圆周均匀多相调制相关辐射计及其灵敏度分析

Uniform circular multiphase modulation correlation radiometer and its sensitivity analysis

针对相关辐射计中由于运算放大器的零点漂移及增益起伏导致测量精度下降的问题,提出了在圆周上进行均匀多相调制的相关辐射计结构,利用最小二乘拟合方法对多相调制的测量结果进行处理,消除了运放零点漂移对相关辐射计测量偏差的影响。基于相关辐射计结构及噪声统计模型,推导了圆周均匀多相调制相关辐射计温度灵敏度的表达式,分析了系统灵敏度与调制阶数、增益起伏、调相误差的关系。分析表明:随着调制阶数的增加,增益起伏和调相误差对灵敏度的影响变小,圆周均匀多相调制相关辐射计的灵敏度趋于理想相关辐射计的灵敏度。

A correlation radiometer structure with uniform multiphase modulation around the circumference is proposed in order to address the issue of decreased measurement accuracy caused by the operational amplifier’s offset drift and gain fluctuation in correlation radiometers.The measurement result is processed using the least square fitting method,which removes the influence of the operational amplifier’s offset drift on the measurement deviation.Based on the structure of the correlation radiometer and the noise statistical model,the expression of the temperature sensitivity of the uniform circular multiphase modulation correlation radiometer is computed,and the relationship between the system sensitivity and phase modulation order,gain fluctuation and phase shift error is analyzed.The analysis shows that with the increase of the modulation order,the influence of gain fluctuation and phase modulation error on the sensitivity becomes smaller,and the sensitivity of the uniform circular multiphase modulation correlation radiometer tends to the sensitivity of the ideal correlation radiometer.