Parameter estimation of signals of universal software radio peripheral （USRP） devices is crucial to solve the problem of phase offsets of received signals in distributed beamforming. For systems that will utilize th...Parameter estimation of signals of universal software radio peripheral （USRP） devices is crucial to solve the problem of phase offsets of received signals in distributed beamforming. For systems that will utilize the closed loop feedback algorithm where the receiver needs to send the received signal strength （RSS） values periodically to the beamforming node so as to take advantage of energy conservation, the frequency and phase of these signals should be estimated before smoothening by nonlinear filters. This article presents the estimation of the frequency offsets of a Gaussian minimum shift keying （GMSK） signal from N210 USRP devices in real time by using the Radix-2 fast Fourier transform （FFT） algorithm in GNURadio. For these green communications devices, most of the needed hardware parts have been software defined, thereby reducing the supposed energy consumption. The frequency offsets from reference carrier frequencies of 900 MHz and 2.4 GHz are less than 3 kHz each before the estimation, but the average offsets are 45 Hz and 100 Hz after the estimation, respectively. The high offset value experienced with the 2.4 GHz carrier was due to consistent interference from devices on that same frequency.展开更多
针对传统数据链测试设备功能单一且不易重构的问题,借鉴虚拟仪器模块化的设计思想,设计实现了一种基于美国国家仪器公司(National Instruments,NI)通用软件无线电平台的数据链测试模拟器。该模拟器采用线性调频信号叠加(Sum of Linear F...针对传统数据链测试设备功能单一且不易重构的问题,借鉴虚拟仪器模块化的设计思想,设计实现了一种基于美国国家仪器公司(National Instruments,NI)通用软件无线电平台的数据链测试模拟器。该模拟器采用线性调频信号叠加(Sum of Linear Frequency Modulation,SoLFM)的方法高效产生具备连续相位的时变信道衰落,包括瑞利衰落、莱斯衰落和对数正态衰落等,并结合多相滤波思想能够精确模拟数据链长时延的多径传播场景。利用矢量网络分析仪对硬件模拟器输出的信道传递函数和信道冲激响应进行实测验证,并对各支路的随机信道衰落包络分布进行统计验证。实测结果表明,该数据链测试模拟器输出的信道函数和统计分布均与理论值吻合,因而可用于数据链装备的系统优化、验证和性能评估。展开更多
在实际测向系统中,当弱信号和强干扰空间临近时,空间谱测向系统仅能对强干扰进行波达方向(Direction of Arrival,DOA)估计,弱信号DOA估计性能下降甚至失效。针对这一问题,研究了空间谱扩展噪声子空间算法结合通道幅相误差校正,在强干扰...在实际测向系统中,当弱信号和强干扰空间临近时,空间谱测向系统仅能对强干扰进行波达方向(Direction of Arrival,DOA)估计,弱信号DOA估计性能下降甚至失效。针对这一问题,研究了空间谱扩展噪声子空间算法结合通道幅相误差校正,在强干扰抑制条件下对弱信号进行DOA估计的方法。该方法对采样信号的噪声协方差进行去加权处理,并对空间谱扩展噪声子空间算法的空间谱导向矢量进行修正。基于通用软件无线电外设(Universal SoftwareRadioPeripheral,USRP)和印刷偶极子线形天线阵构建实验平台,实验结果证明空间谱扩展噪声子空间算法结合改进的通道幅相误差校正方法,能对临近干扰源进行空间谱抑制的同时,实现对弱信号的DOA估计。展开更多
基金supported by the Ministry of Education Malaysia,Universiti Teknologi Malaysia and RUG vote 11H60
文摘Parameter estimation of signals of universal software radio peripheral （USRP） devices is crucial to solve the problem of phase offsets of received signals in distributed beamforming. For systems that will utilize the closed loop feedback algorithm where the receiver needs to send the received signal strength （RSS） values periodically to the beamforming node so as to take advantage of energy conservation, the frequency and phase of these signals should be estimated before smoothening by nonlinear filters. This article presents the estimation of the frequency offsets of a Gaussian minimum shift keying （GMSK） signal from N210 USRP devices in real time by using the Radix-2 fast Fourier transform （FFT） algorithm in GNURadio. For these green communications devices, most of the needed hardware parts have been software defined, thereby reducing the supposed energy consumption. The frequency offsets from reference carrier frequencies of 900 MHz and 2.4 GHz are less than 3 kHz each before the estimation, but the average offsets are 45 Hz and 100 Hz after the estimation, respectively. The high offset value experienced with the 2.4 GHz carrier was due to consistent interference from devices on that same frequency.
文摘针对传统数据链测试设备功能单一且不易重构的问题,借鉴虚拟仪器模块化的设计思想,设计实现了一种基于美国国家仪器公司(National Instruments,NI)通用软件无线电平台的数据链测试模拟器。该模拟器采用线性调频信号叠加(Sum of Linear Frequency Modulation,SoLFM)的方法高效产生具备连续相位的时变信道衰落,包括瑞利衰落、莱斯衰落和对数正态衰落等,并结合多相滤波思想能够精确模拟数据链长时延的多径传播场景。利用矢量网络分析仪对硬件模拟器输出的信道传递函数和信道冲激响应进行实测验证,并对各支路的随机信道衰落包络分布进行统计验证。实测结果表明,该数据链测试模拟器输出的信道函数和统计分布均与理论值吻合,因而可用于数据链装备的系统优化、验证和性能评估。
文摘在实际测向系统中,当弱信号和强干扰空间临近时,空间谱测向系统仅能对强干扰进行波达方向(Direction of Arrival,DOA)估计,弱信号DOA估计性能下降甚至失效。针对这一问题,研究了空间谱扩展噪声子空间算法结合通道幅相误差校正,在强干扰抑制条件下对弱信号进行DOA估计的方法。该方法对采样信号的噪声协方差进行去加权处理,并对空间谱扩展噪声子空间算法的空间谱导向矢量进行修正。基于通用软件无线电外设(Universal SoftwareRadioPeripheral,USRP)和印刷偶极子线形天线阵构建实验平台,实验结果证明空间谱扩展噪声子空间算法结合改进的通道幅相误差校正方法,能对临近干扰源进行空间谱抑制的同时,实现对弱信号的DOA估计。
