【作者】 杨柳；

【导师】 岳继光；

【作者基本信息】 同济大学 ， 控制理论与控制工程， 2007， 硕士

【摘要】 在无线通讯接收机射频前端的电路设计过程中，借助系统仿真对电路整体性能进行验证尤为重要。为此，在仿真阶段，不仅需要建立相应的数学模型来表达每一个电路模块，而且需要模拟实际应用中的干扰因素，使仿真环境更加真实、仿真结果更加贴近于实际结果。幂律噪声(1／f~αNoise)和相位噪声(Phase Noise)是模拟电路中常见的影响因素。其中，幂律噪声是射频接收机和基带模拟电路的重要限制因素。相位噪声在振荡器和锁相环中会引起相位差和多信道之间的干扰，从而导致误码率(bit-error rates，BER’s)增加。本文深入分析了现有的两种幂律噪声产生方法：IIR／FIR滤波器对白噪声滤波法和并联低通滤波器组对白噪声滤波法，从相对误差和运行时间角度对两种噪声综合方法进行比较。在此基础上提出了一个新的相位噪声综合模型，该参数化模型的建模原理是利用每一个并联的低通滤波器构造所期望相位噪声功率谱密度特性的一小段，从而使综合输出在整个频段内表现出所期望的特性。由于MATLAB在开发和验证通信算法时有广泛的应用，因此，选择其作为仿真环境对幂律噪声和相位噪声进行建模和仿真。本文还建立了一个简化的GPS系统中卫星码截获过程的模拟环境，用产生的相位噪声序列来影响粗／截获(coarse／acquisition，C／A)码的截获过程。通过改变相位噪声大小，得到不同频谱特性的相位噪声与C／A码受影响程度之间的关系。通过对仿真结果的时频域验证表明，本文提出的相位噪声时域模型具有输入信号简单、模型参数化和模块独立的优点，对系统仿真和减噪方法的研究具有很好的辅助作用。更多还原

【Abstract】 System simulation is extremely important for verification of large-scale integrated chipsets for wireless applications, such as front-end circuit design for wireless receiver. In order to perform the system level simulation, models for each circuit module as well as disturbance are required.Power low noise (1/f~αNoise) and phase noise are two common interferences in analog circuit. 1/f~αNoise is an important limit factor for radio frequency receiver and base band analog circuit. Phase noise is normally found in phase locked loop and local oscillators, which increase the phase error, multi-channel interference and bit error rates. Two current techniques for generating discrete sequence of 1/f~αnoise are summarized. One is based on finite impulse response (FIR) and infinite impulse response (IIR) filter, the other is based on the structure of several parallel first-order low pass filters. Comparisons will be made between the two methods in point of running time and relative error. Based on the modeling principle of low-pass filters structure for 1/f noise generation, a time-domain model is proposed for phase noise synthesis. The main idea is to separate the noise generation process into different segments and use the low-pass filters structure to process the noise separately in each individual segment. The MATLAB simulation environment was selected because of its wide application for development and evaluation of communication algorithms.Besides, a simplified simulation environment for GPS coarse/acquisition (C/A) code tracking is set up in MATLAB to evaluate the influence of phase noise on C/A code tracking process. Further research is made to find the relationship between the phase noise characterizations and the influences.The simulation results are verified both in frequency domain and time domain. Conclusions can be drawn that the proposed phase noise model has the following advantages: simple, parametric and independent. It can aid system simulation and research on noise reduction.更多还原