CN102866392A - Waveform agility cognition radar system and implementation method - Google Patents
Waveform agility cognition radar system and implementation method Download PDFInfo
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- CN102866392A CN102866392A CN2012103402055A CN201210340205A CN102866392A CN 102866392 A CN102866392 A CN 102866392A CN 2012103402055 A CN2012103402055 A CN 2012103402055A CN 201210340205 A CN201210340205 A CN 201210340205A CN 102866392 A CN102866392 A CN 102866392A
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Abstract
The invention provides a waveform agility cognition radar system and an implementation method. On the condition that an object and clutter scattering characteristic exist fluctuation changes and are unknown, the implementation method comprises the following steps of: emitting range-invariable wave by an emitting end; realizing on-line estimation of the extended object and the clutter scattering characteristic by utilizing optimal treatment of received echo; optimizing and designing emitted waveform to aim at improving the detection performance of the extended object; and realizing emission agility between different pulse groups. By the system and the method, the disappearance distance of the object is effectively increased, and the adaptability of the radar system in a complicated and changeable environment is improved.
Description
Technical field
The present invention relates to radar system and Radar Signal Processing Technology field, be specifically related to prompt cognitive radar system and the implementation method of becoming of a kind of waveform.
Background technology
The tradition radar adopts fixing transmitting usually, improve performance by the self-adaptive processing of receiving end and the design of filtering algorithm, because the waveform of emission is depended in the detection of target to a great extent in measurement, resolution performance and the clutter of radar, for the situation such as complex environment and dense clutter, multiple goal background day by day, transmitted waveform is fixed, when environment changes, be difficult to obtain desirable effect near the self-adaptation of receiving end.
Cognitive radar is a kind of closed loop working method, by the feedback of radar receiving end to transmitting terminal, make radar system can unceasing study and renewal to the understanding of target and environment, and then active accommodation transmitted waveform, elevator system is to the detection performance of target.It has brought very large change to structural framing formation, signal processing flow and the performance index distribution etc. of conventional radar systems, and has proposed simultaneously Secretary.
Adopt the technology of close-loop feedback at radar after, just by the concept of cognitive radar and the macrostructure of system form, by introducing the radar receiver end to the feedback of transmitter terminal, make the prompt change of waveform transmit and receive the principal character that becomes system.
Adopt after a while the technology of sequential hypothesis testing, with the weighted sum that maximizes mahalanobis distance between any two class targets criterion as waveform optimization, utilize radar to receive the posterior probability of the different classes of hypothesis of echo all targets of sequential renewal, carrying out along with radar emission waveform adaptive design, when the posterior probability of a certain classification hypothesis of target during apparently higher than the posterior probability of other all hypothesis, this classification can be judged as target type.But this technology mainly depends on determines known target impulse response, and is only applicable to the radar operative scenario of high s/n ratio, thereby has hindered to a certain extent application and the popularization of this technology.
Further adopt the On-line Estimation technology of statistical model parameter, utilize the spatial statistics model to describe the scattering properties of extra large clutter, propose the prompt change method of a kind of transmitted waveform based on Clutter Model parameter On-line Estimation.The method can minimize the energy of clutter echo, has indirectly improved the detection performance of point target under the strong sea clutter background.
Adopt the detection technique of polarimetric radar, utilize the On-line Estimation to target and clutter polarization scattering characteristics, the victory that has proposed a kind of adaptively selected transmitted waveform polarization mode becomes structure.
The employing of target following technology, to utilize hidden Markov model to describe the variation of expansion target impulse response, evaluated error by minimizing target impulse response utilizes Kalman filter to realize a kind of prompt change method of transmitted waveform of object-oriented tracking as the waveform optimization criterion.But there are a certain distance in the changing pattern of target impulse response and actual radar operative scenario in the method, thereby have affected the practical value of this technology.
Summary of the invention
(1) technical matters to be solved
The present invention is directed under the complex environment expansion target and clutter scattering properties and have fluctuations and unknown situation, the disappearance that has solved target is apart from the technical matters of short and the bad adaptability of radar system under environment complicated and changeable.
(2) technical scheme
The invention provides the cognitive radar system of the prompt change of a kind of waveform, specifically comprise:
Transmitting element is used for to the constant ripple of space radiation amplitude;
Receiving element is used for receiving the first echo signal through after the reflection of expansion target and clutter scatterer;
Target and clutter estimation unit are used for the echoed signal that receives is carried out optimal processing, obtain the estimated value of expansion target impulse response and clutter space covariance;
Detecting unit is used for the second echo signal that receiving element receives is carried out optimal processing, and the second echo signal after processing is detected, and judges whether optimum results reaches predetermined value.
Optionally, described first echo signal is comprised of target echo signal, clutter echoed signal and noise.
Optionally, described target and clutter estimation unit comprise the optimal processing unit, are used for utilizing knowledge accumulation that first echo signal is processed, and described knowledge accumulation comprises the power level of noise and interference.
Optionally, target and clutter estimation unit also comprise the off-line estimation unit, are used for noise and jamming power level are carried out the off-line estimation, obtain the estimated value of expansion target impulse response and clutter space covariance.
Optionally, optimal detection Waveform Design algorithm take maximization output noise assorted than SCNR as Optimality Criteria, carry out the optimization of baseband transmission ripple.
Optionally, the transmitted wave after optimization and the adjustment is constant envelope signal.
Optionally, comprise the Generalized Likelihood Ratio detector module in the detecting unit, for detection of the target second echo signal.
The present invention also provides the prompt change of a kind of waveform cognitive radar implementation method, may further comprise the steps:
A, cognitive radar start working in the prepulse group k: transmitter terminal is to the constant ripple of space radiation amplitude, and after the reflection of this ripple through expansion target and clutter scatterer, receiver end receives first echo signal;
When b, pulse group k finished, receiver end carried out optimal processing to the first echo signal that receives, and obtained the estimated value of expansion target impulse response and clutter space covariance;
C, enter in next-door neighbour's next pulse group K+1: the estimated value of transmitter terminal extension-based target impulse response and clutter space covariance, set and optimize index, adopt optimal detection Waveform Design algorithm, optimize and adjustment baseband transmission ripple, the transmitted wave after adjusting is radiated in the space;
D, receiver end receive second echo signal, and second echo signal carried out optimal processing, when pulse group K+1 finishes, the second echo signal after processing is detected, if optimum results reaches default definite value then no longer adjusts transmitted waveform in pulse group K+2; Otherwise, enter pulse group K+2 and return step a.
Optionally, the constant ripple of amplitude is linear frequency modulation ripple LFM among the step a.
(3) beneficial effect
The present invention has improved detection performance and the disappearance distance of expansion target, has obviously improved the adaptability of radar system under environment complicated and changeable.
Description of drawings
Fig. 1 is the prompt principle function block diagram that becomes of cognitive radar waveform;
Fig. 2 is the prompt cognitive radar system structure collectivity figure of change of waveform;
Fig. 3 is radar system simplified model figure;
Radar system simplified flow chart when Fig. 4 is emission LFM waveform;
Radar system simplified flow chart when Fig. 5 optimizes waveform for emission;
Fig. 6 is the detection statistics result schematic diagram of the prompt change method of transmitted waveform.
Embodiment
Embodiment 1:
The present invention expands target under complex environment and the clutter scattering properties exists under the condition of fluctuations and the unknown, utilize the different waveform of radar system emission to estimate respectively and detect, realized the cognitive radar close-loop feedback structure of " target and clutter estimation-transmitted waveform design-target detection-target and clutter are estimated ", its functional block diagram as shown in Figure 1, cognitive radar system is a closed-loop dynamic feedback system.
The cognitive radar system of the prompt change of described waveform specifically comprises: transmitting element, receiving element, target and clutter estimation unit, object detection unit.Fig. 2 is the prompt cognitive radar system structure collectivity figure of change of waveform.As shown in the figure, transmitting element and transmitted waveform design cell are positioned at transmitter terminal, and receiving element, target and clutter estimation unit, object detection unit are positioned at receiver end.
Wherein transmitting element is used for to the constant ripple of space radiation amplitude;
Receiving element is used for receiving the first echo signal through after the reflection of expansion target and clutter scatterer;
Target and clutter estimation unit are used for the echoed signal that receives is carried out optimal processing, obtain the estimated value of expansion target impulse response and clutter space covariance; Comprising the optimal processing unit be used for utilizing knowledge accumulation that first echo signal is processed, the knowledge accumulation comprises the power level of noise and interference, and the off-line estimation unit that comprises is used for that noise and jamming power level are carried out off-line and estimates;
The transmitted waveform design cell, the estimated value that is used for extension-based target impulse response and clutter space covariance is set the optimization index, and adopt optimal detection Waveform Design algorithm optimization and adjust the concrete form of baseband transmission waveform, optimize and adjust after transmitted wave carry out radiation by transmitting element, corresponding to described optimization and the second echo signal of the transmitted wave after adjusting receive by described receiving element;
Detecting unit is used for the second echo signal that receiving element receives is carried out optimal processing, and the second echo signal after processing is detected, and the calculation optimization result also judges whether optimum results reaches predetermined value.Wherein comprise the Generalized Likelihood Ratio detector module, for detection of the target second echo signal.
Embodiment 2:
Based on the cognitive radar system of the prompt change of above-mentioned emission between different pulse groups, its specific implementation step is as follows:
A: at first work as in the prepulse group k linear frequency modulation ripple LFM signal U that emission is fixing what radar system was started working
k, when target exists, according to radar system simplified model figure shown in Figure 3, receive echoed signal Y
kBy target echo signal SX
t, clutter echoed signal SX
cConsist of with noise N, wherein S represents by column vector U
kThe convolution matrix that transmits that forms, X
tAnd X
cExpression expansion target impulse response column vector and clutter channel column are vectorial respectively.
B: when k pulse group finishes, collect the echoed signal of M subpulse at receiver end, utilization is estimated the off-line of noise and jamming power level, can obtain the optimum On-line Estimation value to expansion target impulse response column vector and clutter space covariance, is expressed as respectively
With
The simple flow of this step as shown in Figure 4.
C: enter in next-door neighbour's next pulse group k+1.When the pulse group begins, obtain to expand the estimated value of target impulse response and clutter covariance based on k pulse group, at the radar transmitter end, the form of define system output SCNR, and take maximization SCNR as Optimality Criteria, adopt optimal detection Waveform Design algorithm to come optimal design to satisfy the constant envelope signal U of actual radar system demand
K+1, the simple flow of this step as shown in Figure 5.
D: the optimum that utilize to obtain transmits, and all adopts the optimum U that transmits in M the subpulse in k+1 pulse group
K+1
E: when k+1 pulse group finishes, based on the echoed signal Y that receives
K+1Make up the Generalized Likelihood Ratio detecting device, detect target and whether occur, and computing system output SCNR is than the improvement situation of last pulse group.If SCNR has remarkable lifting, then in k+2 pulse group, no longer adjust transmitted waveform; Otherwise, enter in k+2 the pulse group, return rapid a.
Fig. 6 is the detection statistics result schematic diagram of the prompt change method of transmitted waveform, has provided receiver operating characteristic curves (ROC) comparison diagram that the method and traditional radar adopt fixed L FM waveform all the time, can find out, at certain false-alarm probability (P
FA) under, institute's extracting method can obtain higher detection probability (P
D), guarantee that cognitive radar has better system performance.
The above only is preferred implementation of the present invention; should be pointed out that for those skilled in the art, under the prerequisite that does not break away from the technology of the present invention principle; can also make some improvement and replacement, these improvement and replacement also should be considered as protection scope of the present invention.
Claims (9)
1. a waveform victory becomes cognitive radar system, it is characterized in that comprising:
Transmitting element is used for to the constant ripple of space radiation amplitude;
Receiving element is used for receiving the first echo signal through after the reflection of expansion target and clutter scatterer;
Target and clutter estimation unit are used for the echoed signal that receives is carried out optimal processing, obtain the estimated value of expansion target impulse response and clutter space covariance;
The transmitted waveform design cell, the estimated value that is used for extension-based target impulse response and clutter space covariance is set the optimization index, and adopt optimal detection Waveform Design algorithm optimization and adjust the concrete form of baseband transmission waveform, optimize and adjust after transmitted wave carry out radiation by transmitting element, corresponding to described optimization and the second echo signal of the transmitted wave after adjusting receive by described receiving element;
Detecting unit is used for the second echo signal that receiving element receives is carried out optimal processing, and the second echo signal after processing is detected, and judges whether optimum results reaches predetermined value.
2. system as claimed in claim 1 is characterized in that described first echo signal is comprised of target echo signal, clutter echoed signal and noise.
3. system as claimed in claim 1 is characterized in that described target and clutter estimation unit comprise the optimal processing unit, is used for utilizing knowledge accumulation that first echo signal is processed, and described knowledge accumulation comprises the power level of noise and interference.
4. system as claimed in claim 3 is characterized in that target and clutter estimation unit also comprise the off-line estimation unit, is used for that noise and jamming power level are carried out off-line and estimates, obtains the estimated value of expansion target impulse response and clutter space covariance.
5. system as claimed in claim 1 is characterized in that, optimal detection Waveform Design algorithm take maximization output noise assorted than SCNR as Optimality Criteria, carry out the optimization of baseband transmission ripple.
6. system as claimed in claim 1 is characterized in that, optimize and adjust after transmitted wave be constant envelope signal.
7. system as claimed in claim 1 is characterized in that, comprises the Generalized Likelihood Ratio detector module in the detecting unit, for detection of the target second echo signal.
8. the cognitive radar implementation method of the prompt change of waveform is characterized in that, may further comprise the steps:
A, cognitive radar start working in the prepulse group k: transmitter terminal is to the constant ripple of space radiation amplitude, and after the reflection of this ripple through expansion target and clutter scatterer, receiver end receives first echo signal;
When b, pulse group k finished, receiver end carried out optimal processing to the first echo signal that receives, and obtained the estimated value of expansion target impulse response and clutter space covariance;
C, enter in next-door neighbour's next pulse group K+1: the estimated value of transmitter terminal extension-based target impulse response and clutter space covariance, set and optimize index, adopt optimal detection Waveform Design algorithm, optimize and adjustment baseband transmission ripple, the transmitted wave after adjusting is radiated in the space;
D, receiver end receive second echo signal, and second echo signal carried out optimal processing, when pulse group K+1 finishes, the second echo signal after processing is detected, if optimum results reaches default definite value then no longer adjusts transmitted waveform in pulse group K+2; Otherwise, enter pulse group K+2 and return step a.
9. method as claimed in claim 8 is characterized in that the constant ripple of amplitude is linear frequency modulation ripple LFM.
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| CN103197297A (en) * | 2013-03-21 | 2013-07-10 | 西安电子科技大学 | Radar moving target detection method based on cognitive framework |
| CN104597440A (en) * | 2015-01-12 | 2015-05-06 | 中国人民解放军63921部队 | Intelligent radar based on target motion matching |
| CN106093906A (en) * | 2016-07-19 | 2016-11-09 | 西安交通大学 | A kind of real-time target method for estimating distance of High-precision high-frequency spectrum utilization rate |
| CN107167775A (en) * | 2017-05-23 | 2017-09-15 | 哈尔滨工业大学 | One kind is based on the anti-multi-hop noise jamming waveform design method of cognitive radar |
| CN108896967A (en) * | 2018-05-11 | 2018-11-27 | 清华大学 | Range extension target detection method and device based on clutter covariance matrix estimation |
| CN110146887A (en) * | 2019-06-11 | 2019-08-20 | 电子科技大学 | Cognition synthetic aperture radar waveform design method based on joint optiaml ciriterion |
| CN110618399A (en) * | 2019-08-26 | 2019-12-27 | 西安空间无线电技术研究所 | Space-based radar electromagnetic spectrum environment cognitive system and interference countermeasure method |
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Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103197297A (en) * | 2013-03-21 | 2013-07-10 | 西安电子科技大学 | Radar moving target detection method based on cognitive framework |
| CN103197297B (en) * | 2013-03-21 | 2014-08-06 | 西安电子科技大学 | Radar moving target detection method based on cognitive framework |
| CN104597440A (en) * | 2015-01-12 | 2015-05-06 | 中国人民解放军63921部队 | Intelligent radar based on target motion matching |
| CN104597440B (en) * | 2015-01-12 | 2017-06-16 | 中国人民解放军63921部队 | Intelligent radar based on target motion match |
| CN106093906A (en) * | 2016-07-19 | 2016-11-09 | 西安交通大学 | A kind of real-time target method for estimating distance of High-precision high-frequency spectrum utilization rate |
| CN107167775A (en) * | 2017-05-23 | 2017-09-15 | 哈尔滨工业大学 | One kind is based on the anti-multi-hop noise jamming waveform design method of cognitive radar |
| CN107167775B (en) * | 2017-05-23 | 2020-05-19 | 哈尔滨工业大学 | Multi-hop clutter interference resisting waveform design method based on cognitive radar |
| CN108896967A (en) * | 2018-05-11 | 2018-11-27 | 清华大学 | Range extension target detection method and device based on clutter covariance matrix estimation |
| CN108896967B (en) * | 2018-05-11 | 2020-11-17 | 清华大学 | Method and device for detecting distance extended target based on clutter covariance matrix estimation |
| CN110146887A (en) * | 2019-06-11 | 2019-08-20 | 电子科技大学 | Cognition synthetic aperture radar waveform design method based on joint optiaml ciriterion |
| CN110618399A (en) * | 2019-08-26 | 2019-12-27 | 西安空间无线电技术研究所 | Space-based radar electromagnetic spectrum environment cognitive system and interference countermeasure method |
| CN110618399B (en) * | 2019-08-26 | 2021-11-16 | 西安空间无线电技术研究所 | Space-based radar electromagnetic spectrum environment cognitive system and interference countermeasure method |
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Application publication date: 20130109 |