Error Analysis for Gas Temperature Measurement Based on the Thermistor

Accurate temperature measurement of the pressurant gas is important,to determine residual propellant in propellant tanks and improve control accuracy of oxidizer to fuel mixture ratio.A thermistor based gas temperature measurement is proposed by measuring temperature of tank wall acquiring the true temperature of the pressurant gas.And,then by analyzing factors such as temperature-thermistor nonlinear characteristics,temperature-voltage processing circuit,A/D acquisition nonlinear characteristics resulting in temperature measurement error,errors of temperature acquisition system is determined.In addition,main error sources of temperature acquisition system is analyzed.Finally,by analyzing the effect of measurement noise resulted from extenal disturbance on the temperature measurement,the temperature measurement accuracy is greatly improved by wavelet de-noising and temperature measurement error of the pessurant gas is determined in the end.