CN113050053A - Method and system for acquiring coherent parameters of distributed coherent radar of moving platform - Google Patents

Method and system for acquiring coherent parameters of distributed coherent radar of moving platform Download PDF

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CN113050053A
CN113050053A CN202110289756.2A CN202110289756A CN113050053A CN 113050053 A CN113050053 A CN 113050053A CN 202110289756 A CN202110289756 A CN 202110289756A CN 113050053 A CN113050053 A CN 113050053A
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coherent
radar
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CN113050053B (en
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杨琪
王元昊
曾旸
王宏强
邓彬
罗成高
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National University of Defense Technology
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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
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract

The application relates to a method and a system for acquiring coherent parameters of a distributed coherent radar of a moving platform. The method comprises the following steps: modeling a detection scene of the distributed coherent radar of the moving platform to obtain a signal transmitting model of the moving platform, a coherent transmitting model of the moving platform and a coherent receiving model of the moving platform, and then establishing a coherent calculation model of the moving platform according to the coherent transmitting model of the moving platform and the coherent receiving model of the moving platform; establishing a state vector of the transmitting coherent parameters according to the coupling relation among the transmitting coherent parameters, and modeling the state vector by adopting a Singer model to obtain a state equation of the transmitting coherent parameters; and determining an observation equation according to the state equation, and determining a Kalman filtering equation according to the observation equation so as to calculate the coherent parameters of the coherent radar. By adopting the method, the coherent parameters of the coherent radar of the mobile platform can be obtained.

Description

Method and system for acquiring coherent parameters of distributed coherent radar of moving platform
Technical Field
The application relates to the technical field of signal processing, in particular to a method and a system for acquiring coherent parameters of a distributed coherent radar of a moving platform.
Background
In recent years, accidents caused by unmanned aerial vehicles are increasing day by day, and research on effective detection technology aiming at targets of the unmanned aerial vehicles in the low-altitude field is urgent. Because the target reflection area of the low-slow small unmanned aerial vehicle is few, the receiving echo of a single radar often has the condition of insufficient signal to noise ratio, and the detection is difficult. The core idea of the distributed coherent radar is to simultaneously superpose multiple paths of transmitting signals at a target, so that the signal-to-noise ratio of an echo is larger than that of a single radar, and the detection capability of a small target is improved. Distributed Coherent radars make signals Coherent by estimating the receive-transmit delay difference and the phase difference between the respective unit radars, which is called Coherent Parameters (CPs). However, due to the maneuverability of the target drone, if a distributed coherent radar with a fixed platform is used, the target may easily fly out of the field of view of the radar. The distributed coherent radar based on the moving platform has the advantages that the fixed platform type distributed coherent radar has incomparable advantages, and taking the unmanned aerial vehicle platform as an example, the distributed coherent radar has strong maneuvering capability and small terrain limitation, and the detection capability is improved. However, the maneuvering of the platform brings many challenges, and the hysteresis of the coherent parameter estimation is an unavoidable problem in the practical trend of the distributed coherent radar of the moving platform, because when the target and the platform move relatively, the coherent parameters learned at the last moment cannot be directly used for coherent emission at the current moment, and a corresponding prediction method needs to be researched.
Disclosure of Invention
Therefore, it is necessary to provide a method and a system for obtaining coherent parameters of a distributed coherent radar of a mobile platform, which can not be realized by the distributed coherent radar of the mobile platform, in order to solve the above technical problems.
A method for obtaining coherent parameters of a distributed coherent radar of a moving platform comprises the following steps:
modeling a detection scene of the distributed coherent radar of the moving platform to obtain a signal transmitting model of the moving platform, a coherent transmitting model of the moving platform and a coherent receiving model of the moving platform; the dynamic platform distributed coherent radar detection scene is composed of a plurality of independent motion platforms which are independent from each other; data are transmitted between the motion platforms through wireless links;
establishing a coherent calculation model of the moving platform according to the transmitting coherent model of the moving platform and the receiving coherent model of the moving platform;
establishing a state vector of the transmitting coherent parameters according to the coupling relation among the transmitting coherent parameters, and modeling the state vector by adopting a Singer model to obtain a state equation of the transmitting coherent parameters;
determining an observation equation according to the state equation, and determining a Kalman filtering equation according to the observation equation;
and determining a predicted transmission parameter sequence corresponding to the transmission phase parameter according to the Kalman filtering equation, and obtaining the phase parameter of the coherent radar according to the predicted transmission phase parameter sequence and the motion platform phase parameter calculation model.
In one embodiment, the method further comprises the following steps: modeling a detection scene of the distributed coherent radar of the moving platform, wherein a moving platform transmitting signal model for obtaining an m-th moving platform transmitting signal is as follows:
Figure BDA0002979698700000021
wherein, TpFor the transmit pulse width, u is the chirp rate, rect (t) is a rectangular function,
Figure BDA0002979698700000022
is a carrier wave, sm(t)＝exp(j2π(m-1)Δft)；
And m represents the serial number of the motion platform when the signal is transmitted, and l represents the serial number of the motion platform when the signal is received. The signal transmitted by the mth motion platform is:
Figure BDA0002979698700000023
in the formula kappamIndicating the synchronization error of the radar m compared to the reference clock,
Figure BDA0002979698700000024
is the initial phase of radar m.
In one embodiment, the method further comprises the following steps: the signal that the mth motion platform transmits reaches the target is expressed as:
Figure BDA0002979698700000025
wherein tau ismRepresenting the time delay, k, of arrival of the signal transmitted by the mth moving platformmFor synchronization errors of the radar compared to the reference clock,
Figure BDA0002979698700000031
synchronization error of the radar with respect to a reference phase;
the total signal arriving at the target is then:
Figure BDA0002979698700000032
setting the radar 1 as a reference radar, the adjusted transmission signals can be expressed as:
Figure BDA0002979698700000033
wherein
Figure BDA0002979698700000034
And
Figure BDA0002979698700000035
for transmitting the coherent parameters, the obtained dynamic platform transmitting coherent model is as follows:
Figure BDA0002979698700000036
Figure BDA0002979698700000037
in one embodiment, the method further comprises the following steps: if the target reflection echo received by the ith motion platform is represented as:
Figure BDA0002979698700000038
where p (t) is the echo signal at the target;
then all the radar received target echoes are superimposed as:
Figure BDA0002979698700000039
setting the radar 1 as a reference radar, the adjusted received signals are expressed as:
Figure BDA00029796987000000310
wherein the content of the first and second substances,
Figure BDA00029796987000000311
and
Figure BDA00029796987000000312
for receiving the coherent parameters, the obtained dynamic platform receiving coherent model is as follows:
Figure BDA00029796987000000313
Figure BDA00029796987000000314
in one embodiment, the method further comprises the following steps: according to the mobile platform transmitting coherent model and the mobile platform receiving coherent model, establishing a mobile platform coherent calculation model as follows:
Figure BDA00029796987000000315
wherein the content of the first and second substances,
Figure BDA00029796987000000316
in the formula rl(n) is measured directly by radar.
In one embodiment, the method further comprises the following steps: according to the coupling relation among the transmitting coherent parameters, establishing the state vector of the transmitting coherent parameters as follows:
Figure BDA0002979698700000041
wherein R < n >]Represents a state vector, rl(n) represents an emission coherent parameter;
modeling the state vector using a Singer model as follows:
Figure BDA0002979698700000042
where alpha is the inverse of the maneuver-related time constant, i.e., the maneuver frequency,
Figure BDA0002979698700000043
is the acceleration variance of the maneuver object;
Figure BDA0002979698700000044
Figure BDA0002979698700000045
the state equation is established as follows:
R[n+1]＝Φ(T,α)R[n]+u[n]
Figure BDA0002979698700000046
Figure BDA0002979698700000047
the drive noise covariance is:
Figure BDA0002979698700000048
Figure BDA0002979698700000051
in one embodiment, the method further comprises the following steps: according to the state equation, determining an observation equation as follows:
z[n]＝HX[n]+v[n]
wherein, H ═ 100]，v[n]＝σ2，σ2Measuring noise for the radar;
according to the observation equation, determining a Kalman filtering equation as follows:
Figure BDA0002979698700000052
P[n|n-1]＝ΦP[n|n]ΦT+Q[n]
K[n]＝P[n|n-1]HT(HP[n|n-1]HT+R)-1
Figure BDA0002979698700000053
P[n|n]＝(I-K[n]H)P[n|n-1]
in one embodiment, the method further comprises the following steps: according to the Kalman filtering equation, the predicted transmission parameter sequence corresponding to the transmission parameter is determined as follows:
Figure BDA0002979698700000054
obtaining coherent radar coherent parameters according to the predicted transmitting coherent parameter sequence and the motion platform coherent calculation model, wherein the coherent radar coherent parameters are as follows:
Figure BDA0002979698700000055
wherein the content of the first and second substances,
Figure BDA0002979698700000056
a system for obtaining coherent parameters of a distributed coherent radar with a moving platform, the system comprising:
the scene modeling module is used for modeling a detection scene of the distributed coherent radar of the moving platform to obtain a signal transmitting model of the moving platform, a coherent transmitting model of the moving platform and a coherent receiving model of the moving platform; the dynamic platform distributed coherent radar detection scene is composed of a plurality of independent motion platforms which are independent from each other; data are transmitted between the motion platforms through wireless links;
the Kalman filtering module is used for establishing a coherent calculation model of the moving platform according to the transmitting coherent model of the moving platform and the receiving coherent model of the moving platform; establishing a state vector of the transmitting coherent parameters according to the coupling relation among the transmitting coherent parameters, and modeling the state vector by adopting a Singer model to obtain a state equation of the transmitting coherent parameters; determining an observation equation according to the state equation, and determining a Kalman filtering equation according to the observation equation;
and the coherent parameter calculation module is used for determining a predicted transmission coherent parameter sequence corresponding to the transmission coherent parameter according to the Kalman filtering equation and obtaining the coherent parameter of the coherent radar according to the predicted transmission coherent parameter sequence and the motion platform coherent calculation model.
According to the method and the system for obtaining the coherent parameters of the distributed coherent radar of the mobile platform, the coupling relation between the transmission coherent parameters and the distances between different platforms and the target is utilized, the distance change sequence is obtained by measuring the distance between the target and the platform, the Kalman filter is designed to predict the distance change sequence in one step, the transmission coherent parameters at the next moment are estimated according to the predicted distance value, and research support is provided for obtaining the coherent parameters of the distributed coherent radar of the mobile platform and designing the system.
Drawings
FIG. 1 is a schematic flow chart illustrating a method for obtaining coherent parameters of a distributed coherent radar of a mobile platform according to an embodiment;
FIG. 2 is a schematic diagram of an embodiment of a motion platform detecting an object;
FIG. 3 is a flow diagram illustrating coherent parameter estimation according to one embodiment;
FIG. 4 is a diagram of a simulation scenario of a distributed coherent radar of the mobile platform according to an embodiment;
FIG. 5 is a graph of the measured range error for each radar in one embodiment (based on singer's model);
FIG. 6 is a diagram showing the range error of each radar in one embodiment (without singer model)
FIG. 7 is a diagram illustrating error variations in coherent parameters of the radar 2 in one embodiment;
FIG. 8 is a diagram illustrating the variation of the error of the coherent parameters of the radar 3 according to an embodiment;
fig. 9 is a block diagram of a coherent parameter acquisition system of a distributed coherent radar of a mobile platform in an embodiment.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
In one embodiment, as shown in fig. 1, a method for obtaining phase-coherent radar parameters of a distributed coherent radar of a mobile platform is provided, which includes the following steps:
102, modeling a detection scene of the distributed coherent radar of the moving platform to obtain a signal transmitting model of the moving platform, a coherent transmitting model of the moving platform and a coherent receiving model of the moving platform.
The moving platform distributed coherent radar can be composed of a plurality of moving platforms, the moving platforms are mutually independent, and data can be transmitted through a wireless link, so that various working modes can be selected. In the MIMO mode, each motion platform transmits orthogonal signals, while each motion platform receives signals. Because the transmitted signals are orthogonal signals, echoes transmitted by different motion platforms can be separated at the end of the receiving motion platform through filtering and the like, then a signal of a certain channel is selected as a reference signal, signals of the rest channels are aligned with the reference signal in time delay and phase based on the reference channel signal, and at the moment, the receiving coherence is finished. After accurate coherent parameters are obtained through an MIMO mode, the system can be switched to a full coherent working mode, the system controls the time and initial phase of signals transmitted by different motion platforms in the full coherent mode, so that the signals transmitted by all the motion platforms reach a target at the same time and in the same phase, primary superposition is formed at the target, coherent transmission is achieved, and the superposed echo is processed on the basis. Two working modes of the dynamic platform distributed coherent system are discussed below. When the system works in an MIMO mode, echoes of signals transmitted by different motion platforms need to be separated, so that orthogonal signals need to be adopted, and orthogonal frequency division signals are adopted to transmit waveforms.
And 104, establishing a coherent calculation model of the motion platform according to the transmitting coherent model of the motion platform and the receiving coherent model of the motion platform.
The distance walk generated by the relative motion of the moving platform and the target is not negligible, and the phase parameter changes accordingly, and the change is mainly caused by the change of the path difference. The purpose of the emission coherent is to generate positive interference at a target, but due to real-time change of the relative position of the platform and the target, and coherent parameter cognition always occurs before coherent synthesis, which means that the emission coherent parameters which are known only by one-time observation cannot correct emission de-coherent, namely, the known knowledge has hysteresis (time and phase synchronization error is not considered to be changed), and in brief, the direct measurement can be realized. Detection scenarios as shown in fig. 2, in platform (target) motion scenarios, it is necessary to make reasonable predictions of transmit coherent parameters to compensate for de-coherence due to the cognitive lag. In brief, the transmit coherent parameter at time n needs to be determined according to the state at time n, but the latest state obtained by measurement is still at time n-1.
And 106, establishing state vectors of the transmitting coherent parameters according to the coupling relation among the transmitting coherent parameters, and modeling the state vectors by adopting a Singer model to obtain a state equation of the transmitting coherent parameters.
And step 108, determining an observation equation according to the state equation, and determining a Kalman filtering equation according to the observation equation.
And 110, determining a predicted transmission coherent parameter sequence corresponding to the transmission coherent parameter according to a Kalman filtering equation, and obtaining the coherent parameter of the coherent radar according to the predicted transmission coherent parameter sequence and a motion platform coherent calculation model.
According to the method for obtaining the coherent parameters of the distributed coherent radar of the mobile platform, the coupling relation between the transmission coherent parameters and the distances between different platforms and the target is utilized, the distance between the target and the platform is measured, the distance change sequence is obtained, the Kalman filter is designed to predict the distance change sequence in one step, the transmission coherent parameters at the next moment are estimated according to the predicted distance value, and research support is provided for obtaining the coherent parameters of the distributed coherent radar of the mobile platform and designing a system.
In one embodiment, modeling a detection scene of a distributed coherent radar of a moving platform, and obtaining a moving platform emission signal model of an m-th moving platform emission signal is as follows:
Figure BDA0002979698700000081
wherein, TpFor the transmit pulse width, u is the chirp rate, rect (t) is a rectangular function,
Figure BDA0002979698700000082
is a carrier wave, sm(t)＝exp(j2π(m-1)Δft)；
And m represents the serial number of the motion platform when the signal is transmitted, and l represents the serial number of the motion platform when the signal is received. The signal transmitted by the mth motion platform is:
Figure BDA0002979698700000083
in the formula kappamIndicating the synchronization error of the radar m compared to the reference clock,
Figure BDA0002979698700000091
is the initial phase of radar m.
In one embodiment, the signal reaching the target from the mth motion platform is expressed as:
Figure BDA0002979698700000092
wherein tau ismRepresenting the time delay, k, of arrival of the signal transmitted by the mth moving platformmFor synchronization errors of the radar compared to the reference clock,
Figure BDA0002979698700000093
synchronization error of the radar with respect to a reference phase;
the total signal arriving at the target is then:
Figure BDA0002979698700000094
setting the radar 1 as a reference radar, the adjusted transmission signals can be expressed as:
Figure BDA0002979698700000095
wherein
Figure BDA0002979698700000096
And
Figure BDA0002979698700000097
for transmitting the coherent parameters, the obtained dynamic platform transmitting coherent model is as follows:
Figure BDA0002979698700000098
Figure BDA0002979698700000099
in one embodiment, if the target reflection echo received by the ith motion platform is represented as:
Figure BDA00029796987000000910
where p (t) is the echo signal at the target;
then all the radar received target echoes are superimposed as:
Figure BDA00029796987000000911
setting the radar 1 as a reference radar, the adjusted received signals are expressed as:
Figure BDA00029796987000000912
wherein the content of the first and second substances,
Figure BDA00029796987000000913
and
Figure BDA00029796987000000914
for receiving the coherent parameters, the obtained dynamic platform receiving coherent model is as follows:
Figure BDA00029796987000000915
Figure BDA00029796987000000916
obviously, at the target, the signals received by the respective platforms cannot be superposed in the same direction, and in order to realize coherent superposition, i.e. coherent reception, of electromagnetic wave energy, the reception delay and the reception phase of each radar need to be adjusted.
In one embodiment, assuming that the target and the platform can be approximately considered as stationary in a single pulse, the coherent parameters cannot be directly measured as known from a coherent model transmitted by the movable platform and a coherent model received by the movable platform
Figure BDA0002979698700000101
Wherein tau islm＝τl+τm+κm-κlRepresenting the time delay, alpha, of the signal transmitted by the mth moving platform to the lth moving platform after being reflected by the targetlmFor the scatterer response on the path,
Figure BDA0002979698700000102
is the phase synchronization error of the two radars.
The schematic diagram of the coherent parameter estimation process is shown in fig. 3, and can be obtained by defining coherent parameters:
Figure BDA0002979698700000103
Figure BDA0002979698700000104
Figure BDA0002979698700000105
Figure BDA0002979698700000106
when the system transmits the same waveform, the receiving end can still obtain the receiving coherent parameters, but can not obtain the transmitting coherent parameters again, so that the conversion relation between the transmitting coherent parameters and the receiving coherent parameters must be established, and the comparison between the transmitting coherent model of the movable platform and the receiving coherent model of the movable platform can obtain:
Figure BDA0002979698700000107
Figure BDA0002979698700000108
in one embodiment, according to the mobile platform transmitting coherent model and the mobile platform receiving coherent model, the method for establishing the mobile platform coherent calculation model comprises the following steps:
Figure BDA0002979698700000109
wherein the content of the first and second substances,
Figure BDA00029796987000001010
in the formula rl(n) is measured directly by radar.
In one embodiment, the transmit coherent parameter and r are knownl(N), l ═ 1,2, …, N, there being a linear coupling relationship, i.e. if possible according to rl(n) predicting rl(n +1) the transmit coherent parameter at time n +1 can be predicted.
According to the coupling relation among the transmitting coherent parameters, establishing the state vector of the transmitting coherent parameters as follows:
Figure BDA0002979698700000111
wherein R < n >]Represents a state vector, rl(n) represents an emission coherent parameter;
modeling the state vector using a Singer model as follows:
Figure BDA0002979698700000112
where alpha is the inverse of the maneuver-related time constant, i.e., the maneuver frequency,
Figure BDA0002979698700000113
is the acceleration variance of the maneuver object;
Figure BDA0002979698700000114
Figure BDA0002979698700000115
the state equation is established as follows:
R[n+1]＝Φ(T,α)R[n]+u[n]
Figure BDA0002979698700000116
Figure BDA0002979698700000117
the drive noise covariance is:
Figure BDA0002979698700000118
Figure BDA0002979698700000121
in one embodiment, based on the state equation, the observation equation is determined as:
z[n]＝HX[n]+v[n]
wherein, H ═ 100]，v[n]＝σ2，σ2Measuring noise for the radar;
according to the observation equation, determining a Kalman filtering equation as follows:
Figure BDA0002979698700000122
P[n|n-1]＝ΦP[n|n]ΦT+Q[n]
K[n]＝P[n|n-1]HT(HP[n|n-1]HT+R)-1
Figure BDA0002979698700000123
P[n|n]＝(I-K[n]H)P[n|n-1]
in one embodiment, according to the kalman filter equation, the sequence of the predicted transmission parameter corresponding to the transmission parameter is determined as follows:
Figure BDA0002979698700000124
obtaining coherent radar coherent parameters according to the predicted transmitting coherent parameter sequence and the motion platform coherent calculation model, wherein the coherent radar coherent parameters are as follows:
Figure BDA0002979698700000125
wherein the content of the first and second substances,
Figure BDA0002979698700000126
through the embodiment, the beneficial effects of the invention are as follows:
1. the method of the invention applies the Kalman prediction filter to the coherent synthesis of the moving platform distributed radar, solves the problem of coherent parameter cognition retardation under the condition, and overcomes the defect that the moving speed of a target needs to be known by a platform motion compensation-based method.
2. The motion modeling of the invention is based on the Singer model, considers the possibility of all maneuvers of the target, can be applied to various maneuvers and has wider application scenes.
3. The method has the characteristics of simplicity in implementation, good stability and universality and the like, and improves the real-time performance of the system by utilizing the characteristics of Kalman filtering and offline gain calculation.
The following description will be given with specific examples.
The present invention has been verified by simulation. The design simulation parameters are as follows:
Figure BDA0002979698700000131
the simulation scenario is shown in fig. 4: the target track is a section of high maneuvering turning, so that the performance of the algorithm for tracking the high maneuvering target is detected. The distance between every two radars is 5 m.
At the beginning stage, each radar transmits orthogonal signals, simultaneously, a Kalman filtering equation is established, filtering estimation is carried out on the distance, at the moment, because the signal energy is weak, the measurement error of the distance is large, the deviation can be seen to be large from the distance error value of the first 20s in the figure 5, at the state switching moment, each radar transmits the same signal, at the moment, the signal-to-noise ratio is improved, the target can be well tracked by utilizing a Kalman prediction filter based on a singer model, the maximum distance error of a target maneuvering section is 4m, the tracking result based on the Kalman prediction filter is shown in figure 6, and the target measurement deviation can be seen to be obviously increased in the maneuvering section. The effectiveness of the method is demonstrated. Fig. 7 and 8 are comparisons between predicted values and actual values of the transmission coherent parameters of the radar 2 and the radar 3, respectively, and it can be seen that the predicted values and the actual values are also very close after the state switching time.
It should be understood that, although the steps in the flowchart of fig. 1 are shown in order as indicated by the arrows, the steps are not necessarily performed in order as indicated by the arrows. The steps are not performed in a strict order unless explicitly stated herein, and may be performed in other orders. Moreover, at least a portion of the steps in fig. 1 may include multiple sub-steps or multiple stages that are not necessarily performed at the same time, but may be performed at different times, and the order of performance of the sub-steps or stages is not necessarily sequential, but may be performed in turn or alternately with other steps or at least a portion of the sub-steps or stages of other steps.
In one embodiment, as shown in fig. 9, there is provided a mobile platform distributed coherent radar coherent parameter acquisition system, including: a scene modeling module 902, a kalman filtering module 904, and a coherent parameter calculation module 906, wherein:
the scene modeling module 902 is used for modeling a detection scene of the distributed coherent radar of the mobile platform to obtain a mobile platform transmitting signal model, a mobile platform transmitting coherent model and a mobile platform receiving coherent model; the dynamic platform distributed coherent radar detection scene is composed of a plurality of independent motion platforms which are independent from each other; data are transmitted between the motion platforms through wireless links;
a kalman filtering module 904, configured to establish a coherent calculation model of the moving platform according to the coherent model transmitted by the moving platform and the coherent model received by the moving platform; establishing a state vector of the transmitting coherent parameters according to the coupling relation among the transmitting coherent parameters, and modeling the state vector by adopting a Singer model to obtain a state equation of the transmitting coherent parameters; determining an observation equation according to the state equation, and determining a Kalman filtering equation according to the observation equation;
and a coherent parameter calculation module 906, configured to determine a predicted transmission coherent parameter sequence corresponding to the transmission coherent parameter according to the kalman filter equation, and obtain a coherent parameter of the coherent radar according to the predicted transmission coherent parameter sequence and the motion platform coherent calculation model.
In one embodiment, the scene modeling module 902 is further configured to model a dynamic platform distributed coherent radar detection scene, and obtain a dynamic platform transmission signal model of an mth motion platform transmission signal as:
Figure BDA0002979698700000151
wherein, TpFor the transmit pulse width, u is the chirp rate, rect (t) is a rectangular function,
Figure BDA0002979698700000152
is a carrier wave, sm(t)＝exp(j2π(m-1)Δft)；
And m represents the serial number of the motion platform when the signal is transmitted, and l represents the serial number of the motion platform when the signal is received. The signal transmitted by the mth motion platform is:
Figure BDA0002979698700000153
in the formula kappamIndicating the synchronization error of the radar m compared to the reference clock,
Figure BDA0002979698700000154
is the initial phase of radar m.
In one embodiment, the scene modeling module 902 is further configured to represent the signal arriving at the target from the mth motion platform as:
Figure BDA0002979698700000155
wherein tau ismRepresenting the time delay, k, of arrival of the signal transmitted by the mth moving platformmFor synchronization errors of the radar compared to the reference clock,
Figure BDA0002979698700000156
synchronization error of the radar with respect to a reference phase;
the total signal arriving at the target is then:
Figure BDA0002979698700000157
setting the radar 1 as a reference radar, the adjusted transmission signals can be expressed as:
Figure BDA0002979698700000158
wherein
Figure BDA0002979698700000159
And
Figure BDA00029796987000001510
for transmitting the coherent parameters, the obtained dynamic platform transmitting coherent model is as follows:
Figure BDA00029796987000001511
Figure BDA00029796987000001512
in one embodiment, the scene modeling module 902 is further configured to, if the ith motion platform receives the target reflected echo, represent:
Figure BDA00029796987000001513
where p (t) is the echo signal at the target;
then all the radar received target echoes are superimposed as:
Figure BDA0002979698700000161
setting the radar 1 as a reference radar, the adjusted received signals are expressed as:
Figure BDA0002979698700000162
wherein the content of the first and second substances,
Figure BDA0002979698700000163
and
Figure BDA0002979698700000164
for receiving the coherent parameters, the obtained dynamic platform receiving coherent model is as follows:
Figure BDA0002979698700000165
Figure BDA0002979698700000166
in one embodiment, the kalman filtering module 904 is further configured to establish, according to the mobile platform transmission coherent model and the mobile platform reception coherent model, a mobile platform coherent computation model as follows:
Figure BDA0002979698700000167
wherein the content of the first and second substances,
Figure BDA0002979698700000168
in the formula rl(n) is measured directly by radar.
In one embodiment, the kalman filtering module 904 is further configured to establish, according to the coupling relationship between the transmission coherent parameters, a state vector of the transmission coherent parameters as follows:
Figure BDA0002979698700000169
wherein R < n >]Represents a state vector, rl(n) represents an emission coherent parameter;
modeling the state vector using a Singer model as follows:
Figure BDA00029796987000001610
where alpha is the inverse of the maneuver-related time constant, i.e., the maneuver frequency,
Figure BDA00029796987000001611
is the acceleration variance of the maneuver object;
Figure BDA00029796987000001612
Figure BDA00029796987000001613
the state equation is established as follows:
R[n+1]＝Φ(T,α)R[n]+u[n]
Figure BDA0002979698700000171
Figure BDA0002979698700000172
the drive noise covariance is:
Figure BDA0002979698700000173
Figure BDA0002979698700000174
in one embodiment, the kalman filtering module 904 is further configured to determine the observation equation as follows according to the state equation:
z[n]＝HX[n]+v[n]
wherein, H ═ 100]，v[n]＝σ2，σ2Measuring noise for the radar;
according to the observation equation, determining a Kalman filtering equation as follows:
Figure BDA0002979698700000175
P[n|n-1]＝ΦP[n|n]ΦT+Q[n]
K[n]＝P[n|n-1]HT(HP[n|n-1]HT+R)-1
Figure BDA0002979698700000181
P[n|n]＝(I-K[n]H)P[n|n-1]
in one embodiment, the coherent parameter calculation module 906 is further configured to determine, according to the kalman filter equation, that the predicted transmission coherent parameter sequence corresponding to the transmission coherent parameter is:
Figure BDA0002979698700000182
obtaining coherent radar coherent parameters according to the predicted transmitting coherent parameter sequence and the motion platform coherent calculation model, wherein the coherent radar coherent parameters are as follows:
Figure BDA0002979698700000183
wherein the content of the first and second substances,
Figure BDA0002979698700000184
for specific limitations of the coherent parameter acquisition system of the moving platform distributed coherent radar, reference may be made to the above limitations of the coherent parameter acquisition method of the moving platform distributed coherent radar, and details are not described herein again. All modules in the dynamic platform distributed coherent radar coherent parameter acquisition system can be completely or partially realized through software, hardware and a combination thereof. The modules can be embedded in a hardware form or independent from a processor in the computer device, and can also be stored in a memory in the computer device in a software form, so that the processor can call and execute operations corresponding to the modules.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by hardware instructions of a computer program, which can be stored in a non-volatile computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. Any reference to memory, storage, database, or other medium used in the embodiments provided herein may include non-volatile and/or volatile memory, among others. Non-volatile memory can include read-only memory (ROM), Programmable ROM (PROM), Electrically Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), Dynamic RAM (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDRSDRAM), Enhanced SDRAM (ESDRAM), Synchronous Link DRAM (SLDRAM), Rambus Direct RAM (RDRAM), direct bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).
The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent application shall be subject to the appended claims.

Claims (9)

1. A method for obtaining a coherent parameter of a distributed coherent radar of a moving platform is characterized by comprising the following steps:
modeling a detection scene of the distributed coherent radar of the moving platform to obtain a signal transmitting model of the moving platform, a coherent transmitting model of the moving platform and a coherent receiving model of the moving platform; the dynamic platform distributed coherent radar detection scene is composed of a plurality of independent motion platforms which are independent from each other; data are transmitted between the motion platforms through wireless links;
establishing a coherent calculation model of the moving platform according to the transmitting coherent model of the moving platform and the receiving coherent model of the moving platform;
establishing a state vector of the transmitting coherent parameters according to the coupling relation among the transmitting coherent parameters, and modeling the state vector by adopting a Singer model to obtain a state equation of the transmitting coherent parameters;
determining an observation equation according to the state equation, and determining a Kalman filtering equation according to the observation equation;
and determining a predicted transmission coherent parameter sequence corresponding to the transmission coherent parameter according to the Kalman filtering equation, and obtaining the coherent parameter of the coherent radar according to the predicted transmission coherent parameter sequence and the motion platform coherent calculation model.
2. The method of claim 1, wherein modeling the moving platform distributed coherent radar detection scenario to obtain a moving platform emission signal model comprises:
modeling a detection scene of the distributed coherent radar of the moving platform, wherein a moving platform transmitting signal model for obtaining an mth moving platform transmitting signal is as follows:
Figure FDA0002979698690000011
wherein, TpFor the transmit pulse width, u is the chirp rate, rect (t) is a rectangular function,
Figure FDA0002979698690000012
is a carrier wave, sm(t)＝exp(j2π(m-1)Δft)；
And m represents the serial number of the motion platform when the signal is transmitted, and l represents the serial number of the motion platform when the signal is received. The signal transmitted by the mth motion platform is:
Figure FDA0002979698690000013
in the formula kappamIndicating the synchronization error of the radar m compared to the reference clock,
Figure FDA0002979698690000021
is the initial phase of radar m.
3. The method of claim 2, wherein modeling the moving platform distributed coherent radar detection scenario to obtain a moving platform emission coherent model comprises:
the signal that the mth motion platform transmits reaches the target is expressed as:
Figure FDA0002979698690000022
wherein tau ismRepresenting the time delay, k, of arrival of the signal transmitted by the mth moving platformmFor synchronization errors of the radar compared to the reference clock,
Figure FDA0002979698690000023
synchronization error of the radar with respect to a reference phase;
the total signal arriving at the target is then:
Figure FDA0002979698690000024
setting the radar 1 as a reference radar, the adjusted transmission signals can be expressed as:
Figure FDA0002979698690000025
wherein
Figure FDA0002979698690000026
And
Figure FDA0002979698690000027
for transmitting the coherent parameters, the obtained dynamic platform transmitting coherent model is as follows:
Figure FDA0002979698690000028
Figure FDA0002979698690000029
4. the method of claim 3, wherein modeling the moving platform distributed coherent radar detection scenario to obtain a moving platform receive coherent model comprises:
if the target reflection echo received by the ith motion platform is represented as:
Figure FDA00029796986900000210
where p (t) is the echo signal at the target;
then all the radar received target echoes are superimposed as:
Figure FDA00029796986900000211
setting the radar 1 as a reference radar, the adjusted received signals are expressed as:
Figure FDA00029796986900000212
wherein the content of the first and second substances,
Figure FDA00029796986900000213
and
Figure FDA00029796986900000214
for receiving the coherent parameters, the obtained dynamic platform receiving coherent model is as follows:
Figure FDA00029796986900000215
Figure FDA00029796986900000216
5. the method of any one of claims 1 to 4, wherein building a coherent calculation model of the moving platform based on the transmitted coherent model of the moving platform and the received coherent model of the moving platform comprises:
according to the mobile platform transmitting coherent model and the mobile platform receiving coherent model, establishing a mobile platform coherent calculation model as follows:
Figure FDA0002979698690000031
wherein the content of the first and second substances,
Figure FDA0002979698690000032
in the formula rl(n) is measured directly by radar.
6. The method as claimed in any one of claims 1 to 4, wherein the establishing a state vector of the transmission coherent parameters according to the coupling relationship between the transmission coherent parameters, and modeling the state vector by using a Singer model to obtain a state equation of the transmission coherent parameters comprises:
according to the coupling relation among the transmitting coherent parameters, establishing the state vector of the transmitting coherent parameters as follows:
Figure FDA0002979698690000037
wherein R < n >]Represents a state vector, rl(n) represents an emission coherent parameter;
modeling the state vector using a Singer model as follows:
Figure FDA0002979698690000033
where alpha is the inverse of the maneuver-related time constant, i.e., the maneuver frequency,
Figure FDA0002979698690000034
is the acceleration variance of the maneuver object;
Figure FDA0002979698690000035
Figure FDA0002979698690000036
the state equation is established as follows:
R[n+1]＝Φ(T,α)R[n]+u[n]
Figure FDA0002979698690000041
Figure FDA0002979698690000042
the drive noise covariance is:
Figure FDA0002979698690000043
Figure FDA0002979698690000044
7. the method of claim 6, wherein determining an observation equation from the state equation and determining a Kalman filter equation from the observation equation comprises:
according to the state equation, determining an observation equation as follows:
z[n]＝HX[n]+v[n]
wherein, H ═ 100]，v[n]＝σ2，σ2Measuring noise for the radar;
according to the observation equation, determining a Kalman filtering equation as follows:
Figure FDA0002979698690000045
P[n|n-1]＝ΦP[n|n]ΦT+Q[n]
K[n]＝P[n|n-1]HT(HP[n|n-1]HT+R)-1
Figure FDA0002979698690000051
P[n|n]＝(I-K[n]H)P[n|n-1]
8. the method of claim 7, wherein determining a predicted transmit coherent parameter sequence corresponding to a transmit coherent parameter according to the Kalman filtering equation, and obtaining a coherent radar coherent parameter according to the predicted transmit coherent parameter sequence and the motion platform coherent calculation model, comprises:
according to the Kalman filtering equation, determining a predicted transmission phase parameter sequence corresponding to the transmission phase parameter as follows:
Figure FDA0002979698690000052
obtaining coherent radar coherent parameters according to the predicted transmitting coherent parameter sequence and the motion platform coherent calculation model, wherein the coherent radar coherent parameters are as follows:
Figure FDA0002979698690000053
wherein the content of the first and second substances,
Figure FDA0002979698690000054
9. a coherent parameter acquisition system for a distributed coherent radar of a mobile platform is characterized by comprising:
the scene modeling module is used for modeling a detection scene of the distributed coherent radar of the moving platform to obtain a signal transmitting model of the moving platform, a coherent transmitting model of the moving platform and a coherent receiving model of the moving platform; the dynamic platform distributed coherent radar detection scene is composed of a plurality of independent motion platforms which are independent from each other; data are transmitted between the motion platforms through wireless links;
the Kalman filtering module is used for establishing a coherent calculation model of the moving platform according to the transmitting coherent model of the moving platform and the receiving coherent model of the moving platform; establishing a state vector of the transmitting coherent parameters according to the coupling relation among the transmitting coherent parameters, and modeling the state vector by adopting a Singer model to obtain a state equation of the transmitting coherent parameters; determining an observation equation according to the state equation, and determining a Kalman filtering equation according to the observation equation;
and the coherent parameter calculation module is used for determining a predicted transmission coherent parameter sequence corresponding to the transmission coherent parameter according to the Kalman filtering equation and obtaining the coherent parameter of the coherent radar according to the predicted transmission coherent parameter sequence and the motion platform coherent calculation model.
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