IDENTIFICATION OF PHASE ERROR BY MULTI-SAMPLING DIGITAL TANLOCKED LOOP(MS-DTL)

A multisampling technique was introduced to the phase error detector of Conventional Digital Tanlocked Loop(C DTL). In this new technique a number of samples ( M ) were taken at nonuniform intervals within one period of the input signal. The novel system is called Multisampling Digital Tanlocked loop(MS DTL). The simulated model on the computer shows that for M =4, the system has a faster locking speed and wider locking in range compared with C DTL.

QFT control based on zero phase error compensation for flight simulator

To improve the robustness of high-precision servo systems, quantitative feedback theory （QFT） which aims to achieve a desired robust design over a specified region of plant uncertainty is proposed. The robust design problem can be solved using QFT but it fails to guarantee a high precision tracking. This problem is solved by a robust digital QFT control scheme based on zero phase error （ZPE） feed forward compensation. This scheme consists of two parts： a QFT controller in the closed-loop system and a ZPE feed-forward compensator. Digital QFT controller is designed to overcome the uncertainties in the system. Digital ZPE feed forward controller is used to improve the tracking precision. Simulation and real-time examples for flight simulator servo system indicate that this control scheme can guarantee both high robust performance and high position tracking precision.

ZERO PHASE ERROR REAL TIME CONTROL FOR FLIGHT SIMULATOR SERVO SYSTEM

Flight simulator is an important device and a typical high performanceposition servo system used in the hardware-in-the-loop simulation of flight control system. Withoutusing the future desired output, zero phase error controller makes the overall system's frequencyresponse exhibit zero phase shift for all frequencies and a very small gain error at low frequencyrange can be achieved. A new algorithm to design the feed forward controller is presented, in orderto reduce the phase error, the design of proposed feed forward controller uses a modified plantmodel, which is a closed loop transfer function, through which the system tracking precisionperformance can be improved greatly. Real-time control results show the effectiveness of theproposed approach in flight simulator servo system.

Study on fast calibration of a ULA's gain and phase error

Array calibration is important in engineering practice. In this paper, fast calibration methods for a ULA's gain and phase errors both in far and near fields are proposed. In the far field, using a single sound source without exact orientation, this method horizontally rotates the array exactly once, performs eigen value decomposition for the covariance matrix of received data, then computes the gain and phase error according to the formulas. In the near field, using the same single sound source, it is necessary to rotate the array horizontally at most three times, build equations according to geometric relations, then solve them. Using the formula proposed in this paper, spherical waves are modified into plane waves. Then eigen values decomposition is performed. These two calibration methods were shown to be valid by simulation and are fast, accurate and easy to use. Finally, an analysis of factors influencing estimation precision is given.

Ultra wideband CMOS digital T-type attenuator with low phase errors

A proposed inductive-phase-compensation ultra wideband CMOS digital T-type attenuator design based on an analysis of minimising phase errors is presented in this letter.In a standard CMOS technology,the proposed attenuator is analytically demonstrated to have low phase errors due to the inductive-phase-compensation network.A design equation is inferred and a wide-band 4dB attenuation bit digital attenuator with low phase errors is designed as a test vehicle for the proposed approach.

Quantitative feedback theory and zero phase error tracking control combined robust control for radar truck leveling simulator

Radar leveling system is the key equipment for improving the radar mobility and survival capability. A combined quantitative feedback theory (QFT) controller is designed for the radar truck leveling simulator in this paper, which suffers from strong nonlinearities and system parameter uncertainties. QFT can reduce the plant uncertainties and stabilize the system, but it fails to obtain high-precision tracking. This drawback can be solved by a robust QFT control scheme based on zero phase error tracking control (ZPETC) compensation. The combined controller not only possesses high robustness, but greatly improves the system performance. To verify the effiectiveness and the potential of the proposed controller, a series of experiments have been carried out. Experimental results have demonstrated its robustness against a large range of parameters variation and high tracking precision performance, as well as its capability of restraining the load coupling among channels. The combined QFT controller can drive the radar truck leveling platform accurately, quickly and stably.

Studies on absorption coefficients of dual-energy γ-rays and measur-ing error correction for multiphase fraction determination

In this article, principle and mathematical method of determining the phase fractions of multiphase flows by using a dual-energy γ -ray system have been described. The dual-energy γ -ray device is composed of radioactive isotopes of 241Am and 137Cs with γ -ray energies of 59.5 and 662 keV, respectively. A rational method to calibrate the absorption coefficient was introduced in detail. The modified arithmetic is beneficial to removing the extra Compton scattering from the measured value. The result shows that the dual-energy γ -ray technique can be used in three-phase flow with average accuracy greater than 95%, which enables us to determine phase fractions almost independent of the flow regime. Improvement has been achieved on measurement accuracy of phase fractions.

Zero phase error control based on neural compensation for flight simulator servo system

Using the future desired input value, zero phase error controller enables the overall system＇s frequency response exhibit zero phase shift for all frequencies and a small gain error at low frequency range, and based on this, a new algorithm is presented to design the feedforward controller. However, zero phase error controller is only suitable for certain linear system. To reduce the tracking error and improve robustness, the design of the proposed feedforward controller uses a neural compensation based on diagonal recurrent neural network. Simulation and real-time control results for flight simulator servo system show the effectiveness of the proposed approach.

Effects of systematic phase errors on optimized quantum random-walk search algorithm

This study investigates the effects of systematic errors in phase inversions on the success rate and number of iterations in the optimized quantum random-walk search algorithm. Using the geometric description of this algorithm, a model of the algorithm with phase errors is established, and the relationship between the success rate of the algorithm, the database size, the number of iterations, and the phase error is determined. For a given database size, we obtain both the maximum success rate of the algorithm and the required number of iterations when phase errors are present in the algorithm. Analyses and numerical simulations show that the optimized quantum random-walk search algorithm is more robust against phase errors than Grover＇s algorithm.

The Influence of Carrier Phase Error on the Performances of Digital Image m-QAM Transmission System

The effect of carrier phase error in digital image transmission system is discussed. Code error rate and SNR with carrier phase error in Gauss white noise channel are calculated, and the transmission system is simulated on computer.

Adaptive Zero Phase Error Feedforward Method for Robotic Force Control

In order to remove the time delay between the input and the output signals of a robot force control system,adaptive zero phase error feedforward(AZPEF)control method is presented and applied to PUMA 560 industrial robot,which has six degree of freedom(6-DOF).The whole adaptive force control algorithm is implemented on TMS320C30 micro-processor whose instruction cycle is 60ns.The results of the force control experiments prove that AZPEF force control makes robot have good robustness and quick response ability.

DOA estimation for mixed signals with gain-phase error array

Most of the direction of arrival(DOA) estimation methods often need the exact array manifold, but in actual applications,the gain and phase of the channels are usually inconsistent, which will cause the estimation invalid. A novel direction finding approach for mixed far-field and near-field signals with gain-phase error array is provided. Based on simplifying the space spectrum function by matrix transformation, DOA of far-field signals is obtained. Consequently, errors of the array are acquired according to the orthogonality of far-field signal subspace and noise subspace.Finally, DOA of near-field signals can be estimated. The method merely needs one-dimensional spectrum searching, so as to improve the computational efficiency on the premise of ensuring a certain accuracy, simulation results manifest the effectiveness of the method.

The Role of Phase Errors Distributions in Phased Array Systems Operations

A comprehensive study on the role of the phase errors distribution on the performances of the phased array systems has been led using a complete and behavioral model for radiation-pattern characteristics. The used model has many input parameters and it has a lot of features, such as parameters simulations with results analysis, unconventional two-dimensional color graph representation capability in order to show more clearly the results. The results of the study have been discussed and reported. The main achievement of this work is the demonstration that the RMS phase error is a valuable figure of merit of phased array systems but it is not sufficient to completely describe the behavior of a real system. Indeed, this work has shown how the phase errors distribution actually affects the performances of the phased arrays antennas.

A Modified Regression Estimator for Single Phase Sampling in the Presence of Observational Errors

In this paper, a regression method of estimation has been used to derive the mean estimate of the survey variable using simple random sampling without replacement in the presence of observational errors. Two covariates were used and a case where the observational errors were in both the survey variable and the covariates was considered. The inclusion of observational errors was due to the fact that data collected through surveys are often not free from errors that occur during observation. These errors can occur due to over-reporting, under-reporting, memory failure by the respondents or use of imprecise tools of data collection. The expression of mean squared error (MSE) based on the obtained estimator has been derived to the first degree of approximation. The results of a simulation study show that the derived modified regression mean estimator under observational errors is more efficient than the mean per unit estimator and some other existing estimators. The proposed estimator can therefore be used in estimating a finite population mean, while considering observational errors that may occur during a study.

一种基于相位误差校正技术的快速启动晶体振荡器

随着超低功耗(Ultra-Low Power,ULP)物联网(Internet of Things,IoT)系统的发展,采用能量注入技术的快速启动晶体振荡器因对IoT系统功耗影响巨大而逐渐成为研究热点.能量注入技术可以显著降低晶体振荡器的启动时间和启动能量,但是对注入源的精度要求苛刻.为了扩大注入频偏容限以及实现高注入效率,本文提出了一种基于延迟锁定环的相位误差校正技术.该技术将注入频偏容限扩大到2%,启动过程的非注入持续时间仅为4个周期,实现了高效注入.本文所述晶体振荡器采用40 nm CMOS工艺设计并流片.在1.0 V电源电压下采用24 MHz晶体进行测试,当注入频偏高达2%时,实现了7.2μs的启动时间,启动能量为5.1 nJ.相比同频偏下的传统注入方案,启动时间缩短了99.66%.

A NEW ALGORITHM FOR ELIMINATING PHASE-SHIFT ERROR IN PHASE SHIFTING INTERFEROMETRY

The effect of phaseshift error in phase shifting interferometry is investigated. A new algorithm with two sets of 4 samples for eliminating phase shift error is presented. The computer simulation and experiment result show that the phase shift offset should be π when the algorithm is used, and this algorithm has gotten better result than the original 4 sample algorithm.

基于最大对比度的联合相位误差校正方法

针对高分辨率逆合成孔径雷达(ISAR)成像过程中,因目标转动所引入的转动相位误差无法被忽略,以及由于转动相位误差使得传统平动相位误差校正方法性能严重下降的问题,提出了一种基于最大对比度的联合相位误差校正的方法,可同时校正残余的平动相位误差和转动相位误差,进一步提高成像的质量。首先利用传统的运动补偿方法对回波信号进行处理,其次根据最大对比度准则,将相位误差校正问题转化为最大对比度优化问题,最后利用改进的拟牛顿算法进行求解。该方法能使高分辨率ISAR进行精准成像,且所得图像聚焦效果良好。通过对仿真数据和实测数据的处理,验证了文中方法的有效性。

基于均匀相位采样提高阻抗谱测量精度的研究

周期性信号采样中,等效采样利用较低采样频率的A/D转换实现高频周期信号的采集,一定程度上弥补欠采样测量精度低的缺陷。为了有效地提高高频测量中阻抗谱测量精度与稳定性,提出一种基于等效采样思想的均匀相位采样的阻抗谱测量方法。利用单片机共时钟基准的模/数转换器(digital to analog convertor,DAC)与数/模转换器(analog to digital convertor,ADC)模块,在完成激励信号产生、输入输出信号同步采集的基础上,合理设计激励信号频率、采集频率与信号重构方法,实现高频信号单周期内均匀相位分布的等效高频采样,同时为克服常规A/D转换速度条件下难以准确实现高频阻抗谱测量的问题提供了新思路。从误差假设与拟合算法的角度,理论上分析证明了该方法降低误差的原因。并通过两种等效电路模型的阻抗谱测量对比实验,表明该方法在所设计的20~100 kHz高频段上,阻抗测量精度与稳定性得到了显著的提高。

相位噪声对 16QAM 通信系统性能影响及其均衡算法研究

在分析相位噪声对16QAM通信性能影响的基础上,提出了一种基于误差判决的多模均衡算法(Multiple Modulus Algorithm Based on Error Judgment,MMA-EJ),该算法不仅利用信号的相位信息消除了卫星通信中载波频偏引入的相位失真,还考虑了多电平幅度调制中不同半径星座点引入的幅度误差影响,因此相对于恒模算法(Constant Modulus Algorithm,CMA)来说,提高了均衡算法的精度。仿真结果表明,与传统的恒模均衡算法相比,提出的基于误差判决的MMA算法不仅可以消除高速信号传输时的码间串扰(Inter Symbol Interference,ISI),还可以消除传输系统中的相位噪声,提高16QAM通信系统的传输性能。

面向无线传感网络的同步时钟技术研究

考虑到传统的时钟同步技术在信息交互过程中产生的延迟具有不确定性,为了消除其对时钟同步的影响,提出了面向无线传感网络的同步时钟技术研究。通过对任意一个网络节点在真实物理时间的本地时间进行变换处理,构建无线传感网络的线性时钟模型,根据高斯分布所具有的加减特性,计算两个连续同步轮次的动态响应时间差值,在离散形式下,构建无线传感网络观测模型。通过计算无线传感网络时钟差值的均值,得到无线传感网络节点的时间戳,将无线传感网络节点数据交互误差补偿的目标函数转换成向量的形式,补偿无线传感网络节点数据交互误差,实现无线传感网络的时钟同步处理。实验结果表明,在微秒级延迟下,该技术的同步精度仍较高,可以有效消除网络信息延迟的不确定性对同步时钟的影响。