A multi-target recognition method for underwater multi-area positioning

Abstract

The present invention belongs to the technical field of buoy array target positioning, and specifically relates to a multi-target identification method for underwater multi-region positioning. The present invention uses a combination of multiple frequency-modulated signals and single-frequency signals to represent identity information. Time-division and frequency-division technology can be used to achieve signal representation of multiple targets and multiple buoys, breaking away from the constraints of a limited number of linear frequency-modulated signals on the number of serviceable targets. In terms of frequency selection, the present invention takes into account the Doppler frequency deviation caused by target movement, and therefore selects frequency points at intervals within the bandwidth, improving the system's anti-Doppler performance. The present invention also considers the problems of multiple users and signal collisions. For multi-user reception, the single-frequency signal length of the cooperative positioning sound signal is designed to be T2(s). As long as the time difference between the cooperative positioning sound signals of multiple users reaching the buoy is T2(s), different users can be distinguished.

Description

Technical Field

[0001] The invention belongs to the technical field of buoy array target positioning, and in particular relates to a multi-target recognition method for underwater multi-area positioning. Background Art

[0002] In a system that uses a buoy array to locate targets, a network of buoys and multiple cooperating targets are involved. The buoy network is deployed in deep, open waters. The buoys form a distributed transponder array based on signal coverage, with several buoys grouped together.

[0003] When a target needs to be located, it emits a cooperative localization sound signal, which is received by the buoy. The buoy then transmits the time of receipt of the cooperative localization sound signal to the receiver, which then uses a correlator and Notch filter to identify the signal and calculate the target's position.

[0004] Because multiple targets and buoys are involved, identity information must be clearly identified during communication. Each target must transmit its own sequence number and the sequence number of the buoy group it wishes to awaken. Upon receiving the signal, the corresponding buoy group transmits a response signal containing the target's sequence number and the buoy's own sequence number. Upon receiving the response signal, the target and buoy numbers are determined, and positioning is performed based on the time the buoy received the cooperative positioning sound signal and the corresponding buoy's position.

[0005] Therefore, designing a signal format and matching signal recognition algorithm to enable a positioning system that can meet the needs of multi-target positioning becomes a pressing issue. Traditional multi-target signal structures typically use only a few linear frequency modulation signals to distinguish different targets. This is susceptible to Doppler effects and can only distinguish a small number of targets to be located. This makes it impossible to distinguish the identities of more than a dozen targets in a buoy array-based positioning system. Summary of the Invention

[0006] The purpose of the present invention is to provide a multi-target recognition method for underwater multi-area positioning, which can meet the needs of identifying and serving multiple targets to be located in a buoy network positioning system.

[0007] A multi-target recognition method for underwater multi-area positioning includes the following steps:

[0008] (1) The target to be located transmits a cooperative positioning sound signal to the nearest buoy group. The signal carries the serial number of the target to be located and the serial number of the buoy group to be awakened.

[0009] The cooperative positioning sound signal is composed of a first frequency-modulated signal, a first single-frequency signal CW1, a second single-frequency signal CW2, and a third single-frequency signal CW3. The first frequency-modulated signal occupies the first T1(s) of the cooperative positioning sound signal, the first single-frequency signal CW1, the second single-frequency signal CW2, and the third single-frequency signal CW3 each occupy T2(s), and the interval between each component is T3(s);

[0010] There are m1 types of the first FM signal; there are n1 types of the first single-frequency signal CW1, with a frequency band range of f1 to f2; there are m1*n1 combinations of the first FM signal and the first single-frequency signal CW1, used to distinguish m*n1 targets to be located; there are n2 types of the second single-frequency signal CW2, with a frequency band range of f2 to f3; there are n3 types of the third single-frequency signal CW3, with a frequency band range of f3 to f4; there are n2*n3 combinations of the second single-frequency signal CW2 and the third single-frequency signal CW3, used to distinguish n2*n3 potential target groups;

[0011] (2) After the buoy group receives the cooperative positioning sound signal, each buoy in the buoy group generates a set of positioning response signals for each target to be positioned that chooses to wake up the buoy group, and transmits them to the receiving end; the positioning response signal includes the buoy's sequence number in the buoy group, the buoy group sequence number, and the sequence number of the target to be positioned;

[0012] (3) After receiving the positioning response signal, the receiver extracts the relevant identity information to achieve multi-target recognition.

[0013] Furthermore, the positioning response signal is composed of a second frequency modulation signal, a fourth single frequency signal CW4, a fifth single frequency signal CW5, and a composite signal. The second frequency modulation signal occupies the first T1(s) time of the positioning response signal, the fourth single frequency signal CW4, the fifth single frequency signal CW5, and the composite signal each occupy T2(s) time, and the interval between each component is T3(s);

[0014] There are m2 types of the second frequency modulation signal, which are used to distinguish m2 potential buoys in the potential buoy group; there are n2 types of the fourth single frequency signal CW4, with a frequency band range of f5 to f6; there are n3 types of the fifth single frequency signal CW5, with a frequency band range of f6 to f7; there are n2*n3 combinations of the fourth single frequency signal CW4 and the fifth single frequency signal CW5, which are used to distinguish n2*n3 potential buoy groups; the composite signal is composed of two sixth single frequency signals CW6; there are n4 types of the sixth single frequency signal CW6, with a frequency band range of f7 to f8; for each target to be located, a composite signal composed of two sixth single frequency signals CW6 is selected.

[0015] The beneficial effects of the present invention are:

[0016] The present invention uses a combination of multiple frequency-modulated signals and single-frequency signals to represent identity information. Time- and frequency-division techniques can be used to achieve signal representation for multiple targets and buoys, eliminating the constraints imposed by a limited number of linear frequency-modulated signals on the number of serviceable targets. Regarding frequency selection, the present invention considers the Doppler shift introduced by target movement and therefore selects frequencies at intervals within the bandwidth, improving the system's anti-Doppler performance. Furthermore, the present invention considers multi-user and signal collision issues. For multi-user reception, the single-frequency signal length of the cooperative positioning acoustic signal is designed to be T2(s). As long as the arrival time of the cooperative positioning acoustic signals from multiple users differs by T2(s) from the buoy, different users can be distinguished. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Flowchart of the present invention

[0018] Figure 2 This is a structural diagram of the cooperative localization sound signal in the present invention.

[0019] Figure 3 This is a structural diagram of the buoy positioning response signal in the present invention.

[0020] Figure 4 FIG. 4 is a structural diagram of cooperative localization of acoustic signals in an embodiment of the present invention.

[0021] Figure 5 2 is a structural diagram of a buoy positioning response signal in an embodiment of the present invention. DETAILED DESCRIPTION

[0022] The present invention will be further described below with reference to the accompanying drawings.

[0023] This invention discloses a multi-target recognition method for underwater multi-area positioning. The method utilizes quasi-orthogonal signals (cooperative positioning acoustic signals and buoy positioning response signals) based on a combination of frequency modulation and single frequency, and signal detection using a Notch filter and correlator. This method addresses the need to identify and serve multiple targets in a buoy positioning system, avoiding the inefficiency of existing similar methods that can only serve a few targets. It also boasts a simple structure, ease of identification, Doppler immunity, and a low error probability.

[0024] (1) The target to be located transmits a cooperative positioning sound signal to the nearest buoy group. The signal carries the serial number of the target to be located and the serial number of the buoy group to be awakened.

[0025] The cooperative positioning sound signal is composed of a first frequency-modulated signal, a first single-frequency signal CW1, a second single-frequency signal CW2, and a third single-frequency signal CW3. The first frequency-modulated signal occupies the first T1(s) of the cooperative positioning sound signal, the first single-frequency signal CW1, the second single-frequency signal CW2, and the third single-frequency signal CW3 each occupy T2(s), and the interval between each component is T3(s);

[0026] There are m1 types of the first FM signal; there are n1 types of the first single-frequency signal CW1, with a frequency band range of f1 to f2; there are m1*n1 combinations of the first FM signal and the first single-frequency signal CW1, used to distinguish m*n1 targets to be located; there are n2 types of the second single-frequency signal CW2, with a frequency band range of f2 to f3; there are n3 types of the third single-frequency signal CW3, with a frequency band range of f3 to f4; there are n2*n3 combinations of the second single-frequency signal CW2 and the third single-frequency signal CW3, used to distinguish n2*n3 potential target groups;

[0027] (2) After the buoy group receives the cooperative positioning sound signal, each buoy in the buoy group generates a set of positioning response signals for each target to be positioned that chooses to wake up the buoy group, and transmits them to the receiving end; the positioning response signal includes the buoy's sequence number in the buoy group, the buoy group sequence number, and the sequence number of the target to be positioned;

[0028] The positioning response signal is composed of a second frequency-modulated signal, a fourth single-frequency signal CW4, a fifth single-frequency signal CW5, and a composite signal. The second frequency-modulated signal occupies the first T1(s) of the positioning response signal, the fourth single-frequency signal CW4, the fifth single-frequency signal CW5, and the composite signal each occupy T2(s), and the interval between each component is T3(s).

[0029] There are m2 types of the second frequency modulation signal, which are used to distinguish m2 potential buoys in the potential buoy group; there are n2 types of the fourth single frequency signal CW4, with a frequency band range of f5 to f6; there are n3 types of the fifth single frequency signal CW5, with a frequency band range of f6 to f7; there are n2*n3 combinations of the fourth single frequency signal CW4 and the fifth single frequency signal CW5, which are used to distinguish n2*n3 potential buoy groups; the composite signal is composed of two sixth single frequency signals CW6; there are n4 types of the sixth single frequency signal CW6, with a frequency band range of f7 to f8; for each target to be located, a composite signal composed of two sixth single frequency signals CW6 is selected.

[0030] (3) After receiving the positioning response signal, the receiver extracts the relevant identity information to achieve multi-target recognition.

[0031] The present invention uses a combination of multiple frequency-modulated signals and single-frequency signals to represent identity information. Time- and frequency-division techniques can be used to achieve signal representation for multiple targets and buoys, eliminating the constraints imposed by a limited number of linear frequency-modulated signals on the number of serviceable targets. Regarding frequency selection, the present invention considers the Doppler shift introduced by target movement and therefore selects frequencies at intervals within the bandwidth, improving the system's anti-Doppler performance. Furthermore, the present invention considers multi-user and signal collision issues. For multi-user reception, the single-frequency signal length of the cooperative positioning acoustic signal is designed to be T2(s). As long as the arrival time of the cooperative positioning acoustic signals from multiple users differs by T2(s) from the buoy, different users can be distinguished.

[0032] Example 1:

[0033] The target to be located transmits a cooperative positioning sound signal, which carries the serial number of the target to be located and the serial number of the buoy group to be awakened.

[0034] Cooperative positioning sound signal design and parameters: signal frequency band: f1~f4, signal structure as follows Figure 2 shown.

[0035] (1) The parameters of the first FM signal are as follows:

[0036] There are m1 first FM signals, numbered 1 to m1. The frequency band selection range is F1∈(f1,f4).

[0037] (2) The parameters of the single-frequency signal CW1 are as follows:

[0038] The single-frequency signal CW1 is s1(t)=Ae j2πft ,t∈(0,T2), a total of n1 types, serial number 1 to n1, frequency band range f1 to f2, specific frequency point selection f=f1+nΔf,n∈0,1,...n1-1. Specific parameters can be set according to the usage scenario.

[0039] (3) The parameters of the single-frequency signal CW2 are as follows:

[0040] The single-frequency signal CW2 is s2(t)=Ae j2πft ,t∈(0,T2), a total of n2 types, serial number 1 to n2, frequency band range f2 to f3, specific frequency point selection f=f2+nΔf,n∈0,1,...n2-1. Specific parameters can be set according to the usage scenario.

[0041] (4) The parameter table of single frequency signal CW3 is as follows:

[0042] The single-frequency signal CW3 is s3(t)=Ae j2πft,t∈(0,T2), a total of n3 types, serial number 1 to n3, frequency band range f3 to f4, specific frequency point selection f=f3+nΔf,n∈0,1,...n3-1. Specific parameters can be set according to the usage scenario.

[0043] After receiving the cooperative positioning sound signal, the buoy group transmits a positioning response signal, which carries the target number, the buoy group number and the information of the buoy in the group.

[0044] Preferably, the design and parameters of the buoy positioning response signal are as follows: signal frequency band: f5~f8, signal structure as follows Figure 3 shown.

[0045] (5) The parameters of the second FM signal are as follows:

[0046] There are m2 second FM signals, numbered 1 to m2. The frequency band selection range is F2∈(f5,f8).

[0047] (6) The parameters of the single-frequency signal CW4 are as follows:

[0048] The single frequency signal CW4 is s4(t)=Ae j2πft ,t∈(0,T2), a total of n2 types, serial number 1 to n2, frequency band range f5 to f6, specific frequency point selection f=f5+nΔf,n∈0,1,...n2-1. Specific parameters can be set according to the usage scenario.

[0049] (7) The parameters of the single-frequency signal CW5 are as follows:

[0050] The single-frequency signal CW5 is s5(t)=Ae j2πft ,t∈(0,T2), a total of n3 types, serial number 1 to n3, frequency band range f6 to f7, specific frequency point selection f=f6+nΔf,n∈0,1,...n3-1. Specific parameters can be set according to the usage scenario.

[0051] (8) The parameters of the single-frequency signal CW6 are as follows:

[0052] The single-frequency signal CW6 is s3(t)=Ae j2πft ,t∈(0,T2), total Type, serial number Frequency band range f7~f8, specific frequency selection Specific parameters can be set according to the usage scenario.

[0053] After receiving the positioning response signal, the receiver applies the Notch filter and correlator to analyze the signal, extract relevant identity information, and realize multi-target recognition.

[0054] Preferably, the receiving end signal processing method is:

[0055] First, a correlator is used to identify the frequency modulated signal, and then a Notch filter is used to identify the single frequency signal. The identified signals are combined to obtain identity information and realize multi-target recognition.

[0056] Example 2:

[0057] like Figure 4 As shown, the signal transmitter generates cooperative positioning acoustic signals in a timed sequence. The FM signal is 40ms long, and the single-frequency signal is 20ms long. Four FM signal types and five CW1 single-frequency signals are available. Combining these two signals can distinguish up to 4*5 = 20 targets. Three CW2 signals and five CW3 signals are available. Combining these two signals can distinguish up to 3*5 = 15 buoy groups. During transmission, the target to be located automatically combines the signals based on its assigned target number and the number of the buoy group to be awakened.

[0058] The buoy receives the cooperative positioning sound signal and identifies it, such as Figure 5 As shown, the buoy positioning response signal is generated in sequence at the same time. The length of each signal should correspond to the cooperative positioning signal. When four buoys form a group, 4 types of FM signals are selected to forward the buoy group number; 3 types of CW4 signals are selected, and 5 types of CW5 signals are selected. The combination of the two can distinguish up to 3*5=15 buoy groups; CW6 signals use a 7-choose-2 mode to distinguish up to Targets to be located.

[0059] The receiving end first uses a correlator to identify the FM signal, then uses a Notch filter to identify the single-frequency signal. The identified signals are combined to obtain identity information, thus achieving multi-target recognition.

[0060] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A multi-target recognition method for underwater multi-area positioning, characterized in that: The following steps are involved: (1) The target to be located transmits a cooperative positioning sound signal to the nearest buoy group. The cooperative positioning sound signal carries the serial number of the target to be located and the serial number of the buoy group to be awakened. The cooperative positioning sound signal is composed of a first frequency-modulated signal, a first single-frequency signal CW1, a second single-frequency signal CW2, and a third single-frequency signal CW3. The first frequency-modulated signal occupies the first T1(s) of the cooperative positioning sound signal, the first single-frequency signal CW1, the second single-frequency signal CW2, and the third single-frequency signal CW3 each occupy T2(s), and the interval between each component is T3(s); There are m1 types of the first frequency modulation signal; there are n1 types of the first single frequency signal CW1, the frequency band range is f1 to f2, and the frequency point f=f1+n a Δf,n a =0,1,...,n1-1; the first FM signal and the first single-frequency signal CW1 have m1*n1 combinations, which are used to distinguish m*n1 targets to be located; the second single-frequency signal CW2 has n2 types, the frequency band range is f2~f3, and the frequency point f=f2+n b Δf,n b =0,1,...,n2-1; the third single frequency signal CW3 has n3 types, the frequency band range is f3~f4, and the frequency point f=f3+n c Δf,n c =0,1,...,n3-1; the second single frequency signal CW2 and the third single frequency signal CW3 have n2*n3 combinations, which are used to distinguish n2*n3 potential marker groups; (2) After the buoy group receives the cooperative positioning sound signal, each buoy in the buoy group generates a set of positioning response signals for each target to be positioned that chooses to wake up the buoy group, and transmits them to the receiving end; the positioning response signal includes the buoy's sequence number in the buoy group, the buoy group sequence number, and the sequence number of the target to be positioned; (3) After receiving the positioning response signal, the receiver extracts the relevant identity information to achieve multi-target recognition.

2. The multi-target recognition method for underwater multi-area positioning according to claim 1, characterized in that: The positioning response signal is composed of a second frequency-modulated signal, a fourth single-frequency signal CW4, a fifth single-frequency signal CW5, and a composite signal. The second frequency-modulated signal occupies the first T1(s) of the positioning response signal, the fourth single-frequency signal CW4, the fifth single-frequency signal CW5, and the composite signal each occupy T2(s), and the interval between each component is T3(s). There are m2 types of the second frequency modulation signal, which are used to distinguish the m2 latent buoys in the latent buoy group; there are n2 types of the fourth single frequency signal CW4, with a frequency band range of f5 to f6, and a frequency point f=f5+n b Δf,n b =0,1,...,n2-1; the fifth single frequency signal CW5 has n3 types, the frequency band range is f6~f7, and the frequency point f=f6+n c Δf,n c =0,1,...,n3-1; the fourth single-frequency signal CW4 and the fifth single-frequency signal CW5 have n2*n3 combinations for distinguishing n2*n3 potential target groups; the composite signal is composed of two sixth single-frequency signals CW6; the sixth single-frequency signal CW6 has n4 types, the frequency band range is f7~f8, and the frequency point f=f7+n d Δf, For each target to be located, a composite signal composed of two sixth single frequency signals CW6 is selected.

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