大距离系数红外测温仪的关键技术研究

针对大距离系数红外测温仪测温距离远和噪声干扰大的特点,提出一种微弱信号数字相敏检测方法.根据相关检测原理,设计了由模拟开关和低通滤波器组成的模拟相敏检波电路,并对此电路的噪声抑制特性进行了分析.基于反相采样累加相关原理,提出了数字相敏检波方法,并对数字相敏检波方法的频率特性进行了分析.实验结果表明,模拟相敏检波电路具有良好的噪声抑制能力;该数字方法能抑制谐波,消除前置处理中引起的直流.与模拟检波方法相比,该数字方法在检测精度和处理速度上也有较大提高.

Research on key technology of long-distance-coefficient infrared thermoscope

Aimed at long detection distance and heavy noise disturbance in the long-distance-coefficient infrared thermoscope,a new digital phase sensitive detection method for weak signal was proposed.According to the correlation detection theory,an analog circuit composed of an analog switch and a low pass filter was designed for phase sensitive detection,and the circuit character of noise suppression was analyzed.Based on the reverse phase sampling accumulation correlation theory,the digital phase sensitive detection method was achieved,and the method's frequency character was analyzed.Experimental results show that the analog circuit for phase sensitive detection can effectively suppress noise.The digital method can restrain harmonic and eliminate the direct current from previous processing.The digital method improves the detection accuracy and the processing speed compared with the analog method.