【作者】 郎健；

【导师】 王超；

【作者基本信息】 天津大学 ， 检测技术与自动化装置， 2006， 硕士

【摘要】 在科学研究和工程实践中,经常会遇到毫伏级信号的检测问题。运用锁相放大器可以测量到传统方法无法测量的微弱量,例如微振动、微电压、微电流及微小温度变化量等,因此,它成为检测微弱信号的重要手段,被广泛应用于物理、化学、生物医学、遥感和材料学等多种领域。本文在对现有LIA进行深入研究的基础上,提出了一种新型的数字锁相放大器设计方案,主要研究工作如下:1.设计了一种新型的数字锁相放大器,以TMS320CV5416 DSP为核心处理器,并使用复杂可编程逻辑器件EPM7064实现外部逻辑控制及系统时序转换,提高了系统的稳定性和实时性。2.设计了高速数据采集电路,该电路使用现今流行的电路结构,利用FIFO将闪烁式模数转换芯片与核心处理器联系起来,获得了较高的采样速率。此外,设计了一套高速数据传输电路,利用计算机并行口和DSP的HPI接口,在主机和DSP之间形成一条高速数据通道,使系统具备高速通讯的能力。3.为配合硬件系统,设计了上位机软件和下位机软件,以完成系统硬件电路的控制、PC和DSP之间通讯及测量数据的处理。应用该测量平台,以信号发生器ESCORT EGC-3230产生信号为被测对象设计了实验,分别研究了测量数据的频谱及正交解调结果,并计算出相对误差及重复性等指标,通过与示波器进行比对,认定该系统符合设计要求。更多还原

【Abstract】 The Detection of the milli-volt signal is often required in scientific research and engineering practice. Many weak signals which can not be detected with the conventional method, such as micro-vibration, weak voltage, weak current and small change of temperature, can be detected through the lock-in amplifier. So the lock-in amplifier is one of important methods for weak signal detection, which has been widely applied in the field of physics, chemistry, biomedicine, remote sensing, material science, etc.In this thesis, the author studied the existing lock-in amplifier in depth and presented a novel design of lock-in amplifier. The main work of this paper is shown as follows:1. A novel digital the lock-in amplifier based on DSP (TMS320CV5416) is designed. The complicated programmable logic device (EPM7064) is used to manipulate the external logic and system time sequence, which improves the stability and real-time ability of the system.2. The high-speed acquisition circuit is designed according to the popular circuit structure, which connects the A/D chip with DSP together to get high acquisition rate through FIFO. Otherwise, a high-speed data acquisition circuit is designed with the parallel interface of computers and the HPI interface of DSP which forms a high-speed tunnel between the host computer and DSP, so that the system can deal with high-speed communication.3. The software for DSP and PC is designed to work with the hardware system, which accomplishes the control of hardware circuit, communication between DSP and PC and calculation of the acquired data.The signal from signal generator (ESCORT EGC-3230) is measured on the platform. According to the spectrum of the data and the result of orthogonal digital demodulation, relative error and repeatability error of the acquired data are obtained. The experimental tests compared with oscillograph show that the system meets the design demand.更多还原