Application of Empirical Orthogonal Functions Parameterization in the Problem of Retrieval of the Tropospheric Thermal Structure by Radiometric Data

Radiophysics and Quantum Electronics - We describe the mathematical tools of the optimal estimation method for retrieval of tropospheric temperature profiles (0–10 km) from radiometric data...     

Modulation Method for Determining the Bearing of a Moving Object from Radio Beacon Signals Orthogonally Polarized in a Circle

Russian Physics Journal - Based on the use of the vector apparatus and the Jones matrices, a polarization-modulation method for bearing of a moving object from radio beacon signals orthogonally...     

Method for Determining the Time Delay of Frequency-Shift Keyed Signals on the Basis of Modified Capon's Method of Minimum Variance

We propose a method for determining the time delay of frequency-shift keyed signals on the basis of the digital filtering algorithm insensitive to carrier-frequency shifts. The filter coefficients correspond to the information-optimal solution of the problem of variance minimization at the linear-filter output. Efficiency of the proposed method is shown under conditions of additive noise and inexact knowledge of the center frequency of the processed-signal spectrum. The developed algorithm permits simple realization for real-time operation on the basis of a digital signal processor. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 51, No. 7, pp. 633–640, July 2008.     

On Complex Delay Time of a Narrow-Band Signal Passing through a Resonant Filter

It is shown that distortion of a narrow-band signal with a gradually varying envelope during passage through a resonant filter can approximately be described in terms of complex delay time. The real part of the delay time can be both positive and negative, depending on the filter type and the carrier frequency of the signal. The imaginary part of the delay time leads to a distortion of the complex envelope of the signal. The intensity envelope of signals without frequency modulation is distorted only slightly, while distortion is considerable even in the case of a fairly small frequency modulation. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 48, No. 8, pp. 711–718, August 2005.     

Radiometric measurements on a plasma induced by a proton beam

The plasma radiation temperature of a neon plasma created by a dc proton beam has been measured. Variations of this temperature versus gas pressure and beam intensity are presented and related to the theoretical variation of the electronic distribution function.     

Effect of Time Delay on Binary Signal Detection via a Bistable System

The effect of time delay on binary signal detection via a bistable system in the presence of white or colored Gaussian noise is investigated. By defining the bit error rate based on the solution of the approximated Fokker- Planck equation, the detector performance is investigated theoretically and is verified by Monte Carlo simulation. It is shown that, when the system parameter or noise intensity is optimally chosen, the increasing time delay generally improves the system performance. It is also shown that it is more difficult to accurately predict the system performance with a larger time delay and correlation time. This may inspire more thorough investigations in cooperative effects of a nonlinear system and time delay on signal processing.     

Polarization Amplitude-Based Method of Determining the Bearing and Roll Angles of an Object in Motion from Orthogonal Circularly Polarized Signals of a Radio Beacon

Russian Physics Journal - The possibility of determining the bearing and roll angles of an object in motion is investigated based on orthogonal left- and right-hand circularly polarized signals...     

Total Electron Content Measurements in the Ionosphere Disturbed by High-Power High-Frequency Waves by the Methods of Incoherent Scattering of Radio Waves and Radio Sounding by Glonass Satellite Signal

Radiophysics and Quantum Electronics - We present the results of comparing the total electron content measurements based on GLONASS satellite signals and the EISCAT UHF incoherent scatter radar...     

基于System Generator的射频直接带通采样MRI信号接收方法

本文将软件无线电技术应用于磁共振成像（Magnetic Resonance Imaging，MRI）信号接收，提出了射频直接带通采样MRI信号接收的方法.基于此接收方法设计了一种MRI信号数字解调方法，该方法利用Xilinx公司推出的数字信号处理（Digital Signal Processing，DSP）设计开发工具——System Generator实现，同时设计验证了能够灵活实现数字下变频（Digital Down Conversion，DDC）功能的DDC系统.仿真与实验平台均验证了该接收方法的正确性和有效性.     

基于改进型反射率基法的资源三号卫星多光谱相机在轨辐射定标研究

针对资源三号卫星(ZY-3)多光谱影像特点,提出了一种改进型反射率基法,实现相机在轨辐射定标。该方法以ZY-3 Level 1A 级影像为数据源,建立严格的几何模型获取定标点处准确的观测几何参数,降低因影像重采样和成像几何产生的误差对辐射定标精度的影响。基于山东东营遥感综合实验,利用两点法和多点法获取ZY-3多光谱相机在轨辐射定标系数。与官方定标系数相比,多点法的定标精度高于两点法定标精度。通过分析各定标点与拟合直线间的离散程度后发现,水体定标点的残差较大,其中绿波段残差值约为67.39%。以置信度95.4%为标准,可将水体定标点判识为误差点。在剔除水体后,采用多点法获得的定标系数除近红外波段相对差异优于5%以外,其他波段相对差异均优于2%。该结果表明该改进型反射率基法能够获得精度可靠的绝对定标系数,可以为其他类似卫星在轨辐射定标提供参考依据。     

克服光纤Mach-Zehnder干涉仪信号衰落的新方法及分析

为了克服光纤Mach-Zehnder干涉仪易受环境因素影响而引起偏置相位漂移从而导致输出信号衰落(波动)的问题,提出一种新的简单方法,即:将干涉仪输出信号分为直流和交流两个分量,通过直流分量的大小来计算交流信号的补偿因子,以达到克服交流信号衰落、稳定检测传感信号的目的在小信号测量情况下,该方法在很大范围内能有效抑制随机温度涨落等因素引起的信号衰落的问题文中对补偿方法的误差和局限性也做了分析和讨论.     

Algorithm for Determining the Coordinates of a Hydroacoustic Source Using the Correlation Function of Its Signal

Acoustical Physics - Abstract—An algorithm for determining the coordinates (distance and depth) of a broadband signal source has been developed, which uses as the input data the parameters of...     

Image Displaying Method of Ground-Based Millimeter Wave Radiometric Imaging System

The image displaying methods used in a millimeter wave radiometric imaging system have great influence on its imaging quality. In order to obtain high quality millimeter wave radiometric images, intensive studies on the image displaying methods are needed. This paper describes the image displaying method of Ground-based 8mm Millimeter Wave Radiometric Imaging (GMWRI) system and compares two different image displaying methods. The experimental results prove the unequal size element arc displaying method fits GMWRI system better.     

On the Negative Delay Time of a Narrow-Band Signal as It Passes Through the Resonant Filter of Absorption

It is shown that a narrow-band signal with smoothly varying envelope can have a negative delay time upon filtering by certain physically realizable filters, i.e., the smooth-signal envelope shifts forward rather than backward. We show that this does not contradict the casuality principle, since the advanced appearance of the signal has the nature of prediction of the future signal level from the time dependence of its level in the past. It is shown that in the case of a negative delay time, the time dependence of a switched-off signal can be recovered, i.e., reception of the untransmitted part of the signal is possible. We propose to use these phenomena for predicting signals of natural and artificial origin.     

Methods for Measuring the Signal of the Phase Calibration of the VLBI Radio Telescopes

Radiophysics and Quantum Electronics - In the majority of modern radio telescopes, which are used for radio interferometry with very long baselines, a special signal is introduced into the signal...     

Use of Global Symmetries in Automated Signal Class Recognition by a Bayesian Method

Automated or semiautomated pattern recognition in multidimensional NMR spectroscopy is strongly hampered by the large number of noise and artifact peaks occurring under practical conditions. A general Bayesian method which is able to assign probabilities that observed peaks are members of given signal classes (e.g., the class of true resonance peaks or the class of noise and artifact peaks) was proposed previously. The discriminative power of this approach is dependent on the choice of the properties characterizing the peaks. The automated class recognition is improved by the addition of a nonlocal feature, the similarities of peak shapes in symmetry-related positions. It turns out that this additional property strongly decreases the overlap of the multivariate probability distributions for true signals and noise and hence largely increases the discrimination of true resonance peaks from noise and artifacts.