# A Fast Calibration Method for Sensors of Atmospheric Detection System
## 2 System Physics Modeling  
### Calibration System Overview  
An overview of the temperature sensor calibration system for ADS is shown in Figure 1a. It is mainly composed of the thermostat, glass tube, fixed fixture, and standard thermometer. The physical photo of the temperature sensor calibration system for ADS is shown in Figure 1b.  
**ADS:** ADS mainly consists of a variety of sensors, a signal acquisition system, a wireless communication module, and a power supply system. The thermal resistance with a negative temperature coefficient is selected as the sensitive element of the temperature sensor in the detection system. Thermistors are susceptible to a variety of factors, including circuits and the environment. At a certain temperature, it is impossible to guarantee accurate resistivity mapping. In addition, the detection system operates at an ambient temperature of \(-80\)\({}^{\circ}\)C and the electronic components of the system operate at a minimum temperature of \(-45\)\({}^{\circ}\)C. Therefore, it is necessary to cover the external surface of the detection system with insulation foam to ensure that the system works properly at low temperatures.  
**Thermostat**: Temperature sensors in the ADS operate between \(-80\)\({}^{\circ}\)C and \(50\)\({}^{\circ}\)C and require calibration tests in thermostats in refrigeration and heating modes. An ethanol bath thermostat is used as calibration equipment. It consists of an ethanol-solution tank, a temperature control system, and a blender. The ethanol tank is equipped with a temperature sensor, through which the temperature control system controls the temperature of ethanol at the set temperature. The blender continuously blends the ethanol while the thermostat is working to ensure uniformity of temperature.  
**Glass tube and fixed fixture**: The ADS cannot be placed directly in the thermostat ethanol solution. It needs to be placed in a glass tube for calibration. The fill gas between the sounder and the glass tube is air. The tube is fixed in an ethanol bath with a polyethylene sheet. The polyethylene sheet holds the glass tube in place and reduces the evaporation of ethanol to a certain extent.  
**Standard thermometer**: The temperature sensor of the ethanol bath is inside the ethanol tank, and the thermal resistance of the detection system actually measures the temperature of the air in the glass tube, which cannot be guaranteed to be the same as the temperature inside the ethanol tank. The standard thermometer is placed inside the glass tube to detect the temperature near the thermistor and revise the calibration accuracy.  
During calibration, a calibration point is set for each change of 10 \({}^{\circ}\)C. The temperature of the thermostat is set to the calibration point, and the temperature values shown by the standard thermometer are observed. When the temperature near the thermistor stabilizes, the thermistor resistance is recorded and the temperature shown in the standard thermometer. The resistance-temperature curve of the thermistor is fitted by the least squares method, and the characteristic temperature curve of the thermistor is obtained.