Orthogonal frequency division multiplexing（OFDM） radar with multicarrier phase-coded waveforms has been recently introduced to achieve high range resolution.The conventional method for obtaining the high resolution ...Orthogonal frequency division multiplexing（OFDM） radar with multicarrier phase-coded waveforms has been recently introduced to achieve high range resolution.The conventional method for obtaining the high resolution range profile（HRRP） is based on matched filters.A method of synthesizing HRRP based on the fast Fourier transform（FFT） and decoding is proposed.The mathematical expressions of HRRP are derived by assuming an elementary scenario of point-scattering targets.Based on the characteristic of OFDM multicarrier signals,it mainly analyzes the influence on HRRP exerted by several factors,such as velocity compensation errors,the sampling frequency offset,and so on.The conclusions are significant for the design of the OFDM imaging radar.Finally,the simulation results demonstrate the validity of the conclusions.展开更多
Sparse-array Synthetic Impulse and Aperture Radar (SIAR) can isotropically radiate by employing multiple frequencies (synthetic pulse) and multiple antennas (synthetic antenna). According to Ambiguity Function(AF), it...Sparse-array Synthetic Impulse and Aperture Radar (SIAR) can isotropically radiate by employing multiple frequencies (synthetic pulse) and multiple antennas (synthetic antenna). According to Ambiguity Function(AF), its range resolution depends only on bandwidth of transmitted signals, however, the distance grating lobes emerge when increasing the time-bandwidth product of transmitted signals. The performance of pulse compression is analyzed with the transmitted signals modulated by phase-coded sequences. It is seen that greater ratio of pulse compression and suppression of range sidelobe in SIAR can be obtained, and its effective range and range resolution is increased as well.展开更多
To obtain the radar High Range Resolution (HRR) profile of the slowly moving ground target in strong clutter background, the Phase-Coded Hopped-Frequency (PCHF) waveform is proposed. By multiple-bursts coherent proces...To obtain the radar High Range Resolution (HRR) profile of the slowly moving ground target in strong clutter background, the Phase-Coded Hopped-Frequency (PCHF) waveform is proposed. By multiple-bursts coherent processing, the HRR profile synthesis, target velocity compensation and clutter compression can be accomplished simultaneously. The new waveform is shown to have good ability to suppress ground clutter and good Electronic Counter-CounterMeasures (ECCM) ability as well. The clutter compression performance of the proposed method is verified by the numerical results.展开更多
Orthogonal frequency division multiplexing (OFDM) waveform enables radar and communication functions simultaneously, which encounters low angle resolution and poor data rate for traditional single input single output ...Orthogonal frequency division multiplexing (OFDM) waveform enables radar and communication functions simultaneously, which encounters low angle resolution and poor data rate for traditional single input single output (SISO) systems. To solve these problems, an integrated radar and communication system (IRCS) with multiple input multiple output (MIMO) OFDM waveform is proposed. The different limitations of radar and communication in designing such a system are investigated. Then, an optimization problem is devised to obtain suitable system parameters, including the number of subcarriers, subcarrier spacing, number of symbols, pulse repetition frequency (PRF) and length of cyclic prefix (CP). Finally, to satisfy the requirements of both radar and communication, the IRCS parameters are derived in three typical cases. Several numerical results are presented to illustrate the demands of radar and communication, inconsistent or consistent, for the IRCS parameters and the superiority of the proposed system.展开更多
In this paper,we study the accuracy of delay-Doppler parameter estimation of targets in a passive radar using orthogonal frequency division multiplexing(OFDM)signal.A coarse-fine joint estimation method is proposed to...In this paper,we study the accuracy of delay-Doppler parameter estimation of targets in a passive radar using orthogonal frequency division multiplexing(OFDM)signal.A coarse-fine joint estimation method is proposed to achieve better estimation accuracy of target parameters without excessive computational burden.Firstly,the modulation symbol domain(MSD)method is used to roughly estimate the delay and Doppler of targets.Then,to obtain high-precision Doppler estimation,the atomic norm(AN)based on the multiple measurement vectors(MMV)model(MMV-AN)is used to manifest the signal sparsity in the continuous Doppler domain.At the same time,a reference signal compensation(RSC)method is presented to obtain highprecision delay estimation.Simulation results based on the OFDM signal show that the coarse-fine joint estimation method based on AN-RSC can obtain a more accurate estimation of target parameters compared with other algorithms.In addition,the proposed method also possesses computational advantages compared with the joint parameter estimation.展开更多
Frequency diverse array(FDA)radar applies a tiny frequency offset across its adjacent transmitting array elements to generate a range-angle-dependent beampattern.The increased degrees-of-freedom(DOFs)in range domain c...Frequency diverse array(FDA)radar applies a tiny frequency offset across its adjacent transmitting array elements to generate a range-angle-dependent beampattern.The increased degrees-of-freedom(DOFs)in range domain can help improve the performance of radar in target detection,localization,and clutter suppression.Passive radar utilizes uncontrollable external signal as illuminator,which makes it difficult to apply traditional frequency diverse process method.However,the third-party illuminator such as Orthogonal Frequency Division Multiplexing(OFDM)signal usually consists of several closely spaced modulated carriers,and it has been widely selected as the illuminator for passive radar in recent years.Considering the orthogonality between even separated subcarriers,we propose a new frequency diverse process method by extracting and processing each subcarrier of received data independently and attempt to provide a range-angle dependent beampattern for OFDM passive radar.Numerical results and real data analyses verify the superiority of frequency diversity process on the received data of OFDM passive radar.展开更多
与线性调频连续波信号不同,采用正交频分复用调制(orthogonal frequency division multiplexing,OFDM)方案信号的雷达,当每个符号上调制的传输信息完全随机时,其模糊函数具有较高的旁瓣;当探测场景中存在较多较强的杂波时,目标回波对应...与线性调频连续波信号不同,采用正交频分复用调制(orthogonal frequency division multiplexing,OFDM)方案信号的雷达,当每个符号上调制的传输信息完全随机时,其模糊函数具有较高的旁瓣;当探测场景中存在较多较强的杂波时,目标回波对应的距离多普勒峰被淹没在脉压积累后的强杂波的旁瓣之下,导致目标无法被识别。目前已有的杂波抑制方案多面临杂波抑制度不足的问题。基于此,本文提出基于贪心策略的高效杂波处理方案,通过自适应逐点抑制强杂波,使旁瓣基底下降,目标信息浮现出来。并与实测数据进行了对比,结果表明,该方法取得了比常规方法更好的杂波抑制性能。展开更多
多输入多输出(MIMO)正交频分复用(OFDM)雷达通常采用等间距子载频交错(ESI),实现不同发射天线信号在频域的正交。然而,ESI存在距离依赖性的角度误差问题。针对该问题,文中提出一种基于距离分复用(RDM)MIMO OFDM雷达的目标参数估计方法...多输入多输出(MIMO)正交频分复用(OFDM)雷达通常采用等间距子载频交错(ESI),实现不同发射天线信号在频域的正交。然而,ESI存在距离依赖性的角度误差问题。针对该问题,文中提出一种基于距离分复用(RDM)MIMO OFDM雷达的目标参数估计方法。首先,建立RDM MIMO OFDM雷达信号模型,获得发射端在距离维的正交波形,使得雷达接收机的天线孔径得到明显扩展,提升角度分辨率;其次,在距离-速度处理和角度估计之间,提出一种二值掩码方法分离不同发射波形,代替了传统的带通滤波器,同时抑制噪声干扰,改善成像质量;最后,仿真验证所提方法的正确性和有效性,结果表明,与ESI相比,所提方法可以有效去除距离依赖性的角度误差,提升成像分辨率和角度参数估计精度。展开更多
多输入多输出(MIMO)正交频分复用(OFDM)雷达通常采用等间距子载频交错(ESI)方式,实现不同发射天线信号在频域的正交。然而,ESI存在距离依赖性的角度误差和距离模糊问题。针对该问题,提出了一种基于距离分复用(RDM)的MIMO OFDM雷达距离...多输入多输出(MIMO)正交频分复用(OFDM)雷达通常采用等间距子载频交错(ESI)方式,实现不同发射天线信号在频域的正交。然而,ESI存在距离依赖性的角度误差和距离模糊问题。针对该问题,提出了一种基于距离分复用(RDM)的MIMO OFDM雷达距离和角度联合估计方法。首先,建立RDM MIMO OFDM雷达信号模型,获得发射端在距离维的正交波形,同时消除了距离依赖性的角度误差;其次,在距离-速度-角度成像处理中采用改进DFT,代替传统DFT实现多普勒估计和校正;此外,在某些发射天线上额外添加相位偏移,打破目标峰值在距离维的等间距分布特性,通过搜索目标峰值距离索引差来确定模糊数,从而求解距离模糊问题。仿真结果验证了所提方法的有效性。展开更多
基金supported by the National Natural Science Foundation of China (6087213461072117)
文摘Orthogonal frequency division multiplexing（OFDM） radar with multicarrier phase-coded waveforms has been recently introduced to achieve high range resolution.The conventional method for obtaining the high resolution range profile（HRRP） is based on matched filters.A method of synthesizing HRRP based on the fast Fourier transform（FFT） and decoding is proposed.The mathematical expressions of HRRP are derived by assuming an elementary scenario of point-scattering targets.Based on the characteristic of OFDM multicarrier signals,it mainly analyzes the influence on HRRP exerted by several factors,such as velocity compensation errors,the sampling frequency offset,and so on.The conclusions are significant for the design of the OFDM imaging radar.Finally,the simulation results demonstrate the validity of the conclusions.
文摘Sparse-array Synthetic Impulse and Aperture Radar (SIAR) can isotropically radiate by employing multiple frequencies (synthetic pulse) and multiple antennas (synthetic antenna). According to Ambiguity Function(AF), its range resolution depends only on bandwidth of transmitted signals, however, the distance grating lobes emerge when increasing the time-bandwidth product of transmitted signals. The performance of pulse compression is analyzed with the transmitted signals modulated by phase-coded sequences. It is seen that greater ratio of pulse compression and suppression of range sidelobe in SIAR can be obtained, and its effective range and range resolution is increased as well.
基金Supported by the National Natural Science Foundation of China (No.60302009).
文摘To obtain the radar High Range Resolution (HRR) profile of the slowly moving ground target in strong clutter background, the Phase-Coded Hopped-Frequency (PCHF) waveform is proposed. By multiple-bursts coherent processing, the HRR profile synthesis, target velocity compensation and clutter compression can be accomplished simultaneously. The new waveform is shown to have good ability to suppress ground clutter and good Electronic Counter-CounterMeasures (ECCM) ability as well. The clutter compression performance of the proposed method is verified by the numerical results.
基金supported by the National Natural Science Foundation of China(6123101761671352)
文摘Orthogonal frequency division multiplexing (OFDM) waveform enables radar and communication functions simultaneously, which encounters low angle resolution and poor data rate for traditional single input single output (SISO) systems. To solve these problems, an integrated radar and communication system (IRCS) with multiple input multiple output (MIMO) OFDM waveform is proposed. The different limitations of radar and communication in designing such a system are investigated. Then, an optimization problem is devised to obtain suitable system parameters, including the number of subcarriers, subcarrier spacing, number of symbols, pulse repetition frequency (PRF) and length of cyclic prefix (CP). Finally, to satisfy the requirements of both radar and communication, the IRCS parameters are derived in three typical cases. Several numerical results are presented to illustrate the demands of radar and communication, inconsistent or consistent, for the IRCS parameters and the superiority of the proposed system.
基金supported by the National Natural Science Foundation of China(6193101562071335)+1 种基金the Technological Innovation Project of Hubei Province of China(2019AAA061)the Natural Science F oundation of Hubei Province of China(2021CFA002)。
文摘In this paper,we study the accuracy of delay-Doppler parameter estimation of targets in a passive radar using orthogonal frequency division multiplexing(OFDM)signal.A coarse-fine joint estimation method is proposed to achieve better estimation accuracy of target parameters without excessive computational burden.Firstly,the modulation symbol domain(MSD)method is used to roughly estimate the delay and Doppler of targets.Then,to obtain high-precision Doppler estimation,the atomic norm(AN)based on the multiple measurement vectors(MMV)model(MMV-AN)is used to manifest the signal sparsity in the continuous Doppler domain.At the same time,a reference signal compensation(RSC)method is presented to obtain highprecision delay estimation.Simulation results based on the OFDM signal show that the coarse-fine joint estimation method based on AN-RSC can obtain a more accurate estimation of target parameters compared with other algorithms.In addition,the proposed method also possesses computational advantages compared with the joint parameter estimation.
基金the National Natural Science Foundation of China(61271400,62071335,61931015)Suzhou Science and Technology Planning Project:Key Industrial Technology Innovation(Prospective Application Research SYG202007)+2 种基金Hubei Province Technology Innovation Special Major Project(2019AAA061)Shenzhen Science and Technology Project(JCYJ20170818112037398)Hubei Province Science Fund for Creative Research Groups(2021CFA002)。
文摘Frequency diverse array(FDA)radar applies a tiny frequency offset across its adjacent transmitting array elements to generate a range-angle-dependent beampattern.The increased degrees-of-freedom(DOFs)in range domain can help improve the performance of radar in target detection,localization,and clutter suppression.Passive radar utilizes uncontrollable external signal as illuminator,which makes it difficult to apply traditional frequency diverse process method.However,the third-party illuminator such as Orthogonal Frequency Division Multiplexing(OFDM)signal usually consists of several closely spaced modulated carriers,and it has been widely selected as the illuminator for passive radar in recent years.Considering the orthogonality between even separated subcarriers,we propose a new frequency diverse process method by extracting and processing each subcarrier of received data independently and attempt to provide a range-angle dependent beampattern for OFDM passive radar.Numerical results and real data analyses verify the superiority of frequency diversity process on the received data of OFDM passive radar.
文摘与线性调频连续波信号不同,采用正交频分复用调制(orthogonal frequency division multiplexing,OFDM)方案信号的雷达,当每个符号上调制的传输信息完全随机时,其模糊函数具有较高的旁瓣;当探测场景中存在较多较强的杂波时,目标回波对应的距离多普勒峰被淹没在脉压积累后的强杂波的旁瓣之下,导致目标无法被识别。目前已有的杂波抑制方案多面临杂波抑制度不足的问题。基于此,本文提出基于贪心策略的高效杂波处理方案,通过自适应逐点抑制强杂波,使旁瓣基底下降,目标信息浮现出来。并与实测数据进行了对比,结果表明,该方法取得了比常规方法更好的杂波抑制性能。
文摘多输入多输出(MIMO)正交频分复用(OFDM)雷达通常采用等间距子载频交错(ESI),实现不同发射天线信号在频域的正交。然而,ESI存在距离依赖性的角度误差问题。针对该问题,文中提出一种基于距离分复用(RDM)MIMO OFDM雷达的目标参数估计方法。首先,建立RDM MIMO OFDM雷达信号模型,获得发射端在距离维的正交波形,使得雷达接收机的天线孔径得到明显扩展,提升角度分辨率;其次,在距离-速度处理和角度估计之间,提出一种二值掩码方法分离不同发射波形,代替了传统的带通滤波器,同时抑制噪声干扰,改善成像质量;最后,仿真验证所提方法的正确性和有效性,结果表明,与ESI相比,所提方法可以有效去除距离依赖性的角度误差,提升成像分辨率和角度参数估计精度。
文摘多输入多输出(MIMO)正交频分复用(OFDM)雷达通常采用等间距子载频交错(ESI)方式,实现不同发射天线信号在频域的正交。然而,ESI存在距离依赖性的角度误差和距离模糊问题。针对该问题,提出了一种基于距离分复用(RDM)的MIMO OFDM雷达距离和角度联合估计方法。首先,建立RDM MIMO OFDM雷达信号模型,获得发射端在距离维的正交波形,同时消除了距离依赖性的角度误差;其次,在距离-速度-角度成像处理中采用改进DFT,代替传统DFT实现多普勒估计和校正;此外,在某些发射天线上额外添加相位偏移,打破目标峰值在距离维的等间距分布特性,通过搜索目标峰值距离索引差来确定模糊数,从而求解距离模糊问题。仿真结果验证了所提方法的有效性。
