相位噪声对QAM性能影响分析

多电平 QAM调制对载波的相位噪声非常敏感。该文研究了慢速相位噪声对 QAM性能的影响 ,推导了相位噪声影响的 1 6QAM误符号概率的理论公式 ,给出了载波相位噪声对1 6QAM误符号率影响的计算机仿真结果。论文得到的理论公式和仿真结果 ,对 QAM调制的单载波通信系统的本振源相位噪声指标确定和系统性能的优化具有重要意义     

相位噪声对多天线QAM性能影响分析

正交幅度调制系统(QAM)对载波的相位噪声非常敏感,多天线技术的使用可以提高通信系统的性能。对QAM系统在当今通信系统中的应用及相位噪声对QAM系统性能影响进行介绍,对多天线QAM系统受相位噪声影响进行了理论分析及仿真验证,并给出了闭式误差向量幅度(EVM)表达式。给出的理论公式及仿真结果对多天线QAM系统相位噪声指标的确定及系统性能分析具有参考意义。     

相位噪声对QAM系统的影响及消除方法分析

分析了相位噪声的成因、测量以及相位噪声对系统的影响.同时通过仿真给出了因相位噪声影响而使系统性能下降的图示表示.列举了消除相位噪声影响所采用的不同方法,并着重分析了高阶QAM对抗相位噪声的最新的解调方法.     

带有相位噪声的MPSK和MDPSK性能统一分析

本文研究了相位噪声场对MPSK、MDPSK性能的影响.首先在统一框架下,推导了AWGN、Nakagami-m衰落和莱斯衰落信道中带有相位噪声时MPSK相干解调和MDPSK差分解调的误符号率;然后运用计算机仿真和数值方法,对误符号率和相位噪声的关系进行了验证;最后通过应用示例,展示了本文工作在系统设计和性能评估中的重要作用.     

载波相位误差对解调性能的影响分析

对MPSK、QAM信号载波相位误差对于解调性能的影响进行了定量分析,推导给出了载波估计方差较小时BPSK、QPSK信号载波相位误差对解调性能影响的表达式。根据定量分析结果,载波估计方差较小时对BPSK、QPSK信号载波估计方差与误码率的关系进行了仿真,仿真结果和理论分析结果是一致的。结果表明在Es/N0为2、载波估计方差小于1×10-2的情况下,载波相位误差对于解调性能的影响小于0.2 dB。     

色散补偿方式对相位调制系统中相位噪声的影响

分别推导了相位调制系统中采用色散预补偿方式和后补偿方式下非线性相位噪声的计算公式,基于此对这两种色散补偿方式下的相位噪声、功率容限以及最优信号峰值功率进行了详细的分析和讨论,结果表明:采用色散预补偿方式较后补偿方式能更有效地抑制非线性相位噪声,其对非线性相位噪声的抑制能力随着信号能量、放大自发辐射(ASE)的功率谱密度以及传输距离的增加而提高;同时,色散预补偿系统具有更高的功率容限;色散的作用使系统的最优信号峰值功率增大,最佳相移大于1rad;色散预补偿系统的最优信号峰值功率大于色散后补偿系统。     

CATV光传输中相位调制抑制相位干涉噪声的理论分析

对附加相位调制抑制相位干涉噪声的方法进行了理论分析与计算,结果表明：在光纤AM－CATV外调制传输系统中,对传输光载波信号引入附加相位调制,当相位调制信号的频率为CATV频带的2倍以上时,可以有效地抑制相位干涉噪声的发生,相位调制度越大,抑制效果越好。     

相位噪声对脉冲多普勒雷达性能的影响

讨论了频率源相位噪声对脉冲多普勒雷达杂波可见度、测速精度、速度分辨力性能的影响,给出了一种用频谱分析仪测量杂波可见度的方法,最后进行了实例分析     

不同类型噪声作用下振荡器的相位噪声分析

相位噪声是振荡器最重要的性能指标.文中从描述振荡器的非线性微分方程出发,提出将噪声作为非线性微分方程的一项,通过建立随机非线性微分方程来分析振荡器的相位噪声,为振荡器的相位噪声提出了一种新的分析方法.用这种方法,在相同强度下,针对白噪声分别为加性和乘性的情形,分析其产生的相位噪声,得出了乘性噪声产生的相位噪声远大于加性噪声所产生的相位噪声的结论.     

对MATLAB实现数字信号的QPSK的频谱分析

调相是信号调制的一种,是用调制信号去控制载波信号角度(频率或相位)变化的一种信号变换方式,可以分为频率调制(FM)和相位调制(PM).信号经过角度调制后,频谱结构将发生变化,频谱分析是处理信号的重要步骤和必要的保证.利用MATLAB7.0语言编制脚本文件,对信号调用相应的函数进行各种调制,并且对其进行频谱分析.     

Phase Noise Spectral Limits in OFDM Systems

OFDM is recognized to be one of the best transmission techniques for wideband wireless communication systems. However, it exhibits two main drawbacks: its large amplitude fluctuation and its sensitivity to phase noise. Here we consider the phase noise impairments, taking care of the phase noise spectrum, which diverges form the classical Wiener model as the carrier frequency increases. Moreover, we show that the phase noise distortion can be decomposed in two terms, one dependent on the symbol under detection and the other dependent on the symbols of adjacent subcarriers, so that the performance degradation depends on both the constellation used in each subcarrier and the phase noise spectrum. As a consequence of this new results, the penalty due to phase noise expressed in terms of the average signal/noise plus interference ratio is not applicable in the case of modulations with non-constant amplitude constellations, such as 16- or 64-QAM. The method proposed here achieves a good accuracy, while keeping a low computational complexity, and it is confirmed by simulations. Roberto Corvaja was born in Padova (Italy) in 1967. He graduated at the Universisty of Padova in Electronic Enginering on 1990 and got his Ph.D. at the Univeristy of Padova in 1994. Since 1994 he is with the Dipartimento di Elettronica e Informatica of the University of Padova as a researcher and assistant professor on digital communications. Between 1994 and 1995 he spent 8 months at Hewlett-Packard Laboratories, Bristol (UK), working on equalization for a DECT receiver. His research activity in the past has regarded optical fibre communications systems and now is devoted to wireless communication systems. Silvano Pupolin was born in Venice, Italy, on February 17, 1947. He received the Laurea degree in Electronic Engineering from the University of Padova, Padova, Italy, in 1970. Since then he joined the Dipartimento di Elettronica e Informatica of the Universita' di Padova, where he currently is a Full Professor of Electrical Communications. He spent the summer 1985 at AT&T Bell Laboratories on leave from Padova, doing research on digital radio systems. He has been actively engaged in researches on digital communication systems since 1970. The topics covered has been: performance of baseband digital comunication systems, line encoding for spectral shaping, timing extraction, direct detection fiber optic system, spread spectrum communication systems, digital radio communications, with emphasis to the adaptive linearization of the High-Power-Amplifier. Actually, he is actively engaged in researches on digital radio, spread s pectrum systems, packet radio networks, personal communication systems and Cellular access to broadband systems for interactive communications. He is also National Project leader for a research on Personal Communication Systems. Dr. Pupolin is a Senior Member of IEEE and Member of AEI.     

低相位噪声信号的谱线宽度

提出了由相位噪声计算信号谱线宽度的计算公式,从而计算出脉冲多普勒雷达频综器输出的激励信号的谱线宽度,并且发现低相位噪声信号的谱线宽度是通用仪表所不能精确测量的.     

数字信号处理在雷达相噪测量中的应用

随着通信和雷达的发展,脉冲信号的相位噪声成了影响整个系统性能的重要因素之一,采用传统模拟相位检波法测量脉冲信号相位噪声是一个非常大的挑战,因为这样的测试系统非常复杂,并且在测量相位噪声之前需要非常繁琐的校准程序,先进的正交数字相位解调和幅度解调技术能很好地解决这个问题。采用正交数字相位解调和幅度解调技术的系统不需要相位检波器和复杂的校准程序,利用极低噪声的参考源和互相关技术,提高了系统动态范围和测量灵敏度,实现了一键式精密测量脉冲相位噪声和调幅噪声。     

微波光子链路中的附加相位噪声分析

针对模拟微波光子链路中附加相位噪声对微波信号相位噪声的恶化问题,详细研究了光链路中白噪声及有色噪声的产生机理,建立了光链路的附加相位噪声理论模型,阐述了附加相位噪声的变化规律,并通过实验证实了模型的正确性。同时针对本振信号的多路光分配典型应用,提出了EDFA 辅助的附加相位噪声优化措施。实验结果表明所提出的相位噪声模型能够有效地应用于微波光子链路,能对附加相位噪声的分析和优化提供理论依据,具有较大的工程指导意义。     

数字锁相环频率源相位噪声分析

首先对频率源相位噪声的原理及其表征进行了简要的阐述,然后从数字锁相环频率源的分析模型出发,对其相位噪声谱密度进行了推导,同时分析了影响相位噪声的各项主要因素．最后提出了提高数字锁相环频率源相位噪声性能的一些方法。     

自偏置锁相环的相位噪声分析

自偏置锁相环被提出以来,被认为能够以简单的电路结构降低锁相环的环内分频比从而改善环路带宽内的相位噪声。从噪声的相关性出发,分析了信号经过自偏置电路后对相位噪声的影响,并通过计算自偏置锁相环的相位传递函数得到其相位噪声模型,对比于传统单环式锁相环结构,其环内分频比并未降低。通过设计一2. 28～2. 52GHz 的自偏置锁相环,对其相位噪声进行测试并与传统单环和偏置式锁相环进行比较,测试结果也表明自偏置锁相技术并不能降低锁相环的带内相位噪声。     

基于PLL环路的卫星QPSK载波调制信号相位跟踪算法

卫星信号接收端天线接收的卫星信号经过射频前端处理后会变成数字中频信号,而相位跟踪是中频信号处理的重要环节,准确的相位跟踪可以为卫星信号解码、测距和定位等功能的准确性提供保障.基于此,该文提出了基于锁相环（Phase Locked Loop,PLL）的卫星QPSK载波调制信号相位跟踪算法.该算法利用多路正交载波和二象反正切鉴相器获取精确的相位差信息,形成闭合回路锁定载波相位以实现跟踪.实验结果表明,多路异相载波的方法可实现更快速的相位锁定,与传统Costas环路和松尾环相比,进入稳态时间分别减少了20%和24%以上,稳态方差分别减小21%和32%.     

Fast Oscillator Phase Noise Estimation Based on AC Analysis

A phase noise simulation method is discussed that is capable of estimating oscillator phase noise using standard AC analysis. Although its accuracy and scope are lower compared to available commercial tools, the simulation method has a number of useful and distinctive properties, including speed and good convergency. Moreover, its is ideally suited to numerically verify insightful behavioral models of oscillators. The principle of AC-based phase noise analysis is reduction of the open-loop gain in an oscillator to a value (1 − ε), with arbitrary but small ε. When the oscillator is simulated using AC noise analysis for a small ε, the simulated output noise spectrum has a Lorentzian shape. By taking a noise value reading at an offset frequency f_m on the −6 dB per octave part of this curve, dividing it by the carrier and subtracting 3 dB to remove the AM noise contribution, a value for L(f_m) is obtained. Two simulation examples, one numerically verifying a behavioral model, and one predicting phase noise of a measured 3.6 GHz LC oscillator, illustrate the practical use of the simulation method. In addition, the AC-based phase noise simulation of a two-integrator oscillator is briefly discussed.