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
Signals arrive out of phase at the intended receiver from collaborative beamforming （CB） nodes due to the instability in the output frequency signals of the universal software radio peripheral＇s （USRP） local osci...Signals arrive out of phase at the intended receiver from collaborative beamforming （CB） nodes due to the instability in the output frequency signals of the universal software radio peripheral＇s （USRP） local oscillator （LO）. These nodes including the target must synchronize their oscillator frequencies for coherent signal reception. In order to do this, frequencies and phases of the signals should be estimated in software defined radio （SDR） and smoothen with nonlinear filters such as the extended Kalman filter （EKF）. The process noise parameters of the NI USRP-2920 nodes will have to be calculated and used with the EKF process noise covariance matrix. These nodes are green communication hardware devices where most of the hardware units are now software defined. This article uses the direct spectrum method to obtain the phase noise values at various frequency offsets of the NI USRP-2920 in order to calculate the power spectral density of fractional frequency fluctuation. By applying the power-law noise model to this obtained value, the generated white frequency noise and random walk frequency noise values are q_1=1.93x10^-21 and q_2=5.86x10^-18, respectively.展开更多
In Electronic Warfare, and more specifically in the domain of passive localization, accurate time synchronization between platforms is decisive, especially on systems relying on TDOA （time difference of arrival） and...In Electronic Warfare, and more specifically in the domain of passive localization, accurate time synchronization between platforms is decisive, especially on systems relying on TDOA （time difference of arrival） and FDOA （frequency difference of arrival）. This paper investigates this issue by presenting an analysis in terms of final localization performance of an experimental passive localization system based on off-the-shelf components. This system is detailed, as well as the methodology used to carry out the acquisition of real data. This experiment has been realized with two different kinds of clock. The results are analyzed by calculating the Allan deviation and time deviation. The choice of these metrics is explained and their properties are discussed in the scope of an airborne bi-platform passive localization context. Conclusions are drawn regarding the overall localization performance of the system.展开更多
Established on October 18th of 2002, the School of Software Engineering of Beijing University of Posts and Telecommunications is one of the 35 national model schools of software engineering approved by the Ministry of...Established on October 18th of 2002, the School of Software Engineering of Beijing University of Posts and Telecommunications is one of the 35 national model schools of software engineering approved by the Ministry of Education and the National Committee of Development and Reform. According to current requirements and international trends, the school has set up its objective as to educate students with multi-level, practical, and composition talents. To this end,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.
基金supported by the Ministry of Education Malaysia,Universiti Teknologi Malaysia and RUG vote 11H60
文摘Signals arrive out of phase at the intended receiver from collaborative beamforming （CB） nodes due to the instability in the output frequency signals of the universal software radio peripheral＇s （USRP） local oscillator （LO）. These nodes including the target must synchronize their oscillator frequencies for coherent signal reception. In order to do this, frequencies and phases of the signals should be estimated in software defined radio （SDR） and smoothen with nonlinear filters such as the extended Kalman filter （EKF）. The process noise parameters of the NI USRP-2920 nodes will have to be calculated and used with the EKF process noise covariance matrix. These nodes are green communication hardware devices where most of the hardware units are now software defined. This article uses the direct spectrum method to obtain the phase noise values at various frequency offsets of the NI USRP-2920 in order to calculate the power spectral density of fractional frequency fluctuation. By applying the power-law noise model to this obtained value, the generated white frequency noise and random walk frequency noise values are q_1=1.93x10^-21 and q_2=5.86x10^-18, respectively.
文摘In Electronic Warfare, and more specifically in the domain of passive localization, accurate time synchronization between platforms is decisive, especially on systems relying on TDOA （time difference of arrival） and FDOA （frequency difference of arrival）. This paper investigates this issue by presenting an analysis in terms of final localization performance of an experimental passive localization system based on off-the-shelf components. This system is detailed, as well as the methodology used to carry out the acquisition of real data. This experiment has been realized with two different kinds of clock. The results are analyzed by calculating the Allan deviation and time deviation. The choice of these metrics is explained and their properties are discussed in the scope of an airborne bi-platform passive localization context. Conclusions are drawn regarding the overall localization performance of the system.
文摘Established on October 18th of 2002, the School of Software Engineering of Beijing University of Posts and Telecommunications is one of the 35 national model schools of software engineering approved by the Ministry of Education and the National Committee of Development and Reform. According to current requirements and international trends, the school has set up its objective as to educate students with multi-level, practical, and composition talents. To this end,
