CN114895303B - High-precision synthetic angle measurement method for distributed radar - Google Patents
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Abstract
The invention discloses a high-precision synthetic angle measurement method of a distributed radar, which comprises the following steps that a radar station respectively carries out single-pulse angle measurement and pulse pressure peak value phase extraction operation on received echo signals; calculating the phase difference of each station relative to a reference radar station to obtain remainder estimation of the real wave path difference; calculating the wave path difference between each station and the reference station, and calculating the fuzzy number of the real wave path difference relative to the wavelength; combining the remainder of the real wave path difference and the fuzzy number of the real wave path difference to obtain a deblurred wave path difference estimated value; and determining a search range according to the target peak signal-to-noise ratio and the single-station angular beam width, determining azimuth pitching search intervals according to the positions of each station and the current beam pointing angle, and calculating a precise angular result synthesized by the distributed array through angular azimuth pitching search by combining the deblurred estimated value of the wave path difference. According to the invention, the two-dimensional coupling grating lobes are released under the condition that azimuth pitching coupling exists by utilizing the target angle measurement data of each radar station, so that the ambiguity-free angle measurement of multi-station coherent combination is realized.
Description
Technical Field
The invention belongs to the technical field of radar signal processing, and particularly relates to a high-precision synthetic angle measurement method of a distributed radar.
Background
The distributed array antenna radar is a new system radar which is used for adapting to the requirements of modern war and improving radar performance and survivability. The distributed array radar is characterized in that a radar antenna array is split into a plurality of small-aperture subarrays and the small-aperture subarrays are distributed, so that the physical aperture of the radar antenna array is enlarged, namely, the distributed array is utilized for arranging, the physical process of the radar antenna array can be increased under the condition that the number of array elements is not increased, and the aim of improving the radar performance is fulfilled; each base station only performs necessary preprocessing work on the intercepted observed echo signals, and then transmits received data to a central processing unit to finish the determination of the target position.
Compared with the conventional array radar, the distributed array has obvious advantages, and the distributed array is characterized in that: (1) improving the target positioning accuracy of the radar system. Compared with the conventional array radar under the condition that the array element numbers are equal, the distributed array radar has larger physical aperture of the antenna array, so that the distributed array radar has higher angle measurement precision; (2) improving the maneuverability of the radar system. The antenna array of the distributed array radar consists of a plurality of antenna subarrays with small apertures, and the antenna array can be arranged on a plurality of mobile platforms to improve the maneuverability, so that the distributed array radar has stronger battlefield viability; (3) The cost of the radar system is reduced and the engineering implementation complexity of the antenna array is reduced. Under the condition that the physical apertures of the antenna arrays are the same, the array element number of the distributed array radar is usually far smaller than that of a conventional array radar, and the complexity of the implementation of the software and hardware cost smart engineering is correspondingly much smaller; (4) improving the reliability and stability of the radar system. When partial array element functions of the distributed radar fail or fail, the distributed array radar can still normally operate, so that the reliability and stability of a radar system are greatly improved.
Because the distances between the sub-arrays which are distributed are far greater than half wavelength, grating lobes with the amplitude close to the main lobe exist on two sides of the main lobe of the distributed array synthetic directional diagram according to the airspace Nyquist sampling theorem, and angle measurement ambiguity caused by the grating lobes influences the angle estimation performance of the distributed array. This is an important issue that currently affects distributed array radar applications.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a high-precision synthetic angle measurement method of a distributed radar. The technical problems to be solved by the invention are realized by the following technical scheme:
a high-precision synthetic angle measurement method of a distributed radar, the high-precision synthetic angle measurement method comprising:
step 1, respectively performing pulse compression, target detection, single pulse angle measurement and pulse pressure peak value phase extraction operation on received echo signals by M distributed radar stations, and correspondingly obtaining received peak signals s m after the echo signals are subjected to the pulse pressure peak value phase extraction operation, wherein m=0, 1.
Step 2, calculating the phase difference delta phi m of the mth radar station relative to the reference radar station according to the phase phi m corresponding to the peak signal s m of the mth radar station, so as to calculate the wave path difference according to the phase difference delta phi m
Step 3, according to the position coordinates of the mth radar station and the pitch angle average valueAnd azimuth average/>Obtaining the wave path/>, of the mth radar stationTo/>, according to the wave path of the mth radar stationObtaining a wave path difference/>, relative to the reference radar stationThe pitch angle average/>For the average of the measured pitch angles of M radar stations, the azimuth average/>An average value of measured azimuth angles for the M radar stations;
Step4, according to the wave path difference Obtaining fuzzy number/>
Step 5, according to the wave path differenceAnd the fuzzy number/>Obtaining deblurred wave path difference/>
Step 6, according to the pitch angle theta and the azimuth angleObtaining the mean square error/>And azimuthal mean square error/>To be according to the pitch angle mean square error/>And azimuthal mean square error/>Correspondingly obtaining the mean square error/>, of the measured pitch angleAnd measuring azimuth mean square error/>
Step 7, searching for intervals in azimuthAnd pitch search interval/>For search scope/>, respectivelyAnd/>Discretizing to obtain azimuth/>, over the search rangeAnd pitch/>For the azimuth interval,Is pitch angle spacing.
In one embodiment of the present invention, the peak signal s m is:
Wherein, gamma represents the intensity of the echo signal, lambda represents the wavelength, w m represents the receiver noise of the mth radar station, and the coordinate of the mth radar station in the northeast day coordinate system is (x m,ym,zm);
The phase ψ m of the peak signal s m is:
Where mod represents the remainder operation and epsilon m represents the phase noise of the w m incoming signal.
In one embodiment of the present invention, the phase difference Δψ m is:
Δψm＝ψm-ψ0
Wherein ψ 0 denotes the phase of the reference radar station when m=0;
the wave path difference The method comprises the following steps:
Wherein ε 0 represents the phase noise of the w 0 -induced signal,
In one embodiment of the invention, the wave pathThe method comprises the following steps:
Wherein, the coordinate of the mth radar station under the northeast day coordinate system is (x m,ym,zm);
The wave path difference is The method comprises the following steps:
Wherein, Representing the wave length of the reference radar station, the coordinates of the m=0 th radar station in the northeast day coordinate system are (x 0,y0,z0).
In one embodiment of the invention, the fuzzy numberThe method comprises the following steps:
Wherein lambda represents the wavelength, Representing a downward rounding function.
In one embodiment of the invention, whenWhen the deblurring wave path difference/>The method comprises the following steps:
When (when) When the deblurring wave path difference/>The method comprises the following steps:
Where mod represents a remainder operation and λ represents a wavelength.
In one embodiment of the invention, the pitch mean square errorAnd the azimuthal mean square error/>The method comprises the following steps of:
where θ 3dB represents the half-power beam width when the single-station array beam is directed to normal, and SNR represents the signal-to-noise ratio of the single-station received signal.
In one embodiment of the present invention, the step 7 includes:
step 7.1, obtaining vectors Corresponding equimodal length perpendicular vectors on the xoy plane/>
Step 7.2, obtaining the coordinates of the mth radar station in the vectorProjection onto/>
Step 7.3, according to the projection corresponding to the mth radar stationProjection corresponding to nth radar stationObtain azimuth equivalent aperture/>
Step 7.4, equivalent aperture according to the azimuthObtain azimuth beam width/>
Step 7.5, according to the azimuth beam widthObtaining the azimuth synthesis theoretical angle measurement error/>To synthesize a theoretical angular error/>, based on the orientationObtain azimuth search interval/>
Step 7.6, obtaining the coordinate in vector of the mth radar stationProjection onto/>
Step 7.7, according to the projection corresponding to the mth radar stationProjection/>, corresponding to nth radar stationObtain the pitching equivalent aperture/>
Step 7.8, according to the pitch equivalent apertureObtain pitch beamwidth/>
Step 7.9, according to the pitch beam widthObtaining pitch synthesis theoretical angle measurement error/>To synthesize a theoretical angular error/>, based on the pitchObtain pitch search interval/>
Step 7.10, according to the azimuth beam widthAnd the elevation beam width/>Establishing a lookup table to measure azimuth/>, according toAnd measuring pitch angle/>Looking up in a lookup table to obtain azimuth beam width/>And pitch beamwidth/>
Step 7.11, according to the azimuth beam widthAnd the elevation beam width/>Corresponding to the azimuth interval/>And pitch interval/>
Step 7.12, search interval with azimuthAnd pitch search interval/>For search scope/>, respectivelyAnd/>Discretizing to obtain azimuth/>, over the search rangeAnd pitch/>
In one embodiment of the invention, the projectionThe method comprises the following steps:
wherein the coordinates of the mth radar station are in the vector The coordinates of the upper projection are (x m,ym);
the azimuth equivalent aperture The method comprises the following steps:
The azimuth beam width The method comprises the following steps:
wherein λ represents wavelength, (°) represents unit degree;
the azimuth synthesis theory angle measurement error The method comprises the following steps:
Wherein, SNR represents signal-to-noise ratio of single station received signal;
The projection is The method comprises the following steps:
Wherein, Representation/>A vertical vector on the plane omega,
The pitch equivalent apertureThe method comprises the following steps:
the elevation beam width The method comprises the following steps:
the pitch synthesis theoretical angle measurement error The method comprises the following steps:
The azimuth beam width The method comprises the following steps:
the elevation beam width The method comprises the following steps:
in one embodiment of the invention, the azimuth angle And the pitch angle/>
Wherein,Representing the search angle as azimuth/>And pitch/>Time-corresponding wave Cheng Chazhi,/>Representing the deblurred path difference.
The invention has the beneficial effects that:
According to the method, under the condition that azimuth pitching coupling exists, the average angle measurement result of each radar array is utilized to realize the simultaneous deblurring of azimuth pitching angles, and the high-precision synthesis angle measurement result of the target under the distributed aperture gain is estimated.
The invention provides a coherent combination angle measurement method of a distributed array radar, which can utilize target angle measurement data of all radar stations to release two-dimensional coupling grating lobes under the condition of azimuth pitching coupling and realize the fuzzy-free angle measurement of multi-station coherent combination.
Drawings
FIG. 1 is a schematic flow chart of a high-precision synthetic angle measurement method of a distributed radar according to an embodiment of the present invention;
FIG. 2 is a flow chart of an implementation of a high-precision synthetic angle measurement method for a distributed radar according to an embodiment of the present invention;
FIG. 3a is a schematic diagram of a northeast coordinate system constructed with three radar stations according to an embodiment of the present invention;
FIG. 3b is a schematic diagram of an array of three-station simulation examples according to an embodiment of the present invention;
FIG. 4a is a schematic diagram of azimuth-elevation coupling in a distributed array synthetic goniometer provided by an embodiment of the present invention;
FIG. 4b is a schematic illustration of the wavelengths of all single-lobe waves Cheng Chayu of a distributed composite lobe provided by an embodiment of the present invention;
FIG. 5a is a schematic diagram of an azimuth beam width result of a distributed radar array calculated by the method according to the embodiment of the present invention under a certain azimuth pitch angle;
FIG. 5b is a diagram of a result of calculating a pitch beam width of a distributed radar array under a pitch angle of a certain azimuth according to the method provided by the embodiment of the present invention;
FIG. 6 is a schematic diagram of azimuth pitch angle search results generated by the method provided by the embodiment of the invention;
Fig. 7a, fig. 7b, fig. 7c, and fig. 7d are graphs respectively comparing the change of the azimuth pitch angle results with SNR and the single-station angle measurement results and the non-coherent combined angle measurement results when the target azimuth pitch angle is (0, 0), (30, 30), (30, 60), (60, 30) according to the method provided by the embodiment of the invention.
Detailed Description
The present invention will be described in further detail with reference to specific examples, but embodiments of the present invention are not limited thereto.
Example 1
Referring to fig. 1 and fig. 2, fig. 1 is a flow chart of a high-precision synthetic angle measurement method of a distributed radar according to an embodiment of the present invention, and fig. 2 is a flow chart of an implementation of the high-precision synthetic angle measurement method of a distributed radar according to an embodiment of the present invention. The embodiment of the invention provides a high-precision synthetic angle measurement method of a distributed radar, which comprises the following steps:
and step 1, respectively performing pulse compression, target detection, single pulse angle measurement and pulse pressure peak value phase extraction operation on the received echo signals by M distributed radar stations, and correspondingly obtaining received peak signals s m after the echo signals are subjected to the pulse pressure peak value phase extraction operation, wherein m=0, 1.
Specifically, each radar station firstly performs pulse compression on the received signal, then performs target detection by using a constant false alarm detection method, and sets the measured azimuth angles of the targets measured by the single pulse angle measurement of each of the M radar stations as respectivelyThe pitch angle measurement results are/>, respectivelyThe peak phases of targets detected by M radar stations are respectively/>And transmitting the parameters measured by the single station (namely the single radar station) to an information fusion center for distributed synthesis angle measurement. Let the coordinates of the mth radar station in the northeast day coordinate system be (x m,ym,zm), m=0, 1,.; azimuth angle of incoming wave direction is/>Pitch angle is theta,/>And θ are both theoretical angles; the direction vector of the direction is/>The projection of the vector formed by the M radar stations and the origin on the direction vector is as follows:
Assuming that the intensity of the received target echo signal is γ, the received peak signals s 0,s1,...,sm,...,sM-1 of the M radar stations may be written as:
Where w 0,w1,...,w1,...,wM-1 is the receiver noise of the M stations, respectively, and λ represents the wavelength. It can be seen that the azimuth angle and pitch angle information of the target are only contained in the phases of the echo signals, and if the peak signal s m phase is ψ m, then under a certain signal-to-noise ratio SNR, ψ 0,ψ1,...,ψm,...,ψM-1 is a random variable, and can be written as:
Where mod represents the remainder operation and epsilon m represents the phase noise of the w m incoming signal.
Step 2, calculating the phase difference delta phi m of the mth radar station relative to the reference radar station according to the phase phi m corresponding to the peak signal s m of the mth radar station, so as to calculate the wave path difference according to the phase difference delta phi m
Specifically, the phase difference of each radar station (divided by m=0 reference radar station) with respect to the reference radar station is calculated based on the peak phase ψ 0,ψ1,...,ψm,...,ψM-1 of each radar station, and the remainder estimation of the true wave path difference is calculated
In this embodiment, the relationship between the target phase and the wave path can be expressed by the following formula:
The path difference extracted by the phase difference Δψ m＝ψm-ψ0 (m+.0) can be calculated by:
Wherein ε 0 represents the phase noise of the w 0 -induced signal,
It is obvious that the process is not limited to,Is the result of the superposition of noise and the real wave path difference is the remainder of the wavelength lambda, and only the/>Cannot get/>Is used for the estimation of the estimated value of (a).
Step 3, according to the position coordinates of the mth radar station and the pitch angle average valueAnd azimuth average/>Obtaining the wave path/>, of the mth radar stationTo/>, according to the wave path of the mth radar stationObtaining the wave path difference/>, relative to a reference radar stationPitch angle average/>For the average value of the measured pitch angles of M radar stations, azimuth average value/>Is the average of the measured azimuth angles of the M radar stations.
Specifically, according to the distributed radar station array position and the average value of the measured azimuth angle results measured by each radar stationAnd measuring the average value of the pitch angle results/>Calculating the wave path difference/>, between each radar station (except the reference radar station) and the reference radar stationFurther calculate the ambiguity/>, of the real wave path difference with respect to the wavelength lambda
In the present embodiment, calculationAverage value/>/>Average value/>Then/>And/>And respectively obtaining non-coherent rough angle measurement results of the distributed radar array. According to/> And the coordinates (x m,ym,zm) of each radar station to obtain the wave path/>, of the target echo signal reaching each radar station
Utilization of the deviceThe calculated difference in the wave path of the mth radar station relative to the reference radar station (i.e., the 0 th radar station) is/>Then there are:
Wherein, Representing the wave length of the reference radar station, the coordinates of the m=0 th radar station in the northeast day coordinate system are (x 0,y0,z0).
Can be regarded as the target real wave path difference/>Is derived from/>And (3) determining.
Step 4, according to the wave path differenceObtaining fuzzy number/>
In particular, consider the use ofEstimate the wave path difference/>The fuzzy numbers of (a) are:
Wherein, Representing a downward rounding function, use/>Whether the ambiguity can be resolved correctly will depend on whether the following holds: /(I)
Step 5, according to the wave path differenceAnd fuzzy number/>Obtaining deblurred wave path difference/>
Specifically, the remainder estimate ΔL 1',ΔL2',...,ΔLm',...,ΔLM-1' of the true path difference and the fuzzy number estimate of the true path difference are combinedObtaining deblurred wave path difference estimation/>
In the case of not considering noise, there are:
Wherein, is an integer Is the number of ambiguities in the wave path difference. Clearly, the true ambiguity is unknown, meaning that no ambiguity-free wave path difference is directly obtained from the phase. Therefore, consider use/>Estimate/>Fuzzy number/>Consider/>The noise near 0 or lambda may have a great influence, and the remainder estimation DeltaL 1',ΔL2',...,ΔLm',...,ΔLM-1' and the fuzzy number estimation of the true wave path difference are utilizedObtaining deblurred wave path difference estimate/>The method of (2) is as follows:
When (when) When deblurring the wave path difference/>The method comprises the following steps:
When (when) When deblurring the wave path difference/>The method comprises the following steps:
step 6, according to the pitch angle theta and the azimuth angle Obtaining the mean square error/>And azimuthal mean square error/>To mean square error/>, according to pitch angleAnd azimuthal mean square error/>Correspondingly obtaining the mean square error/>, of the measured pitch angleAnd measuring azimuth mean square error/>
In particular, the method comprises the steps of,Can be regarded as/>Is apparent/>The concept of phase has been broken away, i.e. there is no ambiguity caused by taking the remainder, and then the embodiment can use/>To obtain the accurate estimation result/>, of the target azimuth and the pitch angleDue to/>Is itself an estimate with errors such that/>From which it cannot be directly solved, the present embodiment uses a search approach to obtain/>
The search range of the azimuth pitch angle in the method is determined according to the precision of the rough angle in the statistical sense. If the half-power beam width of the single-station array surface beam pointing to the normal is theta 3dB, according to the radar parameter estimation theory, the antenna beam points to the pitch angle theta and the azimuth angleWhen the theoretical accuracy of the angle measurement of the single radar station is expressed as follows:
Where SNR represents the signal-to-noise ratio of a single station received signal, And/>Root mean square values between azimuth and elevation angle measurements and true values, respectively.
Averaging the angle measurement results of the M radar stations reduces the angle estimation error to a single station angle measurement errorThe mean square error of azimuth and pitch angle calculated by using a spectrum average method (non-coherent synthesis method) angle measurement method is as follows:
thus will be Respectively brought into the above formula to obtain the pitch angle mean square error/>And azimuthal mean square error/>
The search ranges for setting azimuth angle and pitch angle on the basis are respectively as follows:
search range of azimuth angle:
Search range of pitch angle:
According to the correlation theory of gaussian distribution, the target has a probability of 99.7% falling within the search range. Step 7, searching for intervals in azimuth And pitch search interval/>Respectively to search rangeAnd/>Discretizing to obtain azimuth/>, over a search rangeAnd pitch/> For azimuth interval,/>Is pitch angle spacing.
In a specific embodiment, step 7 may specifically comprise steps 7.1-7.12, wherein:
step 7.1, obtaining vectors Corresponding equimodal length perpendicular vectors on the xoy plane/>
In particular, in the case of joint accurate estimation of azimuth and pitch angles, the theoretical angular accuracy of azimuth and pitch angles is related to the azimuth pitch equivalent aperture of the array in a certain direction of arrival, respectively. When the azimuth angle of the incoming wave direction isThe pitch angle is θ, and the direction vector of the direction is/>Its vector projected on the xoy plane is/>The vector corresponds to the equal modulus length vertical vector on the xoy plane as follows:
step 7.2, obtaining the coordinate in vector of the mth radar station Projection onto/>
Specifically, the coordinates of the mth radar station are in vectorThe projection onto (without normalization) is:
Wherein the coordinates of the mth radar station are in vector The coordinates of the upper projection are (x m,ym). /(I)
Step 7.3, according to the projection corresponding to the mth radar stationProjection/>, corresponding to nth radar stationObtain azimuth equivalent aperture/>
Is provided withIs azimuth angle/>The azimuth equivalent aperture at the pitch angle θ is:
step 7.4, equivalent aperture according to azimuth Obtain azimuth beam width/>Azimuth beam widthThe method comprises the following steps:
where λ represents wavelength, (°) represents unit degree.
Step 7.5, according to azimuth beam widthObtaining the azimuth synthesis theoretical angle measurement error/>To synthesize theoretical angle measurement error/>, according to azimuthObtain azimuth search interval/>
Specifically, when the signal-to-noise ratio is SNR, the azimuth synthesis theoretical angle measurement error is:
then the azimuth search interval is
Step 7.6, obtaining the coordinate in vector of the mth radar stationProjection onto/>
Specifically, considering the pitch angle measurement accuracy of the distributed array, a z-axis and a vector are setThe determined plane is omega, and the knowledge is thatIs a normal to Ω, then define/>For/>A vertical vector on plane Ω, set/>Then/>Can be solved by the following set of procedures:
xΩ 2+yΩ 2+zΩ 2＝1
xΩ>0,yΩ>0,zΩ>0
then the coordinates of the mth radar station are in vector The projections on the two are respectively:
Wherein, Representation/>A vertical vector on plane Ω.
Step 7.7, according to the projection corresponding to the mth radar stationProjection/>, corresponding to nth radar stationObtain the pitching equivalent aperture/>
Is provided withIs azimuth angle/>Pitch equivalent aperture (related to pitch only) at pitch angle θ, then there is: /(I)
Step 7.8, according to pitch equivalent apertureObtain pitch beamwidth/>Pitch beam widthThe method comprises the following steps:
step 7.9 according to the elevation beam width Obtaining pitch synthesis theoretical angle measurement error/>To synthesize theoretical angle measurement error/>, according to pitchObtain pitch search interval/>
When the signal-to-noise ratio is SNR, the pitch synthesis theory angle measurement errorThe method comprises the following steps:
Then pitch search interval
Step 7.10 according to azimuth beam widthAnd pitch beamwidth/>Establishing a lookup table to measure azimuth/>, according toAnd measuring pitch angle/>Looking up in a lookup table to obtain azimuth beam width/>And pitch beamwidth/>
Specifically, all azimuth beamwidths obtained are usedPitch beamwidth/>The corresponding azimuth is/>A lookup table is built for the pitch angle theta, and the azimuth angle/>, is measuredAnd measuring pitch angle/>Querying in a lookup table, the azimuth/>, will be found and measuredAnd measuring pitch angle/>Corresponding azimuth beamwidth/>Pitch beam widthAs azimuth beamwidth/>And pitch beamwidth/>
Step 7.11, according to azimuth beam widthAnd pitch beamwidth/>Corresponding to the azimuth interval/>And pitch interval/>
Specifically, azimuth beam widthAnd pitch beamwidth/>And respectively combining peak signal-to-noise ratio information to calculate azimuth pitch angle measurement intervals used for azimuth pitch search, wherein the azimuth angle intervals are as follows:
The pitch angle interval is:
step 7.12, search interval with azimuth And pitch search interval/>For search scope/>, respectivelyAnd/>Discretizing to obtain azimuth/>, over a search rangeAnd pitch/>
Specifically, search intervals in azimuthAnd pitch search interval/>For search scope/>, respectivelyAnd/>Discretizing a search value/>, within the rangeAnd/>Will have corresponding waves Cheng Chazhi/>Then, the final precise angle measurement result obtained by adopting the distributed array synthesis angle measurement of the invention is as follows:
Wherein, Representing the search angle as azimuth/>And pitch/>Time-corresponding wave Cheng Chazhi,/>Representing the deblurred path difference.
Simulation experiment
To demonstrate the effectiveness of the present invention, the following simulated comparative test was used for further illustration.
(1) Simulation conditions:
As shown in fig. 3b, the distributed radar array includes three radar stations whose coordinates are set as station 1 (0, 0), station 2 (14 m,39m, 0), station 3 (0, 78m, 0), respectively, and waveform parameters of the signals are set as follows: carrier frequency f c =2 GHz, pulse bandwidth b=5 MHz, modulation mode is linear frequency modulation, receiver noise power σ w 2 =0 dB, and signal-to-noise ratio is 15dB. FIG. 3a is a schematic diagram of a northeast coordinate system constructed with three radar stations according to the present invention, the angle between the projection vector of the arrival vector to the xy plane and the x-axis Defined as azimuth angle, and the angle θ of the incoming wave vector and xy plane is defined as pitch angle.
(2) Simulation content and results:
Simulation 1, simulating a synthesized beam pattern of the distributed array when the azimuth pitch is about 40 degrees, and as a result, as shown in fig. 4a, two problems existing in the synthesis of the distributed array can be seen from the graph: 1) A large number of grating lobes exist, and the distributed array angle measurement has the problems of angle measurement ambiguity because the array interval is far larger than half wavelength; 2) The problem of azimuth pitch coupling is that the distributed array is often arranged in a non-completely circular manner, so that in practice, the problem of azimuth pitch coupling exists, namely, the lobe is inclined in an azimuth pitch angle plane, and the inclination degree is different according to the different arrangement manners and the directions of incoming waves, so that great difficulty is brought to the extraction of azimuth pitch combined direction finding of the lobes of the distributed array. FIG. 4b reflects the case of a distributed array of synthetic beam patterns at waves Cheng Chayu, it can be seen that there is no coupling of the lobes between the wave path differences, and therefore accurate lobe extraction can be achieved at wave Cheng Chayu; the method of the invention actually determines which lobe the target is in by using a rough measurement result, eliminates azimuth pitch coupling (de-tilting) of the lobe by using variable substitution (each station phase is converted into the wave path difference of each station relative to a reference station), thereby realizing accurate extraction of the lobe where the target is located, and further carrying out accurate estimation of azimuth pitch angle in the lobe.
Simulation 2, simulation of azimuth beam width lookup table generated by the method of the present invention, as can be seen from fig. 5a and 5b, azimuth pitch aperture of the distributed radar array is different along with the direction of incoming waves, in the method of the present invention, the azimuth beam width lookup table is directly manufactured from the positions of each radar station in the distributed radar array, according to the non-coherent angle measurement resultAnd/>The azimuth beam width is obtained in a table look-up mode, equation operation in real-time processing can be avoided, and the calculated amount is greatly reduced.
Simulation 3, simulating the azimuth pitch angle search result generated by the method, and as shown in fig. 6, obtaining the minimum value of the cost function in the azimuth pitch search at the target azimuth pitch angle position to obtain the target azimuth pitch angle estimation result.
Simulation 4, simulating a comparison graph of distributed azimuth pitching angle measurement results obtained by the method, and as shown in fig. 7a, 7b, 7c and 7d (azimuth pitch angles are respectively set to 0 degree azimuth pitch, 30 degrees azimuth pitch, 60 degrees azimuth pitch and 30 degrees azimuth pitch), comparing the angle measurement precision of the method with that of a single radar station (reference radar station) by a single pulse angle measurement method and a non-coherent average angle measurement method, it can be seen that when the method is adopted, the two-dimensional combined high-precision estimation under the condition of azimuth pitching coupling can be realized by utilizing the synthesized azimuth and pitch apertures provided by a distributed radar array in each incoming wave direction.
According to the method, under the condition that azimuth pitching coupling exists, the average angle measurement result of each radar array is utilized to realize the simultaneous deblurring of azimuth pitching angles, and the high-precision synthesis angle measurement result of the target under the distributed aperture gain is estimated.
The invention provides a coherent combination angle measurement method of a distributed array radar, which can utilize target angle measurement data of all radar stations to release two-dimensional coupling grating lobes under the condition of azimuth pitching coupling and realize the fuzzy-free angle measurement of multi-station coherent combination.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Further, one skilled in the art can engage and combine the different embodiments or examples described in this specification.
Although the application is described herein in connection with various embodiments, other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed application, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the "a" or "an" does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.
The foregoing is a further detailed description of the invention in connection with the preferred embodiments, and it is not intended that the invention be limited to the specific embodiments described. It will be apparent to those skilled in the art that several simple deductions or substitutions may be made without departing from the spirit of the invention, and these should be considered to be within the scope of the invention.
Claims (10)
1. The high-precision synthetic angle measurement method of the distributed radar is characterized by comprising the following steps of:
step 1, respectively performing pulse compression, target detection, single pulse angle measurement and pulse pressure peak value phase extraction operation on received echo signals by M distributed radar stations, and correspondingly obtaining received peak signals s m after the echo signals are subjected to the pulse pressure peak value phase extraction operation, wherein m=0, 1.
Step 2, calculating the phase difference delta phi m of the mth radar station relative to the reference radar station according to the phase phi m corresponding to the peak signal s m of the mth radar station, so as to calculate the wave path difference according to the phase difference delta phi m
Step 3, according to the position coordinates of the mth radar station and the pitch angle average valueAnd azimuth average/>Obtaining the wave path/>, of the mth radar stationTo/>, according to the wave path of the mth radar stationObtaining a wave path difference/>, relative to the reference radar stationThe pitch angle average/>For the average of the measured pitch angles of M radar stations, the azimuth average/>An average value of measured azimuth angles for the M radar stations;
Step4, according to the wave path difference Obtaining fuzzy number/>
Step 5, according to the wave path differenceAnd the fuzzy number/>Obtaining deblurred wave path difference/>
Step 6, according to the pitch angle theta and the azimuth angleObtaining the mean square error/>And azimuth mean square errorTo be according to the pitch angle mean square error/>And azimuthal mean square error/>Correspondingly obtaining the mean square error/>, of the measured pitch angleAnd measuring azimuth mean square error/>
Step 7, searching for intervals in azimuthAnd pitch search interval/>For search scope/>, respectivelyAnd/>Discretizing to obtain azimuth/>, over the search rangeAnd pitch/>For azimuth interval,/>Is pitch angle spacing.
2. The high-precision synthetic angle measurement method of a distributed radar according to claim 1, wherein the peak signal s m is:
Wherein, gamma represents the intensity of the echo signal, lambda represents the wavelength, w m represents the receiver noise of the mth radar station, and the coordinate of the mth radar station in the northeast day coordinate system is (x m,ym,zm);
The phase ψ m of the peak signal s m is:
Where mod represents the remainder operation and epsilon m represents the phase noise of the w m incoming signal.
3. The high-precision synthetic angle measurement method of a distributed radar according to claim 2, wherein the phase difference Δψ m is:
Δψm＝ψm-ψ0
Wherein ψ 0 denotes the phase of the reference radar station when m=0;
the wave path difference The method comprises the following steps:
Wherein ε 0 represents the phase noise of the w 0 -induced signal,
4. The method of high precision synthetic angle measurement for distributed radars as set forth in claim 1, wherein said wave pathThe method comprises the following steps:
Wherein, the coordinate of the mth radar station under the northeast day coordinate system is (x m,ym,zm);
The wave path difference is The method comprises the following steps:
Wherein, Representing the wave length of the reference radar station, the coordinates of the m=0 th radar station in the northeast day coordinate system are (x 0,y0,z0).
5. The method for high-precision synthetic angle measurement of distributed radar according to claim 1, wherein the blur number isThe method comprises the following steps:
Wherein lambda represents the wavelength, Representing a downward rounding function.
6. The high precision synthetic angle measurement method of distributed radar according to claim 1, wherein whenWhen the deblurring wave path difference/>The method comprises the following steps:
When (when) When the deblurring wave path difference/>The method comprises the following steps:
Where mod represents a remainder operation and λ represents a wavelength.
7. The high precision synthetic angle measurement method of distributed radar according to claim 1, wherein the pitch angle mean square errorAnd the azimuthal mean square error/>The method comprises the following steps of:
where θ 3dB represents the half-power beam width when the single-station array beam is directed to normal, and SNR represents the signal-to-noise ratio of the single-station received signal.
8. The method of high precision synthetic angle measurement of a distributed radar according to claim 1, wherein the step 7 comprises:
step 7.1, obtaining vectors Corresponding equi-modal length vertical vector on xoy plane
Step 7.2, obtaining the coordinates of the mth radar station in the vectorProjection onto/>
Step 7.3, according to the projection corresponding to the mth radar stationProjection/>, corresponding to nth radar stationObtain azimuth equivalent aperture/>
Step 7.4, equivalent aperture according to the azimuthObtain azimuth beam width/>
Step 7.5, according to the azimuth beam widthObtaining the azimuth synthesis theoretical angle measurement error/>To synthesize a theoretical angular error/>, based on the orientationObtain azimuth search interval/>
Step 7.6, obtaining the coordinate in vector of the mth radar stationProjection onto/>
Step 7.7, according to the projection corresponding to the mth radar stationProjection/>, corresponding to nth radar stationObtain the pitching equivalent aperture/>
Step 7.8, according to the pitch equivalent apertureObtain pitch beamwidth/>
Step 7.9, according to the pitch beam widthObtaining pitch synthesis theoretical angle measurement error/>To synthesize a theoretical angular error/>, based on the pitchObtain pitch search interval/>
Step 7.10, according to the azimuth beam widthAnd the elevation beam width/>Establishing a lookup table to measure azimuth/>, according toAnd measuring pitch angle/>Looking up in a lookup table to obtain azimuth beam width/>And pitch beamwidth/>
Step 7.11, according to the azimuth beam widthAnd the elevation beam width/>Corresponding to the azimuth interval/>And pitch interval/>
Step 7.12, search interval with azimuthAnd pitch search interval/>For search scope/>, respectivelyAnd/>Discretizing to obtain azimuth/>, over the search rangeAnd pitch/>
9. The high precision synthetic angle measurement method of distributed radar according to claim 8, wherein the projectionThe method comprises the following steps:
wherein the coordinates of the mth radar station are in the vector The coordinates of the upper projection are (x m,ym);
the azimuth equivalent aperture The method comprises the following steps:
The azimuth beam width The method comprises the following steps:
wherein λ represents wavelength, (°) represents unit degree;
the azimuth synthesis theory angle measurement error The method comprises the following steps:
Wherein, SNR represents signal-to-noise ratio of single station received signal;
The projection is The method comprises the following steps:
Wherein, Representation/>A vertical vector on plane Ω,/>
The pitch equivalent apertureThe method comprises the following steps:
the elevation beam width The method comprises the following steps:
the pitch synthesis theoretical angle measurement error The method comprises the following steps:
The azimuth beam width The method comprises the following steps:
the elevation beam width The method comprises the following steps:
10. the method of high precision synthetic angle measurement of a distributed radar of claim 1, wherein the azimuth angle And the pitch angle/>
Wherein,Representing the search angle as azimuth/>And pitch/>Time-corresponding wave Cheng Chazhi,/>Representing the deblurred path difference.
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