In this paper,a time-frequency associated multiple signal classification(MUSIC)al-gorithm which is suitable for through-wall detection is proposed.The technology of detecting hu-man targets by through-wall radar can b...In this paper,a time-frequency associated multiple signal classification(MUSIC)al-gorithm which is suitable for through-wall detection is proposed.The technology of detecting hu-man targets by through-wall radar can be used to monitor the status and the location information of human targets behind the wall.However,the detection is out of order when classical MUSIC al-gorithm is applied to estimate the direction of arrival.In order to solve the problem,a time-fre-quency associated MUSIC algorithm suitable for through-wall detection and based on S-band stepped frequency continuous wave(SFCW)radar is researched.By associating inverse fast Fouri-er transform(IFFT)algorithm with MUSIC algorithm,the power enhancement of the target sig-nal is completed according to the distance calculation results in the time domain.Then convert the signal to the frequency domain for direction of arrival(DOA)estimation.The simulations of two-dimensional human target detection in free space and the processing of measured data are com-pleted.By comparing the processing results of the two algorithms on the measured data,accuracy of DOA estimation of proposed algorithm is more than 75%,which is 50%higher than classical MUSIC algorithm.It is verified that the distance and angle of human target can be effectively de-tected via proposed algorithm.展开更多
In this paper, a new phase preserving algorithm-the short IFFT algorithm for the burst-mode ScanSAR processing is presented. Analysis and simulation are done to verify the phase accuracy of this algorithm. Finally, th...In this paper, a new phase preserving algorithm-the short IFFT algorithm for the burst-mode ScanSAR processing is presented. Analysis and simulation are done to verify the phase accuracy of this algorithm. Finally, the phase accuracy of this algorithm by making interferogram with simulated burst-mode INSAR data is illustrated. The results show that this new algorithm works well for interferometric application of ScanSAR data.展开更多
昼夜混合路径条件下低频天波传播特性的研究对导航授时系统中应用模式拓展及低电离层参数反演均具有重要的研究意义.本文以地—电离层中100 kHz载频罗兰-C信号的时域有限差分(Finite Difference Time Domain,FDTD)仿真为前提,基于传统...昼夜混合路径条件下低频天波传播特性的研究对导航授时系统中应用模式拓展及低电离层参数反演均具有重要的研究意义.本文以地—电离层中100 kHz载频罗兰-C信号的时域有限差分(Finite Difference Time Domain,FDTD)仿真为前提,基于传统的过零检测和快速傅里叶变换(Fast Fourier Transform,FFT)/逆快速傅里叶变换(Inverse Fast Fourier Transform,IFFT)频谱相除算法,对昼夜混合信道(传播路径为东西取向)中地面接收的一跳天波进行模式区分及特性分析.给出了在白天至夜晚、夜晚至白天两种突变电离层下罗兰-C一跳天波中不同模式随收发距离的变化规律,同时给出了模式干涉区域优势场量的分布情况.结果表明,对于昼夜混合模型,一跳天波中存在来自不同高度及昼夜突跳边界反射的多种模式,基于传统方法检测的幅度相位存在不稳定干涉效应,模式界定困难,而基于FFT/IFFT频谱相除算法能够将主要模式进行细化区分,从而获得更高精度、更平稳的模式特性.展开更多
Orthogonal frequency division multiplexing (OFDM) is vastly used in wireless networks. Its superiority relies on the fact that information can be split in large amount of frequencies. Each frequency is called informat...Orthogonal frequency division multiplexing (OFDM) is vastly used in wireless networks. Its superiority relies on the fact that information can be split in large amount of frequencies. Each frequency is called information subcarrier. OFDM exhibits excellent annotation in channel fades and interferers as only a few subcarriers can be affected and consequently a small part of the original data stream can be lost. Orthogonality between frequencies ensures better spectrum management and obviates the danger of intersymbol interference. However, an essential problem exists. OFDM systems have high peak to average power ratio. This implies large fluctuations in signal power, ending up in increasing complexity of ADCs and DACs. Also, power amplifiers must work in a larger linear dynamic region. In this paper we present two new techniques for reducing Peak to Average Power Ratio (PAPR), that can be added in any OFDM system and we compare them with other existing schemes.展开更多
文摘In this paper,a time-frequency associated multiple signal classification(MUSIC)al-gorithm which is suitable for through-wall detection is proposed.The technology of detecting hu-man targets by through-wall radar can be used to monitor the status and the location information of human targets behind the wall.However,the detection is out of order when classical MUSIC al-gorithm is applied to estimate the direction of arrival.In order to solve the problem,a time-fre-quency associated MUSIC algorithm suitable for through-wall detection and based on S-band stepped frequency continuous wave(SFCW)radar is researched.By associating inverse fast Fouri-er transform(IFFT)algorithm with MUSIC algorithm,the power enhancement of the target sig-nal is completed according to the distance calculation results in the time domain.Then convert the signal to the frequency domain for direction of arrival(DOA)estimation.The simulations of two-dimensional human target detection in free space and the processing of measured data are com-pleted.By comparing the processing results of the two algorithms on the measured data,accuracy of DOA estimation of proposed algorithm is more than 75%,which is 50%higher than classical MUSIC algorithm.It is verified that the distance and angle of human target can be effectively de-tected via proposed algorithm.
文摘In this paper, a new phase preserving algorithm-the short IFFT algorithm for the burst-mode ScanSAR processing is presented. Analysis and simulation are done to verify the phase accuracy of this algorithm. Finally, the phase accuracy of this algorithm by making interferogram with simulated burst-mode INSAR data is illustrated. The results show that this new algorithm works well for interferometric application of ScanSAR data.
文摘昼夜混合路径条件下低频天波传播特性的研究对导航授时系统中应用模式拓展及低电离层参数反演均具有重要的研究意义.本文以地—电离层中100 kHz载频罗兰-C信号的时域有限差分(Finite Difference Time Domain,FDTD)仿真为前提,基于传统的过零检测和快速傅里叶变换(Fast Fourier Transform,FFT)/逆快速傅里叶变换(Inverse Fast Fourier Transform,IFFT)频谱相除算法,对昼夜混合信道(传播路径为东西取向)中地面接收的一跳天波进行模式区分及特性分析.给出了在白天至夜晚、夜晚至白天两种突变电离层下罗兰-C一跳天波中不同模式随收发距离的变化规律,同时给出了模式干涉区域优势场量的分布情况.结果表明,对于昼夜混合模型,一跳天波中存在来自不同高度及昼夜突跳边界反射的多种模式,基于传统方法检测的幅度相位存在不稳定干涉效应,模式界定困难,而基于FFT/IFFT频谱相除算法能够将主要模式进行细化区分,从而获得更高精度、更平稳的模式特性.
文摘Orthogonal frequency division multiplexing (OFDM) is vastly used in wireless networks. Its superiority relies on the fact that information can be split in large amount of frequencies. Each frequency is called information subcarrier. OFDM exhibits excellent annotation in channel fades and interferers as only a few subcarriers can be affected and consequently a small part of the original data stream can be lost. Orthogonality between frequencies ensures better spectrum management and obviates the danger of intersymbol interference. However, an essential problem exists. OFDM systems have high peak to average power ratio. This implies large fluctuations in signal power, ending up in increasing complexity of ADCs and DACs. Also, power amplifiers must work in a larger linear dynamic region. In this paper we present two new techniques for reducing Peak to Average Power Ratio (PAPR), that can be added in any OFDM system and we compare them with other existing schemes.
