介绍一种用于测量指数衰减信号时间常数的数字处理方案 ,它采用固定相移的数字式相敏器检测跟踪被测寿命。具有补偿衰落信号相关和不相关偏差的能力 ,而且信噪比较高。本系统已经在测量荧光衰减时间中得到成功的应用。该测温仪从 0℃到 5 0 0℃的温度误差小于 0 .5℃。 A digital processing scheme for measuring the time constants of exponential decay signals is introduced. It uses a digital phase detector with a fixed phase shift to detect and measure the measured lifetime. With the ability to compensate for correlated and uncorrelated fading signals, and high signal to noise ratio. The system has been successfully used in the measurement of fluorescence decay time. The thermometer temperature error from 0 ℃ to 500 ℃ less than 0.5 ℃.