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CN114814748B - A high-precision satellite target radar echo signal generation method based on STK - Google Patents

A high-precision satellite target radar echo signal generation method based on STK Download PDF

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CN114814748B
CN114814748B CN202210280976.3A CN202210280976A CN114814748B CN 114814748 B CN114814748 B CN 114814748B CN 202210280976 A CN202210280976 A CN 202210280976A CN 114814748 B CN114814748 B CN 114814748B
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radar
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stk
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CN114814748A (en
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陈秀玲
夏双志
耿虎军
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CETC 54 Research Institute
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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
    • G01S7/40—Means for monitoring or calibrating
    • G01S7/4052—Means for monitoring or calibrating by simulation of echoes
    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2111/00—Details relating to CAD techniques
    • G06F2111/04—Constraint-based CAD

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Abstract

本发明公开了一种基于STK的高精度卫星目标雷达回波信号生成方法，主要解决太空目标探测场景的目标回波信号高精度仿真问题。实现过程：1、搭建仿真场景；2、确定卫星对发射雷达和接收雷达均可见的若干个卫星可见时段；3、确定有效回波信号的接收时段和发射时段；4、确定收到有效回波信号的采样时刻序列；5、获取在有效回波信号的发射时段内所有时刻的卫星位置数据；6、计算发射时刻和目标时刻；7、计算信号的有效回波信号；8、仿真接收信号中的噪声部分；9、得到雷达回波信号的仿真结果；本发明借助STK对太空目标探测场景的精确还原和所提供的高精度卫星位置数据，设计出适合于实际工程需要的雷达回波信号数据生成方法。

The present invention discloses a high-precision satellite target radar echo signal generation method based on STK, which mainly solves the problem of high-precision simulation of target echo signals in space target detection scenarios. Implementation process: 1. Build a simulation scenario; 2. Determine several satellite visible time periods in which the satellite is visible to both the transmitting radar and the receiving radar; 3. Determine the receiving time period and the transmitting time period of the effective echo signal; 4. Determine the sampling time sequence of the received effective echo signal; 5. Obtain the satellite position data at all times within the transmitting time period of the effective echo signal; 6. Calculate the transmitting time and the target time; 7. Calculate the effective echo signal of the signal; 8. Simulate the noise part in the received signal; 9. Obtain the simulation result of the radar echo signal; The present invention uses STK to accurately restore the space target detection scenario and the high-precision satellite position data provided to design a radar echo signal data generation method suitable for actual engineering needs.

Description

STK-based high-precision satellite target radar echo signal generation method
Technical Field
The invention relates to a method for generating radar echo signals of high-precision satellite targets based on STK, which is particularly suitable for target echo signal simulation of space target detection scenes.
Background
The existing radar echo signal generation method is mostly used for generating time-varying position data based on set target track parameters and is suitable for low-altitude slow-speed flight scenes. For satellite detection scenarios, such methods have significant limitations in terms of their application to echo data generation, data processing, and in terms of radar system planning and design guidance: 1) The scene scale is small, and the influence of factors such as earth curvature, atmospheric perturbation, orbit decay generated by a resistance model and the like on a received signal is generally not considered; 2) The difficulty in acquiring the mathematical closed expression of the irregular elliptical orbit of the satellite motion track is high, and approximate processing is generally needed, so that the simulation precision is affected. Therefore, the method cannot be well used for solving the problem of radar echo signal generation of a high-precision satellite target.
Disclosure of Invention
The invention aims to avoid the defects in the background art and provide a method for generating radar echo signals of a high-precision satellite target based on STK. The invention fully considers the feasibility of radar echo signal generation of the high-precision satellite target, and can adapt to the actual engineering requirement of echo data generation under the space target detection scene by means of accurate restoration of the space target detection scene by the STK and the provided high-precision satellite position data.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
A method for generating a high-precision satellite target radar echo signal based on STK comprises the following steps:
Firstly, calculating a time interval delta t STK of STK feedback satellite position data according to the phase precision requirement of an echo signal, then building an STK simulation scene containing all transmitting radars, receiving radars and satellites to be observed in the STK, and setting the time interval delta t STK of the feedback satellite position data in the STK simulation scene;
step two, for any echo signal transmission path, determining a plurality of satellite visible time periods visible to both transmitting radars and receiving radars according to the STK and the signal transmission model;
Step three, respectively calculating the distance from the satellite to the transmitting radar and the receiving radar for the starting time and the ending time of each satellite visible time period, dividing the distance by the speed of light to obtain the transmitting transmission time delay and the receiving transmission time delay, and determining the receiving time period of the effective echo signal And emission period
Step four, according to the sequence of the sampling time of the receiving radarAnd a reception period of the effective echo signalIntersection of the two is obtainedIs a subset of (a)I.e. the sequence of sampling instants at which the active echo signal is received,At the position ofComplement of (a)I.e. a sequence of received sample moments at which no valid echo signal is received,At the same time isIs a subset of (a);
Step five, acquiring the transmitting time period of the effective echo signal through the STK Satellite position data at all times inWherein, AndIs an integer multiple of Δt STK;
step six, according to the step five Satellite position data withinFor a pair ofThe reception sampling time of any effective echo signalCalculating the emission time one by linear interpolationAnd the target time
Seventh step of aligning one by oneIn (a) reception sampling instantCalculating the effective echo signal of the signal ifOrder of principleBy means ofCorresponding emission timeAnd the target timeCalculation ofEffective echo signal at moment of timeIf it isEffective echo signal
Step eight, sampling time sequences at the receiving end according to the received noise powerAt any time of (a)Simulating noise portions in a received signal
Step nine, one by one pairIn the reception sampling timeIs effective in echo signalsAnd noise signalAnd summing to obtain a simulation result of the radar echo signals.
Further, in the first step, the STK simulation scenario specifically includes:
Determining basic parameters of a radar echo signal generating system of a high-precision satellite target based on STK, wherein the system comprises M transmitting radars, N receiving radars on the ground and S satellites to be observed in space, and ECEF coordinates of all transmitting radars and receiving radars and the orbit number of the satellites to be observed are known; defining a global coordinate system of the system as an ECEF coordinate system, defining a local coordinate system of a transmitting radar and a receiving radar, and assuming that the positions, the postures and the directivities of signal radiation of the transmitting radar and the receiving radar are kept constant; forming an echo signal transmission path for the signal transmission process among any transmitting radar, any satellite to be observed and any receiving radar; it is assumed that the RCS of all satellites is constant and known in the time and angle domains.
Further, the constraint condition of the time interval Δt STK of the STK feedback satellite position data in the first step is:
Wherein R e is the earth radius, M e is the earth mass, G is the gravitational constant, w e is the earth rotation angular rate, H tar,min is the minimum orbit height of the satellite to be observed, f c is the signal frequency, and c is the speed of light.
Further, the signal transmission model in the second step is as follows:
The transmitted signal is denoted S tr(t)＝B(t)exp(jη)·exp(j2πfc t), B (t) is the baseband signal, η is the initial phase of the transmitted signal; transmitting radar at transmitting time The transmitted signal is propagated in free space and then at the target timeReaching the satellite to be observed, the signal is scattered by the satellite, and is transmitted in free space and then is received at the momentArrival receiving radar, receiving radar is inThe signal from the target received at the moment is obtained after down-conversionThe method comprises the following steps:
wherein, Is the power of the baseband signal and,Is a normalized baseband signal, λ=c/f c is the signal wavelength; In order to transmit the antenna gain term, AndRespectively shown inAzimuth and pitch angles of the satellite target position in the local coordinate system of the transmitting radar,In order to receive the antenna gain term,AndRespectively shown inThe satellite target position at the moment is receiving the azimuth and pitch angles of the radar local coordinate system,AndRespectively areThe transmission path length from the time satellite to the transmitting radar and the receiving radar, σ, is the RCS of the satellite to be observed.
Further, in the second step, the satellite has a plurality of visible periods for both transmitting radar and receiving radar:
The visible time periods of the STK simulation scene output satellite to the transmitting radar and the receiving radar are respectively recorded as AndWherein I tr is the number of periods of satellite versus transmitted radar visibility,Is the visible period of the ith tr time-continuous satellite for transmitting radar, and the starting time isThe termination time isI re is the number of periods of visibility of the satellite to the receiving radar,Is the visible period of the receiving radar of the ith re time-continuous satellite, and the starting time isThe termination time is
Several periods of satellite visibility for which the satellites are visible to both transmitting and receiving radars are noted: Wherein I vs is the number of periods of time that the satellite is visible to both transmitting radar and receiving radar, and I vs is the number of any one of the periods of time.
Further, the third step is specifically:
re-recording several satellite visibility periods t vs as For the followingEach of the successive time periods ofAcquisition with STKDistance of time satellite in transmitting radar local coordinate systemAndAnd calculates the target timeCorresponding emission time
Thereby, it is obtainedIs thatThe corresponding signal transmission period, namely the transmission period of the effective echo signal; wherein,
Distance data of satellite in receiving radar local coordinate system obtained by STKAndCalculating a target timeCorresponding time of reception
Thereby, it is obtainedIs thatCorresponding signal receiving time periods, namely receiving time periods of effective echo signals; wherein the method comprises the steps of
Further, the fourth step is specifically:
Defining the sampling sequence number of the receiving end as a set N S＝{n|0≤n≤Nsample -1, and then recording the sampling time sequence of the receiving end as Wherein N sample is the total sampling point number of the receiving end;
Will be And (3) withIs defined by the respective subsets of (a)Respectively solving intersections to respectively obtain a set of receiving sampling moments of the ith vs visible time periodUnion of these setsIs a sequence of receiving sampling time corresponding to all visible time periods, and a sequence of receiving sampling time without receiving effective echo signalsAnd is present inIs a mathematical relationship of (a).
Thus, the method for generating the radar echo signal of the high-precision satellite target based on the STK is completed.
Compared with the background technology, the invention has the following beneficial effects:
The invention comprehensively considers the satellite position precision and signal phase precision requirements of radar echo signal generation, and designs a radar echo signal data generation method of a high-precision satellite target suitable for actual engineering requirements by means of accurate restoration of a space target detection scene by STK and provided high-precision satellite position data.
The satellite position accuracy is high, the STK platform is used for acquiring high-accuracy target position data, the highest accuracy can be up to 10 -9 m, and the accuracy of simulation data is greatly improved;
The invention has high simulation phase precision of the echo signals, carries out quantitative analysis on the mathematical relationship between the phase error of the effective echo signal simulation and the system parameters and the STK data parameters, and provides definite constraint conditions for the STK data parameters under the condition of setting the phase precision;
The invention has wide applicability and engineering realizability, and the STK software has better interaction characteristics and can be suitable for different programming platforms.
Drawings
Fig. 1 is a flow chart of the present invention.
Fig. 2 is a schematic diagram of a scenario in which the ground station-satellite single-pass path length estimation error is maximum.
Detailed Description
The invention is further described below with reference to the drawings and detailed description.
Referring to fig. 1 and 2, the generation of echo signals of a single satellite by a single-shot single-receiver radar system is accomplished as follows.
Firstly, calculating a time interval delta t STK of STK feedback satellite position data according to the phase precision requirement of an echo signal, then building an STK simulation scene containing a transmitting radar, a receiving radar and a satellite to be observed in the STK, and setting the time interval delta t STK of the feedback satellite position data in the STK simulation scene.
First, basic parameters of a STK-based radar return signal generation system for high-precision satellite targets are determined. The earth mass M e, the earth radius R e, and the gravitational constant G are known. The definition system is provided with a transmitting radar and a receiving radar, and the heights of the transmitting radar and the receiving radar from the ground are 0. The object to be observed is a satellite object. The orbit height range of the satellite is H tar∈[Htar,min,Htar,max, and the orbit radius of the satellite is designated as R tar＝Re+Htar.
The global coordinate system of the system is defined as ECEF coordinate system (Earth's Fixed coordinate system, earth-Centered, earth Fixed). A local coordinate system of the transmitting radar and the receiving radar is defined, and it is assumed that the positions, attitudes, and directivities of signal radiation of the transmitting radar and the receiving radar are all kept constant, that is: in the global coordinate system, the origin of the local coordinate system of the transmitting radar and the receiving radar and the global coordinates of the coordinate axes are constant. Wherein the global coordinates of the transmitting radar areGlobal coordinates of the receiving radar areGlobal coordinates of satellite at arbitrary time tWill follow its rotation around the earth and its true value can be determined by means of the number of tracks, etc., in the present methodIs provided by the STK software. The RCS of the satellite is σ in the time domain and in each observation azimuth and pitch angle.
Secondly, determining the transmission parameters, the receiving parameters and the simulation precision requirements of the received signals:
1) Transmitting a signal:
the baseband signal transmitted by the transmitting radar is recorded as Where S B (t) is the normalized baseband signal and P tr (t) is the power of the transmit signal. Carrier frequency f c, primary phase η. The transmitted signal of the transmitting radar is written as:
Str(t)＝B(t)exp(jη)·exp(j2πfct) (1)
2) Receiving a signal:
The transmitted signal is received and reflected by the satellite through free space transmission, and reaches the receiving radar after being propagated again through free space, and the received continuous signal is denoted as S rx,pre (t). Down-converting the signal to obtain S rx (T), sampling according to sampling frequency F s (sampling period T s＝1/Fs), and receiving a signal sequence S re [ n ]:
The effective echo signal and noise signal in S re [ n ] are denoted as S rx(nTs) and S N(nTs), respectively.
Wherein, Is an estimate of S re n,Is an estimate of S rx(nTs). N sample is the total number of samples taken from the radar.
The boltzmann constant k, the system noise temperature T system, and the loop bandwidth B system are defined.
3) Simulation accuracy requirement of received signal
Defining the system precision: requiring an estimate of the effective echo signal during an observation periodThe phase error with its true value S rx(nTs) does not exceed Deltapsi e, the delay error does not exceedTotal path length of transmitting and receiving the estimation error is not more thanC is the speed of light.
Again, determining the phase accuracy of the echo signal requires calculating the time interval Δt STK for the STK to feed back satellite position data.
STKs are capable of providing two types of typical satellite data:
Class I data: the period of visibility of the satellite to the radar.
The method comprises the steps of setting visibility constraint conditions of a transmitting radar and a receiving radar, wherein the STK can provide a visible time period of the satellite for the transmitting radar and the receiving radar respectively, and polar coordinates (alpha tr,βtr,Ltr) of the satellite in a local coordinate system of the transmitting radar in the time period, and the meanings of the polar coordinates are azimuth angle, pitch angle and distance of the satellite in the local coordinate system of the transmitting radar respectively. The polar coordinates (α re,βre,Lre) of the satellite in the local coordinate system of the receiving radar are also obtained.
Class II data: global coordinates of the satellites.
Because of the influence of non-spherical gravitational perturbation, atmospheric resistance perturbation and the like, the actual motion trail of the satellite is not a regular ellipse, and it is difficult to obtain a closed solution taking time as an independent variable and a satellite position function in a global coordinate system. The STK has high accuracy of the two types of position data and can provide global coordinates and local coordinates of satellites. But both types of data are "discrete in time intervals" rather than continuous in time. Where "discrete time intervals" means position data of adjacent time instants provided by the STK, the time interval Δt STK is constant and can be set as desired. In version STK11.2, the lowest value of the time interval is Δt STK＝10-5 s. The situation where the single-pass path length estimation error of the earth station-satellite is maximum when estimating satellite position using linear interpolation is shown in fig. 2. In fig. 2, a 1-earth 2-satellite orbit 3-ground station 4-interpolation method start time satellite position 5-interpolation method end time satellite position 6-interpolation method calculates an intermediate time satellite position 7-intermediate time satellite actual position, and the satellite is at the zenith of the ground station; the orbital plane of the satellite is coplanar with the equatorial plane of the earth and the site is located at the equator. The satellites and any point on the equator rotate in longitudinal directions but in opposite directions. At this time, the angular velocity of the satellite relative to the radar station is the largest, and the path estimation error is the largest with the same Δt STK.
By STK, global coordinates of satellites at two moments t b and t d separated by Deltat STK are accurately obtainedAndAt an intermediate timeThe true value of the global coordinates of the satellite isThe earth center, the ground station and the satellite are just three points collinear. The estimated value of the global coordinate of the satellite at the time t m isCalculating a true path length and an estimated path length in the scene:
Ltar＝Htar (4)
Where L tar is the true path length of the satellite to the ground station at time t m, Is the estimated satellite-to-ground station path length at time t m using a linear interpolation function. w e is the angular velocity of the earth rotation, w tar is the angular velocity of the satellite rotation around the earth, and there is the following relationship:
thus, there is an upper bound on transmit or receive path estimation error:
The total path estimation error of transmission and reception is bounded:
to the right of the inequality is a monotonically increasing function of Δt STK.
The system accuracy requirement Δl t.r≤ΔLe meets the requirement if the upper bound of Δl t.r is lower than Δl e:
By deduction, it is possible to obtain:
The right side of the inequality sign of equation (10) is a monotonically increasing function of R tar.
If the eccentricity of the satellite orbit is large, resulting in a large range of satellite-to-earth distance variation, the minimum value of Δl t.r occurs when the satellite-to-earth distance is minimal, and the above equation is modified as:
to this end, an upper bound is determined for the space between the STK and the two data types The time interval Deltat STK should not exceed when the STK data is acquired
In this embodiment, the requirement Δψ e is not higher than 0.5 degree, under different track height and operating frequency combinations, can be calculated according to equation (11)As shown in table 1:
TABLE 1
It can be seen that the minimum time interval requirement for the STK position data is far greater than the minimum time interval of 10 -5 s for the STK software settable position data in any combination, and is not lower than the STK default configuration value of 10 -3 s, which indicates that the embodiment has wide applicability.
Finally, setting up an STK simulation scene containing a transmitting radar, a receiving radar and a satellite to be observed in STK software according to the first step, and setting the time interval of STK feedback satellite position data to be delta t STK.
And step two, for the echo signal transmission path, determining a plurality of satellite visible time periods visible to both the transmitting radar and the receiving radar according to the STK and the signal transmission model.
First, a constructed signal transmission model is determined, and a mathematical expression of the received signal is determined. For any echo signal transmission path, the model mainly comprises: the method comprises the steps of transmitting radar transmitting signals, enabling the signals to reach satellites to be observed in the path after free space propagation, enabling the signals to be scattered by the satellites, and enabling the signals to reach receiving radars after free space propagation.
According to step one, the transmitted signal is denoted S tr(t)＝B(t)exp(jη)·exp(j2πfc t).
The process of transmitting a transmitted signal from a transmitting radar to a satellite target:
1) At the position of Time of day, transmit signal
2) The signal is transmitted in space;
3) At the position of At the moment the signal arrives at the satellite, recorded asAnd is called asThe "satellite time".
The transmission path length in this process is the transmission of radar toThe distance of the position of the target at the moment, i.eThus, the transmission delays are:
wherein, under the condition of determining the transmitting radar position and the satellite motion trail, one is given to the target moment Corresponding to a unique emission time
Comparing signalsAndThe normalized waveforms of the peak power of the two are the same, but the peak power of the two is different. Based on this, the first and second light sources,Can be expressed as
Wherein, Representation ofTime signal power, particularly expressed as
In the formula,In order to transmit the antenna gain term,AndRespectively represent the targetsAzimuth and pitch angles of the moment position in the local coordinate system of the transmitting radar.
Based on the analysis, the satellite is inTime of day received from transmitting radar is expressed as
The process of signal transmission from satellite to receiving radar:
1) At the position of At the moment, the signal received by the satellite from the transmitting radar is
2) The signal is transmitted in space;
3) At the position of At the moment, the signal arrives at the receiving radar and is received, recorded as
The transmission path length in this process is the reception radar toThe distance of the position of the target at the moment, i.eThe transmission delay of this procedure is then
Accordingly have
Wherein, under the condition of determining the coordinates of the receiving radar and the motion trail of the target, the moment when one signal reaches the receiving radar is givenCorresponding to the unique satellite received signal time
Comparing signalsAndThe peak normalized waveforms are the same, but the peak powers of the two are different. Based on this, the first and second light sources,Can be expressed as
Wherein, Is a signalAnd (3) withThe value of which is determined by the radar equation.
According to the radar equation,Can be expressed as
Wherein, In order to receive the antenna gain term,AndRespectively represent satellitesThe coordinate position of the moment is in the azimuth angle and the pitch angle of the local coordinate system of the receiving radar.
By combining the analysis, the radar is receivedTime-of-day received signal from targetIs that
Wherein,
Combining (15) (20) (21) and forThe down-conversion process is carried out so as to obtain a frequency-converted signal,The effective echo signals at the moment are:
then, several satellite visibility periods are obtained from the STK simulation scene, in which the satellites are visible to both the transmitting radar and the receiving radar.
The visible time periods of the STK simulation scene output satellite to the transmitting radar and the receiving radar are respectively recorded asAndWherein I tr is the number of periods of satellite versus transmitted radar visibility,Is the visible period of the ith tr time-continuous satellite for transmitting radar, and the starting time isThe termination time isI re is the number of periods of visibility of the satellite to the receiving radar,Is the visible period of the receiving radar of the ith re time-continuous satellite, and the starting time isThe termination time is
Several periods of satellite visibility for which the satellites are visible to both transmitting and receiving radars are noted: Wherein I vs is the number of periods of time that the satellite is visible to both transmitting radar and receiving radar, and I vs is the number of any one of the periods of time.
Step three, respectively calculating the distance from the satellite to the transmitting radar and the receiving radar for the starting time and the ending time of each satellite visible time period, dividing the distance by the speed of light to obtain the transmitting transmission time delay and the receiving transmission time delay, and determining the receiving time period of the effective echo signalAnd emission period
Re-recording several satellite visibility periods t vs asFor the followingEach of the successive time periods ofAcquisition with STKDistance of time satellite in transmitting radar local coordinate systemAndAnd calculates the target timeCorresponding emission time
Thereby, it is obtainedIs thatThe corresponding signal transmission period, namely the transmission period of the effective echo signal; wherein,
Distance data of satellite in receiving radar local coordinate system obtained by STKAndCalculating a target timeCorresponding time of reception
Thereby, it is obtainedIs thatCorresponding signal receiving time periods, namely receiving time periods of effective echo signals; wherein the method comprises the steps of
Step four, according to the sequence of sampling time of receiving endAnd a reception period of the effective echo signalDetermining a sequence of sampling instants at which valid echo signals are receivedAnd a received sampling time sequence without receiving a valid echo signal
Defining the sampling sequence number of the receiving end as a set N S＝{n|0≤n≤Nsample -1, and then recording the set of the sampling time of the receiving end as
Will beAnd (3) withIs defined by the respective subsets of (a)Respectively solving intersections to respectively obtain a set of receiving sampling moments in the ith vs visible time periodTheir unionIs the set of all overall visible received sampling instants. The set of received sampling moments when no valid echo signal is received is recorded asAnd is present inIs a mathematical relationship of (a).
Step five, acquiring the transmitting time period of the effective echo signal through the STKSatellite position data at all times inWherein, AndIs an integer multiple of Δt STK.
Step six, in all satellite visible time periods, according to the step fiveSatellite position data withinFor a pair ofThe receiving sampling time of any effective echo signal in the above-mentioned two-dimensional data is used for calculating transmitting time and target time one by means of linear interpolation method.
Specifically, toIs a subset of (a)The elements thereof are obtained according to the following method, namely the sampling momentCorresponding transmitting timeAnd satellite time of dayThe main process comprises the following steps:
1) The construction function:
For any sampling instant t 3, its corresponding target instant t=t 2 must satisfy f (t 2) =0. In the neighborhood near t=t 2, f (t) is a monotonically increasing function, and satellite time of each sampling point under the accuracy constraint condition can be estimated by using a dichotomy method by utilizing monotonicity of the function.
Since L re (t) cannot be accurately obtained, the subsequent calculation is carried out byInstead of this, the first and second heat exchangers,Is a high-precision estimate of L re (t) obtained by combining the STK data and using a linear interpolation function.
2) Interpolation calculates transmit and receive path lengths:
the satellite in-process can be obtained through the fifth step Global coordinates within. Calculating satellite global coordinates at any time t arb requires the use of interpolation:
First, two nearest STK moments at t arb are determined:
next, the STK is obtained Global satellite coordinates of the two momentsAnd
Then, an estimated value of global coordinates of the satellite at time t arb is obtained using a linear interpolation function:
Finally, calculating the estimated path length from the satellite at time t arb to the transmitting radar and the receiving radar:
3) Calculation of Corresponding toAnd
AndThere is the relationship:
(a) Setting time Eta takes a positive real number, f (t a) is calculated, and eta is adjusted to ensure that f (t a) is less than 0; setting timeCalculating f (t b), and f (t b) > 0;
(b) If t b-ta＜2Δte, output AndOtherwise, performing (c);
(c) Calculation of Time of dayIf it isThen update t b＝ttemp ifThen t a＝ttemp is updated and (b) is returned.
Thus far, getCorresponding toAndAnd calculate to obtain
4) Calculation ofCorresponding toAnd
AndThere is the relationship:
(a) Setting time Calculating f (t a) and ensuring that f (t a) < 0; setting timeCalculating f (t b), and f (t b) > 0;
(b) If t b-ta＜2Δte, output AndOtherwise, performing (c);
(c) Calculation of Time of dayIf it isThen update t b＝ttemp ifThen t a＝ttemp is updated and (b) is returned.
Thus far, getCorresponding toAndAnd calculate to obtain
Seventh step of aligning one by oneIn (a) reception sampling instantCalculating the effective echo signal of the signal ifOrder of principleBy means ofCorresponding emission timeAnd the target timeCalculation ofEffective echo signal at moment of timeIf it isEffective echo signal
Specifically, forIs a subset of (a)Calculating any sampling time in the sampling timeEffective echo signal in received signalAmplitude and phase of (a):
Will be Carrying-in formula (22), obtaining:
Step eight, sampling time sequences at the receiving end according to the received noise power At any time of (a)Simulating noise portions in a received signal
Noise power of the receiving radar of the computing system:
Pn＝k·Tsystem·Bsystem (40)
any time of (a) Is subjected to both real and imaginary partsIs obtained by generating a pseudo random number:
wherein, Is the real part of the noise signal,Is the imaginary part of the noise signal.
Step nine, one by one pairIn the reception sampling timeIs effective in echo signalsAnd noise signalAnd summing to obtain a simulation result of the radar echo signals.
Thus, the method for generating the high-precision satellite target radar echo signal based on the STK is completed.

Claims (4)

1.一种基于STK的高精度卫星目标雷达回波信号生成方法，其特征在于，包括以下步骤：1. A method for generating high-precision satellite target radar echo signals based on STK, characterized in that it comprises the following steps: 步骤一、根据回波信号的相位精度要求计算STK反馈卫星位置数据的时间间隔ΔtSTK，然后在STK中搭建含有所有发射雷达、接收雷达和待观测卫星的STK仿真场景，并将STK仿真场景中的反馈卫星位置数据的时间间隔设定为ΔtSTK；Step 1: Calculate the time interval Δt STK for STK to feedback satellite position data according to the phase accuracy requirement of the echo signal, then build a STK simulation scene containing all transmitting radars, receiving radars and satellites to be observed in STK, and set the time interval for feedback satellite position data in the STK simulation scene to Δt STK ; 步骤二、对任一回波信号传输路径，根据STK和信号传输模型，确定卫星对发射雷达和接收雷达均可见的若干个卫星可见时段；Step 2: for any echo signal transmission path, according to STK and the signal transmission model, determine several satellite visible periods during which the satellite is visible to both the transmitting radar and the receiving radar; 步骤三、分别对每一个卫星可见时段的起始和终止时刻，计算卫星到发射雷达和接收雷达的距离，除以光速得到发射传输时延和接收传输时延，并确定有效回波信号的接收时段和发射时段 Step 3: Calculate the distance from the satellite to the transmitting radar and the receiving radar for the start and end time of each satellite visible period, divide it by the speed of light to get the transmission delay and the receiving delay, and determine the receiving period of the effective echo signal. and launch period 步骤四、根据接收雷达采样时刻的序列和有效回波信号的接收时段两者求交集得到的子集即收到有效回波信号的采样时刻序列，在TNS中的补集即未收到有效回波信号的接收采样时刻序列，同时是的子集；Step 4: According to the sequence of receiving radar sampling time and the receiving period of effective echo signal The intersection of the two is Subset of That is, the sampling time sequence of the effective echo signal received, Complement in T NS That is, the receiving sampling time sequence in which no valid echo signal is received. At the same time A subset of 步骤五、通过STK获取在有效回波信号的发射时段内所有时刻的卫星位置数据其中，并且是ΔtSTK的整数倍；Step 5: Obtain the transmission period of the effective echo signal through STK Satellite position data at all times in, and is an integer multiple of Δt STK ; 步骤六、根据步骤五所获取的内的卫星位置数据对中的任一有效回波信号的接收采样时刻通过线性内插法逐一计算发射时刻和目标时刻 Step 6: Based on the data obtained in step 5 Satellite location data within right The receiving sampling time of any valid echo signal in The emission times are calculated one by one by linear interpolation and target time 步骤七、逐一对中的接收采样时刻计算信号的有效回波信号，若则令利用对应的发射时刻和目标时刻计算时刻的有效回波信号若有效回波信号 Step 7: One by one The receiving sampling time in Calculate the effective echo signal of the signal, if Then use The corresponding launch time and target time calculate The effective echo signal at the time like Valid echo signal 步骤八、根据接收噪声功率，在接收端采样时刻序列的任一时刻仿真接收信号中的噪声部分 Step 8: According to the received noise power, the sampling time sequence is At any time Simulating the Noise Portion of a Received Signal 步骤九、逐一对内的接收采样时刻的有效回波信号与噪声信号求和，得到雷达回波信号的仿真结果；Step 9: One by one The receiving sampling time within The effective echo signal Signal with noise Add up and get the simulation result of radar echo signal; 其中，步骤一中STK仿真场景具体为：The STK simulation scenario in step 1 is as follows: 确定基于STK的高精度卫星目标的雷达回波信号生成系统的基本参数，系统包括地面上M台发射雷达、N台接收雷达以及太空中S颗待观测卫星，所有发射雷达和接收雷达的ECEF坐标以及待观测卫星的轨道根数均已知；定义系统的全局坐标系为ECEF坐标系，定义发射雷达和接收雷达的局部坐标系，并且假定发射雷达和接收雷达的位置、姿态和信号辐射的方向性均保持恒定；对于任一发射雷达、任一待观测卫星和任一接收雷达三者间的信号传输过程构成一条回波信号传输路径；假定所有卫星的RCS在时域和角度域恒定且已知；Determine the basic parameters of the radar echo signal generation system of high-precision satellite targets based on STK. The system includes M transmitting radars on the ground, N receiving radars and S satellites to be observed in space. The ECEF coordinates of all transmitting radars and receiving radars and the orbital elements of the satellites to be observed are known. Define the global coordinate system of the system as the ECEF coordinate system, define the local coordinate systems of the transmitting radar and the receiving radar, and assume that the position, attitude and signal radiation directionality of the transmitting radar and the receiving radar remain constant. The signal transmission process between any transmitting radar, any satellite to be observed and any receiving radar constitutes an echo signal transmission path. Assume that the RCS of all satellites is constant and known in the time domain and angle domain. 其中，步骤一中STK反馈卫星位置数据的时间间隔ΔtSTK取值的约束条件为：Among them, the constraint condition for the time interval Δt STK of STK feedback satellite position data in step 1 is: 其中，Re为地球半径，Me为地球质量，G为引力常量，we为地球自转角速率，Htar,min为待观测卫星的最小轨道高度，fc为信号频率，c为光速；Where, Re is the radius of the Earth, Me is the mass of the Earth, G is the gravitational constant, we is the angular rate of the Earth's rotation, Htar ,min is the minimum orbital altitude of the satellite to be observed, fc is the signal frequency, and c is the speed of light; 其中，步骤二中信号传输模型为：Among them, the signal transmission model in step 2 is: 发射信号记作Str(t)＝B(t)exp(jη)·exp(j2πfct)，B(t)是基带信号，η是发射信号的初相；发射雷达在发射时刻所发射的信号，经过自由空间传播后在目标时刻到达待观测卫星，信号随即被卫星散射，经过自由空间传播后在接收时刻到达接收雷达，接收雷达在时刻接收的来自目标的信号，经过下变频后，得到为：The transmitted signal is recorded as S tr (t) = B (t) exp (jη) · exp (j2πf c t), where B (t) is the baseband signal and η is the initial phase of the transmitted signal. The transmitted signal, after propagating through free space, reaches the target time When the signal reaches the satellite to be observed, it is scattered by the satellite and propagates through free space. Arrives at the receiving radar, the receiving radar The signal received from the target at any time is converted to for: 其中，是基带信号的功率，是归一化后的基带信号，λ＝c/fc是信号波长；为发射天线增益项，和分别表示在时刻卫星目标位置在发射雷达本地坐标系中的方位角和俯仰角，为接收天线增益项，和分别表示在时刻的卫星目标位置在接收雷达局部坐标系的方位角和俯仰角，和分别是时刻卫星到发射雷达和接收雷达的传输路径长度，σ是待观测卫星的RCS。in, is the power of the baseband signal, is the normalized baseband signal, λ＝c/f c is the signal wavelength; is the transmitting antenna gain term, and Respectively expressed in The azimuth and elevation angles of the satellite target position in the local coordinate system of the transmitting radar at this moment, is the receiving antenna gain term, and Respectively expressed in The azimuth and elevation angles of the satellite target position at the moment in the receiving radar local coordinate system, and They are is the transmission path length from the satellite to the transmitting radar and the receiving radar at time t, and σ is the RCS of the satellite to be observed. 2.根据权利要求1所述的基于STK的高精度卫星目标雷达回波信号生成方法，其特征在于，步骤二中卫星对发射雷达和接收雷达均可见的若干个卫星可见时段为：2. The high-precision satellite target radar echo signal generation method based on STK according to claim 1 is characterized in that the satellite visible time periods during which the satellite is visible to both the transmitting radar and the receiving radar in step 2 are: STK仿真场景输出卫星对发射雷达和接收雷达的可见时段，分别记作和其中，Itr是卫星对发射雷达可见时段的个数，是第itr个时间连续的卫星对发射雷达的可见时段，起始时刻为终止时刻为Ire是卫星对接收雷达可见时段的个数，是第ire个时间连续的卫星对接收雷达的可见时段，起始时刻为终止时刻为 The STK simulation scenario outputs the visible period of the satellite to the transmitting radar and the receiving radar, which are recorded as and Where I tr is the number of periods during which the satellite is visible to the transmitting radar, is the visible period of the ith time-continuous satellite to the transmitting radar, starting at End time is I re is the number of periods during which the satellite is visible to the receiving radar, is the visible period of the i- th time-continuous satellite to the receiving radar, starting at End time is 卫星对发射和接收雷达均可见的若干个卫星可见时段，记作：其中，Ivs是卫星对发射雷达和接收雷达均可见时段的个数，ivs是其中任一时段的编号。The number of satellite visibility periods during which the satellite is visible to both the transmitting and receiving radars is denoted as: Where I vs is the number of periods when the satellite is visible to both the transmitting radar and the receiving radar, and i vs is the number of any period. 3.根据权利要求2所述的基于STK的高精度卫星目标雷达回波信号生成方法，其特征在于，步骤三具体为：3. The high-precision satellite target radar echo signal generation method based on STK according to claim 2 is characterized in that step three specifically comprises: 将若干个卫星可见时段Τvs重新记作对于中每一个连续时段利用STK获取时刻卫星在发射雷达局部坐标系中的距离和并计算目标时刻对应的发射时刻 Rewrite the visible period of several satellites Τ vs as for Each consecutive period Get using STK The distance between the satellite and the transmitting radar in the local coordinate system at this moment and And calculate the target time The corresponding launch time 由此，获得是对应的信号发射时段，即有效回波信号的发射时段；其中， Thus, we obtain yes The corresponding signal transmission period is the transmission period of the effective echo signal; wherein, 利用STK获取的卫星在接收雷达局部坐标系中的距离数据和计算目标时刻对应的接收时刻 The distance data of the satellite in the local coordinate system of the receiving radar obtained by STK and Calculate target time Corresponding receiving time 由此，获得是对应的信号接收时段，即有效回波信号的接收时段；其中 Thus, we obtain yes The corresponding signal receiving period is the receiving period of the effective echo signal; 4.根据权利要求3所述的基于STK的高精度卫星目标雷达回波信号生成方法，其特征在于，步骤四具体为：4. The method for generating high-precision satellite target radar echo signals based on STK according to claim 3, wherein step 4 is specifically: 将接收端的采样序号定义为集合ΝS＝{n|0≤n≤Nsample-1}，继而将接收端采样时刻序列记作其中Nsample是接收端的总采样点数；The sampling sequence number of the receiving end is defined as the set NS = {n|0≤n≤N sample -1}, and then the sampling time sequence of the receiving end is recorded as Where N sample is the total number of sampling points at the receiving end; 将与的各子集分别求交集，分别得到第ivs个可见时段的接收采样时刻集合这些集合的并集是所有可见时段对应的接收采样时刻序列，未收到有效回波信号的接收采样时刻的序列且存在的数学关系。Will and Each subset of Find the intersection respectively and get the receiving sampling time set of the ith vs visible period respectively. The union of these sets It is the sequence of receiving sampling times corresponding to all visible time periods, and the sequence of receiving sampling times when no valid echo signal is received and exists The mathematical relationship of .
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