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AUTOFOCUSING OF SYNTHETIC HRR RADAR USING STEPPED FREQUENCY WAVEFORMS
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作者 朱岱寅 朱兆达 戴明桢 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 1999年第1期14-20,共7页
Most operating radar systems don′t have sufficient frequency bandwidth to produce high range resolution(HRR) profile of a target. But we can use stepped frequency waveform in a narrow band coherent radar to obtai... Most operating radar systems don′t have sufficient frequency bandwidth to produce high range resolution(HRR) profile of a target. But we can use stepped frequency waveform in a narrow band coherent radar to obtain the HRR profile of a target. For moving targets which are of great importance in practical radar usage, autofocusing,i.e. phase correction, is a necessary and critical step of the synthetic HRR processing. The purpose of autofocusing is to remove the radial motion effect of the target from radar echoes, and only reserve the stepped frequency effect which is the basis of synthetic HRR capability. We investigate two autofocusing approaches for synthetic HRR radars using stepped frequency waveform in this paper. The first is motion fitting method. This method depends on a certain parametric model, and is computationally expensive. Then we propose the iterative dominant scatterer method. It is robust, non parametric and simple in computation in comparison with the motion fitting method. Experimental results based on data acquired by using a metallised scale model B 52 in a microwave anechoic chamber reveal the validity and effectiveness of the method. 展开更多
关键词 radars high range resolution autofocusing approaches stepped frequency waveforms
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Compensation for the Influence of Radar-Target Relative Speed on Step Frequency MMW Target Identification
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作者 杨军 祁载康 《Journal of Beijing Institute of Technology》 EI CAS 1998年第4期380-387,共8页
Aim To study the influence of radar-target relative speed on frequency MMW high-resolution ore-dimension distance profile and the compensation for it. Methods Based on the distance travelled by the electromagnetic wa... Aim To study the influence of radar-target relative speed on frequency MMW high-resolution ore-dimension distance profile and the compensation for it. Methods Based on the distance travelled by the electromagnetic wave, analyses were made for the compensation algorithm and the expression of the inverse FFT base distance was given.The relative importance of different compensation terms was studied in great detail. The concept of searching compensation was put forward. Results and Condclusion Dcm-△Dvimis the be distance of inverse FFT transformation, the effect caused by the distance △Dim on one-dimension profile is negligible, and the effect caused by the distance Dvim should not be neglected and must be compensated. 展开更多
关键词 MMW millimeter wave radar step frequency one-dimension distance profile velocity compensation
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Novel imaging methods of stepped frequency radar based on compressed sensing 被引量:4
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作者 Jihong Liu Shaokun Xu Xunzhang Gao Xiang Li 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2012年第1期47-56,共10页
The theory of compressed sensing (CS) provides a new chance to reduce the data acquisition time and improve the data usage factor of the stepped frequency radar system. In light of the sparsity of radar target refle... The theory of compressed sensing (CS) provides a new chance to reduce the data acquisition time and improve the data usage factor of the stepped frequency radar system. In light of the sparsity of radar target reflectivity, two imaging methods based on CS, termed the CS-based 2D joint imaging algorithm and the CS-based 2D decoupled imaging algorithm, are proposed. These methods incorporate the coherent mixing operation into the sparse dictionary, and take random measurements in both range and azimuth directions to get high resolution radar images, thus can remarkably reduce the data rate and simplify the hardware design of the radar system while maintaining imaging quality. Ex- periments from both simulated data and measured data in the anechoic chamber show that the proposed imaging methods can get more focused images than the traditional fast Fourier trans- form method. Wherein the joint algorithm has stronger robustness and can provide clearer inverse synthetic aperture radar images, while the decoupled algorithm is computationally more efficient but has slightly degraded imaging quality, which can be improved by increasing measurements or using a robuster recovery algorithm nevertheless. 展开更多
关键词 radar imaging compressed sensing (CS) stepped frequency random sampling.
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Simutaneous radar imaging and velocity measuring with step frequency waveforms 被引量:4
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作者 Yuan Haotian Wen Shuliang Cheng Zhen 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2009年第4期741-747,共7页
The principle and method of both radar target imaging and velocity measurement simultaneously based on step frequency waveforms is presented. Velocity compensation is necessary in order to obtain the good High resolut... The principle and method of both radar target imaging and velocity measurement simultaneously based on step frequency waveforms is presented. Velocity compensation is necessary in order to obtain the good High resolution range profile since this waveform is greatly sensitive to the Doppler shift. The velocity measurement performance of the four styles is analyzed with two pulse trains consisted of positive and negative step frequency waveforms. The velocity of targets can be estimated first coarsely by using the pulse trains with positive-positive step frequency combination, and then fine by positive-negative combination. Simulation results indicate that the method can accomplish the accurate estimation of the velocity with efficient computation and good anti-noise performance and obtain the good HRRP simultaneously. 展开更多
关键词 high resolution radar step frequency waveform velocity measuring high resolution range profile.
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Grating lobes suppression method for stepped frequency GB-SAR system 被引量:3
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作者 Tao Zeng Cong Mao +3 位作者 Cheng Hu Mao Zhu Weiming Tian Jingjing Ren 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2014年第6期987-995,共9页
A grating lobes suppression method for chirp-subpulse stepped frequency(CSSF) signals is proposed, which is applied to deformation monitoring using the ground based synthetic aperture radar(GB-SAR) system. This me... A grating lobes suppression method for chirp-subpulse stepped frequency(CSSF) signals is proposed, which is applied to deformation monitoring using the ground based synthetic aperture radar(GB-SAR) system. This method is based on accurate estimation and correction of the phase and amplitude error along two dimensions(range and azimuth), i.e., the error estimation inside the subpulse(in-subpulse error) and across the stepped frequency subpulses(cross-subpulse error) of transmitted CSSF signals. Validated both with simulated data and experimental data recorded in the deformation monitoring campaign, it can be seen that the method as well as the relative conclusions can be fully and effectively applied to most of the stepped frequency systems. 展开更多
关键词 chirp-subpulse stepped frequency signal(CSSF) sup-pression of grating lobes ground based synthetic aperture radar differential interferometer SAR error analysis
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A Novel 2-D Signal Processing Scheme for Quasi-Random Step Frequency Signal 被引量:2
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作者 位寅生 刘永坦 许荣庆 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2003年第3期77-80,共4页
Due to the heavy congestion in HF bands, HF radars are restricted to operating within narrow frequency bands. To improve the system bandwidth and avoid heavy interference bands, a quasi-random step frequency signal wi... Due to the heavy congestion in HF bands, HF radars are restricted to operating within narrow frequency bands. To improve the system bandwidth and avoid heavy interference bands, a quasi-random step frequency signal with discontinuous bands is presented. A novel two-dimensional signal processing scheme for this signal is proposed on the basis of delicate signal analysis. Simulation results demonstrate that the scheme could successfully realize the resolutions by decoupling the range-Doppler ambiguity, and effectively suppress the maximal sidelobe. Moreover, the scheme is simple and has good numerical stability. 展开更多
关键词 Random step frequency Sidelobe suppression Signal processing.
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Analysis and application of wavelet transform in target imaging and detection of stepped frequency MMW radar 被引量:1
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作者 ZhaoBin 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2005年第1期11-20,共10页
The imaging and target detection methods for stepped frequency signal based on the wavelet transform and its power spectrum are investigated. Not only an imaging and target detection algorithm for stepped frequency si... The imaging and target detection methods for stepped frequency signal based on the wavelet transform and its power spectrum are investigated. Not only an imaging and target detection algorithm for stepped frequency signal based on the wavelet transform, but also its respective power spectrum are proposed. The multisampling property of stepped frequency signal is studied and wavelet transform is well suited for analyzing the signal. After multisampling property of stepped frequency signal being studied, it is shown that the wavelet transform is appropriate to analyze the signal. Based on the theory, the wavelet power spectrum analysis is applied to obtain the target range profile and the binary wavelet transform is used to perform target detection. To determine a suitable wavelet scaling for imaging of range profile's MMW radar, the distance resolution ΔR technique is proposed. The effectiveness of this new method is evaluated using simulated noisy radar signal. Results show that the proposed method can bring out the exactness and low computational complexity of this method. 展开更多
关键词 MMW radar wavelets transform stepped frequency range profile.
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ANALYSIS AND PROCESSING OF LMF-COSTAS STEPPED FREQUENCY RADAR SIGNAL
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作者 Mu Shanxiang Ji Xiaoli Li Ming Li Xingguo (School of Electron. Eng. & Optoelectronic Tech., Nanjing Univ. of Sci. & Tech., Nanjing 210094) 《Journal of Electronics(China)》 2003年第6期407-413,共7页
Linear Modulated Frequency (LMF) Costas Stepped Frequency Radar (SFR) signal is introduced. Its ambiguity function is derived and analyzed in detail and its feasibility is validated in theory. The scheme of the propos... Linear Modulated Frequency (LMF) Costas Stepped Frequency Radar (SFR) signal is introduced. Its ambiguity function is derived and analyzed in detail and its feasibility is validated in theory. The scheme of the proposed signal processing is also presented. The results of theoretic analysis and simulation show that, by using the proposed signal and increasing the bandwidth of the total stepped frequency, the ambiguity sidelobe is well suppressed and the range-velocity coupling in the stepped frequency radar is also greatly weakened. 展开更多
关键词 Stepped frequency Linear Modulated frequency (LMF) Costas frequency coding Ambiguity function Doppler influence
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Qatar Airways Steps Up Frequency to Shanghai
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《China's Foreign Trade》 2006年第4期56-,共1页
  Fourth Weekly Falight Added To China's Commercial Capital.   Doha, QATAR - Qatar Airways has stepped up frequency on its highly-popular Doha - Shanghai route with the introduction of a fourth weekly schedul...   Fourth Weekly Falight Added To China's Commercial Capital.   Doha, QATAR - Qatar Airways has stepped up frequency on its highly-popular Doha - Shanghai route with the introduction of a fourth weekly scheduled flight.   …… 展开更多
关键词 Qatar Airways Steps Up frequency to Shanghai
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Direct Digital Frequency Control Based on the Phase Step Change Characteristic between Signals
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作者 Zhao-Min Jia Xu-Hai Yang +3 位作者 Bao-Qi Sun Xiao-Ping Zhou Bo Xiang Xin-Yu Dou 《Chinese Physics Letters》 SCIE CAS CSCD 2017年第9期29-32,共4页
We present a new digital phase lock technology to achieve the frequency control and transformation through high precision multi-cycle group synchronization between signals without the frequency transformation circuit.... We present a new digital phase lock technology to achieve the frequency control and transformation through high precision multi-cycle group synchronization between signals without the frequency transformation circuit. In the case of digital sampling, the passing zero point of the phase of the controlled signal has the phase step characteristic, the phase step of the passing zero point is monotonic continuous with high resolution in the phase lock process, and using the border effect of digital fuzzy area, the gate can synchronize with the two signals, the quantization error is reduced. This technique is quite different from the existing methods of frequency transformation and frequency synthesis, the phase change characteristic between the periodic signals with different nominal is used. The phase change has the periodic phenomenon, and it has the high resolution step value. With the application of the physical law, the noise is reduced because of simplifying frequency transformation circuits, and the phase is locked with high precision. The regular phase change between frequency signals is only used for frequency measurement, and the change has evident randomness, but this randomness is greatly reduced in frequency control, and the certainty of the process result is clear. The experiment shows that the short term frequency stability can reach 10-12/s orders of magnitude. 展开更多
关键词 Direct Digital frequency Control Based on the Phase Step Change Characteristic between Signals
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Simple PID Parameter Tuning Method Based on Outputs of the Closed Loop System 被引量:12
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作者 HAN Jianda ZHU Zhiqiang +1 位作者 JIANG Ziya HE Yuqing 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2016年第3期465-474,共10页
Most of the existing PID parameters tuning methods are only effective with pre-known accurate system models, which often require some strict identification experiments and thus infeasible for many complicated systems.... Most of the existing PID parameters tuning methods are only effective with pre-known accurate system models, which often require some strict identification experiments and thus infeasible for many complicated systems. Actually, in most practical engineering applications, it is desirable for the PID tuning scheme to be directly based on the input-output response of the closed-loop system. Thus, a new parameter tuning scheme for PID controllers without explicit mathematical model is developed in this paper. The paper begins with a new frequency domain properties analysis of the PID controller. After that, the definition of characteristic frequency for the PID controller is given in order to study the mathematical relationship between the PID parameters and the open-loop frequency properties of the controlled system. Then, the concepts of M-field and θ-field are introduced, which are then used to explain how the PID control parameters influence the closed-loop frequency-magnitude property and its time responses. Subsequently, the new PID parameter tuning scheme, i.e., a group of tuning rules, is proposed based on the preceding analysis. Finally, both simulations and experiments are conducted, and the results verify the feasibility and validity of the proposed methods. This research proposes a PID parameter tuning method based on outputs of the closed loop system. 展开更多
关键词 PID control characteristic frequency step response frequency property
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Stepped frequency chirp signal imaging radar jamming using two-dimensional nonperiodic phase modulation 被引量:1
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作者 Qihua WU Feng ZHAO +3 位作者 Tiehua ZHAO Xiaobin LIU Junjie WANG Shunping XIAO 《Frontiers of Information Technology & Electronic Engineering》 SCIE EI CSCD 2023年第3期433-446,共14页
Stepped frequency chirp signal obtains high-resolution radar images by synthesizing multiple narrowband chirp pulses.It has been one of the most commonly used wideband radar waveforms due to its lower demand for radar... Stepped frequency chirp signal obtains high-resolution radar images by synthesizing multiple narrowband chirp pulses.It has been one of the most commonly used wideband radar waveforms due to its lower demand for radar instant bandwidth.In this paper,we propose a radar jamming method using two-dimensional nonperiodic phase modulation against stepped frequency chirp signal imaging radar.Using the unique property of nonperiodic phase modulation,the proposed method can generate high-level sidelobes that perform as a special blanket jamming along both the range and azimuth directions and make the target unrecognizable.Then,the influence of different modulation parameters,such as the code width and duty ratio,are further discussed.Based on this,the corresponding parameter design principles are presented.Finally,the validity of the proposed method is demonstrated by the Yake-42 plane data simulation and measured unmanned aerial vehicle data experiment. 展开更多
关键词 Radar jamming Stepped frequency chirp signal Nonperiodic phase modulation Wideband radar
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Research of Hybrid Modulation Radar Signal
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作者 Kai-Feng Guo Yun Lin +1 位作者 Meng Wang Xiao-Chun Xu 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2013年第3期35-39,共5页
Based on the advantage of phase coded signal and stepped frequency signal,a new hybrid modulation signal is introduced in this paper. It combines phase code modulation during the pulse with stepped frequency modulatio... Based on the advantage of phase coded signal and stepped frequency signal,a new hybrid modulation signal is introduced in this paper. It combines phase code modulation during the pulse with stepped frequency modulation between the pulses, which is named as phase-coded stepped-frequency ( PCSF ) signal. By analyzing its waveform and ambiguity function,the comparison between Stepped-Frequency ( SF) signal and PCSF signal is given,which shows that the PCSF signal is better than SF signal. Finally,the signal processing method with two stage compressed processing is presented. The simulation results show that this new hybrid modulation radar signal can get a higher stepped frequency than ordinary SF signal,realize the same equivalent bandwidth with less pulse number,and solve the conflict among the stepped frequency,the number of pulse, and transmit average power. Under the premises of a certain range resolution,this new hybrid modulation radar signal not only raises the data rate of radar system,but also reduces Doppler sensitivity with a good prospect, and the effect of one-dimensional range profile is much better than that of traditional SF signal. Therefore,this new hybrid modulation radar signal can be widely used in application. 展开更多
关键词 phase coded stepped frequency hybrid modulation signal ambiguity function signal processing
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HPRF pulse Doppler stepped frequency radar 被引量:9
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作者 LONG Teng REN LiXiang 《Science in China(Series F)》 2009年第5期883-893,共11页
Stepped frequency radar is a well known scheme to generate high range resolution profile (HRRP) of targets. Through appropriate radar parameter design, the radar enables both unambiguous velocity measurement and hig... Stepped frequency radar is a well known scheme to generate high range resolution profile (HRRP) of targets. Through appropriate radar parameter design, the radar enables both unambiguous velocity measurement and high resolution ranging within a single dwell in a high pulse repetition frequency (HPRF) mode. This paper analyzes in detail the design principle of the HPRF stepped frequency radar system, the solution to its ambiguity issue, as well as its signal processing method. Both theoretical analysis and simulation results demonstrate that the proposed radar scheme can work independently to solve the problem of motion compensation, and is therefore highly applicable to many new types of radar. 展开更多
关键词 DFT HPRF pulse Doppler radar stepped frequency radar
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