基于System Generator的数字锁相放大器研究

发布时间：2018-06-22 15:52

本文选题：数字锁相 + System　；参考：《东华理工大学》2015年硕士论文

【摘要】：锁相放大器是一种微弱信号检测仪器,用来提取如在黏度测量、微波特性研究、光纤瓦斯检测等工程领域中传感器输出的微弱信号。锁相放大器是一种通过研究被检测信号的特点与相关性,并对被噪声淹没的微弱有用信号进行提取的技术。在传统数字锁相放大器基础上,本文完成了一种基于System Generator的数字锁相放大器设计。系统采用System Generator软件构建,让数字锁相放大器的开发更为简单、减少工程量;解决数字锁相放大器参考信号频率手动配置的问题;利用数字窄带低通滤波技术,改善了数字锁相放大器的信噪比,提高了数字锁相放大器的检测精度。在分析了现有锁相放大器的基础上,即包括相关函数、相关检测原理、模拟和数字锁相放大器的整体结构等内容,完成了基于System Generator的数字锁相放大器的系统设计。系统由前置滤波模块、抗混叠模块,采样模块,FPGA模块组成。本文针对系统中FPGA实现进行了设计。首先以System Generator作为硬件开发平台,利用System Generator上提供的DSP模块,并结合FFT等相应技术,设计了与待测微弱信号频率自动匹配的参考信号发生模型;其次把多采样速率信号处理的方法应用在FPGA上,实现数字窄带低通滤波器的设计,完成了新型数字锁相放大器的设计与实现。在以上基础上,将基于System Generator的数字锁相放大器应用于黏度测量。通过软、硬件协同仿真测试与板载验证,分析结果表明基于System Generator的数字锁相放大器与以往数字锁相放大器相比,信噪改善比提高到56dB以上,窄带低通滤波器的品质因素Q可达105以上。本文设计的数字锁相放大器可以检测500KHz以下的信号,输入信号信噪比36dB以下时提取信号幅值的相对误差小于2%,检测范围为5uV~5V。这些性能指标满足西安某公司黏度测量的要求,具有一定的实际应用价值。
[Abstract]:The phase-locked amplifier is a kind of weak signal detection instrument, which is used to extract the weak signal output in the engineering fields such as viscosity measurement, microwave characteristic research, optical fiber gas detection and so on. The phase-locked amplifier is a technique for extracting weak and useful signals submerged by noise by studying the characteristics and correlation of the detected signals. Based on the traditional digital phase-locked amplifier, a digital phase-locked amplifier based on system Generator is designed in this paper. The system is constructed by system Generator software, which makes the development of digital phase-locked amplifier simpler, reduces the amount of work, solves the problem of manual configuration of reference signal frequency of digital phase-locked amplifier, and utilizes digital narrowband low-pass filtering technology. The signal-to-noise ratio of the digital phase-locked amplifier is improved, and the detection accuracy of the digital phase-locked amplifier is improved. Based on the analysis of the existing phase-locked amplifier, including the correlation function, the principle of correlation detection, the simulation and the whole structure of the digital phase-locked amplifier, the system design of the digital phase-locked amplifier based on the system Generator is completed. The system consists of prefilter module, anti-aliasing module, sampling module and FPGA module. In this paper, the FPGA implementation of the system is designed. Firstly, the system Generator is used as the hardware development platform, using the DSP module provided by the system Generator, and combining with the corresponding technology such as FFT, the reference signal generation model is designed to automatically match the frequency of the weak signal to be measured. Secondly, the method of multi-sampling rate signal processing is applied to FPGA to realize the design of digital narrowband low-pass filter, and the design and implementation of a new digital phase-locked amplifier. On the basis of above, the digital phase-locked amplifier based on system Generator is applied to viscosity measurement. The analysis results show that compared with the previous digital phase-locked amplifier, the signal-noise ratio of the digital phase-locked amplifier based on system Generator is more than 56dB. The quality factor Q of narrowband lowpass filter can be more than 105. The digital phase-locked amplifier designed in this paper can detect the signal below 500kHz. The relative error of extracting signal amplitude is less than 2 when the SNR of input signal is below 36dB, and the detection range is 5uV / 5V. These performance indexes meet the requirements of viscosity measurement of a company in Xi'an, and have certain practical application value.
【学位授予单位】：东华理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN722

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