Analysis of Schottky-Barrier Millimetric Varactor Doublers

An analysis of abrupt-junction millimetric varactor doublers using Schottky diodes is performed and numerically implemented to evaluate conditions of maximum output power. This power level, the efficiency, and the circuit parameters have been derived as a function of the geometrical and physical parameters of the junction. Physical phenomena which allow the application of the model up to the plasma resonance frequency in epilayer are taken into account. Comparison of available experimental data with the theory developed is repotted.     

有振幅调制和位相畸变光束的聚焦特性

用广义惠更斯－菲涅耳衍射积分和统计光学方法对有振幅调制和位相畸变光束的聚焦特性作了详细研究，并对有位相畸变光束的光束质量Ｍ２因子作了分析     

加性噪声对微波光电振荡器相位噪声的影响

微波光电振荡器是一种基于微波光子技术的高频微波信号发生装置,它能够产生超高频谱纯度及超低相位噪声的微波信号。研究了典型的微波光电振荡器相位噪声产生机理及相位噪声谱密度。从构成微波光电振荡器的核心器件出发,分析了开环状态下,微波光电振荡器中的加性噪声来源及其对相位噪声的影响。     

Phase and Amplitude Noise Analysis in Microwave Oscillators Using Nodal Harmonic Balance

In this paper, a nodal harmonic balance (HB) formulation is presented for the phase and amplitude noise analysis of free-running oscillators. The implications of using different constraints in the resolution of the perturbed-oscillator equations are studied. The obtained formulation allows the prediction of the possible spectrum resonances without ill conditioning at low frequency offset from the carrier. The noise spectrum is meaningfully expressed in terms of the eigenvalues of a newly defined matrix, obtained from the linearization of the nodal HB system about the steady-state solution. The cases of real or complex-conjugate dominant eigenvalues are distinguished. The developed phase-noise formulation is extended to a system of two coupled oscillators. The phase and amplitude noise analyses have been applied to a push-push oscillator at 18 GHz, a bipolar oscillator at 1 GHz, and a coupled system of two field-effect transistor oscillators at 6 GHz.     

有振幅调制和位相畸变激光通过空间滤波器的传输

用广义惠更斯-菲涅耳衍射积分和统计光学方法对有振幅调制和位相畸变激光通过空间滤波器的传输特性作了详细研究.并对空间滤波器中滤波小孔最佳尺寸的选取条件进行了讨论.数值计算结果表明,最佳滤波小孔尺寸与系统菲涅耳数、光束截断参数以及光束的位相畸变参数等有关.     

Performance of Coherent Phase and Amplitude Digital Modulations with Carrier Recovery Noise

A model of decision feedback carrier recovery noise is presented as a function of the number of symbols over which the carrier is derived. For this model, quantitative results for performance degradation in BPSK, QPSK, 8-phase, 16-QAM, 32-QAM, and 64-QAM coherent demodulators are presented. When the carrier is derived from only the last symbol, these results reduce to the performance for differential detection. Carrier integration over 100 symbols is shown to be adequate to provide performance quite close to ideal for all the modulations considered.     

复加性白高斯噪声中随机幅值多项式相位信号的Cramer—Rao下界

本文考虑了在复的白高斯加性噪声中观测的多个随机幅值多项式相位信号的参数估计问题，导出了多项式相位系数估计以及幅值样本均值的Ｆｉｓｈｅｒ信息矩阵，因而利用数值计算可得到相应的Ｃｒａｍｅｒ－Ｒａｏ界（ＣＲＢ），模拟结果验证了所得结果的正确性。     

Time and Amplitude Statistics for Electromagnetic Noise in Mines

The time and amplitude statistics illustrated are important and useful in describing the time-dependent, measured electromagnetic (EM) noise in mines. They are 1) Allan variance analyses (AVA), 2) interpulse spacing distributions (ISD), 3) pulse duration distributions (PDD), 4) average crossing rates (ACR), and 5) amplitude probability distributions (APD). These statistics are illustrated using a rather large store of raw analog data measured in operatioal mines through computer software techniques. The curves generated for the figures characterize the noise environment in the mines from which the corresponding data were taken, and should aid in the design of reliable communication systems for such mines.     

利用振幅关联函数研究超短脉冲中的时空耦合效应

提出了一种利用振幅关联函数来分析超短脉冲中时空耦合效应的方法。定义了振幅关联度和关联带宽来衡量时空耦合的严重程度。给出了不同空间啁啾程度的脉冲光束的时空分布图。采用振幅关联函数研究了超短脉冲中的一些振幅耦合效应,如由角色散元件引起的一阶空间啁啾和角色散效应以及由衍射引起的二阶空间啁啾效应,并给出了相应的振幅关联度的解析表达式。结果表明,由于宽带激光脉冲的衍射和折射与频率密切相关,导致其振幅关联度下降并出现时空耦合。具体地,角色散引起的空间啁啾将会随着传输距离的增大而减弱直至趋于一定值。另外,由自由空间衍射引起的二阶空间啁啾效应也会随着传输距离的增大而减弱。最后,由角色散元件引起的角色散效应并不会随着传输距离的变化而变化。     

Jitter and Amplitude Noise Accumulations in Cascaded All-Optical Regenerators

This paper proposes and demonstrates a simulation model to systematically investigate jitter accumulations in cascaded all-optical 2R regenerators. The simulation results indicate that when the pattern dependence from the memory effect is minimized, the jitter accumulation depends critically on the degree of the regenerative nonlinearity. Studies of tradeoffs between the jitter from bandwidth limitation and the signal-to-noise-ratio degradation help identify the optimized regenerator bandwidth for various degrees of regenerative nonlinearity. The simulation then considers the pattern dependence from the memory effect and finds that it can severely degrade the cascadability of an optical 2R regenerator and can make it worse than that of a linear optical amplifier (optical 1R). The simulation results show good matches to the experimental results of an optical 2R regenerator based on a semiconductor optical amplifier based Mach-Zehnder interferometer. To overcome the jitter accumulation associated with the optical 2R regeneration, we experimentally demonstrate an optical 3R regenerator for optical nonreturn-to-zero signals with all-optical clock recovery. The experiments achieve more than 1000-hop cascadability for pseudorandom binary sequence 2³¹-1 inputs with a 100-km recirculation loop using lab fiber. Field trial experiments then demonstrate a more than 1000-hop cascadability for a 3R spacing of 66 km and a 100-hop cascadability for a 3R spacing of 264 km.     

幅差法干扰源定位异常波动分析

幅差法定位是针对静止轨道卫星入站干扰源定位的有效方法之一,该方法基于同星多个波束间的干噪比差值进行定位,定位的关键在于同星干噪比差值的获取以及覆盖区域内G/T差值参考数据的准确度。但在实际应用中,由于GEO卫星的实际倾角并非为0,且当该倾角大到一定程度时会出现定位结果随时间和干扰发射频率波动等现象。通过多地长时间干扰试验数据积累和数据处理,从多角度分析了定位结果异常波动的原因,并提出了相应的可能解决措施,为幅差法干扰定位精度提升提供了下一步研究思路。     

Measured Amplitude Distribution of Automotive Ignition Noise

This paper describes a series of tests conducted 1) to statistically characterize the amplitude distribution of automotive ignition noise, and 2) determine whether such test results can be reproduced. Some tests showed the amplitude distribution to be Weibull and others indicated a log normal distribution. However, under controlled conditions the results obtained from an individual vehicle were quite repeatable.     

Discrete Amplitude Noise Components of Amplifier Klistrons

Journal of Communications Technology and Electronics - Abstract—The kinematic theory of discrete klystron noise associated with the rectified voltage ripple of power sources is presented. The...     

乘性和加性噪声相关背景下的二维谐波频率估计

本文利用二维循环统计量方法对乘性噪声之间相关、乘性噪声和加性噪声之间也相关这种复杂噪声背景下的谐波恢复问题进行了研究.首先,提出了二维噪声互可混的概念,用它来体现多个二维噪声之间的关系;然后,在乘性噪声为非零均值时,定义了二维循环均值来估计信号频率.在乘性噪声和加性噪声为零均值时,定义特殊的二维六阶时间平均多矩谱切片来估计信号频率.仿真实验证明了算法的有效性.     

乘性和加性噪声中二维谐波频率估计

噪声中的谐波恢复问题是信号处理领域的一个典型问题,在众多领域中有着广泛的应用。本文主要研究零均值乘性和加性噪声并存下的二维谐波信号频率估计问题,提出了一种基于数据矩阵的奇异值分解和子空间的旋转不变性的零均值乘性和加性噪声中的谐波频率的估计方法。乘性噪声为零均值情形下传统的估计方法往往难以直接应用或估计失效。本文利用谐波模型信号特征,通过对观测信号进行平方运算构造了一个数据矩阵。通过对数据矩阵的特征值进行理论分析,结合子空间旋转不变性,得到了零均值乘性和加性噪声中的谐波频率和数据矩阵之间的一种内在关系。这个性质可以用于零均值乘性和加性噪声并存下的二维谐波信号频率估计,并且所得的二维频率能自动配对。仿真实验验证了本文所提算法的有效性。      

乘性和加性噪声中二维谐波的参数估计

本文从循环平稳的观点出发来研究乘性和加性噪声中二维谐波的参数估计问题,利用循环累积量的性质证明了二维二阶循环累积量单一记录估计的统计性质.在此基础上,对于零均值乘性噪声中的二维谐波信号提出了基于二阶循环累积量的二维谐波分量个数和频率对的估计方法,并分别得到了估计的强收敛速度.仿真试验验证了所提方法的性能.     

几何光学近似区的相位起伏和幅度起伏

研究了几何光学近似区的相位起伏和幅度起伏.分三种模型:平面波、球面波和高斯光束,Tatarskii给出了平面波的结果,本文进一步给出了球面波和高斯光束的结果.对于平面波和球面波,考虑了在几何光学近似区,发射端的相位扰动如何影响接收端的幅度起伏;对于高斯光束,考虑了发射端自适应光学共轭相位对接收端的幅度起伏的影响.结论是:对于平面波,只有折射率不均匀媒质的相位起伏的曲率项对幅度起伏有贡献,只有发射端的相位扰动的曲率项能影响总体的幅度起伏;对于球面波,折射率不均匀媒质相位起伏的倾斜项和曲率项共同对幅度起伏有贡献,只有发射端相位扰动的曲率项能影响总体的幅度起伏;对于高斯光束,折射率不均匀媒质相位起伏的倾斜项和曲率项共同对幅度起伏有贡献,发射端的自适应光学共轭相位的倾斜项和曲率项共同作用于总体的幅度起伏.     

Accurate Determination of Varactor Resistance at UHF and Its Relation to Parametric Amplifier Noise Temperature

A thorough investigation is made on the frequency-dependent properties of a varactor diode loss resistance at UHF. The variation of the losses with frequency in a varactor diode mounted cavity has been theoretically investigated, and it is shown that the previously reported inverse-squared frequency dependence of the varactor loss resistance can be attributed to the distributed cavity losses transformed across the varactor diode. A new measurement technique is introduced in which the circuit losses are first matched to the input line instead of the varactor loss resistance as an application of the relative impedance method. Measurements carried out with this technique for five different varactor diodes showed that the loss resistances of these diodes are not frequency dependent. It is also shown that the choice of the varactor diode capacitance plays an important role on the parametric amplifier noise temperature at UHF. In an experimental parametric amplifier the effect of varactor diode capacitance on the noise temperature has been demonstrated. It has been theoretically and experimentally shown that, generally, varactor diodes having higher capacitances result in better noise temperature at UHF.     

RCS动态测量雷达幅度相位校准技术

某相参雷达散射截面积(RCS)动态测量雷达可采用脉冲压缩技术,其接收机信号输出幅度、相位校准需要有标准信号源,目前国内能够买到的国外综合信号源,远不能满足校准要求.文中采用等效自校准原理,研制了RCS动态测量雷达幅度、相位校准系统,解决了采用脉冲压缩技术的RCS动态测量雷达的幅度、相位校准问题.     

系统幅相监测中的倒相现象及其消除

在由阵列天线构成的雷达系统中,为保证各阵元能量按设计有效合成(空间合成或电路合成),必须对各通道的幅度和相位进行监测.通常监测工作通过一定的测试通道来完成,测试通道中的不同混频方式直接决定了测试相位值的正相或反相.由于接收通道的混频方式的不同,使相位值出现倒相,造成雷达对波达方向的错误估计,导致雷达测量的错误,必须予以消除.