【作者】 杨艳；

【导师】 曾一凡；

【作者基本信息】 沈阳工业大学 ， 信号与信息处理， 2009， 硕士

【摘要】 随着高温超导材料的超导温度不断提升,极大地促进了这一领域的发展,使得高温超导材料得到了广泛的应用。因此如何低成本地、准确地测量高温超导材料的临界转变温度的工作就变得至关重要。本文详细描述了基于一种微弱信号检测方法—锁定放大器来采集强噪声干扰下的R-T信号的高温超导材料的临界R-T(电阻—温度)检测系统的设计思想,基本原理,硬件实现,软件编程等方面的内容。本系统的电阻信号采集部分,把采集来的包含电阻信息的微弱电压信号进行放大并进行带通滤波后,与来自参考通道的与测量信号同频同相的参考信号进行模拟乘法处理,然后再进行必要的放大和低通滤波步骤后送至A/D转换芯片进行模数转换,再把转换后的信号送至单片机进行后续的处理。本系统的温度采集部分,把通过铜-康铜热电偶采集到的信号进行放大后送A/D转换芯片进行模数转换,再把转换后的信号送至单片机进行后续的处理,从而实现了对高温超导材料的R-T两路信号的采集并通过串口把采集到的两路信号传送到PC中,后利用功能强大的LabVIEW程序对采集来的两路信号进行后续的处理和显示。系统以AD公司的AD630作为整个系统的核心部件—模拟乘法器,以软件可编程控制的V/F转换器AD650作为系统的A/D部件。本系统利用锁定放大原理,检测高温超导环境中微弱的超导电阻,具有精度高、抗干扰能力强等优点,同时大大降低了开发的成本,缩短了开发系统的周期。更多还原

【Abstract】 With the rising temperature of high-temperature superconducting material, it greatly promotes the development of this area and makes high-temperature superconducting material widely used. Therefore, it becomes critical to achieve a low-cost, accurate system for the critical transition temperature measurement of high-temperature superconducting material.This paper using a weak signal detection approach-lock-in amplifier to acquire the R-T signals under strong noises describes the design idea, the basic principle, the hardware and the software of the system. The resistance acquisition part of the system amplifies, band-pass filteres the weak voltage signal containing the resistance information, multiplies the reference signal from the reference channel with the same frequency phase as the measurement signal, making the necessary amplification and low-pass filtering step, then sends the signal to the A / D conversion chip for analog-digital conversion and converts the signal which is sent to the microcontroller for the follow-up treatment. The temperature acquisition part of this system amplifies the signal from the copper-constantan thermocouple, sends the signal to the A / D conversion chip for analog-digital conversion and then sends the signal to the microcontroller for the follow-up treatment. Therefore it achieves the R-T two-way signals acquisition of the high-temperature superconducting material, then sends the signals to the PC through serial port, and uses the powerful LabVIEW program to process and display the collected signals.Using the principle of lock-in amplifier, the system detects weak resistance signal under the high-temperature superconducting environment. It has high accuracy and strong anti-interference ability. At the same time it greatly reduces the cost of development and shortenes the development cycle of the system.更多还原