火灾探测小信号幅频特性测试装置设计

Design of Small Amplitude and Frequency Characteristics Test Device for Fire Detection

为提高火灾预警设备信号处理精度,本装置模拟火灾探测小信号,实现小信号近程和远程幅频特性测试.近程装置主要由模拟小信号源、滤波器、放大器、检波器等电路组成,远程装置在近程通信基础上通过有线和无线两种方式实现远距离通信.信号源由DDS芯片AD9854产生,通过处理器STM32控制该信号的频率和幅值输出,该信号经过LPF滤波后,由可控增益放大器实现0~40d B可调放大,然后由AD8367进行有效值转换,再经过ADC采集有效值,DAC将数据传输到示波器,实现近程幅频特性曲线的显示;远程有线通信由双绞线传输信号,远程无线通信通过Wi Fi转换电路ESP8266连接路由器,与电脑组网后通过上位机软件MATLAB GUI显示幅频特性曲线,经过测试该装置能够达到测量精度,为智能火灾预警设备设计提供技术依据.

In order to improve the signal processing accuracy of fire early warning equipment,the device is designed for simulating fire detection signal and realizing the test of short-range and long-range amplitude frequency characteristics.The short-range device mainly consists of small analog signal source,filter,amplifier,detector and other circuits.The long-range device can achieve wired and wireless communications for a long-distance based on short-range communication.Small signal source is produced by the DDS chip AD9854.Frequency and amplitude are controled by the processor STM32.After filtering by the LPF,the signal gain could be adjusted from 0 to 40dB with controlled gain amplifier.Valid value is convered by the AD8367 and acquired by the ADC.DAC data is transmissed to the oscilloscope to achieve short-range amplitude-frequency characteristic curve display.The long-range wired communication is transmitted by the twisted-pair cable,and the long-range wireless communication is connected to the router through the WiFi conversion cir?cuit,amplitude-frequency characteristic curve is displayed through the host computer software MATLAB GUI on the computer.After testing,the device can achieve measurement accuracy and provide technical basis for design of intelligent fire warning equipment.