自适应一阶和二阶PMD补偿的理论与实验研究

理论上分析了两阶段补偿器能够同时完全补偿一阶及二阶PMD(去偏振项)的机理。以两个偏振控制器和两段保偏光纤组成PMD模拟器,采用DOP方法完成了10Gb／s NRZ码高速光纤通信系统自适应一阶和二阶PMD补偿的实验研究。结果表明：补偿前系统一阶、二阶PMD分别为60ps、4200ps^2,而补偿后分别为8ps、50ps^2,补偿时间小于100ms。通过PMD补偿,NRZ码眼图得到很好恢复。建立起的自适应补偿系统可以很好地同时补偿系统中的一阶、二阶PMD。     

链式静止同步补偿器控制系统的研究与设计

该文基于串联多电平技术,完成一套链式静止同步补偿器控制系统的研究与设计。根据反馈解耦控制算法和单级倍频载波相移正弦脉宽调制方法,采用串联多电平技术,以TMS320F28335为核心处理器,采用软件算法实现补偿器直流侧电压均衡控制。设计链式结构的三相电压源逆变器,构成链式静止同步补偿器系统,实现系统无功补偿控制。经过试验测试,结果表明:该系统的无功补偿效果与理论一致,设计可行、可靠。     

基于Laguerre函数的高压力非线性传感器补偿研究

针对高压力传感器线性化输出的结果不准确的现象,研究了具有针对性的Duffing非线性系统。用传感器的输出数据作为补偿器的输入,传感器的输入数据作为补偿器的输出,进行基于Laguerre函数的非线性动态补偿器的设计研究。该方法无需知道传感器的非线性阶数,对于外界干扰有较强的抑制作用,对于时延对象也具有一定的优势。利用该补偿器对传感器进行动态补偿,将补偿结果与阶跃响应输出进行对比,结果表明该非线性模型补偿的有效性。     

电涡流传感器非线性补偿电路设计

电涡流位移传感器输出特性非线性明显,为改善传感器线性度,需要进行输出信号的非线性补偿.通过在电涡流传感器前置电路的基础上增加非线性补偿电路模块,可以改善传感器线性度.为获得实用的线性化补偿器,根据传感器位移电压测量数据,先确定其非线性函数关系及线性补偿范围,以函数补偿法为基础采用开环补偿与闭环补偿,分别进行了非线性补偿电路设计,通过模拟电路实现了相关函数运算功能.借助电路仿真手段,可方便地确定电路的结构与具体电路参数.对实际非线性补偿电路进行了测试,实验结果表明,所设计的非线性补偿电路结构简单,能有效改善传感器的线性度.     

F/1.3抛物面零检验补偿器设计

根据会聚光路中使用的Offner补偿器和平行光路中使用的两片式补偿器的要求,设计出了四个针对F/1.3抛物面的补偿器,并从剩余波像差、公差要求、加工工艺性、装调等方面对它们的性能做出比较,确定了三个可用于实际补偿检验的设计结果,其剩余波像差均小于/35。所述补偿器的设计方法和要求具有普遍性,设计结果也可用于同类型主镜补偿器的设计。     

飞机燃油伺服系统温度补偿器性能测试系统设计

针对飞机燃油伺服系统温度补偿器性能测试传统方法精度不高,效率低下的问题,根据温度补偿器的性能要求、技术条件,应用现代传感器技术、计算机辅助测试技术,设计出了一套温度补偿器性能测试系统,给出了该测试系统的总体设计方案,介绍了温度补偿器原理与测试系统的各个组成单元,如控制单元、检测台架、数据采集调理模块、控制模块、显示模块、数据传输模块等.该检测系统已经应用到飞机燃油伺服系统温度补偿器的测试中,人机界面友好,精确度和快速性都满足要求,而且只需要更换传感器或少量硬件即可测试其他的温度补偿器,具有良好的可移植性.     

基于FLANN算法的速度传感器动态补偿

磁电式速度传感器由于自身工作原理,其固有频率下限值受到结构和体积的限制.应用于振动测试时常需对其工作频带进行补偿扩展,以使其能检测固有频率以下的速度信号.本文针对磁电式速度传感器,建立了其动态数学模型,给出了一种基于函数链人工神经网络(FLANN)算法的动态补偿策略.分析对比了采用传感器输入输出设计的FLANN算法补偿器与采用零极点配置法进行动态补偿的效果.结果表明,采用FLANN算法设计的补偿器具有更小的补偿误差,且有效扩展了速度传感器的使用频带,很好地满足了工程上超低频振动测量的要求.     

压杆测压系统的快速补偿技术

该文针对长距离压杆测压系统的频谱带宽不足问题,在常规电缆补偿技术的基础上,提出一种系统整体补偿方法。设计相应的补偿电路,利用Multisim电路仿真软件进行辅助设计和优化,同时利用扫频方法和阶跃响应方法估算系统的带宽,通过现场测试,补偿后测试系统的带宽达到约600 k Hz,输出信号幅值为原系统的1/2,满足压杆测压系统的带宽需求。制作相应的补偿器,测试得到补偿前后系统的幅频曲线和阶跃响应曲线,两种曲线均证明补偿后系统的带宽优于补偿前系统带宽,说明系统整体补偿方法的有效性,为现场测试系统的频谱快速补偿提供参考。     

基于DOP监测的PMD补偿的实现与性能分析

针对偏振模色散(PMD)限制光纤通信系统向高速率和长距离发展的问题,本文提出了基于偏振度(DOP)监测的PMD动态自适应补偿系统的设计方案.该方法根据DOP与差分群时延(DGD)之间的关系,通过控制算法实现DOP最佳值的搜索和跟踪,由DOP的变化反映PMD的大小及其补偿效果,采用调节偏振控制器波片的角度和可变时延线,调整两基本偏振态,不断优化DOP使其趋于最佳值,构建了闭环补偿系统.实验结构表明,发生裂化的信号波形得到了有效恢复,眼图张开度得到明显改善.实验中,系统的补偿响应时间约为110 ms,补偿后信号的误码率为3.59e-16,达到了系统对传输误码率的要求.     

舵机电液伺服加载复合控制方法研究

为解决飞机舵面加载控制中出现的强干扰、耦合等问题,分析被动式加载系统中干扰力矩的特点,对前馈补偿方法中存在的高阶微分补偿控制器物理上难以实现以及模型失配问题,提出了基于改进型前馈补偿结构和FCMAC-PID控制算法相结合的复合控制方法.在前馈补偿控制器设计中采用加载马达输出转轴角速度作为补偿输入,该种补偿器不仅有效地消除了多余力矩,而且降低了整个系统以及补偿器的阶次.针对普通PID控制器快速性和稳定性之间的矛盾,研究了FCMAC-PID控制器,在保证稳定性的同时快速性得到了改善.仿真表明:采用补偿复合控制器可以有效消除扰动,系统能快速准确跟踪载荷谱.     

Scheme for feed-forward polarization mode dispersion compensation

We propose a feed-forward polarization mode dispersion (PMD) compensator with three segments that is capable of compensating for the first- and second-order PMD in a transmission fiber. All control parameters are analytically obtained by the PMD concatenated rules. The influence of all possible perturbations on the compensation is investigated with Monte Carlo simulations. The main advantage of our PMD compensation module over the models reported so far is that it shows excellent robustness to all possible perturbations.     

Polarization-mode-dispersion compensator using a polarization beam splitter and quarter-wave plates

We propose a Michelson-interferometer-type polarization-mode-dispersion (PMD) compensator with one polarization beam splitter and quarter-wave plates. We experimentally demonstrate the proposed PMD compensator with fiber devices and show the PMD compensation ability to be 104 ps by the fixed-analyzer method.     

A new experimental approach to second-order polarization mode dispersion analysis for optical communications systems

This article analyzes the polarization mode dispersion (PMD) in optical fibers and presents a new approach for its measurement. This approach permits the combined analysis of the first-order PMD and the second-order polarization mode dispersion (SOPMD) in optical systems for different values of temperature. The relation between SOPMD and the differential group delay (DGD) in a single-mode fiber is discussed. The analysis is based on time/wavelength and temperature variations changing/impacting PMD and DGD measured values. We present long-term statistical characteristics of SOPMD acquired by a PMD emulator constructed with some pieces of high birefringence fiber, and the correlation between the SOPMD, depolarization (Depol) and polarization-dependent chromatic dispersion (PCD) was investigated. A new interpretation of SOPMD is presented to analyze the problem of the temperature spectral stability. The actual techniques for SOPMD determination, consequently Depol and PCD, use the variation with time and/or wavelength. In some studies, the results obtained for SOPMD are correlated to first-order PMD. We demonstrate experimentally that the temperature is an important factor for the correlation between SOPMD and PMD and cannot be neglected in the optimization of high-speed optical communications links.     

偏振模色散对NRZ码和RZ码的40Gbit/s系统性能影响的仿真分析

偏振模色散(PMD)是进一步提高现有光纤通信系统单信道速率必须克服的障碍之一。本文基于已铺设光纤的典型值,针对偏振模色散对采用NRZ码和RZ码的40Gbit／s光纤通信系统的性能影响进行了分析与仿真。结果表明,考虑PMD的影响时,采用RZ码的系统并不一定比采用NRZ码的系统的传输性能好,而在占空比[0,1]之间存在一个最佳值,此时,高速系统受偏振模色散的影响最小。这对于研究、设计高速光纤通信系统时选择合适的码型和RZ码的占空比,具有重要的参考意义。     

利用DOP数值搜索的偏振模色散补偿算法

根据光域动态反馈的PMD补偿方案中在线测量的偏振度波动特点,提出了一种基于搜索最优DOP数值的PMD补偿控制算法。此算法在以变步长精确搜索全局最值的基础上,采用近似定步长的搜索策略,避免陷入局部极值区域,得到全局最优DOP数值,从而较好地补偿高速光纤链路中的PMD。将此算法用于人工神经网络训练的仿真中,能够使训练后的网络达到最小网络误差,提高网络的泛化能力。仿真结果验证了该算法的正确性和良好的搜索性能。     

Enhanced method for the reconstruction of zero-dispersion wavelength maps of optical fibers by measurement of continuous-wave four-wave mixing efficiency

The zero-dispersion wavelength map of an optical fiber can be obtained from measurement of end-to-end four-wave mixing efficiency at various wavelengths. A fast and unambiguous algorithm for reconstruction of the zero-dispersion wavelength map of an optical fiber by measurement of four-wave mixing efficiency is proposed. This method can produce high-resolution results in a few seconds. We also study the limitations of this technique that are due to polarization-mode dispersion (PMD). Simple practical rules to avoid the effects of PMD in such measurements are established.     

Phaselet-based current differential protection scheme based on transient capacitive current compensation

Time-domain compensation of capacitive current, derived from differential equation of pi-equivalent circuit of the transmission line, is introduced into a practical phaselet-based current differential protection scheme. First thoughtful analyses with comparisons are carried out for the time-domain compensation algorithm and also both the phasor compensation method and Bergeron transmission line model method. And then Electromagnetic Transients Program (EMTP) simulations are performed for the three compensation methods mentioned above. The simulation results show that this time-domain compensation method can effectively overcome shortcomings of other two methods, for example, disabling compensation for transient capacitive current, or huge computation consumption and high rate sampling which are far beyond the communication and sampling capabilities that the existing relay devices can offer. As a result phaselet algorithm with 5 ms data window can be applied to current differential protection, hence the trip time is reduced, and the selectivity and sensitivity of protection are enhanced. And also protection devices operating with lower sampling frequency and communication rate present are available for this scheme.     

偏振模色散(PMD)及其波长扫描测量技术

本文描述偏振模色散(PMD)的成因及对通讯系统的影响。介绍一种使用波长扫描的方法测量PMD的技术,并对这一测量方法的主要误差来源、测量范围进行了分析。