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.

• 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。