received signal, the average signal arrival time is calculated as the actual measured signal arrival time.

[0019] Specifically, a plurality of the receiving transducers in a vertical row use the same cable to transmit the received signal to the system host. The cable signal transmission includes a power supply, a ground line, and multiple signal lines, and separate frequency impedance matching is performed on the multiple signal lines.

[0020] Secondly, the present invention also provides a multi-channel system of single-transmitter and multi-receiver based on river acoustic tomography flow measurement, comprising a host, a plurality of transmitting transducers and receiving transducers with independent functions; the plurality of receiving transducers are arranged vertically downward in a row and at a certain interval, and in response to the change of water body sound velocity, each receiving transducer performs single-channel frequency impedance matching to maintain matching in receiving sensitivity; according to the change of water body sound velocity at different temperatures, the arrangement interval of each vertically arranged receiving transducer is adjusted, and the distance between adjacent receiving transducers is such that the water temperature difference is more than 1°C;

[0021] A vertical row of multiple receiving transducers receives the sound waves from the sending transducer on the opposite side of the river and transmits them to the host. The host is used to eliminate abnormal signals and calculate the average signal arrival time as the actual measurement signal arrival time based on the weight ratio of the remaining signals.

[0022] Furthermore, the host is also used to adjust the receiving gain of the pre-stage amplifier to improve the transmission quality of the received signal, and adjust the amplification gain of the pre-stage according to the receiving sensitivity of each receiving transducer at the operating frequency.

[0023] Furthermore, the transmitting transducer and the receiving transducer arranged in the same side of the river channel, the distance between the transmitting transducer and the nearest receiving transducer is maintained at more than 2 times the wavelength; the system also includes a temperature detector, which is used to collect the water temperature at the position where the vertically arranged transducers are located when multiple receiving transducers are arranged in the same side of the river channel; the host calculates and adjusts the layout spacing of each vertically arranged receiving transducer according to the change of the sound velocity of the water body at different temperatures and refers to the corresponding data table of the sound velocity and temperature of water, so that the distance between adjacent receiving transducers is such that the water temperature difference is more than 1°C.

[0024] Furthermore, a plurality of the receiving transducers in a vertical column use the same cable to transmit the received signal to the system host. The cable signal transmission includes a power supply, a ground line, and multiple signal lines, and separate frequency impedance matching is performed on the multiple signal lines.

[0025] Furthermore, the host is used to filter and delete abnormal signals, calculate the signal-to-noise ratio of the received signal of each receiving transducer, and obtain the weight ratio of each received signal; then, based on the weight ratio of each received signal, calculate the average signal arrival time as the actual measurement signal arrival time.

[0026] The technical advantages brought by the system and deployment control method of the present invention are as follows:

[0027] (1) Compared with the existing systems that mostly use integrated transceiver transducers and a single-transmitter-single-receiver channel control method, multiple receiving transducers are not arranged vertically according to depth, and mutual echo interference and the influence of water depth and temperature on sound speed are not considered.

[0028] The river acoustic tomography flow measurement system of the present invention adopts a multi-channel receiving design of single transmission and multiple reception, and a unique layout control method considering the influence of wavelength and water temperature, combined with a multi-parameter weight ratio algorithm, to solve the problem of changes in water temperature, impurities, and water pressure of the transducer in the water caused by changes in factors such as climate, sunshine time, geographical location, and ship driving interference during the transmission of acoustic waves in water by acoustic tomography, which leads to the deterioration of the quality of sound wave signal reception or the disappearance of the signal. The method and system of the present invention overcome the influence of changes in the quality of sound lines and sound wave signals caused by external environmental factors, making the measurement calculation more accurate.

[0029] The scheme of the present invention adopts a transmitting transducer and a receiving transducer with independent functions, and sets a transmitting transducer on one side of the river bank to send signals, while a vertical row of receiving transducers is matched on the opposite side of the river bank to receive sound wave signals, which not only reduces the mutual interference of multiple echoes of sound wave signals sent on the same side. In addition, by using receiving transducers with different installation depths, when encountering changes in water temperature, impurities, and water pressure where the transducers are located, the signal reception conditions of multiple receiving transducers are comprehensively considered to prevent the failure of a single receiving transducer from affecting the overall situation, make up for the loss of a single receiving signal, enhance the anti-interference of the signal, and improve the quality of the receiving signal, as well as the stability and measurement durability.

[0030] (2) Through a large number of experiments, the team of the present invention has found that keeping the distance between the transmitting transducer and the nearest receiving transducer at more than twice the wavelength can avoid being too close to each other, and the rebound sound waves that appear when transmitting can cause interference. In addition, the water temperature of the position where the vertically arranged transducer is located is collected; the host establishes a data table corresponding to the sound velocity and temperature of water according to the change of the sound velocity of the water body at different temperatures, and calculates and adjusts the layout spacing of each vertically arranged receiving transducer, so that the distance between adjacent receiving transducers is greater than 1°C. Because it is found that due to the serious temperature stratification of part of the riverbed in the middle of the river, different temperatures have a great impact on the sound velocity. When the sound line has begun to be obviously stratified in the riverbed, the adjacent layout spacing calibrated according to the water temperature can also be shortened or lengthened. According to the layout method of the present invention, the influence of the water environment on the change of the sound velocity can be greatly eliminated, interference can be reduced, and the quality of the received sound wave signal and the measurement stability can be improved. The experiment proves that the method of the present invention improves the signal measurement accuracy by 6-8% compared with the above-mentioned existing measurement method. The system's measurement stability is maintained for more than 2 years, which is 2-3 times higher than the existing measurement system, and is more adaptable to the measurement of rivers in the north that are frozen or have heavy rains. Because the present invention comprehensively considers the influence of the temperature of different water layers on the speed of sound, and also introduces a multi-parameter weight ratio algorithm, the measurement accuracy is improved.

[0031] (3) This system uses independent transmitting transducers and receiving transducers, which is more cost-effective. A row of vertical receiving transducers all use the same cable to perform frequency impedance matching on multiple signal lines. The stability of signal acquisition is improved. This design can greatly reduce the number of personnel maintenance and is convenient for deployment on the river bank. The host has a high degree of intelligence, fast calculation, and stronger anti-interference applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is the schematic diagram of the amplification circuit of the system receiving transducer.

[0033] Figure 2 It is a schematic diagram of a single-transmitter-multiple-receiver multi-channel system based on river acoustic tomography flow measurement of the present invention.

[0034] Figure 3 It is a sonic temperature gauge of water in the method of the present invention.

[0035] Figure 4 It is a schematic diagram of a plurality of receiving transducers arranged vertically in a row according to the present invention.

[0036] Figure 5 It is a schematic diagram of the signals received by the five receiving transducers.

[0037] Figure 6 is a schematic diagram of a cable connecting a plurality of the receiving transducers. DETAILED DESCRIPTION

[0038] The technical solution in the embodiment of the invention will be clearly and completely described below in conjunction with the drawings in this embodiment.

[0039] The embodiment of the present invention provides a multi-channel system deployment control method for single-transmitter-multiple-receiver based on river acoustic tomography flow measurement, which adopts the following steps.

[0040] Step (1), using independent function transmitting transducers and receiving transducers, multiple receiving transducers are arranged in a row vertically downward and at a certain interval, in response to the change of water sound velocity, each receiving transducer performs single-channel frequency impedance matching to maintain matching in receiving sensitivity.

[0041] For the operating frequency (frequency band) of the transmitting transducer, each receiving transducer has relatively consistent receiving sensitivity in the operating frequency band, that is, the frequency band receiving sensitivity error of the receiving transducers installed in the same river section is ±1.5dB. An impedance analyzer is used to measure the frequency impedance characteristics of the receiving transducer for unified matching and adjustment.

[0042] Step (2), adjusting the receiving gain of the pre-stage amplifier to improve the transmission quality of the received signal, and adjusting the amplification gain of the pre-stage according to the receiving sensitivity of each receiving transducer at the operating frequency.

[0043] like Figure 1 As shown, the system receives the amplifying circuit of the transducer, and the back end is connected to the AD acquisition circuit.

[0044] Adjust the receiving gain of the pre-amplifier, that is, adjust the ratio of R4 / R3 and R7 / R6 to achieve the best reception signal transmission, and adjust the pre-amplification gain according to the receiving sensitivity of each receiving transducer at the operating frequency (frequency band), so that each receiving transducer can have an electrical signal of uniform size (2.7V~3.3V for the single-chip microcomputer system) on the electrical signal collected by the system AD after amplification, and then transmit the amplified signal back to the main computing device for data analysis.

[0045] For example, taking the adjustment process as an example, the receiving sensitivity of receiving transducer A is -200dB (V / uPa), and the receiving sensitivity of receiving transducer B is -160dB. Because the optimal acquisition voltage of the AD acquisition circuit is between 2.7 and 3.3V (calculated according to 3.2V), according to the sound intensity of 200uPa, for receiving transducer A, the ratio of R4 / R3 and R7 / R6 needs to be adjusted to 3.2, that is, 10.1dB gain; for receiving transducer B, the values ​​of R4 / R3 and R7 / R6 need to be adjusted to reach a voltage of 3.2V on the AD acquisition circuit, then the value of R4 / R3 of transducer B should be 2.56, that is, 8.16dB gain.

[0046] Step (3), according to the change of water body sound velocity at different temperatures, the layout spacing of each vertically arranged receiving transducer is adjusted, and the distance between adjacent receiving transducers is separated so that the water temperature difference is more than 1°C.

[0047] like Figure 2 As shown, the multi-channel system of single-transmitter and multiple-receiver based on river acoustic tomography flow measurement of the present invention includes a host (not shown in the figure), multiple independent function transmitting transducers and receiving transducers; it can also include a wireless transmission device, and the host can connect the transmitting transducer and the receiving transducer through a wireless network or a data cable. The multiple receiving transducers are formed into a row vertically downward and arranged at a certain interval. As an embodiment of the layout control method, a transmitting transducer with independent function can be set on one side of the river bank, and a corresponding row of multiple receiving transducers can be set vertically on the opposite bank of the river to form the simplest system architecture. Of course, more transmitting transducers and receiving transducers can be added according to the actual width and depth of the river.

[0048] The transmitting transducer and receiving transducer arranged on the same side of the river channel are kept at a distance of more than 2 times of the wavelength from the nearest receiving transducer, so as to avoid interference caused by rebound sound waves when transmitting when they are too close.

[0049] In addition, based on the accumulation of a large amount of experimental data in the early stage, a water sound velocity temperature table was established, see the attached Figure 3 .

[0050] Multiple receiving transducers are arranged vertically in a row on the same side of the river. According to the change of water body sound velocity in different water layer temperatures, the arrangement spacing of each vertically arranged receiving transducer is adjusted. The distance between adjacent receiving transducers is such that the water temperature difference is more than 1°C. As for how wide the 1°C distance is, it depends on the actual riverbed temperature. The water temperature difference between two adjacent transducers must be more than 1°C, and the distance should be more than 2 times the wavelength to reduce mutual signal interference.

[0051] The bottom receiving transducer is fixed by a heavy pile to ensure that the whole row of multiple receiving transducers is vertically downward. Figure 4 As shown in the figure, there are five receiving transducers, and the distances between them are L1, L2, L3, and L4. Since the temperature stratification of some riverbeds in the middle of the river is serious, and the sound line has begun to stratify in the middle of the riverbed, the water temperature calibration distance can also be shortened or lengthened for this reason; Figure 4 The lengths of L1, L2, L3, and L4 are all determined by the speed of sound at the underwater location.

[0052] Step (4), after a row of vertical receiving transducers receives the sound waves transmitted by the transmitting transducer on the opposite side of the river, the signal-to-noise ratio of the received signal of each receiving transducer is calculated to obtain the weight ratio of each received signal. Then, based on the weight ratio of each received signal, the average signal arrival time is calculated as the actual measured signal arrival time.

[0053] Specifically, after the deployment is completed, the acoustic tomography system drives the transmitting transducer to send sound waves through the host, and matches a corresponding row of multiple receiving transducers set on the other side of the river. After receiving the sound waves from the opposite side, the signal transmitted back by each receiving transducer is analyzed, and abnormal signals such as excessively poor signals, excessively strong signals, and no signals are deleted. The average signal arrival time is calculated according to the weight ratio of the remaining signals as the actual measurement signal arrival time.

[0054] For example: receiving transducers 1 to 5 all transmit signals back, and the arrival times of the signals are t1, t2, t3, t4, and t5 respectively. According to the temperature of each transducer and the algorithm, the weight ratio x of each transducer is obtained. According to the formula t=x1×t1+x2×t2+x3×t3+x4×t4+x5×t5, the average time t is calculated.

[0055] The following is an example of the test: the signals received by the five transducers are as follows: Figure 5 The signal-to-noise ratios of the calculated signals are 25.6, 36.3, 43, 34.7, and 30.2 respectively. According to the formula Q1 is the weight ratio of signal 1, X1 is the signal-to-noise ratio of signal 1, (X1+X2+X3+X4+.......+Xn) is the sum of all signal-to-noise ratios, and the weight ratio of each signal is calculated. The five signals will be calculated with normalized signal-to-noise ratios of 0.15, 0.21, 0.25, 0.20, and 0.18 as weight calculation results.

[0056] Among the signals received by the five transducers, each signal has an arrival time (t1, t2, t3, t4, t5). The average arrival time is calculated based on the weight ratio of the five signals. The formula is as follows:

[0057] t=0.15×t1+0.21×t2+0.25×t3+0.20×t4+0.18×t5

[0058] Through multiple measurements and statistical methods, we can obtain more stable arrival time results with smaller errors, and finally get the average time of the section, which can be used to calculate more accurate river flow results later.

[0059] Embodiment 2 of the present invention further provides a multi-channel system for single-transmitter and multi-receiver based on river acoustic tomography flow measurement, using the above method of the present invention, such as Figure 2As shown, the system includes a host (not shown in the figure), multiple independent function transmitting transducers and receiving transducers; it may also include a wireless transmission device, and the host can connect the transmitting transducer and the receiving transducer through a wireless network or a data cable. Multiple receiving transducers are arranged vertically downward in a row and arranged at a certain distance. In response to the change of water sound velocity, each receiving transducer performs single-channel frequency impedance matching to maintain matching in receiving sensitivity; according to the change of water sound velocity at different temperatures, the arrangement spacing of each vertically arranged receiving transducer is adjusted, and the distance between adjacent receiving transducers is separated so that the water temperature difference is more than 1°C.

[0060] A row of vertical receiving transducers receives the sound waves from the transmitting transducer on the opposite side of the river and transmits them to the host. The host is used to eliminate excessively poor signals, excessively strong signals and abnormal signals, and calculates the average signal arrival time according to the weight ratio of the remaining signals as the actual measurement signal arrival time.

[0061] The host is also used to adjust the receiving gain of the pre-stage amplifier to improve the transmission quality of the received signal, and adjust the amplification gain of the pre-stage according to the receiving sensitivity of each receiving transducer at the working frequency.

[0062] The transmitting transducer and the receiving transducer are arranged on the same side of the river channel, and the distance between the transmitting transducer and the nearest receiving transducer is maintained at more than 2 times of the wavelength; the system also includes a temperature detector, which is arranged on multiple receiving transducers arranged on the same side of the river channel, and collects the water temperature at the position where the vertically arranged transducers are located; the host calculates and adjusts the layout spacing of each vertically arranged receiving transducer according to the change of water sound velocity at different temperatures and refers to the water sound velocity and temperature corresponding data table, so that the distance between adjacent receiving transducers is greater than 1°C.

[0063] like Figure 6 As shown, a plurality of the receiving transducers in a vertical row all use the same cable to transmit the received signal to the system host. The cable signal transmission includes a power supply, a ground line, and a plurality of signal lines, and frequency impedance matching is performed separately for the plurality of signal lines.

[0064] The host is used to filter and delete excessively poor signals, excessively strong signals and abnormal signals, calculate the signal-to-noise ratio of the received signal of each receiving transducer, and obtain the weight ratio of each received signal; then, based on the weight ratio of each received signal, calculate the average signal arrival time as the actual measured signal arrival time.

[0065] The present invention is based on a multi-channel system of single-transmitter and multiple-receiver for river acoustic tomography flow measurement, which solves the problem that the quality of sound wave signal reception deteriorates or the signal disappears due to changes in water temperature, impurities, and water pressure of the transducer caused by changes in climate, sunshine time, geographical location, human interference and other factors during the transmission of sound waves in water. Through experimental tests, the existing system with one transmitter and one receiver has a probability of 6-8% of receiving weak sound wave signals or even sudden signal disappearance when facing a river with a river width of more than 100 meters and a depth of more than 12 meters. However, the probability of the same situation occurring when the system of the present invention is tested is about 0.2%.

[0066] All external environmental factors can cause changes in multiple sound lines, such as Figure 4 For example, if the water temperature, impurities, and water pressure of the transducer change, the receiving transducer 1 may not receive any signal at all, and the receiving transducer 2 may receive overlapping signals arriving from multiple paths. If transducers 3, 4, and 5 are installed on the same vertical plane, the transmitted sound wave signal can be guaranteed to be received, making up for the missing signals of receiving transducers 1 and 2, and enhancing the anti-interference ability of the signal. This structural design can greatly reduce the number of personnel maintenance, while ensuring the real-time stability and durability of the signal.

[0067] The method and system of the present invention arrange multiple receiving transducers vertically downward and at a certain interval to cope with the situation where some transducers cannot receive signals due to changes in the sound velocity of the water body; single-channel frequency impedance matching is performed for each receiving transducer, and each transducer maintains approximately the same receiving sensitivity (with an error of ±1.5dB), and multiple AD channels are used for simultaneous acquisition to reduce interference and improve signal quality. The temperature changes at the positions of the vertically arranged transducers are collected, and the arrangement spacing of each receiving transducer is determined according to the changes in the sound velocity of the water body at different temperatures, which can greatly improve the stability of the received signal.

Claims

1. A multi-channel system layout control method for single-transmitter-multiple-receiver based on river acoustic tomography flow measurement, characterized in that: Includes steps: (1) Using independent transmitting transducers and receiving transducers, multiple receiving transducers are arranged in a row vertically downward at a certain interval. In response to the change in water sound velocity, each receiving transducer performs single-channel frequency impedance matching to ensure matching in receiving sensitivity; (2) adjusting the receiving gain of the pre-stage amplifier to improve the transmission quality of the received signal, and adjusting the amplification gain of the pre-stage amplifier according to the receiving sensitivity of each receiving transducer at the operating frequency; (3) In terms of the layout of the receiving transducers, according to the change of water sound velocity at different temperatures, the layout spacing of each vertically arranged receiving transducer is adjusted, and the distance between adjacent receiving transducers is such that the water temperature difference is more than 1°C; (4) After a row of vertical receiving transducers receives the sound waves transmitted by the transmitting transducer on the opposite side of the river, abnormal signals are eliminated and the average signal arrival time is calculated according to the weight ratio of the remaining signals as the actual measured signal arrival time.

2. The method for controlling the deployment of a multi-channel system of single-transmitter-multiple-receiver based on river acoustic tomography flow measurement according to claim 1 is characterized in that: Step (2) specifically includes: The receiving gain of the pre-amplifier is adjusted to improve the transmission quality of the received signal, and the amplification gain of the pre-stage is adjusted according to the receiving sensitivity of each receiving transducer at the operating frequency, so that each receiving transducer can have a unified electrical signal on the electrical signal collected by the system AD after amplification.

3. The method for controlling the deployment of a multi-channel system of single-transmitter-multiple-receiver based on river acoustic tomography flow measurement according to claim 1 is characterized in that: Step (3) specifically includes: The transmitting transducer and the receiving transducer are arranged on the same side of the river channel, and the distance between the transmitting transducer and the nearest receiving transducer is maintained at more than 2 times the wavelength; Multiple receiving transducers are arranged on the same side of the river channel to collect the water temperature at the location of the vertically arranged transducer. According to the change of water sound velocity at different temperatures and the corresponding data table of water sound velocity and temperature, the layout spacing of each vertically arranged receiving transducer is calculated and adjusted. The distance between adjacent receiving transducers is such that the water temperature difference is more than 1°C.

4. The method for controlling the deployment of a multi-channel system of single-transmitter-multiple-receiver based on river acoustic tomography flow measurement according to any one of claims 1 to 3, characterized in that: A plurality of the receiving transducers arranged vertically in a row all use the same cable to transmit the received signals to the system host. The cable signal transmission includes a power supply, a ground line, and a plurality of signal lines. Frequency impedance matching is performed on the plurality of signal lines separately.

5. The method for controlling the deployment of a multi-channel system of single-transmitter-multiple-receiver based on river acoustic tomography flow measurement according to claim 1 is characterized in that: Step (4) specifically includes: After receiving the sound waves transmitted by the transmitting transducer on the opposite side of the river, a plurality of vertical receiving transducers in a row filter and delete abnormal signals, calculate the signal-to-noise ratio of the receiving signal of each receiving transducer, and obtain the weight ratio of each receiving signal; Then, according to the weight ratio of each received signal, the average signal arrival time is calculated as the actual measured signal arrival time.

6. A multi-channel system for single-transmitter and multi-receiver based on river acoustic tomography flow measurement, characterized in that: It includes a host, multiple independent transmitting transducers and receiving transducers; multiple receiving transducers are arranged vertically downward in a row and at a certain distance. In response to the change of water sound velocity, each receiving transducer performs single-channel frequency impedance matching to keep matching in receiving sensitivity; according to the change of water sound velocity at different temperatures, the arrangement spacing of each vertically arranged receiving transducer is adjusted, and the distance between adjacent receiving transducers is separated so that the water temperature difference is more than 1°C; A vertical row of multiple receiving transducers receives the sound waves from the sending transducer on the opposite side of the river and transmits them to the host. The host is used to eliminate abnormal signals and calculate the average signal arrival time as the actual measurement signal arrival time based on the weight ratio of the remaining signals.

7. A multi-channel system for single-transmitter and multi-receiver based on river acoustic tomography flow measurement according to claim 6, characterized in that: The host is also used to adjust the receiving gain of the pre-stage amplifier to improve the transmission quality of the received signal, and adjust the amplification gain of the pre-stage according to the receiving sensitivity of each receiving transducer at the working frequency.

8. The multi-channel system of single-transmitter-multiple-receiver based on river acoustic tomography flow measurement according to claim 6, characterized in that: The transmitting transducer and the receiving transducer are arranged on the same side of the river channel, and the distance between the transmitting transducer and the nearest receiving transducer is maintained at more than 2 times the wavelength; The system also includes a temperature detector for collecting water temperatures at the locations of the vertically arranged transducers arranged on the same side of the river channel; the host calculates and adjusts the spacing of each vertically arranged receiving transducer according to the change of the sound velocity of the water body at different temperatures and with reference to the corresponding data table of the sound velocity and temperature of water, so that the distance between adjacent receiving transducers is such that the water temperature difference is more than 1°C.

9. The multi-channel system of single-transmitter-multiple-receiver based on river acoustic tomography flow measurement according to claim 6, characterized in that: A plurality of the receiving transducers arranged vertically in a row all use the same cable to transmit the received signals to the system host. The cable signal transmission includes a power supply, a ground line, and a plurality of signal lines. Frequency impedance matching is performed on the plurality of signal lines separately.

10. The multi-channel system of single-transmitter-multiple-receiver based on river acoustic tomography flow measurement according to claim 6, characterized in that: The host is used to filter and delete excessively poor signals, excessively strong signals and abnormal signals, calculate the signal-to-noise ratio of the received signal of each receiving transducer, and obtain the weight ratio of each received signal; then, based on the weight ratio of each received signal, calculate the average signal arrival time as the actual measured signal arrival time.

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