船载高频地波雷达(High Frequency Surface Wave Radar, HFSWR)的平台机动运动会使目标回波信号发生展宽,引起目标回波幅度和信噪比降低,进而对目标波达方向估计(Direction of Arrival, DOA)产生不利的影响。针对船载地波雷达展宽目标DO...船载高频地波雷达(High Frequency Surface Wave Radar, HFSWR)的平台机动运动会使目标回波信号发生展宽,引起目标回波幅度和信噪比降低,进而对目标波达方向估计(Direction of Arrival, DOA)产生不利的影响。针对船载地波雷达展宽目标DOA估计问题,本文提出了一种基于时频信息Toeplitz协方差重构的展宽目标DOA估计方法。该方法首先采用结合航向补偿的时频分析处理,来提取展宽目标信号的脊线,可为充分利用展宽目标时频信息来构建协方差矩阵奠定基础。然后对构建的协方差矩阵进行Toeplitz化,实现了非平稳噪声的抑制,提高了目标信噪比,解决了展宽目标信噪比下降的问题,从而实现目标的方位角估计。最后,通过仿真和实测数据对本文提出的方法进行验证,结果表明本文所提方法在相同信噪比和目标展宽程度下均方根误差比单峰值MUSIC和DBF方法减小了1.2°,证明了本文所提方法的有效性。展开更多
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
Multiple maneuvedng targets signal processing in high frequency radar is challenging due to the following difficulties： the interference between signals is severe because of significant spread of the target Doppler s...Multiple maneuvedng targets signal processing in high frequency radar is challenging due to the following difficulties： the interference between signals is severe because of significant spread of the target Doppler spectrum, the low signal to clutter ratio （SCR） environment degrades the performance of signal process- ing algorithms. This paper addresses this challenging problem by using an S2-method and an adaptive clutter rejection scheme. The proposed S2-method improves the S-method by eliminating inter- ference between signals, and thus it enables multi-target signals to be reconstructed individually. The proposed adaptive clutter rejec- tion scheme is based on an adaptive notch filter, which is designed according to the envelop of the clutter spectrum. Experiments with simulated targets added into radar sea clutter echo and real air target data illustrate the effectiveness of the proposed method.展开更多
Ultrahigh resolution synthetic aperture radar(SAR)imaging for ship targets is significant in SAR imaging,but it suffers from high frequency vibration of the platform,which will induce defocus into SAR imaging results....Ultrahigh resolution synthetic aperture radar(SAR)imaging for ship targets is significant in SAR imaging,but it suffers from high frequency vibration of the platform,which will induce defocus into SAR imaging results.In this paper,a novel compensation method based on the sinusoidal frequency modulation Fourier-Bessel transform(SFMFBT)is proposed,it can estimate the vibration errors,and the phase shift ambiguity can be avoided via extracting the time frequency ridge consequently.By constructing the corresponding compensation function and combined with the inverse SAR(ISAR)technique,well-focused imaging results can be obtained.The simulation imaging results of ship targets demonstrate the validity of the proposed approach.展开更多
针对高频地波雷达(High frequency surface wave radar,HFSWR)在探测中产生的回波数据,传统的人工识别和分类方法存在工作量大、效率低和主观性强等问题,本研究在分析一阶海杂波、电离层杂波和射频干扰的回波数据特性的基础上,创新性地...针对高频地波雷达(High frequency surface wave radar,HFSWR)在探测中产生的回波数据,传统的人工识别和分类方法存在工作量大、效率低和主观性强等问题,本研究在分析一阶海杂波、电离层杂波和射频干扰的回波数据特性的基础上,创新性地提出了基于YOLOv5识别模型的HFSWR杂波和干扰识别分类方法。该方法旨在帮助研究人员在海量实验数据中快速筛选出符合其科学研究需求的数据集,从而提高研究效率和数据准确性。在具体实施过程中,通过采用批量实测距离-多普勒(Range-Doppler,RD)谱数据对所提出模型进行训练和分析,使该方法能够在频域范围内对杂波和干扰进行有效识别。本研究以该识别分类算法为核心,进一步基于Python语言设计了一款地波雷达智能杂波和干扰识别分类软件。经过严格的批量实测数据测试验证,该软件能够满足设计需求,具有良好的可靠性,极大地提高了研究人员筛选有效实测数据的工作效率,为科学研究工作提供了有力的技术支撑。展开更多
High frequency surface wave radar (HFSWR) is well proved to have over the horizon (OTH) detection capability to weak aerial targets, such as concealed airplanes or cruise missiles. The most important problem of detect...High frequency surface wave radar (HFSWR) is well proved to have over the horizon (OTH) detection capability to weak aerial targets, such as concealed airplanes or cruise missiles. The most important problem of detection of fast and small targets using HFSWR is earlier warning, i.e. enlargement of detection range oftargets. Therefore, the detection threshold should be decreased as low as possible, but numerous false alarms are brought about at the same time. On this condition, conventional track initiation techniques, which normally require the probability of false alarm to be at the level of 10-6, will initiate enormous false tracks and lead to abnormal operation of tracking system. An adaptive modified hough transform (AMHT) track initiator is proposed accordingly and the relation of detection range to the performance of track initiator is analyzed in this paper. Simulations are performed to confirm the capability of track initiation to fast and small targets in dense clutter by AMHT track initiator. The tolerable probability of false alarm of detector can reach the level of 10 -3 . And it performs better than track initiator based on modified hough transform (MHT).展开更多
Digital down converter （DDC） is the main part of the next generation high frequency （HF） radar. In order to realize the single chip integrations of digital receiver hardware in the next generation HF Radar, a new ...Digital down converter （DDC） is the main part of the next generation high frequency （HF） radar. In order to realize the single chip integrations of digital receiver hardware in the next generation HF Radar, a new design for DDC by using FPGA is presented. Some important and practical applications are given in this paper, and the result can prove the validity. Because we can adjust the parameters freely according to our need, the DDC system can be adapted to the next generation HF radar system.展开更多
文摘船载高频地波雷达(High Frequency Surface Wave Radar, HFSWR)的平台机动运动会使目标回波信号发生展宽,引起目标回波幅度和信噪比降低,进而对目标波达方向估计(Direction of Arrival, DOA)产生不利的影响。针对船载地波雷达展宽目标DOA估计问题,本文提出了一种基于时频信息Toeplitz协方差重构的展宽目标DOA估计方法。该方法首先采用结合航向补偿的时频分析处理,来提取展宽目标信号的脊线,可为充分利用展宽目标时频信息来构建协方差矩阵奠定基础。然后对构建的协方差矩阵进行Toeplitz化,实现了非平稳噪声的抑制,提高了目标信噪比,解决了展宽目标信噪比下降的问题,从而实现目标的方位角估计。最后,通过仿真和实测数据对本文提出的方法进行验证,结果表明本文所提方法在相同信噪比和目标展宽程度下均方根误差比单峰值MUSIC和DBF方法减小了1.2°,证明了本文所提方法的有效性。
文摘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.
基金supported by the State Key Program of National Natural Science Foundation of China(61032011)
文摘Multiple maneuvedng targets signal processing in high frequency radar is challenging due to the following difficulties： the interference between signals is severe because of significant spread of the target Doppler spectrum, the low signal to clutter ratio （SCR） environment degrades the performance of signal process- ing algorithms. This paper addresses this challenging problem by using an S2-method and an adaptive clutter rejection scheme. The proposed S2-method improves the S-method by eliminating inter- ference between signals, and thus it enables multi-target signals to be reconstructed individually. The proposed adaptive clutter rejec- tion scheme is based on an adaptive notch filter, which is designed according to the envelop of the clutter spectrum. Experiments with simulated targets added into radar sea clutter echo and real air target data illustrate the effectiveness of the proposed method.
基金supported by the National Natural Science Foundation of China(61871146)the Fundamental Research Funds for the Central Universities(FRFCU5710093720)。
文摘Ultrahigh resolution synthetic aperture radar(SAR)imaging for ship targets is significant in SAR imaging,but it suffers from high frequency vibration of the platform,which will induce defocus into SAR imaging results.In this paper,a novel compensation method based on the sinusoidal frequency modulation Fourier-Bessel transform(SFMFBT)is proposed,it can estimate the vibration errors,and the phase shift ambiguity can be avoided via extracting the time frequency ridge consequently.By constructing the corresponding compensation function and combined with the inverse SAR(ISAR)technique,well-focused imaging results can be obtained.The simulation imaging results of ship targets demonstrate the validity of the proposed approach.
文摘针对高频地波雷达(High frequency surface wave radar,HFSWR)在探测中产生的回波数据,传统的人工识别和分类方法存在工作量大、效率低和主观性强等问题,本研究在分析一阶海杂波、电离层杂波和射频干扰的回波数据特性的基础上,创新性地提出了基于YOLOv5识别模型的HFSWR杂波和干扰识别分类方法。该方法旨在帮助研究人员在海量实验数据中快速筛选出符合其科学研究需求的数据集,从而提高研究效率和数据准确性。在具体实施过程中,通过采用批量实测距离-多普勒(Range-Doppler,RD)谱数据对所提出模型进行训练和分析,使该方法能够在频域范围内对杂波和干扰进行有效识别。本研究以该识别分类算法为核心,进一步基于Python语言设计了一款地波雷达智能杂波和干扰识别分类软件。经过严格的批量实测数据测试验证,该软件能够满足设计需求,具有良好的可靠性,极大地提高了研究人员筛选有效实测数据的工作效率,为科学研究工作提供了有力的技术支撑。
文摘High frequency surface wave radar (HFSWR) is well proved to have over the horizon (OTH) detection capability to weak aerial targets, such as concealed airplanes or cruise missiles. The most important problem of detection of fast and small targets using HFSWR is earlier warning, i.e. enlargement of detection range oftargets. Therefore, the detection threshold should be decreased as low as possible, but numerous false alarms are brought about at the same time. On this condition, conventional track initiation techniques, which normally require the probability of false alarm to be at the level of 10-6, will initiate enormous false tracks and lead to abnormal operation of tracking system. An adaptive modified hough transform (AMHT) track initiator is proposed accordingly and the relation of detection range to the performance of track initiator is analyzed in this paper. Simulations are performed to confirm the capability of track initiation to fast and small targets in dense clutter by AMHT track initiator. The tolerable probability of false alarm of detector can reach the level of 10 -3 . And it performs better than track initiator based on modified hough transform (MHT).
文摘Digital down converter （DDC） is the main part of the next generation high frequency （HF） radar. In order to realize the single chip integrations of digital receiver hardware in the next generation HF Radar, a new design for DDC by using FPGA is presented. Some important and practical applications are given in this paper, and the result can prove the validity. Because we can adjust the parameters freely according to our need, the DDC system can be adapted to the next generation HF radar system.
