CN112782710A - Low-orbit space target tracking method and system based on interferometry system - Google Patents
Low-orbit space target tracking method and system based on interferometry system Download PDFInfo
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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
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
- G01S17/06—Systems determining position data of a target
- G01S17/08—Systems determining position data of a target for measuring distance only
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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
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/66—Tracking systems using electromagnetic waves other than radio waves
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Abstract
A low-orbit space target tracking method and system based on an interferometry system relate to the technical field of aerospace, and aim to establish a new active moving mode target tracking technical means through application improvement of interferometry technology and multi-base radar technology, and improve the accuracy and reliability of low-orbit non-cooperative space target tracking. The method comprises the steps of constructing a combined tracking strategy in a one-transmitting and multi-receiving mobile station distribution mode, wherein a main station transmits electromagnetic waves and measures target distance and angle, a base line formed by a secondary station and the main station carries out high-precision time difference measurement, and then the characteristics of system measurement information composition are utilized to establish a multi-method combined interference phase ambiguity resolution strategy, so that target tracking under different system constraints and tracking timeliness requirements is realized.
Description
Technical Field
The invention relates to the technical field of aerospace, in particular to a low-orbit space target tracking method and system based on an interferometry system.
Background
With the increasingly deep technical development and the increasingly deep space application, the threat of space fragments to the in-orbit spacecraft is increased continuously, the potential confrontation under a specific environment is strengthened gradually, the innovative application of a reliable high-precision measurement technology is urgently needed, and the tracking capability of non-cooperative space targets such as the space fragments is improved. Specifically, on one hand, the efficiency and the precision of target tracking are improved, and on the other hand, the maintenance capability of the measuring system is also improved.
At present, two main systems of optics and radar are mainly used for tracking low-orbit space targets. The former mainly obtains high-precision angle measurement data, and obtains target position or track information through a plurality of devices or long-time observation, but the measurement system has larger dependence on weather conditions. The device can provide distance measurement, angle measurement and speed measurement information, can realize single-device calculation, but the conventional radar angle measurement accuracy is limited, and the tracking accuracy is limited. In addition, existing spatial target measurement devices are typically bulky and may be less resistant to interference and sustained operation in future high-intensity applications or harsh countermeasure conditions.
The interferometry technique utilizes multiple stations to obtain the time difference (i.e., range difference) from a space target to different stations through radio interferometry, corresponding to the measurement of the projection of the spacecraft orbit along the baseline direction. The interferometry is practically equivalent to high-precision angle measurement, and the high-precision direction of arrival is calculated by utilizing spatially separated equipment (antennas) to obtain target reflected (scattered) electromagnetic waves and further through the relative position and phase interference processing between the equipment, so that the space target tracking and measuring precision is obviously improved. However, most of the current interferometric systems are applied to the orbit measurement of high orbit space targets and deep space spacecraft, and rely on long-term accumulation. In addition, most of the existing interferometry is fixed layout, and needs external guide information with certain precision, which is not beneficial to practical application in a high-intensity mode.
Therefore, the invention gives full play to the precision advantage of interferometric measurement, adopts a one-shot-multiple-shot maneuvering multi-station mode, provides a tracking measurement method and a system based on an interferometric measurement system, and provides a new technical means for tracking the non-cooperative low-orbit space target.
Disclosure of Invention
The invention aims to solve the technical problem that a low-orbit non-cooperative space target tracking method and system of a one-shot and multi-shot interferometry system are provided based on an interferometry technology and a multi-base radar technology and face the tracking requirement of a near-earth space non-cooperative spacecraft, and the information acquisition requirement of situation awareness tasks such as space debris monitoring is met.
In order to achieve the purpose, the invention fully utilizes the characteristics of small equipment scale and high angle measurement precision of an interference measurement system, combines an active detection and multi-station interference advantage design measurement method, realizes system configuration by receiving, transmitting, separately arranging and flexibly arranging stations, and achieves the purposes of reducing system processing difficulty, improving target tracking precision and enhancing system flexibility and reliability.
The invention provides a low-orbit space target tracking method based on an interferometry system, which comprises the following steps:
step 1: adopting a one-transmission and multi-reception measurement mode to construct a measurement model:
transmitting electromagnetic waves through a master station antenna and receiving target echoes to obtain target distance and angle measurement information; the plurality of secondary station antennas only receive the target echoes, and are combined with the main station to form a plurality of measurement baselines to obtain the time difference of the echoes reaching each survey station; combining a plurality of time difference measurement equations with a master station ranging equation to form a measurement model for target fine tracking;
step 2: interference phase ambiguity resolution strategy:
ambiguity initial value calculation based on primary positioning information of a main station is carried out, and ambiguity estimation accuracy and reliability are improved by changing two modes of electromagnetic wave frequency and mobile station base line configuration and utilizing the characteristic that interference phase ambiguities measured by different frequencies and different base lines are relatively prime;
and step 3: target tracking and positioning:
a mode of positioning first and then orbit determination is adopted, a short baseline connection line interference measurement mode is introduced, and the target real-time position and speed estimation is carried out by combining the high-precision positioning of the main station and the high-precision time difference measurement information of the baseline; combining the space target multi-turn tracking data to realize high-precision orbit estimation; and the selectable mode of the differential observation system is constructed by adjusting the layout of the observation stations, so that the positioning and orbit determination precision is further improved.
Further, the step1 comprises the following steps:
and (3) radar measurement modeling of the master station:
adopting a conventional three-coordinate radar measurement mode, transmitting a signal and receiving an echo, and extracting distance and angle information from a target to a master station radar antenna phase center from the echo; the modeling is performed by taking x (t) ═ x (t), y (t), z (t) as the three-dimensional coordinates of the target spatial position at time t]TThe central position X of the radar antenna phase of the master station0(t)＝[x0(t),y0(t),z0(t)]TThe master station measurement model is a typical mobile three-coordinate radar measurement model
Where ρ is0(t)、A0(t)、E0(t) are distance, azimuth and pitch measurements, respectively, all varying with time.
Further, the step1 comprises the following steps:
multi-station interferometry modeling:
all stations receive target echo at the same time, and the time difference of the signals arriving at the secondary station and the primary station is tau10、τ20、τ30Respectively calculating the time difference of the same signal arriving at the secondary station and the primary station as follows:
where c is the speed of light, ρ0(t)、ρ1(t)、ρ2(t)、ρ3(t) are respectively target to Master station X0(t) and secondary station X1(t)、 X1(t)、X3Distance of (t) (. rho)1(t)、ρ2(t)、ρ3The measurement equation of (t) is similar to the first equation of (11); recording the signal wavelength as lambda, and the phase observed quantity and the integer ambiguity obtained by the interference measurement of the main station 0 and the auxiliary station i are respectively phii0(t) and N (t), then
φ10(t)+λ·Ni0(t)＝ρi(t)-ρ0(t) (8)
In summary, the baseline interferometry model is
Further, the step2 comprises the following steps:
and (3) resolving ambiguity by using a main station positioning result:
firstly: calculating and acquiring a target space position measured value X (t) through coordinate transformation;
secondly, the method comprises the following steps: according to the known site coordinates X of two stations forming a base lineA(t) and XB(t) calculating a distance difference of the target at the baseline measurement;
and thirdly: according to the spectral characteristics of the measured signal, the integer constant speed is recorded, and the ambiguity in the distance difference is
And finally: analyzing the calculation precision of the integer ambiguity according to the precision of X (t), and if the right-end denominator error isOver 0.5 lambda, N will beABAnd (5) as an initial value of the ambiguity, switching to the next link, and otherwise, ending the ambiguity calculation process.
Further, the step2 comprises the following steps:
and (3) variable frequency deblurring:
firstly, selecting a transmitting frequency point f1And f2Calculating the integer ambiguity by equation (15); due to the measurement error of X (t) obtained by the main station, a plurality of values of the calculated ambiguity exist
And
second, since the target location and baseline are determined, so
And
a corresponding relation exists, a combination which is consistent with the two is selected from the set of the previous step, and the corresponding is possible ambiguity estimation;
and finally, if a plurality of groups of corresponding elements exist, increasing the transmitting frequency points and guiding the unique common elements of the plurality of groups of sets, thereby obtaining the final ambiguity estimation value.
Further, the step2 comprises the following steps:
multi-baseline deblurring:
firstly, arranging each measuring station according to a target prior orbit, so that the lengths of all base lines are mutually prime, and the unambiguous range is increased;
and secondly, calculating each baseline ambiguity by utilizing X (t) obtained by the main station, and obtaining an ambiguity calculation value through a set corresponding relation.
Further, the step 3 comprises the following steps:
and (3) interference measurement:
firstly, for the measuring stations forming the connecting line measuring base line, the measuring precision of the corresponding time difference is improved by using the same time-frequency standard and eliminating modes such as common errors;
secondly, because the relative position relation of each base line is known, the base line resolving result is used as a reference, and auxiliary information is provided for ambiguity calculation of other base lines of the system;
and (3) real-time positioning:
firstly, combining a space target orbit dynamics model and the measurement model provided in the first step, and establishing a motion equation and a measurement equation of a target;
secondly, establishing a composite filter for real-time filtering of the target position and speed according to the system characteristics;
high-precision rail fixing:
after each tracking circle of the target is finished, combining the measurement data of more than three circles by adopting the measurement model provided in the step1 and combining a spacecraft dynamics constraint model to perform precise orbit determination on the target;
after each orbit determination calculation, evaluating the contribution of the current base line to the orbit calculation in time, forecasting the orbit of the next circle, adjusting the configuration of the base line according to the evaluation result of the base line and the forecast result of the orbit, and serving for the subsequent measurement and improvement of the orbit;
precision optimization:
under the condition that observation conditions allow, a differential interference measurement mode is introduced, so that the measurement accuracy is further improved, and the accuracy of target positioning and orbit determination is improved.
Furthermore, the composite filter comprises a main filter and an auxiliary filter, and the main filter forms a dimension-expanding combined filtering model by utilizing all information of the active measurement information of the main station and the passive measurement information of the multiple stations; and the secondary filter only utilizes the three-coordinate information of the main station radar to calculate the target position information in real time.
The invention discloses a low-orbit space target tracking system based on an interferometry system, which adopts a low-orbit non-cooperative space target tracking method and comprises a system composition, a system deployment mode and a system working flow, wherein the system composition comprises a transmitting-receiving antenna system, a signal acquisition and data preprocessing system, a data transmission system and a data comprehensive processing system; the system deployment mode comprises a main station and a plurality of secondary stations, and adopts transceiving split placement and mobile vehicle-mounted; the system has the following working procedures: and adopting the strategies of multi-station cooperation, decentralized acquisition and centralized processing.
The invention can realize the following beneficial technical effects:
for tracking of low-orbit non-cooperative space targets, the existing method and system are difficult to give consideration to both precision and flexibility, and the application under the high-strength confrontation condition is limited. The invention provides a target tracking method and a target tracking system in an active moving mode based on an interferometric technical system, and the target tracking method and the target tracking system have the advantages of high tracking precision, low processing complexity, flexible deployment, low construction cost and wide application, and particularly comprise the following steps:
(1) according to the method and the system, the target high-precision distance measurement and time difference (angle measurement) information can be obtained at the same time, the target observation geometry can be flexibly improved by adjusting the survey station layout to optimize the baseline configuration, and a high-precision high-reliability target tracking result is obtained at a lower processing cost;
(2) according to the method and the system, the flexibility of the system can be fully utilized, the algorithm complexity of phase ambiguity resolution in interferometry is reduced by optimally designing the type of the transmitted signal and the arrangement mode of the mobile baseline, and the time difference extraction precision is improved at lower processing cost;
(3) according to the method and the system, a receiving and transmitting separately-arranged mode is adopted, each measuring station adopts a mobile platform, the system can freely select a deployment site and a baseline configuration, can be dynamically adjusted in a measuring gap and even a measuring process, can meet the measuring precision and reliability requirements of different targets, and improve the self-confrontation and survival capability of the system.
(4) According to the method and the system, the designed interference measurement system has the advantages of small system scale, single-station measurement function and strong universality of software and hardware, and can greatly reduce the system construction cost while ensuring the target tracking precision;
(5) the method and the system can be expanded to a non-cooperative space target measurement mode, and the measurement of the non-cooperative space target is realized through receiving space signals radiated by the target or self telemetering and load working signals and the like and through interference baselines obtained by a plurality of receiving stations.
(6) The method and the system can be directly applied to low-orbit space target tracking and can be expanded to a medium-high orbit target, and meanwhile, the methods such as interference phase solution blurring and baseline configuration design have certain reference significance for the development of the theory and technology of interferometry.
Drawings
FIG. 1 is a schematic diagram of one-shot multiple-shot spatial target interferometry based on the present invention;
FIG. 2 is a schematic diagram of differential interferometry;
FIG. 3 is a schematic diagram of the principal components and deployment of an interferometric system according to an embodiment of the invention;
fig. 4 is a schematic system flow diagram of the present invention.
Detailed Description
The invention provides a low-orbit non-cooperative space target tracking method and system based on a one-shot multi-shot interferometry system. In the following, embodiments and features of the embodiments in the present application may be combined with each other without conflict, and specific embodiments of the present invention will be described in detail.
1. Low-orbit space target tracking method based on one-shot multi-shot interferometry
The invention provides a one-transmission multi-reception space target interferometry, which takes one-transmission three-reception as an example, and a measurement schematic diagram is shown in figure 1. Through 1 emission master station and 3 secondary stations, combine single-station radar location and many baseline time difference measurement, realize non-cooperative space target position and orbit calculation of high accuracy. The specific process comprises three main steps of measurement model construction, interference phase ambiguity resolution and target tracking and positioning. The number of receiving secondary stations can be increased or decreased depending on the need for tracking and constraints on construction costs, etc.
The method comprises the following steps: measurement model construction
Transmitting electromagnetic waves through a master station antenna and receiving target echoes to obtain target distance and angle measurement information; the plurality of secondary station antennas only receive target echoes, and are combined with the main station to form a plurality of measurement baselines to obtain the time difference of the echoes reaching each survey station; combining a plurality of time difference measurement equations with a master station ranging equation to form a measurement model for target fine tracking; the method comprises the steps of establishing a mathematical model of the relation between the space position of a space target and measurement information according to the observation geometry and the type of the measurement information in a mode that a main station transmits and a main station and an auxiliary station receive simultaneously. According to the measurement schematic diagram of fig. 1, the modeling includes two links of a master station radar measurement and a multi-station interferometry.
Step 1: master station radar measurement modeling
The master station adopts a conventional three-coordinate radar measurement mode, transmits signals and receives echoes, and extracts distance and angle information from a target to the radar antenna phase center of the master station from the echoes. The procedure is modeled as follows, and the three-dimensional coordinates of the target space position at time t are X (t) ([ x (t), y (t), z (t))]TThe central position X of the radar antenna phase of the master station0(t)＝[x0(t),y0(t),z0(t)]TThe master station measurement model is a typical mobile three-coordinate radar measurement model
Where ρ is0(t)、A0(t)、E0(t) are distance, azimuth and pitch measurements, respectively, all varying with time.
Step 2: multi-station interferometric modeling
The multi-station interferometry is exemplified by a measurement system of one primary station and 3 secondary stations, and the measurement model of the procedure is given, and other cases can be similarly derived. Specifically, each station receives target echoes simultaneously, and the time difference between the arrival of the recording signals at the secondary station and the primary station is τ10、τ20、τ30The time difference of arrival of the same signal at the secondary station and the primary station is calculated as follows
Where c is the speed of light, ρ0(t)、ρ1(t)、ρ2(t)、ρ3(t) are respectively target to Master station X0(t) and secondary station X1(t)、 X1(t)、X3Distance of (t) (. rho)1(t)、ρ2(t)、ρ3The measurement equation of (t) is similar to the first equation of (11). Here, the primary station is used as the starting point of time difference calculation, the starting reference is changed, and similarly, tau can be calculated01、τ21And τ31And the number of the 4 stations is only 3 independent baselines, and the number of the corresponding independent time difference measurement information is only 3.
Recording the signal wavelength as lambda, and the phase observed quantity and the integer ambiguity obtained by the interference measurement of the main station 0 and the auxiliary station i are respectively phii0(t) and N (t), then
φ10(t)+λ·Ni0(t)＝ρi(t)-ρ0(t) (13)
In summary, the baseline interferometry model is
Station position X in equations (11) and (14)0(t)、X1(t)、X2(t)、X3(t) can be obtained by its own positioning system, considered as a known quantity, and in order to simplify the processing difficulty and improve the phase measurement accuracy, the position of the measuring station can be fixed within the measurement time of one tracking arc of the target.
It should be noted that in the modeling equation of the step, no matter the master station radar measurement or the multi-station time difference measurement, measurement system errors and random errors are inevitable, the specific composition analysis and processing strategy needs to be specifically analyzed in the application process, and the relevant details are not detailed in the invention.
Step two: interferometric phase ambiguity resolution strategy
The method comprises the steps of sequentially realizing ambiguity initial value resolving based on primary positioning information of a main station by adopting a multi-method combined resolving strategy, and improving ambiguity estimation accuracy and reliability by changing two modes of electromagnetic wave frequency and mobile station base line configuration and utilizing the characteristic of relatively prime interference phase ambiguity measured by different frequencies and different base lines; the step is to solve the whole-cycle ambiguity of the phase difference by processing the interference measurement signal of the base line formed by the multiple stations, and provide a basis for calculating the target position or the track according to the time difference. As shown in fig. 2, the present invention improves the phase ambiguity accuracy and reliability step by using a calculation strategy of three ring segments.
Step 1: disambiguation of position results using a Master station
The step is to provide target three-coordinate measurement information by using a master station radar and acquire an initial value of the ambiguity of the interferometric measurement.
First, a target spatial position measurement value x (t) is obtained by calculation through coordinate transformation.
Secondly, according to the known site coordinates X of the two stations forming the base lineA(t) and XB(t) calculating the distance difference of the target under the baseline measurement.
Thirdly, according to the frequency spectrum characteristics of the measured signal, the integer constant speed is recorded, and the ambiguity in the distance difference is
Finally, analyzing the calculation precision of the integer ambiguity according to the precision of X (t), and if the error of the denominator at the right end exceeds 0.5 lambda, determining NABAnd (5) as an initial value of the ambiguity, switching to the next link, and otherwise, ending the ambiguity calculation process.
In order to improve the calculation accuracy and reliability of the ambiguity and reduce the uncertainty influence of the single-point coordinates of the main station, N of continuous multiple moments can be taken in one measurementABThe average or median of (t) is taken as the ambiguity calculation result.
Step 2: variable frequency deblurring
The steps give full play to the advantages of active measurement, and the ambiguity resolution precision is improved by designing the frequency of a transmitting signal and combining different frequency points.
Firstly, selecting a transmitting frequency point f1And f2The integer ambiguity is calculated by equation (15). Due to the measurement error of X (t) obtained by the main station, a plurality of values of the calculated ambiguity exist
And
second, since the target location and baseline are determined, so
And
there is a corresponding relation, and the combination of the two is selected from the set of the above steps, and the corresponding is the possible ambiguity estimation.
And finally, if a plurality of groups of corresponding elements exist, increasing the transmitting frequency points and guiding the unique common elements of the plurality of groups of sets, thereby obtaining the final ambiguity estimation value.
Step 3: multi-baseline deblurring
The steps are that the layout flexibility of the mobile measuring station is utilized, the direction and the length of a space base line are designed, the observation geometry is changed, and the ambiguity resolution precision is improved.
Firstly, arranging each measuring station according to a target prior orbit, so that the lengths of all base lines are mutually prime numbers, and increasing the unambiguous range.
And secondly, calculating each baseline ambiguity by using X (t) obtained by the main station, and acquiring ambiguity calculation values by collecting corresponding relations in a manner similar to Step 2. If a baseline combination is difficult to achieve with accurate ambiguity fixing, the baseline configuration can be changed appropriately during the measurement.
Step three: target tracking and positioning
The method of positioning first and then fixing rails is adopted, so that the requirements of target tracking tasks with different timeliness are met; on the basis of improving the time difference measurement accuracy by introducing a short baseline connection line interference measurement mode, firstly, combining the high-accuracy positioning of a main station and the high-accuracy time difference measurement information of a baseline, and estimating the real-time position and the speed of a target by a real-time filtering algorithm, and secondly, combining the multi-turn tracking data of a space target to realize high-accuracy track estimation; in addition, the selectable mode of the differential observation system is constructed by adjusting the layout of the measuring stations, so that the positioning and orbit determination precision is further improved.
The step uses the measurement information to complete the real-time position and speed and high-precision orbit calculation of the space target. As shown in fig. 3, the present invention adopts a method of positioning first and then fixing rail to meet different timeliness task requirements, and mainly comprises 4 main links, as follows.
Step 1: interferometric measurement
The invention obtains the multi-station time difference based on the interference measurement as the main measurement information of target tracking. The steps are that in the measuring process, individual measuring stations are selected to form a base line below 1km, a short base line connection interference measuring mode is established, and measuring accuracy is improved.
Firstly, for the measuring stations forming the connecting line measuring base line, the measuring precision of the corresponding time difference is improved by using the same time-frequency standard and eliminating modes such as common errors and the like.
Secondly, because the relative position relation of each base line is known, the base line resolving result is used as a reference, and auxiliary information is provided for ambiguity calculation of other base lines of the system.
Step 2: real-time positioning
The method mainly aims at the target tracking requirement of a single circle, and is characterized in that the active measurement information of a main station and the passive measurement information of multiple stations are comprehensively utilized to calculate the position and the speed of a target in real time and provide real-time positioning information of the target.
Firstly, combining a space target orbit dynamics model and the measurement model provided in the first step, establishing a motion equation and a measurement equation of the target. The orbit dynamics model can refer to relevant books and is not described in detail here.
And secondly, establishing a composite filter for real-time filtering of the target position and speed according to the system characteristics. The composite filter comprises a main filter and an auxiliary filter, the main filter forms an extended combined filter model by utilizing all information of active measurement information of a main station and passive measurement information of a plurality of stations, namely ranging, angle measurement and time difference information, the target position and speed are calculated, and the result is output as positioning information. The secondary filter only utilizes the three-coordinate information of the radar of the main station to calculate the target position information in real time, on one hand, an initial value is provided in the initialization stage of the main filter, on the other hand, the initial value is used as the check information of the main filter during the normal operation period, and abnormal phenomena such as filter divergence and the like caused by the abnormality of an interferometric system are avoided.
Step 3: high-precision rail fixing
The method mainly aims at the requirement of target high-precision tracking, and combines the measurement information of a plurality of circles to realize target track estimation. This step involves two main links.
Firstly, after each tracking circle of the target is finished, the measurement model provided in the first step is adopted, measurement data of more than three circles are combined, and the spacecraft dynamics constraint model is combined to perform precise orbit determination of the target. The calculation adopts a statistical orbit determination method, and the initial value of the orbit is obtained from Step 2.
And secondly, after each orbit determination calculation, the contribution of the current base line to the orbit calculation is evaluated in time, the orbit of the next circle is forecasted, and the configuration of the base line is adjusted according to the evaluation result and the forecast result of the base line, so that the subsequent orbit measurement and improvement are provided.
Step 4: precision optimization
The step is to introduce a differential interference measurement mode under the condition that observation conditions allow, so that the measurement precision is further improved, and the precision of target positioning and orbit determination is improved.
According to the observation capability of the observation station, if reference sources (such as a radio frequency source, a navigation satellite and the like) which are viewed by the observation station in common exist in the observation sight direction of the target in a certain period of time, as shown in fig. 4, the observation of the reference sources and the target by the observation station are combined to form a differential observation system, so that the common system error influence of clock error between the stations and the like is eliminated.
2. Low-orbit space target tracking system based on one-shot multi-shot interferometry
The embodiment of the invention also provides a design scheme of the low-orbit non-cooperative space target tracking system based on the one-shot multiple-shot interferometry system, and the detailed design steps of the system composition and the working flow are as follows.
The method comprises the following steps: design of system components
As an implementation mode, the system is composed of a transmitting and receiving antenna system, a signal acquisition and data preprocessing system, a data transmission system, a data comprehensive processing system and the like.
The receiving and transmitting antenna system obtains original signals for distance measurement, angle measurement and time difference measurement in a multi-station combined mode;
the signal acquisition and processing system completes the acquisition and preprocessing of the original data required by the single-station positioning and the interferometry;
the data transmission system selects a flexibly adopted information transmission strategy according to different distance base lengths and system constraints, and is responsible for collecting the acquired signals to the data comprehensive processing system;
the data comprehensive processing system comprises three parts of signal interference processing, real-time positioning and high-precision orbit determination resolving, and is used for respectively finishing the acquisition of time difference measurement data, the real-time filtering resolving of target position and speed and the high-precision track determination of a target by combining multiple circles of tracking data.
Step two: system deployment style design
The system comprises a main station and a plurality of secondary stations, and is deployed in the modes of transmitting and receiving separately, mobile vehicle-mounted, flexible communication, decentralized processing and the like, and the deployment principles are as follows:
a master station is additionally provided with a receiving and transmitting integrated antenna, a secondary station is additionally provided with a receiving antenna, and a plurality of receiving antennas can be additionally arranged on one survey station to form a short baseline for connection measurement (such as the master station and the secondary station 1 in fig. 1);
a signal acquisition and preprocessing system is distributed in each station, a main station acquisition system finishes ranging, angle measurement signal acquisition and preprocessing and acquisition and preprocessing of signals before interference, and a secondary station acquisition system finishes acquisition and preprocessing of signals before interference;
the data transmission system is responsible for collecting the collected signals to the data comprehensive processing system, and communication means such as direct-connected optical fibers, special networks or encrypted 5G are flexibly adopted by different distance base lines according to needs, as shown in FIG. 1;
the data integrated processing system completes signal interference processing and target positioning solution, and can be deployed in a separate processing center or arranged in a master station.
Step three: system workflow design
The system adopts the strategy of multi-station cooperation, decentralized acquisition and centralized processing, and the working process can be briefly expressed as follows:
flexibly setting the layout of each station according to the target prior information, and guiding a master station radar to autonomously track a target;
after the master station captures the target and obtains the positioning information, guiding the secondary station to track;
collecting the measurement information of the primary station and the secondary station, and extracting the high-precision multi-station time difference;
the target high-precision real-time positioning is realized by using the distance measurement information of the master station and the multi-station time difference information;
evaluation of the contribution of the base line to the track, improvement of the station layout;
and combining the observation data of multiple circles to perform target precise orbit determination.
In summary, the present invention provides a low-orbit space target tracking method and system based on an interferometric system, the method includes the following steps: constructing a measurement model, an interference phase ambiguity resolution strategy and target tracking and positioning by adopting a one-transmission and multi-reception measurement mode; the system comprises a system composition, a system deployment mode and a system workflow, wherein the system composition comprises a receiving and transmitting antenna system, a signal acquisition and data preprocessing system, a data transmission system and a data comprehensive processing system; the system deployment mode comprises a main station and a plurality of secondary stations, and adopts transceiving split placement and mobile vehicle-mounted; the system has the following working procedures: and adopting a strategy of multi-station cooperation, distributed acquisition and centralized processing. According to the invention, through application improvement of an interferometric measurement technology and a multi-base radar technology, a new active moving mode target tracking technical means is established, the precision and reliability of low-orbit non-cooperative space target tracking are improved, a multi-method combined interferometric phase ambiguity resolution strategy is established by using the characteristics of system measurement information composition, and target tracking under different system constraints and tracking timeliness requirements is realized.
In the previous description, numerous specific details were set forth in order to provide a thorough understanding of the present invention. The foregoing description is only a preferred embodiment of the invention, which can be embodied in many different forms than described herein, and therefore the invention is not limited to the specific embodiments disclosed above. And that those skilled in the art may, using the methods and techniques disclosed above, make numerous possible variations and modifications to the disclosed embodiments, or modify such equivalent embodiments, without departing from the scope of the claimed invention. Any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention are within the scope of the technical solution of the present invention.
Claims (9)
1. A low-orbit space target tracking method based on an interferometry system is characterized in that: the method comprises the following steps:
step 1: adopting a one-transmission and multi-reception measurement mode to construct a measurement model:
transmitting electromagnetic waves through a master station antenna and receiving target echoes to obtain target distance and angle measurement information; the plurality of secondary station antennas only receive the target echoes, and are combined with the main station to form a plurality of measurement baselines to obtain the time difference of the echoes reaching each survey station; combining a plurality of time difference measurement equations with a master station ranging equation to form a measurement model for target fine tracking;
step 2: interference phase ambiguity resolution strategy:
ambiguity initial value calculation based on primary positioning information of a main station is carried out, and ambiguity estimation accuracy and reliability are improved by changing two modes of electromagnetic wave frequency and mobile station base line configuration and utilizing the characteristic that interference phase ambiguities measured by different frequencies and different base lines are relatively prime;
and step 3: target tracking and positioning:
a mode of positioning first and then orbit determination is adopted, a short baseline connection line interference measurement mode is introduced, and target real-time position and speed estimation is carried out by combining the high-precision positioning of the main station and the high-precision time difference measurement information of the baseline; combining the space target tracking data for multiple circles to realize high-precision orbit estimation; and the selectable mode of the differential observation system is constructed by adjusting the layout of the observation stations, so that the positioning and orbit determination precision is further improved.
2. The low-orbit spatial target tracking method according to claim 1, characterized in that: the step1 further comprises the following steps:
and (3) radar measurement modeling of the master station:
adopting a conventional three-coordinate radar measurement mode, transmitting signals and receiving echoes, and extracting distance and angle information from a target to a master station radar antenna phase center from the echoes; the modeling is performed by taking x (t) ═ x (t), y (t), z (t) as the three-dimensional coordinates of the target spatial position at time t]TThe central position X of the radar antenna phase of the master station0(t)＝[x0(t),y0(t),z0(t)]TThe master station measurement model is a typical mobile three-coordinate radar measurement model
Where ρ is0(t)、A0(t)、E0(t) are distance, azimuth and pitch measurements, respectively, all varying with time.
3. The low-orbit spatial target tracking method according to claim 2, characterized in that: the step1 further comprises the following steps:
multi-station interferometry modeling:
the stations receiving the target echoes simultaneously and recording the arrival of signals at the secondary station and the primary stationTime differences are respectively tau10、τ20、τ30Respectively calculating the time difference of the same signal arriving at the secondary station and the primary station as follows:
where c is the speed of light, ρ0(t)、ρ1(t)、ρ2(t)、ρ3(t) are respectively target to Master station X0(t) and secondary station X1(t)、X1(t)、X3Distance of (t) (. rho)1(t)、ρ2(t)、ρ3The measurement equation of (t) is similar to the first equation of (11); recording the signal wavelength as lambda, and the phase observed quantity and the integer ambiguity obtained by the interference measurement of the main station 0 and the auxiliary station i are respectively phii0(t) and N (t), then
φ10(t)+λ·Ni0(t)＝ρi(t)-ρ0(t) (3)
In summary, the baseline interferometry model is
4. The low-orbit spatial target tracking method according to claim 1, characterized in that: the step2 further comprises the following steps:
and (3) resolving ambiguity by using a main station positioning result:
firstly: calculating and acquiring a target space position measured value X (t) through coordinate transformation;
secondly, the method comprises the following steps: according to the known site coordinates X of two stations forming a base lineA(t) and XB(t) calculating a distance difference of the target at the baseline measurement;
and thirdly: according to the spectral characteristics of the measured signal, the integer constant speed is recorded, and the ambiguity in the distance difference is
And finally: analyzing the calculation precision of the integer ambiguity according to the precision of X (t), and if the error of the denominator at the right end exceeds 0.5 lambda, judging that N is equal toABAnd (5) as an initial value of the ambiguity, switching to the next link, and otherwise, ending the ambiguity calculation process.
5. The low-orbit spatial target tracking method according to claim 4, characterized in that: the step2 further comprises the following steps:
and (3) variable frequency deblurring:
firstly, selecting a transmitting frequency point f1And f2Calculating the integer ambiguity by equation (15); due to the measurement error of X (t) obtained by the main station, a plurality of values of the calculated ambiguity exist
And
second, since the target location and baseline are determined, so
And
a corresponding relation exists, a combination which is consistent with the two is selected from the set of the previous step, and the corresponding is possible ambiguity estimation;
and finally, if a plurality of groups of corresponding elements exist, increasing the transmitting frequency points and guiding the public elements of the plurality of groups of sets to be unique, thereby obtaining the final ambiguity estimation value.
6. The low-orbit spatial target tracking method according to claim 5, characterized in that: the step2 further comprises the following steps:
multi-baseline deblurring:
firstly, arranging each measuring station according to a target prior orbit, so that the lengths of all base lines are mutually prime, and increasing the non-fuzzy range;
and secondly, calculating each baseline ambiguity by utilizing X (t) obtained by the main station, and obtaining an ambiguity calculation value through a set corresponding relation.
7. The low-orbit spatial target tracking method according to claim 1, characterized in that: the step 3 further comprises the following steps:
and (3) interference measurement:
firstly, for the measuring stations forming the connecting line measuring base line, the measuring precision of the corresponding time difference is improved by using the same time-frequency standard and eliminating modes such as common errors;
secondly, because the relative position relation of each base line is known, the base line resolving result is used as a reference, and auxiliary information is provided for ambiguity calculation of other base lines of the system;
and (3) real-time positioning:
firstly, combining a space target orbit dynamics model and the measurement model provided in the first step, and establishing a motion equation and a measurement equation of a target;
secondly, establishing a composite filter for real-time filtering of the target position and speed according to the system characteristics;
high-precision rail fixing:
after each tracking circle of the target is finished, combining the measurement data of more than three circles by adopting the measurement model provided in the step1 and combining a spacecraft dynamics constraint model to perform precise orbit determination on the target;
after each orbit determination calculation, evaluating the contribution of the current base line to the orbit calculation in time, forecasting the orbit of the next circle, adjusting the configuration of the base line according to the evaluation result of the base line and the forecast result of the orbit, and serving for the subsequent measurement and improvement of the orbit;
precision optimization:
under the condition that observation conditions allow, a differential interference measurement mode is introduced, so that the measurement accuracy is further improved, and the accuracy of target positioning and orbit determination is improved.
8. The low-orbit spatial target tracking method according to claim 7, characterized in that: the composite filter comprises a main filter and an auxiliary filter, and the main filter forms a combined filtering model for dimension expansion by utilizing all information of the active measurement information of the main station and the passive measurement information of the multiple stations; and the secondary filter only utilizes the three-coordinate information of the master radar to calculate the target position information in real time.
9. A low-orbit space target tracking system based on an interferometry system, which adopts the low-orbit space target tracking method according to any one of claims 1 to 8, and is characterized in that: the system comprises a system composition, a system deployment mode and a system working process, wherein the system composition comprises a receiving and transmitting antenna system, a signal acquisition and data preprocessing system, a data transmission system and a data comprehensive processing system; the system deployment mode comprises a main station and a plurality of secondary stations, and adopts transceiving split placement and mobile vehicle-mounted; the system has the following working procedures: and adopting the strategies of multi-station cooperation, decentralized acquisition and centralized processing.
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