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CN108344983B - A passive radar direction finding method and system - Google Patents

A passive radar direction finding method and system Download PDF

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Publication number
CN108344983B
CN108344983B CN201810135283.9A CN201810135283A CN108344983B CN 108344983 B CN108344983 B CN 108344983B CN 201810135283 A CN201810135283 A CN 201810135283A CN 108344983 B CN108344983 B CN 108344983B
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target
measured
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radiation source
echo signal
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CN108344983A (en
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刘玉春
程琳
王洪雁
朱思峰
朱海
朱磊
豆桂平
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Hon Hai Precision Industry Co Ltd
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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
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/41—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section

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  • Computer Networks & Wireless Communication (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
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  • Radar Systems Or Details Thereof (AREA)

Abstract

本发明公开一种无源雷达测向方法及系统。该测向方法包括：获取接收机绕转动中心转动的轨迹函数，所述接收机绕转动中心转动的轨迹为椭圆轨迹；根据所述轨迹函数获取待测目标的斜距历程函数，所述斜距历程函数为外辐射源信号经过所述待测目标到达接收机经过的历程函数；根据所述斜距历程确定回波信号；构建待测目标识别区域的信号识别矩阵；根据所述回波信号和所述信号识别矩阵获取待测目标的方位角。采用本发明的测向方法及系统，能够对目标区域进行精细测向，提高分辨的精度；大大减小占地面积，其布站较为方便；减小了所需数据存储空间，使得运算进一步高效。

Figure 201810135283

The invention discloses a passive radar direction finding method and system. The direction finding method includes: acquiring a trajectory function of a receiver rotating around a rotation center, and the trajectory of the receiver rotating around the rotation center is an elliptical trajectory; The history function is the history function of the external radiation source signal passing through the target to be measured to reach the receiver; the echo signal is determined according to the slant range history; the signal identification matrix of the identification area of the target to be measured is constructed; according to the echo signal and The signal identification matrix obtains the azimuth angle of the target to be measured. The direction finding method and system of the present invention can perform precise direction finding on the target area and improve the resolution accuracy; greatly reduce the floor space, and the station layout is more convenient; the required data storage space is reduced, and the operation is further efficient .

Figure 201810135283

Description

Passive radar direction finding method and system
Technical Field
The invention relates to the field of radars, in particular to a passive radar direction finding method and system.
Background
At present, the traditional direction-finding method mainly comprises the direction finding of a real aperture radar or an array antenna, and the azimuth resolution of the traditional direction-finding method is 0.89 lambda/D, wherein lambda is the signal wavelength, and D is the radar aperture or the array antenna length. The traditional direction-finding radar needs to adopt a large-aperture antenna or a long array antenna, and the manufacturing and using cost is high. In addition, the traditional direction-finding radar actively emits electromagnetic waves, so that the traditional direction-finding radar is attacked by an enemy anti-radiation missile in military application and has poor survivability.
Recently, a novel radar direction-finding system has appeared, which adopts a civil external radiation source, the receiver makes uniform circular motion around the rotation center of the civil external radiation source, and the azimuth resolution of the system is 0.36 lambda/r, wherein r is the rotation radius of the receiver. The direction-finding system is simple in structure and good in system resolution capability. However, the receiver in the direction-finding system does uniform circular motion, so that the occupied area of the system is large, and the radar station distribution is difficult. In addition, the direction-finding system has the resolution of 0.36 lambda/r at all azimuth angles, and the region of interest cannot be finely resolved.
Disclosure of Invention
The invention aims to provide a passive radar direction finding method and a passive radar direction finding system, so that the occupied area of the system is reduced, meanwhile, the interested area is finely distinguished, and the distinguishing precision is improved.
In order to achieve the purpose, the invention provides the following scheme:
a passive radar direction finding method, the direction finding method comprising:
acquiring a track function of a receiver rotating around a rotation center, wherein the track of the receiver rotating around the rotation center is an elliptical track;
acquiring a slope distance history function of the target to be detected according to the track function, wherein the slope distance history function is a history function of the external radiation source signal passing through the target to be detected and reaching a receiver;
determining an echo signal according to the slope distance process;
constructing a signal identification matrix of an identification area of a target to be detected;
and acquiring the azimuth angle of the target to be detected according to the echo signal and the signal identification matrix.
Optionally, the obtaining a slope distance history function of the target to be measured according to the track function specifically includes:
obtaining the slope distance history function of the target to be measured according to the track function as R (t) ═ RT+R0Acos α cos (ω t) -bsin α sin (ω t), wherein R (t) represents the slant range course of the target to be measured, RTIs the distance, R, between the object to be measured and the external radiation source0The distance from the target to be measured to the rotation center is defined as a, a is a semi-major axis of the elliptical trajectory, b is a semi-minor axis of the elliptical trajectory, α is an azimuth angle of the target to be measured, and ω t is θ which is an angle of rotation of the elliptical trajectory.
Optionally, the determining an echo signal according to the ramp distance history specifically includes:
acquiring an external radiation source signal f (t) ═ exp { j2 pi ft };
determining the initial echo signal of the target to be detected according to the external radiation source signal and the slope distance history function of the target to be detected as follows:
Figure BDA0001576084900000021
after demodulating and discretely sampling the initial echo signal, obtaining a processed echo signal:
Figure BDA0001576084900000022
wherein f (t) is an external radiation source signal, g (t) is an initial echo signal of a target to be detected, g (m) is a processed echo signal of the target to be detected, exp { j … … } is in a complex exponential form, f is the frequency of the external radiation source signal, t represents the time for a receiver to receive the signal, σ is the scattering intensity of the target to be detected, R (t) represents the slant range course of the target to be detected, C represents the light speed, λ represents the wavelength of the external radiation source signal, R (t) represents the time for the receiver to receive the signal, andTis the distance, R, between the object to be measured and the external radiation source0Is the distance from the target to be measured to the rotation center, a is the semi-major axis of the elliptical track, b is the semi-minor axis of the elliptical track, α is the azimuth angle of the target to be measured, ω t is θ the rotation angle of the elliptical track, Δ t is the time step of system sampling, M represents the mth sampling, M is the total sampling number in the imaging process, M is 1,2, …, M,
Figure BDA0001576084900000023
optionally, the constructing a signal identification matrix of the target identification area to be detected specifically includes:
the signal identification matrix for constructing the identification area of the target to be detected is as follows:
Figure BDA0001576084900000031
wherein M is 1,2, …, M, N is 1,2, … N, wherein delta α is the step of traversal, and the traversal is performed for N times.
Optionally, the obtaining an azimuth angle of the target to be measured according to the echo signal and the signal identification matrix specifically includes:
determining a direction finding preprocessing matrix of the target to be detected: f (m, n) ═ G (m) G*(m, n); wherein f (m, n) is the direction finding preprocessing matrix, G (m) is an echo signal, and G (m, n) is the signal identification matrix;
determining a position function of the target to be measured:
Figure BDA0001576084900000032
wherein M represents the M-th sampling, M is the total sampling frequency in the imaging process, N represents the N-th traversal, and N times of traversal are totally performed;
determining the peak value of a position function F (n) of the target to be measured;
and determining the azimuth angle of the target to be detected to be n delta α rad according to the n value corresponding to the peak value of the position function F (n) of the target to be detected.
A passive radar direction-finding system, the direction-finding system comprising:
the receiver rotation track function acquisition module is used for acquiring a track function of the receiver rotating around a rotation center, and the track of the receiver rotating around the rotation center is an elliptical track;
the system comprises a slope distance history function acquisition module of a target to be detected, a track function acquisition module and a data processing module, wherein the slope distance history function acquisition module is used for acquiring a slope distance history function of the target to be detected according to the track function, and the slope distance history function is a history function through which an external radiation source signal passes through the target to be detected and reaches a receiver;
the echo signal determining module is used for determining an echo signal according to the slope distance process;
the signal identification matrix construction module is used for constructing a signal identification matrix of the identification area of the target to be detected;
and the azimuth angle acquisition module of the target to be detected is used for acquiring the azimuth angle of the target to be detected according to the echo signal and the signal identification matrix.
Optionally, the slope distance history function obtaining module of the target to be measured obtains a slope distance history function of the target to be measured according to the track function, where the slope distance history function is R (t) ═ RT+R0Acos α cos (ω t) -bsin α sin (ω t), wherein R (t) represents the slant range course of the target to be measured,RTis the distance, R, between the object to be measured and the external radiation source0The distance from the target to be measured to the rotation center is defined as a, a is a semi-major axis of the elliptical trajectory, b is a semi-minor axis of the elliptical trajectory, α is an azimuth angle of the target to be measured, and ω t is θ which is an angle of rotation of the elliptical trajectory.
Optionally, the echo signal determination module specifically includes:
an external radiation source signal acquisition unit for acquiring an external radiation source signal f (t) ═ exp { j2 π ft };
an initial echo signal determining unit, configured to determine, according to the external radiation source signal and the slant range history function of the target to be detected, that an initial echo signal of the target to be detected is:
Figure BDA0001576084900000041
the processed echo signal acquisition unit is used for demodulating and discretely sampling the initial echo signal to obtain a processed echo signal:
Figure BDA0001576084900000042
wherein f (t) is an external radiation source signal, g (t) is an initial echo signal of a target to be detected, g (m) is a processed echo signal of the target to be detected, exp { j … … } is in a complex exponential form, f is the frequency of the external radiation source signal, t represents the time for a receiver to receive the signal, σ is the scattering intensity of the target to be detected, R (t) represents the slant range course of the target to be detected, C represents the light speed, λ represents the wavelength of the external radiation source signal, R (t) represents the time for the receiver to receive the signal, andTis the distance, R, between the object to be measured and the external radiation source0Is the distance from the target to be measured to the rotation center, a is the semi-major axis of the elliptical track, b is the semi-minor axis of the elliptical track, α is the azimuth angle of the target to be measured, ω t is θ the rotation angle of the elliptical track, Δ t is the time step of system sampling, M represents the mth sampling, M is the total sampling number in the imaging process, M is 1,2, …, M,
Figure BDA0001576084900000043
optionally, the signal identification matrix constructing module constructs a signal identification matrix of the target identification area to be detected as follows:
Figure BDA0001576084900000044
wherein M is 1,2, …, M, N is 1,2, … N, wherein delta α is the step of traversal, and the traversal is performed for N times.
Optionally, the azimuth obtaining module of the target to be measured specifically includes:
the direction finding preprocessing matrix determining unit is used for determining a direction finding preprocessing matrix of the target to be detected: f (m, n) ═ G (m) G*(m, n); wherein f (m, n) is the direction finding preprocessing matrix, G (m) is an echo signal, and G (m, n) is the signal identification matrix;
a position function determining unit of the object to be measured, configured to determine a position function of the object to be measured:
Figure BDA0001576084900000051
wherein M represents the M-th sampling, M is the total sampling frequency in the imaging process, N represents the N-th traversal, and N times of traversal are totally performed;
the peak value determining unit of the position function of the target to be measured is used for determining the peak value of the position function F (n) of the target to be measured;
and the azimuth angle determining unit of the target to be detected is used for determining the azimuth angle of the target to be detected to be n delta α rad according to the n value corresponding to the peak value of the position function F (n) of the target to be detected.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
compared with the direction finding direction of the conventional receiver circular scanning passive radar, the passive radar direction finding method based on receiver elliptical scanning has the following obvious advantages: firstly, the circular scanning passive radar has the same target angle resolution in all areas, and cannot perform fine direction finding on key areas, but the invention can enable the elliptical semi-minor axis to be usedThe target area is pointed, the length of the semimajor axis is properly increased to realize fine direction finding of the target area, and the resolution precision is improved; secondly, the circular scanning radar occupies the area of pi r2R is the rotation radius of the receiver, the rotation track of the receiver is an ellipse, the occupied area of the receiver is pi ab, and the occupied area can be greatly reduced by adjusting b, so that the station distribution is more convenient; thirdly, the method omits the step of establishing the echo signal matrix in the data processing process, reduces the required data storage space and enables the operation to be further efficient.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
FIG. 1 is a schematic flow chart of a passive radar direction finding method according to the present invention;
FIG. 2 is a schematic structural diagram of a passive radar direction-finding system according to the present invention;
FIG. 3 is a schematic diagram illustrating a positional relationship between a receiver and a target to be measured and an external radiation source according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of the angular resolution of each azimuth for a first simulation using the method and system of the present invention;
FIG. 5 is a schematic diagram of the resolution result of a second simulation performed using the method and system of the present invention;
FIG. 6 is a schematic diagram of a resolution result of a third simulation performed by the method and system of the present invention;
FIG. 7 is a schematic diagram of a resolution result of a fourth simulation performed by the method and system of the present invention;
FIG. 8 is a diagram illustrating a resolution result of a fifth simulation performed by the method and system of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. 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.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Fig. 1 is a schematic flow chart of a passive radar direction finding method according to the present invention. As shown in fig. 1, the direction finding method includes:
step 100: a trajectory function of the receiver rotation about the center of rotation is obtained. The track of the receiver rotating around the rotation center is an elliptical track, a rectangular coordinate system is established by taking the rotation center as the origin of coordinates according to the semi-major axis and the semi-minor axis of the receiver rotating around the rotation center, the semi-major axis direction of the elliptical track is the X-axis direction, and the minor axis direction is the Y-axis direction, and at the moment, the function expression of the elliptical track can be determined, namely, the function of the track.
At this time, the coordinate of the external radiation source is assumed to be (x)t,yt) The rectangular coordinate and the polar coordinate of the target to be measured are respectively (x)0,y0)、(R0α), the receiver coordinates are (x)r,yr) Then the following relationship exists:
Figure BDA0001576084900000071
wherein R is0The distance from the target to be measured to the rotation center is defined as a, a is a semi-major axis of the elliptical trajectory, b is a semi-minor axis of the elliptical trajectory, α is an azimuth angle of the target to be measured, and ω t is θ which is an angle of rotation of the elliptical trajectory.
Step 200: and acquiring a slope distance history function of the target to be measured according to the track function. And the slant distance process function is a process function through which an external radiation source signal passes through the target to be detected and reaches a receiver. Specifically, the slope distance history function of the target to be measured is R (t) ═ RT+R0Acos α cos (ω t) -bsin α sin (ω t), wherein R (t) represents the slant range course of the target to be measured, RTIs the distance, R, between the object to be measured and the external radiation source0The distance from the target to be measured to the rotation center, a is the semi-major axis of the elliptical track, b is the semi-minor axis of the elliptical track, α is the azimuth angle of the target to be measured, and ω t is θ the rotation angle of the elliptical track.
Figure BDA0001576084900000072
Since the distance from the receiver to the target to be measured is much greater than the distance from the receiver to the rotation center, the above equation can be derived.
Step 300: and determining an echo signal according to the slope distance process.
The specific process of determining the echo signal is as follows:
acquiring an external radiation source signal f (t) ═ exp { j2 pi ft }; the external radiation source signal is usually a civil signal, and is generally a narrow-band signal, so that the external radiation source signal can be expressed by the formula;
determining the initial echo signal of the target to be detected according to the external radiation source signal and the slope distance history function of the target to be detected as follows:
Figure BDA0001576084900000081
after demodulating and discretely sampling the initial echo signal, obtaining a processed echo signal:
Figure BDA0001576084900000082
wherein f (t) is an external radiation source signal, g (t) is an initial echo signal of a target to be detected, g (m) is a processed echo signal of the target to be detected, exp { j … … } is in a complex exponential form, f is the frequency of the external radiation source signal, t represents the time for a receiver to receive the signal, σ is the scattering intensity of the target to be detected, and R (t) represents the target to be detectedThe slope distance course of (1), C represents the speed of light, RTIs the distance, R, between the object to be measured and the external radiation source0Is the distance from the target to be measured to the rotation center, a is the semi-major axis of the elliptical track, b is the semi-minor axis of the elliptical track, α is the azimuth angle of the target to be measured, ω t is θ the rotation angle of the elliptical track, Δ t is the time step of system sampling, M represents the mth sampling, M is the total sampling number in the imaging process, M is 1,2, …, M,
Figure BDA0001576084900000083
step 400: and constructing a signal identification matrix of the identification area of the target to be detected. The signal identification matrix of the target identification area to be detected is constructed as follows:
Figure BDA0001576084900000084
wherein M is 1,2, …, M, N is 1,2, … N, wherein delta α is the step of traversal, and the traversal is performed for N times.
Step 500: and acquiring the azimuth angle of the target to be detected according to the echo signal and the signal identification matrix. The method specifically comprises the following steps:
determining a direction finding preprocessing matrix of the target to be detected: f (m, n) ═ G (m) G*(m, n); wherein f (m, n) is the direction finding preprocessing matrix, G (m) is echo signal, G (m, n) is the signal identification matrix, G (m, n) is*(m, n) is a conjugate matrix of G (m, n); at this time, the direction-finding pre-processing matrix is:
Figure BDA0001576084900000091
determining a position function of the target to be measured:
Figure BDA0001576084900000092
wherein M represents the M-th sampling, M is the total sampling frequency in the imaging process, N represents the N-th traversal, and N times of traversal are totally performed;
determining the peak value of a position function F (n) of the target to be measured;
and determining the azimuth angle of the target to be detected to be n delta α rad according to the n value corresponding to the peak value of the position function F (n) of the target to be detected.
Specifically, the derivation process of f (n) is as follows:
Figure BDA0001576084900000093
wherein
Figure BDA0001576084900000094
Figure BDA0001576084900000095
J0(. cndot.) is a zero order Bessel function.
Within a 3dB beam, it can be approximated as
Figure BDA0001576084900000096
Thus, it is possible to provide
Figure BDA0001576084900000097
Therefore, the method comprises the following steps:
Figure BDA0001576084900000098
as can be seen from the above formula, when n Δ α is α, that is, n is α/Δ α, f (n) has a peak M | σ |, and the azimuth angle of the target to be measured can be determined according to the peak.
From the above equation, it can be seen that, according to the property of the bezier function, when α is 0 or pi rad, D (α) ═ b, the direction finding result is
Figure BDA0001576084900000101
The resolution is 0.36 lambda/b, when α is 0.5 pi or 1.5 pi rad, D (α) ═ a, the direction finding result is
Figure BDA0001576084900000102
The resolution was 0.36 λ/a.
The above analysis shows that the direction finding performance is the worst when the target is located in the X-axis direction (α is 0 or π rad). conversely, the direction finding performance is the best when the target is located in the Y-axis direction (α is 0.5 π or 1.5 π rad). moreover, if the length of the semimajor axis is increased, the resolution is reduced in the Y-axis direction, so the resolution performance is further improved.
Fig. 2 is a schematic structural diagram of the passive radar direction finding system of the present invention. As shown in fig. 2, the direction finding system includes:
a receiver rotation trajectory function obtaining module 201, configured to obtain a trajectory function of a receiver rotating around a rotation center, where a trajectory of the receiver rotating around the rotation center is an elliptical trajectory;
the system comprises a slope distance history function obtaining module 202 of the target to be measured, which is used for obtaining a slope distance history function of the target to be measured according to the track function, wherein the slope distance history function is a history function of an external radiation source signal passing through the target to be measured and reaching a receiver;
an echo signal determining module 203, configured to determine an echo signal according to the ramp distance history;
the signal identification matrix construction module 204 is used for constructing a signal identification matrix of the target identification area to be detected;
and an azimuth angle obtaining module 205 of the target to be measured, configured to obtain an azimuth angle of the target to be measured according to the echo signal and the signal identification matrix.
The slope distance history function obtaining module 202 of the target to be measured obtains a slope distance history function of the target to be measured according to the track function, where R (t) RT+R0Acos α cos (ω t) -bsin α sin (ω t), wherein R (t) represents the slant range course of the target to be measured, RTIs the distance, R, between the object to be measured and the external radiation source0The distance from the target to be measured to the rotation center is defined as a, a is a semi-major axis of the elliptical trajectory, b is a semi-minor axis of the elliptical trajectory, α is an azimuth angle of the target to be measured, and ω t is θ which is an angle of rotation of the elliptical trajectory.
The echo signal determination module 203 specifically includes:
an external radiation source signal acquisition unit for acquiring an external radiation source signal f (t) ═ exp { j2 π ft };
an initial echo signal determining unit, configured to determine, according to the external radiation source signal and the slant range history function of the target to be detected, that an initial echo signal of the target to be detected is:
Figure BDA0001576084900000111
the processed echo signal acquisition unit is used for demodulating and discretely sampling the initial echo signal to obtain a processed echo signal:
Figure BDA0001576084900000112
wherein f (t) is an external radiation source signal, g (t) is an initial echo signal of a target to be detected, g (m) is a processed echo signal of the target to be detected, exp { j … … } is in a complex exponential form, f is the frequency of the external radiation source signal, t represents the time for a receiver to receive the signal, σ is the scattering intensity of the target to be detected, R (t) represents the slant range course of the target to be detected, C represents the light speed, λ represents the wavelength of the external radiation source signal, R (t) represents the time for the receiver to receive the signal, andTis the distance, R, between the object to be measured and the external radiation source0Is the distance from the target to be measured to the rotation center, a is the semi-major axis of the elliptical track, b is the semi-minor axis of the elliptical track, α is the azimuth angle of the target to be measured, ω t is θ the rotation angle of the elliptical track, Δ t is the time step of system sampling, M represents the mth sampling, M is the total sampling number in the imaging process, M is 1,2, …, M,
Figure BDA0001576084900000113
the signal identification matrix constructing module 204 constructs a signal identification matrix of the target identification area to be detected as follows:
Figure BDA0001576084900000114
wherein M is 1,2, …, M, N is 1,2, … N, wherein delta α is the step of traversal, and the traversal is performed for N times.
The azimuth angle obtaining module 205 of the target to be measured specifically includes:
the direction finding preprocessing matrix determining unit is used for determining a direction finding preprocessing matrix of the target to be detected: f (m, n) ═ G (m) G*(m, n); wherein f (m, n) is the direction finding preprocessing matrix, G (m) is an echo signal, and G (m, n) is the signal identification matrix;
a position function determining unit of the object to be measured, configured to determine a position function of the object to be measured:
Figure BDA0001576084900000121
wherein M represents the M-th sampling, M is the total sampling frequency in the imaging process, N represents the N-th traversal, and N times of traversal are totally performed;
the peak value determining unit of the position function of the target to be measured is used for determining the peak value of the position function F (n) of the target to be measured;
and the azimuth angle determining unit of the target to be detected is used for determining the azimuth angle of the target to be detected to be n delta α rad according to the n value corresponding to the peak value of the position function F (n) of the target to be detected.
An embodiment of the present invention is provided below, and fig. 3 is a schematic diagram illustrating a position relationship between a receiver, an object to be measured, and an external radiation source according to an embodiment of the present invention. The method comprises the following specific steps:
step 1, establishing a direction-finding model. The direction-finding system utilizes the region of interest of the civil narrow-band external radiation source to fix a target to carry out fine direction finding. In the direction finding process, an external radiation source and a target are fixed, a receiver rotates around a rotation center, the track of the receiver is an ellipse, the interested area is placed in the direction of a short axis, a coordinate system is established by taking the rotation center as an origin, the direction of the long axis as an X axis and the direction of the short axis as a Y axis, namely the interested area is in the direction of the Y axis (both positive and negative directions).
Suppose the external radiation source coordinate is (x)t,yt) The rectangular coordinate and the polar coordinate of the fixed target are respectively (x)0,y0)、(R0α), the receiver coordinates are(xr,yr) Then the following relationship exists:
Figure BDA0001576084900000122
and step 2, determining the slope distance process. The slant range process refers to the propagation distance of the signal from the external radiation source to the target and then to the receiver, and the distance from the external radiation source to the target is not changed in the direction finding process because the external radiation source and the target are fixed, and the distance is assumed to be RTAnd the range of the target to the receiver is:
Figure BDA0001576084900000123
the ramp history is therefore:
R(t)＝RT+R0-acosαcos(ωt)-bsinαsin(ωt)
it can be seen that in the direction finding process, R in the course of the slope distanceT+R0Remains unchanged and therefore has no effect on the direction finding result.
Step 3, determining the demodulated discretized echo signal:
Figure BDA0001576084900000131
and 4, constructing a signal identification matrix of the target identification area, traversing the azimuth angle of the target in the direction finding process at (0,2 pi rad), wherein the traversing step is delta α, and searching for N times.
Figure BDA0001576084900000132
m＝1,2,…,M；n＝1,2,…N。
And 5: direction finding preprocessing matrix calculation:
Figure BDA0001576084900000133
step 6: and summing the direction-finding preprocessing matrix in a time dimension, then performing modulus extraction, and determining the azimuth angle of the target to be detected at the peak position of the direction-finding preprocessing matrix.
Position function of the object to be measured:
Figure BDA0001576084900000134
wherein
Figure BDA0001576084900000135
J0(. cndot.) is a zero order Bessel function.
The effects of the present embodiment are further illustrated by the following simulation experiments.
Simulation conditions
The invention is insensitive to the position of an external radiation source, the coordinate of the external radiation source is assumed to be (10000m,15000m), the receiver rotates an elliptical track, the semiminor axis b is 3m, sampling is carried out for 1000 times in the rotation process, and the sampling step length of an elliptical angle parameter is 0.002 pi rad. Without loss of generality, the scattering intensity of the target in the simulation is 1.
Emulated content
Carrying out first simulation: on the basis of the above simulation conditions, the angular resolution of the target in different directions can be obtained by using a civil external radiation source with a signal frequency of 300MHz, the semi-major axis a being 30m and the semi-minor axis b being 3m, and as a result, fig. 4 shows an angular resolution diagram of each azimuth angle for the first simulation by using the method and system of the present invention. As can be seen from the simulation chart, when the target azimuth angle is 0.5 π rad and 1.5 π rad (i.e. occurring in the positive or negative direction of the Y axis), the resolution performance is the best, and the resolution is 0.012 rad; when the target azimuth is π rad, 2 π rad (i.e., occurring in either the positive or negative direction of the X-axis), the resolution is the worst, with a resolution of 0.12 rad.
And (3) second simulation: two fixed targets exist in the observation area, the polar coordinates of the two fixed targets are respectively (5000m,0.5 pi rad), (7500m, pi rad), and a civil external radiation source with the signal frequency of 300MHz is used. FIG. 5 is a schematic diagram of a resolution result of a second simulation performed by the method and system of the present invention. As shown in fig. 5, since the two targets have different orientations, the two targets have different resolving performances, so that the invention can perform focused monitoring on the region of interest.
And (3) third simulation: there are 4 random targets in the region (i.e. the region of interest) near the azimuth angle of 0.5 π rad, and the simulation result is shown in FIG. 6, and FIG. 6 is a schematic diagram of the resolution result of the third simulation performed by the method and system of the present invention. In fig. 6, ", the target is located in the position, and it can be seen that the present invention can accurately perform direction finding on the target, and the target is located in the region of interest, and the resolution is high. Therefore, the invention can simultaneously detect the direction of multiple targets and verify the correctness and the practicability of the direction detection.
Fourth simulation: when the frequency of the external radiation source is 100MHz, the minor axis and the half axis are unchanged, the length of the semi-major axis is 5m, 10m and 30m respectively, the direction of the target at 0.5 pi rad is measured, the simulation result is shown in FIG. 7, and FIG. 7 is a schematic diagram of the resolution result of the fourth simulation performed by the method and the system of the present invention. As can be seen from fig. 7, the resolving power increases with the increase of the longer half axis.
And (4) fifth simulation: the length of the semimajor axis is 15m, when the frequency of the external radiation source is 50MHz, 100MHz, 300MHz, respectively, the direction of the target located at 0.5 pi rad is measured, the simulation result is shown in fig. 8, and fig. 8 is a schematic diagram of the resolution result of the fifth simulation performed by the method and the system of the present invention. As can be seen from fig. 8, the resolution performance increases with the increase of the frequency of the external radiation source signal.
In conclusion, the invention adopts the elliptical scanning, which can greatly save the occupied area of the radar system, so the station distribution is more convenient. In addition, because the region of interest is arranged in the direction of the elliptical semi-minor axis, the angular resolution can be improved, and the region is monitored in an important way. The resolution performance can be further improved by increasing the length of the semimajor axis, adopting high-frequency external radiation source signals and the like. In the data processing process, the method omits the step of establishing the echo signal matrix, reduces the required data storage space and ensures that the operation is further efficient.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the system disclosed by the embodiment, the description is relatively simple because the system corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.

Claims (8)

1.一种无源雷达测向方法，其特征在于，所述测向方法包括：1. a passive radar direction finding method, is characterized in that, described direction finding method comprises: 获取接收机绕转动中心转动的轨迹函数，所述接收机绕转动中心转动的轨迹为椭圆轨迹；Obtaining a trajectory function of the receiver rotating around the rotation center, where the receiver rotating around the rotation center is an elliptical trajectory; 根据所述轨迹函数获取待测目标的斜距历程函数，所述斜距历程函数为外辐射源信号经过所述待测目标到达接收机经过的历程函数；所述斜距历程函数为R(t)＝RT+R0-acosαcos(ωt)-bsinαsin(ωt)，其中R(t)表示待测目标的斜距历程，RT为待测目标与外辐射源之间的距离，R0是待测目标到转动中心的距离，a为所述椭圆轨迹的半长轴，b为所述椭圆轨迹的半短轴，α为待测目标方位角，ωt＝θ是椭圆轨迹转动的角度；The slant range history function of the target to be measured is obtained according to the trajectory function, and the slant range history function is the history function of the external radiation source signal passing through the target to be measured to the receiver; the slant range history function is R(t )=R T +R 0 -acosαcos(ωt)-bsinαsin(ωt), where R(t) represents the oblique distance history of the target to be measured, R T is the distance between the target to be measured and the external radiation source, and R 0 is The distance from the target to be measured to the center of rotation, a is the semi-major axis of the elliptical trajectory, b is the semi-minor axis of the elliptical trajectory, α is the azimuth angle of the target to be measured, and ωt=θ is the angle at which the elliptical trajectory rotates; 根据所述斜距历程确定回波信号；determining an echo signal according to the slope distance history; 构建待测目标识别区域的信号识别矩阵；Construct the signal recognition matrix of the target recognition area to be tested; 根据所述回波信号和所述信号识别矩阵获取待测目标的方位角。The azimuth angle of the target to be measured is acquired according to the echo signal and the signal identification matrix. 2.根据权利要求1所述的测向方法，其特征在于，所述根据所述斜距历程确定回波信号，具体包括：2. The direction finding method according to claim 1, wherein the determining of the echo signal according to the slant range history specifically comprises: 获取外辐射源信号f(t)＝exp{j2πft}；Obtain the external radiation source signal f(t)=exp{j2πft}; 根据所述外辐射源信号和所述待测目标的斜距历程函数确定待测目标的初始回波信号为：According to the external radiation source signal and the slope distance history function of the target to be measured, the initial echo signal of the target to be measured is determined as:
Figure FDA0002256065130000011
Figure FDA0002256065130000011
 对所述初始回波信号解调并离散采样后，获得处理后的回波信号：After demodulating and discretely sampling the initial echo signal, the processed echo signal is obtained:
Figure FDA0002256065130000012
Figure FDA0002256065130000012
 其中，f(t)为外辐射源信号，g(t)为待测目标的初始回波信号，g(m)为待测目标的处理后的回波信号，exp{j……}为复数的指数形式，f为所述外辐射源信号的频率，t表示接收机接收信号的时间，σ为待测目标的散射强度，R(t)表示所述待测目标的斜距历程，C表示光速，λ表示外辐射源信号的波长，RT为待测目标与外辐射源之间的距离，R0是待测目标到转动中心的距离，a为所述椭圆轨迹的半长轴，b为所述椭圆轨迹的半短轴，α为待测目标方位角，ωt＝θ是椭圆轨迹转动的角度；Δt为系统采样的时间步长，m表示第m次采样，M为在成像过程中总采样次数，m＝1,2,…,M，
Figure FDA0002256065130000021
Among them, f(t) is the external radiation source signal, g(t) is the initial echo signal of the target to be measured, g(m) is the processed echo signal of the target to be measured, and exp{j...} is a complex number The exponential form of , f is the frequency of the external radiation source signal, t is the time when the receiver receives the signal, σ is the scattering intensity of the target to be measured, R(t) is the slope distance history of the target to be measured, and C is the Speed of light, λ represents the wavelength of the external radiation source signal, R T is the distance between the target to be measured and the external radiation source, R 0 is the distance from the target to be measured to the center of rotation, a is the semi-major axis of the elliptical trajectory, b is the semi-minor axis of the elliptical trajectory, α is the azimuth angle of the target to be measured, ωt=θ is the rotation angle of the elliptical trajectory; Δt is the time step of the system sampling, m represents the mth sampling, and M is the imaging process. Total sampling times, m=1,2,...,M,
Figure FDA0002256065130000021
 3.根据权利要求2所述的测向方法，其特征在于，所述构建待测目标识别区域的信号识别矩阵，具体包括：3. direction finding method according to claim 2, is characterized in that, described constructing the signal identification matrix of the target identification area to be measured, specifically comprises: 构建待测目标识别区域的信号识别矩阵为：The signal recognition matrix for constructing the target recognition area to be tested is:
Figure FDA0002256065130000022
Figure FDA0002256065130000022
 其中，m＝1,2,…,M；n＝1,2,…N；其中Δα为遍历步长，共遍历N次。Among them, m=1,2,...,M; n=1,2,...N; where Δα is the traversal step size, which is traversed N times in total. 4.根据权利要求1所述的测向方法，其特征在于，所述根据所述回波信号和所述信号识别矩阵获取待测目标的方位角，具体包括：4. The direction finding method according to claim 1, wherein the obtaining the azimuth angle of the target to be measured according to the echo signal and the signal identification matrix specifically comprises: 确定待测目标的测向预处理矩阵：f(m,n)＝g(m)G*(m,n)；其中f(m,n)为所述测向预处理矩阵，g(m)为回波信号，G(m,n)为所述信号识别矩阵；Determine the direction finding preprocessing matrix of the target to be measured: f(m,n)=g(m)G * (m,n); where f(m,n) is the direction finding preprocessing matrix, g(m) is the echo signal, and G(m,n) is the signal identification matrix; 确定待测目标的位置函数：
Figure FDA0002256065130000023
其中m表示第m次采样，M为在成像过程中总采样次数，n表示第n次遍历，共遍历N次；Determine the position function of the target to be measured:
Figure FDA0002256065130000023
Where m represents the mth sampling, M is the total number of samplings in the imaging process, n represents the nth traversal, and a total of N traversals; 确定所述待测目标的位置函数F(n)的峰值；Determine the peak value of the position function F(n) of the target to be measured; 根据所述待测目标的位置函数F(n)的峰值对应的n值，确定待测目标的方位角为nΔαrad。According to the value of n corresponding to the peak value of the position function F(n) of the target to be measured, the azimuth angle of the target to be measured is determined as nΔαrad. 5.一种无源雷达测向系统，其特征在于，所述测向系统包括：5. A passive radar direction finding system, wherein the direction finding system comprises: 接收机转动的轨迹函数获取模块，用于获取接收机绕转动中心转动的轨迹函数，所述接收机绕转动中心转动的轨迹为椭圆轨迹；a trajectory function acquisition module for the rotation of the receiver, used for acquiring the trajectory function of the receiver rotating around the rotation center, and the trajectory of the receiver rotating around the rotation center is an elliptical trajectory; 待测目标的斜距历程函数获取模块，用于根据所述轨迹函数获取待测目标的斜距历程函数，所述斜距历程函数为外辐射源信号经过所述待测目标到达接收机经过的历程函数；所述斜距历程函数为R(t)＝RT+R0-acosαcos(ωt)-bsinαsin(ωt)，其中R(t)表示待测目标的斜距历程，RT为待测目标与外辐射源之间的距离，R0是待测目标到转动中心的距离，a为所述椭圆轨迹的半长轴，b为所述椭圆轨迹的半短轴，α为待测目标方位角，ωt＝θ是椭圆轨迹转动的角度；The slant range history function acquisition module of the target to be measured is used to obtain the slant range history function of the target to be measured according to the trajectory function. History function; the slope distance history function is R(t)=R T +R 0 -acosαcos(ωt)-bsinαsin(ωt), where R(t) represents the slope distance history of the target to be measured, and R T is the distance to be measured The distance between the target and the external radiation source, R 0 is the distance from the target to be measured to the center of rotation, a is the semi-major axis of the elliptical trajectory, b is the semi-minor axis of the elliptical trajectory, and α is the orientation of the target to be measured angle, ωt=θ is the angle of rotation of the elliptical trajectory; 回波信号确定模块，用于根据所述斜距历程确定回波信号；an echo signal determination module, configured to determine an echo signal according to the slope distance history; 信号识别矩阵构建模块，用于构建待测目标识别区域的信号识别矩阵；The signal identification matrix building module is used to construct the signal identification matrix of the target identification area to be tested; 待测目标的方位角获取模块，用于根据所述回波信号和所述信号识别矩阵获取待测目标的方位角。The azimuth angle acquisition module of the target to be measured is configured to acquire the azimuth angle of the target to be measured according to the echo signal and the signal identification matrix. 6.根据权利要求5所述的测向系统，其特征在于，所述回波信号确定模块，具体包括：6. The direction finding system according to claim 5, wherein the echo signal determination module specifically comprises: 外辐射源信号获取单元，用于获取外辐射源信号f(t)＝exp{j2πft}；an external radiation source signal acquisition unit, used to acquire the external radiation source signal f(t)=exp{j2πft}; 初始回波信号确定单元，用于根据所述外辐射源信号和所述待测目标的斜距历程函数确定待测目标的初始回波信号为：An initial echo signal determination unit, configured to determine the initial echo signal of the target to be measured according to the external radiation source signal and the slope distance history function of the target to be measured:
Figure FDA0002256065130000031
Figure FDA0002256065130000031
 处理后的回波信号获取单元，用于对所述初始回波信号解调并离散采样后，获得处理后的回波信号：The processed echo signal acquisition unit is used to demodulate and discretely sample the initial echo signal to obtain the processed echo signal:
Figure FDA0002256065130000032
Figure FDA0002256065130000032
 其中，f(t)为外辐射源信号，g(t)为待测目标的初始回波信号，g(m)为待测目标处理后的回波信号，exp{j……}为复数的指数形式，f为所述外辐射源信号的频率，t表示接收机接收信号的时间，σ为待测目标的散射强度，R(t)表示所述待测目标的斜距历程，C表示光速，λ表示外辐射源信号的波长，RT为待测目标与外辐射源之间的距离，R0是待测目标到转动中心的距离，a为所述椭圆轨迹的半长轴，b为所述椭圆轨迹的半短轴，α为待测目标方位角，ωt＝θ是椭圆轨迹转动的角度；Δt为系统采样的时间步长，m表示第m次采样，M为在成像过程中总采样次数，m＝1,2,…,M，
Figure FDA0002256065130000041
Among them, f(t) is the external radiation source signal, g(t) is the initial echo signal of the target to be measured, g(m) is the echo signal of the target to be measured after processing, and exp{j...} is a complex number In exponential form, f is the frequency of the external radiation source signal, t is the time when the receiver receives the signal, σ is the scattering intensity of the target to be measured, R(t) is the slope distance history of the target to be measured, and C is the speed of light. , λ represents the wavelength of the external radiation source signal, R T is the distance between the target to be measured and the external radiation source, R 0 is the distance from the target to be measured to the center of rotation, a is the semi-major axis of the elliptical trajectory, b is the The semi-minor axis of the elliptical trajectory, α is the azimuth angle of the target to be measured, ωt=θ is the rotation angle of the elliptical trajectory; Δt is the time step of the system sampling, m represents the mth sampling, and M is the total number of samples in the imaging process. Sampling times, m=1,2,...,M,
Figure FDA0002256065130000041
 7.根据权利要求6所述的测向系统，其特征在于，所述信号识别矩阵构建模块构建待测目标识别区域的信号识别矩阵为：7. direction finding system according to claim 6, is characterized in that, the signal identification matrix that described signal identification matrix building module constructs target identification area to be measured is:
Figure FDA0002256065130000042
Figure FDA0002256065130000042
 其中，m＝1,2,…,M；n＝1,2,…N；其中Δα为遍历步长，共遍历N次。Among them, m=1,2,...,M; n=1,2,...N; where Δα is the traversal step size, which is traversed N times in total. 8.根据权利要求5所述的测向系统，其特征在于，所述待测目标的方位角获取模块，具体包括：8. The direction finding system according to claim 5, wherein the azimuth angle acquisition module of the target to be measured specifically comprises: 测向预处理矩阵确定单元，用于确定待测目标的测向预处理矩阵：f(m,n)＝g(m)G*(m,n)；其中f(m,n)为所述测向预处理矩阵，g(m)为回波信号，G(m,n)为所述信号识别矩阵；The direction finding preprocessing matrix determination unit is used to determine the direction finding preprocessing matrix of the target to be measured: f(m,n)=g(m)G * (m,n); where f(m,n) is the direction finding preprocessing matrix, g(m) is the echo signal, and G(m,n) is the signal identification matrix; 待测目标的位置函数确定单元，用于确定待测目标的位置函数：
Figure FDA0002256065130000043
其中m表示第m次采样，M为在成像过程中总采样次数，n表示第n次遍历，共遍历N次；The position function determination unit of the target to be measured is used to determine the position function of the target to be measured:
Figure FDA0002256065130000043
Where m represents the mth sampling, M is the total number of samplings in the imaging process, n represents the nth traversal, and a total of N traversals; 待测目标位置函数的峰值确定单元，用于确定所述待测目标的位置函数F(n)的峰值；a peak value determination unit of the position function of the target to be measured, for determining the peak value of the position function F(n) of the target to be measured; 待测目标的方位角确定单元，用于根据所述所述待测目标的位置函数F(n)的峰值对应的n值，确定待测目标的方位角为nΔαrad。The azimuth angle determination unit of the target to be measured is configured to determine the azimuth angle of the target to be measured as nΔαrad according to the n value corresponding to the peak value of the position function F(n) of the target to be measured.
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