CN113866771A - Method for underwater target detection - Google Patents
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- CN113866771A CN113866771A CN202111395611.7A CN202111395611A CN113866771A CN 113866771 A CN113866771 A CN 113866771A CN 202111395611 A CN202111395611 A CN 202111395611A CN 113866771 A CN113866771 A CN 113866771A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
- G01S15/02—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems using reflection of acoustic waves
- G01S15/04—Systems determining presence of a target
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
- G01P3/64—Devices characterised by the determination of the time taken to traverse a fixed distance
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- Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
Abstract
The invention discloses a method for detecting an underwater target, belongs to the field of ocean detection methods, and solves the technical problem that the detection calculation efficiency of the method in the prior art on the target is low. The device comprises a buoy, a vertical line array, a horizontal expansion array and a compass auxiliary system, wherein the buoy is provided with the vertical line array and the horizontal expansion array; the horizontal spreading arrays are arranged in a biorthogonal and symmetrical array; the vertical linear array transmits double-pulse detection signals for measuring underwater target state parameters by the horizontal expansion array, wherein the state parameters are at least the distance, the direction and the speed of a target object; the double-pulse detection signals received by the horizontal expansion array are subjected to signal preprocessing, and the preprocessed signals are subjected to beam forming and matched filtering to generate a two-dimensional spectrogram of the azimuth and the distance of the underwater target object; performing constant false alarm processing on the two-dimensional spectrogram to determine an active detection spectrogram; and the active detection spectrogram determines the current target state parameter of the detection target by a coordinate method. The method is used for submitting the accuracy of ocean target detection.
Description
Technical Field
The invention belongs to the field of ocean detection methods, and particularly relates to an underwater target detection method.
Background
The aviation sonar buoy has good platform noise performance, can detect radiation noise and active detection echo of an underwater target, realizes passive detection and active detection, obtains information of the direction, distance and speed of the target, and has wide application prospect in anti-submergence, underwater target detection and ocean monitoring.
Currently, an aviation sonar buoy mainly adopts a form of transmitting a single detection pulse to detect an underwater target, and commonly used pulse forms include a CW pulse, an HFM pulse, an LFM pulse, and a CW + LFM (chirp signal, insensitive signal) combined pulse, wherein:
the CW signal is a Doppler sensitive signal used for measuring the target speed, but because the underwater acoustic channel is slowly time-varying and has serious frequency selective fading, the CW pulse has failure condition in the actual use;
the HFM pulse and the LFM pulse are used for inhibiting reverberation and simultaneously carrying out high-precision ranging on a target, but because the HFM pulse and the LFM pulse belong to Doppler insensitive signals, velocity information of the target cannot be provided;
in order to make up for the deficiency that the doppler-insensitive signal cannot measure the target velocity, a scholars in the active detection field has proposed a CW + LFM combined pulse form, but the CW signal is also affected by channel fading.
In view of the above, the present invention is particularly proposed.
Disclosure of Invention
The invention aims to provide a method for detecting an underwater target, which solves the technical problem that the detection calculation efficiency of the method in the prior art on the target is low. The technical scheme of the scheme has a plurality of technical beneficial effects, which are described as follows:
the method for detecting the underwater target is suitable for the buoy to actively detect the underwater moving target, and comprises the following steps:
s101: the buoy is provided with a vertical line array and a horizontal expansion array, wherein: the vertical linear array is used for detecting the emission of signals, the horizontal extension array is used for receiving target echoes, and a compass auxiliary system is installed;
s102: the horizontal spreading arrays are arranged in a biorthogonal and symmetrical array; the vertical linear array transmits double-pulse detection signals for measuring underwater target state parameters by the horizontal expansion array, wherein the state parameters are at least the distance, the direction and the speed of a target object;
s103: the double-pulse detection signals received by the horizontal expansion array are subjected to signal preprocessing, and the preprocessed signals are subjected to beam forming and matched filtering (analog amplification and data acquisition) so as to generate a two-dimensional spectrogram of the azimuth and the distance of an underwater target object; two-dimensional map of non-velocity and distance
S104: and performing constant false alarm processing on the two-dimensional spectrogram to determine an active detection spectrogram so as to improve the echo signal-to-noise ratio of the target object, reduce false alarm interference and background noise and improve the detection probability of the target. Compared with the traditional CFAR method-constant false alarm processing method, the method has the advantages that the hardware operation amount is reduced, and the cost is saved. According to the traditional CFAR method, noise calculation is carried out on the whole area of a two-dimensional spectrogram, and the method only carries out two times of one-dimensional constant false alarm processing on a distance dimension and an orientation dimension.
S105: and the active detection spectrogram passes through the current target state parameter of the coordinate method target.
Compared with the prior art, the technical scheme provided by the invention has the following beneficial effects:
the invention adopts a double LFM pulse form, and the determination of the target radial velocity is completed by measuring the time delay interval of two pulses. The method improves the defect that the target speed cannot be provided by adopting a single HFM pulse and an LFM pulse, and avoids the problem of new ratio loss caused by channel fading of the CW pulse.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a block diagram of a float active signal processing flow;
FIG. 2 is a schematic diagram of a horizontally expanded array of buoys;
FIG. 3 is a schematic diagram of a dual LFM detection pulse;
fig. 4 is a schematic diagram of an improved constant false alarm processing method.
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It is noted that various aspects of the embodiments are described below within the scope of the appended claims. It should be apparent that the aspects described herein may be embodied in a wide variety of forms and that any specific structure and/or function described herein is merely illustrative. Based on the disclosure, one skilled in the art should appreciate that one aspect described herein may be implemented independently of any other aspects and that two or more of these aspects may be combined in various ways. For example, an apparatus may be implemented and/or a method practiced using any number of the aspects set forth herein. Additionally, such an apparatus may be implemented and/or such a method may be practiced using other structure and/or functionality in addition to one or more of the aspects set forth herein.
It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention, and the drawings only show the components related to the present invention rather than the number, shape and size of the components in practical implementation, and the type, quantity and proportion of the components in practical implementation can be changed freely, and the layout of the components can be more complicated.
In addition, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, it will be understood by those skilled in the art that aspects may be practiced without these specific details. In order that those skilled in the art will better understand the disclosure, the invention will be described in further detail with reference to the accompanying drawings and specific embodiments. The terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.
The method for detecting underwater target shown in fig. 1 is suitable for the active detection of underwater moving target by a buoy, and comprises the following steps:
s101: the buoy is provided with a vertical line array and a horizontal expansion array, wherein: the vertical line array is used for transmitting detection signals, the horizontal expansion array is used for receiving target echoes, and a compass auxiliary system is installed, wherein the products and the system are all products in the prior art, and the model of the compass auxiliary system is TCM5 electronic compass of the United states PNI company;
s102: the horizontal expansion array is arranged in a biorthogonal and symmetrical array, the vertical linear array transmits double-pulse detection signals for measuring underwater target state parameters by the horizontal expansion array, and the state parameters at least comprise the distance, the azimuth and the speed of a target object, specifically:
as shown in fig. 2, the horizontal spreading array is arranged in a biorthogonal and symmetrical array, preferably, a m-shaped structure is provided, for example, the horizontal spreading array includes 8 spreading arms, an included angle between any two adjacent spreading arms is 45 degrees, each spreading arm has 4 receiving hydrophone elements, 32 receiving hydrophones in total are used for receiving target echo signals, reference numeral in fig. 1 is defined as a serial number of the receiving hydrophone, signals received by each element are xi (t), i is 1,2, …,32, and the purpose of biorthogonal and symmetrical array arrangement is that: the horizontal expansion array adopts the biorthogonal symmetric array, so that the azimuth measurement ambiguity of the underwater target can be effectively avoided, the azimuth measurement precision and the distance measurement precision of the underwater target are improved, and the stability and the reliability of the measurement result are ensured.
The vertical line array transmits double-pulse detection signals in the form of transmitting two linear frequency modulation signals with consistent parameters, the pulse width is T, the bandwidth is B, a guard interval T is arranged between the two linear frequency modulation signals, the selection of the T is larger than the channel extension length of a target and a buoy, the initial value is general, the default value is 0.5s, preferably, the double-pulse detection signals are in the form of double LFM pulses, and the determination of the radial velocity of the target is completed by measuring the time delay interval of the two pulses, as shown in figure 3, the double LFM pulse form is applied to the technology of the field of ocean detection, the defect that a single-pulse signal is easy to fail is overcome, or the condition that the HFM pulse and the LFM pulse belong to insensitive signals and cannot provide velocity information of the target is avoided, and the aim to adopt sensitive signals for detection and complete the detection of the target in the ocean.
S103: the double-pulse detection signals received by the horizontal expansion array are subjected to signal preprocessing, such as analog amplification and data acquisition. Performing beam forming and matched filtering on the preprocessed signals to generate a two-dimensional spectrogram of the azimuth and the distance of the underwater target object, wherein the two-dimensional spectrogram is a two-dimensional map with non-speed and non-distance, and specifically comprises the following steps:
the buoy collects signals of the horizontal extended array elements in real time; preprocessing echo signals received by the horizontal expansion array and performing beam forming processing; and performing matched filtering processing on the data subjected to the beam forming processing.
The processing method of the matched filtering comprises the following steps:
FD_Sig_Bi＝FFT[Bi(t)]
FD_Sig_Ref＝FFT[Sig_Ref]
S104: and performing constant false alarm processing on the two-dimensional spectrogram to determine an active detection spectrogram, so as to improve the echo signal-to-noise ratio of the target object, reduce false alarm interference and background noise, and improve the detection probability of the target. The method only processes two times of one-dimensional constant false alarm of distance dimension and direction dimension, and specifically comprises the following steps:
the method comprises the following steps of performing distance dimension one-dimensional constant false alarm processing on an underwater target object in a two-dimensional spectrogram, and performing orientation dimension one-dimensional constant false alarm processing after processing to obtain the two-dimensional spectrogram after constant false alarm processing, aiming at reducing the number of interference points of the target object in the two-dimensional spectrogram, and specifically implementing the following steps:
as shown in fig. 4, a protection window P1 and a reference window R1 are arranged in the distance dimension, and a protection window P2 and a reference window R2 are arranged in the azimuth dimension, wherein the size of P1 is 3 times the reciprocal of the bandwidth of the chirp signal, and the size of R1 is 2 times the reciprocal of the bandwidth of the chirp signal;
calculating the speed of the underwater target, and calculating the time T' of two peak values according to the result of the matched filtering peak value at the maximum position of the target strength azimuth, wherein the target speed calculation formula is approximately as follows:
further, the geodetic coordinate true azimuth of the underwater target needs to be calculated, the target azimuth theta' calculated by using the horizontal expansion array is corrected, and the following conditions are met:
θoutθ' - ε, wherein: epsilon is the horizontal course angle of the horizontal extended array recorded by the compass auxiliary system, and the value is the north-east included angle thetaoutIs the final corrected target position.
S105: and actively detecting the current target state parameter of the spectrogram through a coordinate method target.
And (3) performing distance calculation of the underwater target object on the obtained constant false alarm processed two-dimensional spectrogram by using a conventional method in the prior art, for example, calculating target state parameters including speed, azimuth, distance parameters and the like by using a coordinate method.
The invention adopts a double LFM pulse form, and the determination of the target radial velocity is completed by measuring the time delay interval of two pulses. The method improves the defect that the target speed cannot be provided by adopting a single HFM pulse and an LFM pulse, and avoids the problem of new ratio loss caused by channel fading of the CW pulse. Because the method only carries out matched filtering processing once on the data after the wave beam is formed, compared with the traditional CW + LFM combined pulse method, the method improves the calculation efficiency of the whole algorithm. In addition, under the condition that the buoy active detection signal is determined, the traditional two-dimensional constant false alarm detection mostly adopts a 'field character grid' form, and the calculation amount is large. Compared with the conventional two-dimensional constant false alarm detection, the method only considers two dimensions, and improves the calculation efficiency.
The products provided by the present invention are described in detail above. The principles and embodiments of the present invention are explained herein using specific examples, which are presented only to assist in understanding the core concepts of the present invention. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the invention without departing from the inventive concept, and those improvements and modifications also fall within the scope of the claims of the invention.
Claims (7)
1. A method for detecting underwater target is suitable for the buoy to actively detect underwater moving target, and is characterized by comprising the following steps:
s101: the buoy is provided with a vertical line array and a horizontal expansion array, wherein: the vertical linear array is used for detecting the emission of signals, the horizontal extension array is used for receiving target echoes, and a compass auxiliary system is installed;
s102: the horizontal spreading arrays are arranged in a biorthogonal and symmetrical array; the vertical linear array transmits double-pulse detection signals for measuring underwater target state parameters by the horizontal expansion array, and the state parameters at least comprise the distance, the azimuth and the speed of a target object;
s103: the double-pulse detection signals received by the horizontal expansion array are subjected to signal preprocessing, and the preprocessed signals are subjected to beam forming and matched filtering to generate a two-dimensional spectrogram of the azimuth and the distance of the underwater target object;
s104: performing constant false alarm processing on the two-dimensional spectrogram to determine an active detection spectrogram;
s105: and the active detection spectrogram determines the current target state parameter of the detection target by a coordinate method.
2. The method of claim 1, wherein S103: the method for signal preprocessing of the double-pulse detection signals received by the horizontal spreading array comprises the following steps:
the buoy acquires the elementary signals of the horizontal expansion array in real time, and performs preprocessing and beam forming processing on the echo signals received by the horizontal expansion array;
and performing matched filtering processing on the data subjected to the beam forming processing.
3. The method of claim 1, wherein the method in S104 comprises:
performing one-dimensional constant false alarm processing on the distance dimension of the underwater target object in the two-dimensional spectrogram;
and after the processing, performing one-dimensional constant false alarm processing of the azimuth dimension to determine a two-dimensional spectrogram after the constant false alarm processing.
4. The method of claim 3, wherein the vertical linear array of S102 transmits the dual pulse probing signals in the form of two chirps with identical parameters, the chirps have a pulse width T and a bandwidth B, and a guard interval T is set between the two chirps, and the guard interval T is selected to be greater than a channel spreading length of the target and the buoy.
5. The method of claim 3, wherein the distance dimension one-dimensional constant false alarm processing of the underwater target object is performed in the two-dimensional spectrogram, and the processing is followed by the azimuth dimension one-dimensional constant false alarm processing, comprising:
a protection window P1 and a reference window R1 are disposed in the distance dimension, and a protection window P2 and a reference window R2 are disposed in the azimuth dimension, wherein:
the size of P1 is 3 times of the bandwidth reciprocal of the chirp signal, and the size of R1 is 2 times of the bandwidth reciprocal of the chirp signal.
6. The method of claim 5, wherein S105: the method for determining the current target state parameter of the detection target by the active detection spectrogram through a coordinate method comprises the following steps:
calculating the speed of the underwater target, and calculating the time T' of two peak values according to the result of the matched filtering peak value at the maximum position of the target strength azimuth, wherein a target speed calculation formula meets the following requirements:
7. The method of claim 6, wherein: the method also comprises a method for calculating the true azimuth of the geodetic coordinates of the underwater target, wherein the azimuth theta' of the target calculated by the horizontal expansion array is corrected and meets the following requirements: thetaoutθ' - ε, wherein: epsilon is the horizontal course angle theta of the horizontal extended array recorded by the Luoshi auxiliary systemoutIs the final corrected target position.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20180024235A1 (en) * | 2013-10-13 | 2018-01-25 | Oculii Corp | Systems and methods for 4-dimensional radar tracking |
| CN111198374A (en) * | 2020-01-13 | 2020-05-26 | 哈尔滨工程大学 | Doppler sensitive signal moving target underwater sound detection method based on space-time-frequency joint interference suppression |
| CN112362153A (en) * | 2020-09-15 | 2021-02-12 | 中国人民解放军军事科学院国防科技创新研究院 | Low-frequency active underwater sound detection system and method based on UUV platform |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20180024235A1 (en) * | 2013-10-13 | 2018-01-25 | Oculii Corp | Systems and methods for 4-dimensional radar tracking |
| CN111198374A (en) * | 2020-01-13 | 2020-05-26 | 哈尔滨工程大学 | Doppler sensitive signal moving target underwater sound detection method based on space-time-frequency joint interference suppression |
| CN112362153A (en) * | 2020-09-15 | 2021-02-12 | 中国人民解放军军事科学院国防科技创新研究院 | Low-frequency active underwater sound detection system and method based on UUV platform |
Non-Patent Citations (1)
| Title |
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| 徐雅倩;郭高峰;刘方正;: "拖线阵声纳探测技术研究现状及发展趋势", 价值工程, no. 09, 28 March 2017 (2017-03-28) * |
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