Ubiquitous radar is a new radar system that provides continuous and uninterrupted multifunction capability within a coverage volume. Continuous coverage from close-in ＂pop-up＂ targets in clutter to long-range target...Ubiquitous radar is a new radar system that provides continuous and uninterrupted multifunction capability within a coverage volume. Continuous coverage from close-in ＂pop-up＂ targets in clutter to long-range targets impacts selection of waveform parameters. The coherent processing interval （CPI） must be long enough to achieve a certain signal-to-noise ratio （SNR） that ensures the efficiency of detection. The condition of detection in the case of low SNR is analyzed, and three different cases that would occur during integration are discussed and a method to determine the CPI is presented. The simulation results show that targets detection with SNR as low as -26 dB in the experimental system can possibly determine the CPI.展开更多
分析了加窗和实信号情况下相干线谱检测器的检测性能。从频谱泄漏现象出发,通过对实信号做加窗处理,有效地降低了信号傅里叶变换后频谱泄漏的旁瓣级,提升了弱信号的探测能力;针对分段处理时同一频率不同数据段出现的相位差,采用相位补...分析了加窗和实信号情况下相干线谱检测器的检测性能。从频谱泄漏现象出发,通过对实信号做加窗处理,有效地降低了信号傅里叶变换后频谱泄漏的旁瓣级,提升了弱信号的探测能力;针对分段处理时同一频率不同数据段出现的相位差,采用相位补偿的方法,实现了各段数据的相干叠加。理论分析和计算机仿真表明,相比于平均功率谱检测器(Average Power Processor,AVGPR),加窗相位补偿检测器(Window Phase-Compensated Processor,WPCPR)有10 lg L(L为分段数)信噪比的提高,从而拓宽了相干线谱检测的适用范围。此外,还从频域波束形成的角度,给出了WPCPR能提高信噪比的一种物理解释,并指出了仿真中信噪比增益与理论值存在差异的原因。展开更多
This paper considers multi-frequency passive radar and develops a multi-frequency joint direction of arrival(DOA)estimation algorithm to improve estimation accuracy and resolution.The developed algorithm exploits the ...This paper considers multi-frequency passive radar and develops a multi-frequency joint direction of arrival(DOA)estimation algorithm to improve estimation accuracy and resolution.The developed algorithm exploits the sparsity of targets in the spatial domain.Specifically,we first extract the required frequency channel data and acquire the snapshot data through a series of preprocessing such as clutter suppression,coherent integration,beamforming,and constant false alarm rate(CFAR)detection.Then,based on the framework of sparse Bayesian learning,the target’s DOA is estimated by jointly extracting the multi-frequency data via evidence maximization.Simulation results show that the developed algorithm has better estimation accuracy and resolution than other existing multi-frequency DOA estimation algorithms,especially under the scenarios of low signalto-noise ratio(SNR)and small snapshots.Furthermore,the effectiveness is verified by the field experimental data of a multi-frequency FM-based passive radar.展开更多
雷达技术是为了探测远距离目标而发展起来的。弹载雷达处理回波信号,实现对移动目标的测速与测距。微弱运动目标的“远距、低可探测、高机动”性使传统的检测方法难以识别、探测、跟踪。为提高对这类目标的检测能力,常会对信号进行积累...雷达技术是为了探测远距离目标而发展起来的。弹载雷达处理回波信号,实现对移动目标的测速与测距。微弱运动目标的“远距、低可探测、高机动”性使传统的检测方法难以识别、探测、跟踪。为提高对这类目标的检测能力,常会对信号进行积累。但由于目标的运动,长时间积累会产生跨越距离走动单元与跨速度单元现象。研究了匀加速运动目标回波信号模型,分析其中引起距离走动的分项,分析比较用一阶与二阶Keystone算法校正距离走动的效果,选择用CZT-IFFT(Chirp-Z transformation-inverse fast fourier transform)的方法实现二阶Keystone校正距离弯曲与距离走动,并对比了不同校正方法的信噪比改善效果。展开更多
文摘Ubiquitous radar is a new radar system that provides continuous and uninterrupted multifunction capability within a coverage volume. Continuous coverage from close-in ＂pop-up＂ targets in clutter to long-range targets impacts selection of waveform parameters. The coherent processing interval （CPI） must be long enough to achieve a certain signal-to-noise ratio （SNR） that ensures the efficiency of detection. The condition of detection in the case of low SNR is analyzed, and three different cases that would occur during integration are discussed and a method to determine the CPI is presented. The simulation results show that targets detection with SNR as low as -26 dB in the experimental system can possibly determine the CPI.
文摘分析了加窗和实信号情况下相干线谱检测器的检测性能。从频谱泄漏现象出发,通过对实信号做加窗处理,有效地降低了信号傅里叶变换后频谱泄漏的旁瓣级,提升了弱信号的探测能力;针对分段处理时同一频率不同数据段出现的相位差,采用相位补偿的方法,实现了各段数据的相干叠加。理论分析和计算机仿真表明,相比于平均功率谱检测器(Average Power Processor,AVGPR),加窗相位补偿检测器(Window Phase-Compensated Processor,WPCPR)有10 lg L(L为分段数)信噪比的提高,从而拓宽了相干线谱检测的适用范围。此外,还从频域波束形成的角度,给出了WPCPR能提高信噪比的一种物理解释,并指出了仿真中信噪比增益与理论值存在差异的原因。
基金supported by the National Natural Science Foundation of China(62071335,61931015,61831009)the Technological Innovation Project of Hubei Province of China(2019AAA061).
文摘This paper considers multi-frequency passive radar and develops a multi-frequency joint direction of arrival(DOA)estimation algorithm to improve estimation accuracy and resolution.The developed algorithm exploits the sparsity of targets in the spatial domain.Specifically,we first extract the required frequency channel data and acquire the snapshot data through a series of preprocessing such as clutter suppression,coherent integration,beamforming,and constant false alarm rate(CFAR)detection.Then,based on the framework of sparse Bayesian learning,the target’s DOA is estimated by jointly extracting the multi-frequency data via evidence maximization.Simulation results show that the developed algorithm has better estimation accuracy and resolution than other existing multi-frequency DOA estimation algorithms,especially under the scenarios of low signalto-noise ratio(SNR)and small snapshots.Furthermore,the effectiveness is verified by the field experimental data of a multi-frequency FM-based passive radar.
文摘雷达技术是为了探测远距离目标而发展起来的。弹载雷达处理回波信号,实现对移动目标的测速与测距。微弱运动目标的“远距、低可探测、高机动”性使传统的检测方法难以识别、探测、跟踪。为提高对这类目标的检测能力,常会对信号进行积累。但由于目标的运动,长时间积累会产生跨越距离走动单元与跨速度单元现象。研究了匀加速运动目标回波信号模型,分析其中引起距离走动的分项,分析比较用一阶与二阶Keystone算法校正距离走动的效果,选择用CZT-IFFT(Chirp-Z transformation-inverse fast fourier transform)的方法实现二阶Keystone校正距离弯曲与距离走动,并对比了不同校正方法的信噪比改善效果。
