Some linear approaches reported recently without postprocessing to fir system identification are discussed . this paper improves the question of the promulgation of error due to estimating middle parameter frequently in other related methods , and presents a direct algorithm of estimating parameter without estimating middle coefficient . through proper mathematic means , for example , singular value decomposition ( svd ) or total - least squares solution ( tls ) , this algorithm smoothes the noise and improves effectively the estimation performance 和2阶统计量相比，高阶统计量不仅能够有效抑制高斯有色噪声的影响，而且能够揭示随机过程的相位特性，因此，高阶统计量是解决非高斯、非最小相位、非因果系统和有色高斯噪声环境的系统辨识和处理问题的重要分析工具。
According to the relational expression of torsional vibration of the measuring point on crankshaft and the excited moment of each cylinder of internal combustion engine ( ice ) , the working condition of each cylinder was monitored and the fault of cylinder - scoring was diagnosed using the amplitude and phase characteristic of 0 . 5 order torsional vibration 摘要依据内燃机轴系测点扭振与各缸激振力矩的关系式，利用0 . 5谐次扭振的幅值与相位特性，进行内燃机各缸作功状态监测和拉缸故障诊断。
The key components in laser gyro is he - ne ring laser , and the reciprocal action theory between light and medium is the base in studying the ring laser , use the lamb half classical theory , and on the base of density matrix theory , the optical brounch equation was established , which described the movement of amplifying medium atom in the ring syntonic cavity , and according to the medium polarize theory the self consistent equations was deduced , which describe the light intensity and phasic of the counter - propagating wave . on the basis of this equations , adopted the simulation software matlab and virtual instrument programming language labwindows / cvi , we can do some simulated experiments in study the phenomenas such as amplify and dispersive characteristic of medium , mode pushing effection , burned hole effection and pattern competition , lock - in of frequency and the characteristic of light intensity and phasic of the counter - propagating wave in laser gyro 激光陀螺的核心部件为he - ne环形激光器，而掌握光与介质的相互作用理论是研究激光器的关键，采用拉姆半经典理论为主，在密度矩阵理论的基础上，推导环形谐振腔中描述he - ne气体增益介质原子运动的光学布洛赫方程，运用介质极化理论得出描述激光陀螺反向行波的光强、位相所满足的自洽场方程组，在此基础上，运用matlab仿真软件和虚拟仪器编程语言labwindows / cvi ，对激光陀螺中的介质增益色散特性、频率牵引效应、烧孔效应及模竞争、闭锁效应及环激光的光强和相位特性进行仿真试验研究，并且运用全量子理论，对激光工作原理进行分析，得出二能级系统单模辐射场的光子数密度分布，得出激光场的光子统计分布，仿真激光场的动态建立过程。
Based on the amplitude and phase of two - order cyclic spectrum of phase - code signals , a novel cyclic spectrum estimation approach is proposed to estimate the carrier frequency , chip width , amplitude , initial phase , timing epoch of spreading code under no parameter information . this approach is computationally efficient , and is easy to be implemented , and it shows a good estimation accuracy over analysis 基于相位编码信号循环谱的幅度和相位特性，提出了二阶循环平稳参数估计方法，可庄没有任何参数信息情况下，实现载频、码片时宽、幅度、初相、编码序列初始时间等参数的估计，估计方法计算量少，易于实现，且有良好的估计精度。
This paper introduces some practicable way of eta , presents the principle of each method and compares their virtues and shortcomings . among them , the vca ( voltage controlled amplify ) becomes prominent for its good characteristics , such as wide output dynamic range , low nonlinear distortion , flat amplitude - frequency characteristics , high amplitude resolution 对衰减器的总体方案和实现方法作了全面的分析、并着重分析了电路设计和研制中的各个关键问题，如动态范围，幅频特性，相位特性，非线性失真等。
In addition , from the point of view of practicality , we make a study of experiment and application for double - exposure digital holographic interferometry , namely measuring gradn and grad / i of plane optical flat and measuring phase modulation characteristic of a kind of liquid crystal spatial light modulator ( lc - slm ) - liquid crystal television ( lctv ) 另外，本文还从实用的角度出发对二次曝光数字全息干涉术进行了实验及应用的研究，具体就是平面平晶gradn和gradh的测量以及液晶空间光调制器( lc - slm )中液晶电视( lctv )的相位特性的测量。
