基于NiosⅡ的光纤光栅传感系统解调技术的研究

基于Altera公司的32位嵌入式软核处理器NiosⅡ, 设计了一种四通道分布式光纤光栅传感网络的并行波长解调系统, 对解调系统的光路和硬件电路进行设计。解调系统的硬件电路以现场可编程门阵列(FPGA)为核心, 对整形为矩形脉冲的光电转换信号电压进行采集和信号处理, 可与上位机实现通用非同步收发传输器(UART)和通用串行总线(USB)通信, 在上位机上实现光纤光栅波长解调的动态显示和光栅中心波长标定, 可高速、高精度并行解调上百个外界被测信号。与目前具有同样功能的其他波长解调系统相比, 具有灵活、稳定、易维护、高速、高精度等优点, 可被应用到大型多点安全监测工程。给出具体的波长解调和标定的实例, 精度可达到±2 pm。

Research on the Demodulation Techniques for the Sensing System of Fiber Grating Based on the Nios Ⅱ

Based on Altera′s 32 bit embedded soft-core processor Nios Ⅱ, the parallel wavelength demodulation system of a four-channel distributed fiber Bragg grating sensor network was designed. The optical system and hardware circuit for demodulation system were designed specifically. Field-programmable gate array(FPGA) is the core of the hardware circuit, which can collect and process the photoelectric signal voltage transformed to rectangular voltage pulse. The hardware circuit can communicate the signal to the computer through the universal asynchronous receiver transmitter(UART) and universal serial bus(USB). The computer can display a dynamic fiber grating wavelength demodulation process and calibrate the Bragg grating center wavelength. The system can demodulate accurately hundreds of outside signals at one time. Compared with other wavelength demodulators with the same functions, it has many advantages, such as flexibility, stabilization, easy maintenance, high-speed, high-precision, and so on. The wavelength demodulation system can be used extensively in large-scale multipoint monitor engineering. At last, an example of wavelength demodulation and calibration is given and precision can reach to ± 2 pm.