Multi-beam fishing sonar system with combined transmitting and receiving of dual transducers

Abstract

The present invention provides a multi-beam fishing sonar system with dual transducer elements combined for transmitting and receiving, which includes a signal processing unit, a transceiver unit, and a transducer array; the transducer array includes M rows and N columns of elements, where M and N are natural numbers and M is an even number; the transceiver unit includes M / 2 rows and N columns of transceiver channels; every two adjacent elements in each column are connected to one of the transceiver channels; the transceiver channels are connected to the signal processing unit. The multi-beam fishing sonar system with dual transducer elements combined for transmitting and receiving according to the present invention can reduce the number of underwater acoustic transmitting and receiving channels by half, and also reduce the signal processing calculation amount by half, greatly reducing the complexity of the system.

Description

Technical Field

[0001] The present invention relates to the field of multi-beam fishing sonar systems for marine fisheries, and in particular to a multi-beam fishing sonar system that combines the transceiver functions of two transducers. Background Art

[0002] As one of the most widely used and typical fishing aids in marine fisheries, a fishing sonar (fish finder) is a main tool for detecting the position, size, and movement of marine fish schools using hydroacoustic methods. The types of fish finders can be divided into vertical single-beam fish finders, horizontal fish finders, vertical dual-frequency fish finders, split-beam fish finders, and multi-beam fishing sonars, etc. Among them, the multi-beam fishing sonar can obtain a farther spatial detection range and a higher angular resolution ability, which is extremely helpful for improving the fishing efficiency of pelagic fisheries trawling and purse seining. However, due to its use of multi-beam technology, the implementation complexity is high, the system is large, and the price is expensive, which limits its large-scale use.

[0003] Traditional multi-beam fishing sonars use a multi-element planar array. A certain number of elements are distributed in the vertical and horizontal directions of the array. Typically, it is an 8×8 array, that is, 8 columns of elements in the vertical direction and 8 rows of elements in the horizontal direction. Each element is individually connected to a channel receiver / transmitter and connected to a signal processor. Different directive transmit or receive beams are generated through signal processing, so as to realize the detection of different directions in the water area. The number of receive / transmit channels of this system is equal to the number of elements. Signal processing requires the operation and processing ability corresponding to the number of elements. The system complexity is high, the hardware cost is large, and the requirements for the signal processor are also high.

[0004] Please refer to Figure 1, The traditional all-round digital multi-beam fish school detection system consists of a transducer array, a receiver, a transmitter, a transceiver converter, a signal processing host, a display, a keyboard, etc. Among them, the display and the keyboard (including the mouse) are used in combination with the signal processing host to complete the display of sonar detection images and the input and control of set parameters. The fishing sonar transducer array consists of N columns vertically and M rows horizontally, and its N×M elements correspond to N×M receiving channels and transmitting channels. The multi-beam fishing sonar realizes the detection of fish schools in different directions by first transmitting multiple beam acoustic signals and then receiving multiple underwater acoustic echo signals in different directions through beamforming. The conversion of the transmitting and receiving processes is controlled by the signal processing main control machine. During the transmitting process, the signal processing host generates drive signals corresponding to multiple channels of beams according to the set parameters. There is a certain phase difference between the drive signals of each channel to realize the beam pointing of sound waves in different directions in water. The electrical signals are sent to the corresponding transducer elements through the transmitter, and each element independently converts the electrical signal into an underwater acoustic signal. During the receiving process, each element in the transducer array independently converts the underwater acoustic signal into an electrical signal. After the analog signal processing including filtering, amplification, down-conversion, and analog-to-digital conversion is performed by the receiver corresponding to each transducer, it is sent to the signal processing host. In the signal processing host, the signals of each channel are phase-shifted according to the parameter settings to obtain beams in different directions. Summary of the Invention

[0005] Aiming at the deficiencies in the above-mentioned prior art, the present invention provides a multi-beam fishing sonar system that combines the transmitting and receiving of two transducer elements, which can reduce the number of underwater acoustic transmitting and receiving channels by half and also reduce the signal processing calculation amount by half, greatly reducing the complexity of the system.

[0006] To achieve the above object, the present invention provides a multi-beam fishing sonar system that combines the transmitting and receiving of two transducer elements, including a signal processing unit, a receiving and transmitting unit, and a transducer array; the transducer array includes M rows and N columns of elements, M and N are natural numbers, and M is an even number; the receiving and transmitting unit includes M / 2 rows and N columns of receiving and transmitting channels; every two adjacent elements in each column are connected to one receiving and transmitting channel; the receiving and transmitting channel is connected to the signal processing unit.

[0007] Preferably, each receiving and transmitting channel includes a receiver, a transmitter, a transceiver converter, a combiner, and a phase shifter; the receiver and the transmitter are respectively communicatively connected to the signal processing unit; the transceiver converter is communicatively connected to the receiver, the transmitter, and the signal processing unit; the combiner is connected to the transceiver converter and one element corresponding to the current receiving and transmitting channel; the phase shifter is connected to the combiner and the other element corresponding to the current receiving and transmitting channel.

[0008] Preferably, the phase shifter includes an LC delay circuit.

[0009] Preferably, the LC delay circuit includes:

[0010] A first resistor;

[0011] A capacitor, the first end of which is connected to the first resistor;

[0012] A second resistor, the first end of which is connected to the second end of the capacitor, and the second end of which is grounded;

[0013] An inductor, the first end of which is connected to the first end of the second resistor; and

[0014] A third resistor, the first end of which is connected to the second end of the inductor.

[0015] Preferably, the signal processing unit includes a signal processing host, a display, and an input device; the display and the input device are connected to the signal processing host; the receiving and transmitting channel is connected to the signal processing host.

[0016] Due to the adoption of the above technical solutions, the present invention has the following beneficial effects:

[0017] Through the cooperation of the phase shifter and the combiner, after fixing the phase shift of the two transducer array elements according to the preset inclination angle, the signal transmission and signal reception are combined; the number of underwater acoustic transmission and reception channels can be reduced by half, and the signal processing calculation amount is also reduced by half, greatly reducing the complexity of the system. Description of the Drawings

[0018] Figure 1 It is a schematic structural diagram of a traditional omnidirectional digital multi-beam fish school detection system;

[0019] Figure 2 It is a schematic structural diagram of a multi-beam fishing sonar system with combined transceiver of two transducer elements according to an embodiment of the present invention;

[0020] Figure 3 It is a circuit diagram of the LC delay circuit according to an embodiment of the present invention;

[0021] Figure 4 It is an equivalent diagram of the odd rows of the multi-beam fishing sonar system with combined transceiver of two transducer elements according to an embodiment of the present invention;

[0022] Figure 5 It is an equivalent diagram of the even rows of the multi-beam fishing sonar system with combined transceiver of two transducer elements according to an embodiment of the present invention.

[0023] Figure 6It is the equivalent diagram of the j-th column of the multi-beam fishing sonar system with dual transducer arrays combined for transceiver in the embodiment of the present invention;

[0024] Figure 7 It is the comparison diagram of the beam directivity waveforms between the present invention and the traditional fishing sonar system when the total beam inclination angle is 0 degree;

[0025] Figure 8 It is the comparison diagram of the beam directivity waveforms between the present invention and the traditional fishing sonar system when the total beam inclination angle is -10 degrees;

[0026] Figure 9 It is the comparison diagram of the beam directivity waveforms between the present invention and the traditional fishing sonar system when the total beam inclination angle is -30 degrees;

[0027] Figure 10 It is the comparison diagram of the beam directivity waveforms between the present invention and the traditional fishing sonar system when the total beam inclination angle is -45 degrees. Detailed implementation manners

[0028] Next, according to the attached Figures 2 to 10 , the preferred embodiments of the present invention are given and described in detail to better understand the functions and features of the present invention.

[0029] Please refer to Figure 2 , a multi-beam fishing sonar system with dual transducer arrays combined for transceiver in the embodiment of the present invention includes a signal processing unit 1, a receiving and transmitting unit 2, and a transducer array 3; the transducer array 3 includes M rows and N columns of elements 31, M and N are natural numbers, and M is an even number; the receiving and transmitting unit 2 includes M / 2 rows and N columns of receiving and transmitting channels 21; every two adjacent elements 31 in each column are connected to a receiving and transmitting channel 21; the receiving and transmitting channels 21 are connected to the signal processing unit 1.

[0030] Among them, each receiving and transmitting channel 21 includes a receiver 211, a transmitter 212, a transceiver converter 213, a combiner 214, and a phase shifter 215; the receiver 211 and the transmitter 212 are respectively communicatively connected to the signal processing unit 1; the transceiver converter 213 is communicatively connected to the receiver 211, the transmitter 212, and the signal processing unit 1; the combiner 214 is connected to the transceiver converter 213 and an element 31 corresponding to the current receiving and transmitting channel 21; the phase shifter 215 is connected to the combiner 214 and another element 31 corresponding to the current receiving and transmitting channel 21.

[0031] Among them, the signal processing unit 1 includes a signal processing host 11, a display 12, and an input device 13; the display 12 and the input device 13 are connected to the signal processing host 11; the receiving and transmitting channels 21 are connected to the signal processing host 11. The input device 13 can be a keyboard.

[0032] The signal processing host 11, the display 12, and the input device 13 are used in cooperation to complete the display of sonar detection images, the input of set parameters, control, etc.

[0033] In this embodiment, the phase shifter 215 includes an LC delay circuit.

[0034] Please refer to Figure 3 , the LC delay circuit includes: a first resistor R0, a capacitor C, a second resistor RL, an inductor L, and a third resistor R1; the first end of the capacitor C is connected to the first resistor R0; the first end of the second resistor RL is connected to the second end of the capacitor C, and the second end of the second resistor RL is grounded; the first end of the inductor L is connected to the first end of the second resistor RL; the first end of the third resistor R1 is connected to the second end of the inductor L.

[0035] Please refer to Figure 2 and Figure 3 , a multi-beam fishing sonar system with dual transducer elements combined for transmitting and receiving according to an embodiment of the present invention, the transducer array 3 is composed of N columns and M rows (where M is an even number) of elements 31 in the horizontal direction. For each column, two adjacent elements 31 correspond to one transmit-receive channel 21. Therefore, its N×M elements 31 use N×M / 2 transmit-receive channels 21. The multi-beam fishing sonar realizes the detection of fish schools in different directions by first transmitting multiple beam acoustic signals and then realizing the reception of underwater acoustic echo signals in multiple different directions through beamforming. The conversion of the transmission and reception processes is controlled by the signal processing main control machine 11.

[0036] In a multi-beam fishing sonar system with dual transducer elements combined for transmitting and receiving according to an embodiment of the present invention, during the transmission process, the signal processing host 11 generates drive signals for the corresponding beams of multiple channels according to the set parameters. There is a certain phase difference between the drive signals of each channel to achieve adjustable directional transmitting beamforming in different directions. The electrical signals are sent to the corresponding two elements 31 through the transmitter 212. According to the situation that the fishing sonar usually sweeps the sea at an inclination angle generally between -5° and -10°, a phase shifter 215 is added to one of the element 31 channels for phase shifting. A common phase shifting circuit is an LC delay circuit. Here, the phase shifter 215 is a passive phase shifter, and its principle and implementation are relatively simple. However, the phase shift value cannot be changed during the use of the fishing sonar system. That is, the beam at this inclination angle is a fixed value, which is equivalent to performing fixed vertical direction transmitting beamforming for the dual elements 31. Finally, each element 31 converts the electrical signal into an underwater acoustic signal. The overall transmitting beam directivity is the result of the combined action of two-stage beamforming, namely, N×M / 2 channel adjustable beamforming and dual element 31 fixed beamforming.

[0037] During the receiving process, each element 31 in the transducer array 3 independently converts the underwater acoustic signal into an electrical signal. Before performing dual-channel merging, a receiving beam with a fixed inclination angle is generated by the phase shifter 215. After the analog signal processing including filtering, amplification, down-conversion, and analog-to-digital conversion is performed by the receivers 211 corresponding to the respective elements 31, the signals are sent to the signal processing host 11. In the signal processing host 11, the signals of each channel are phase-shifted according to the parameter settings to obtain adjustable beams in different directions. The overall receiving beam directivity is the result of the combined action of the two-stage beamforming processes of N×M / 2-channel adjustable beamforming and the fixed beamforming of the dual elements 31.

[0038] The overall transmit or receive beam directivity is the result of the combined action of the two-stage beamforming processes. One stage is the adjustable beam. Therefore, both the horizontal directivity and the vertical directivity of the overall transmit or receive beam are adjustable. According to the planar array beamforming principle, since the horizontal directivity of the overall transmit or receive beam is equivalently obtained by independently calculating the horizontal directivity and the vertical directivity and then multiplying them, that is, the overall directivity is:

[0039]

[0040] where θ and are the equivalent angles in the vertical plane and the horizontal plane of the underwater acoustic signal respectively, D V is the directivity of a column of transducer elements, and D H is the directivity of a row of transducer elements.

[0041] Please refer to Figures 2 to 6 , when viewed from the horizontal direction, for the i-th row, when the i-th row is odd, the equivalent transceiver system is as Figure 4 , and it can be seen that it is the same as the traditional single-element corresponding single-channel fishing sonar system. When the i-th row is even, the equivalent transceiver system is as Figure 5 . Compared with the traditional fishing sonar system, each channel has an additional same phase shifter 215. From the beamforming principle, it can be known that simultaneous phase shifting of each channel by the same amount does not affect the directivity of the beamforming. In summary, when viewed from the horizontal direction, whether the row is odd or even, its horizontal beam directivity remains unchanged.

[0042] When viewed from the vertical direction, for the equivalent transceiver system of the j-th column, please refer to Figure 6 , and it can be seen that there are significant differences from the traditional single-element corresponding single-channel fishing sonar system, and the number of channels is reduced. Its vertical beamforming is equivalent to performing beamforming twice, that is:

[0043] D V (θ) = D V1 (θ0)D V2 (θ)

[0044] where, D V1For the fixed beamforming of two-channel double dipoles; θ0 is the fixed angle, usually from -5° to -10°; D V2 is the adjustable beamforming of M / 2 channels.

[0045] A multi-beam fishing sonar system for combining the receiving and transmitting of two transducer dipoles according to an embodiment of the present invention. The detection performance of the entire system depends on the two beamforming processes in the vertical direction. By simulating and comparing the beam directivity differences between the fishing sonar of the present invention and the traditional fishing sonar, the fixed inclination angle is set to -10°, the number of vertical dipoles is 8, and the dipole spacing is 0.5 wavelengths, as Figure 7 shown. It can be seen that when the total beam inclination angle is 0 degrees (i.e., horizontal pointing), the vertical beam directivity of the fishing sonar of the present invention is not much different from that of the traditional fishing sonar; please refer to Figure 8 ; when the total beam inclination angle is -10 degrees, the vertical beam directivity diagram of the fishing sonar of the present invention completely overlaps with that of the traditional fishing sonar, without performance loss; please refer to Figure 9 ; when the total beam inclination angle is -30 degrees, the vertical beam directivity of the fishing sonar of the present invention is about 10% lower than that of the traditional fishing sonar, and the performance degradation is still within an acceptable range; please refer to Figure 10 ; when the total beam inclination angle is -45 degrees, the vertical beam directivity of the fishing sonar of the present invention is about 30% lower than that of the traditional fishing sonar, and there are relatively large side lobes. At this time, the performance degradation is serious. In summary, the total vertical directivity is equivalent to that of the traditional fishing sonar when at the fixed inclination angle. As the difference between the total inclination angle and the fixed inclination angle increases, the performance gradually decreases. When the angle difference is within 20°, the performance degradation is not obvious.

[0046] Generally, multi-beam fishing sonars are used in trawling and purse-seine fishing boats for fish school detection during the fishing process. They perform sea sweeping during the navigation of the fishing boat. The usage scenario is generally to work at a fixed inclination angle or near the fixed inclination angle, and the scenario of working at a large inclination angle is very rare. Therefore, the benefits of reducing the system complexity and cost brought by the present invention are far greater than the disadvantages of performance loss in its infrequently used scenarios.

[0047] The present invention has been described in detail above in conjunction with the embodiments of the accompanying drawings. Those of ordinary skill in the art can make various variations of the present invention according to the above description. Therefore, certain details in the embodiments should not constitute a limitation to the present invention, and the protection scope of the present invention will be defined by the scope of the appended claims.

Claims

1. A multi-beam fishing sonar system that combines the transmitting and receiving functions of two transducer arrays, characterized in that, It includes a signal processing unit, a transceiver unit, and a transducer array; the transducer array includes M rows and N columns of elements, where M and N are natural numbers and M is an even number; the transceiver unit includes M / 2 rows and N columns of transceiver channels; every two adjacent elements in each column are connected to one of the transceiver channels; The transceiver channels are connected to the signal processing unit. Among them, each transceiver channel includes a receiver, a transmitter, a transceiver converter, a combiner, and a phase shifter; the receiver and the transmitter are respectively communicatively connected to the signal processing unit; the transceiver converter is communicatively connected to the receiver, the transmitter, and the signal processing unit; the combiner is connected to the transceiver converter and one of the elements corresponding to the current transceiver channel; the phase shifter is connected to the combiner and the other element corresponding to the current transceiver channel; The transducer array is composed of N columns and M rows (where M is an even number) of elements. Every two adjacent elements in each column correspond to one transceiver channel. Therefore, its N×M elements use N×M / 2 transceiver channels; the multi-beam fishing sonar realizes detecting fish schools in different directions by first transmitting multiple beam acoustic signals and then achieving receiving underwater acoustic echo signals in multiple different directions through beamforming. The conversion between the transmitting and receiving processes is controlled by the signal processing unit; During the transmitting process, the signal processing unit generates drive signals for the beams corresponding to multiple channels according to the set parameters. There is a certain phase difference between the drive signals of each channel to achieve an adjustable directional transmitting beamforming in different directions. The electrical signals are sent to the corresponding two elements through the transmitter. According to the situation that the sea-sweeping process of the fishing sonar is usually at an inclination angle generally between -5° and -10°, a phase shifter is added to one of the element channels for phase shifting. A common phase-shifting circuit is, for example, an LC delay circuit. Here, the phase shifter is a passive phase shifter. However, the phase-shifting value cannot be changed during the use of the fishing sonar system. That is, the beam at this inclination angle is a fixed value, which is equivalent to a fixed vertical-direction transmitting beamforming for the double elements. Finally, each element converts the electrical signal into an underwater acoustic signal. The overall transmitting beam directivity is the result of the combined action of the two-stage beamforming processes of N×M / 2-channel adjustable beamforming and double-element fixed beamforming; During the receiving process, each element in the transducer array independently converts the underwater acoustic signal into an electrical signal. Before the dual-channel combination, a receiving beam with a fixed inclination angle is generated through the phase shifter. After the analog signal processing including filtering, amplification, down-conversion, and analog-to-digital conversion and other processes through the receivers corresponding to each element, it is sent to the signal processing unit. In the signal processing unit, the signals of each channel are phase-shifted according to the parameter settings to obtain adjustable beams in different directions. The overall receiving beam directivity is the result of the combined action of the two-stage beamforming processes of N×M / 2-channel adjustable beamforming and double-element fixed beamforming; The overall transmit or receive beam directivity is the result of the combined action of two-stage beamforming processes. One stage is an adjustable beam, so both the horizontal and vertical directivities of the overall transmit or receive beam are adjustable. According to the beamforming principle of a planar array, since the horizontal directivity of the overall transmit or receive beam is equivalent to the product of independently obtained horizontal and vertical directivities, that is, the overall directivity is: where θ and are the equivalent angles in the vertical plane and the horizontal plane of the underwater acoustic signal respectively, D V is the directivity of a column of transducer elements, and D H is the directivity of a row of transducer elements.

2. The multi-beam fishing sonar system with combined transmitting and receiving of dual transducers according to claim 1, characterized in that The phase shifter includes an LC delay circuit.

3. The multi-beam fishing sonar system with combined transmitting and receiving of dual transducers according to claim 2, characterized in that, The LC delay circuit includes: A first resistor; A capacitor, the first end of which is connected to the first resistor; A second resistor, the first end of which is connected to the second end of the capacitor, and the second end of the second resistor is grounded; An inductor, the first end of which is connected to the first end of the second resistor; and A third resistor, the first end of which is connected to the second end of the inductor.

4. The multi-beam fishing sonar system with combined transmitting and receiving of dual transducers according to claim 3, characterized in that, The signal processing unit includes a signal processing host, a display, and an input device; the display and the input device are connected to the signal processing host; the receive-transmit channel is connected to the signal processing host.

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