Control Module Design Of Direct Method Reflectance Measurement System

The reflectivity basis method is the most widely used method in the orbit calibration of remote sensors.The method is to select the characteristic field with uniform surface characteristics as the observation target,and obtain the satellite remote sensing data and field instrument observation data,combined with radiation.The transmission model quantitatively calculates the radiance or reflectivity of the load into the enthalpy to achieve on-orbit radiation calibration of the remote sensor.The paper investigates the measurement method of surface reflectivity,analyzes the advantages and disadvantages of manual measurement and automatic measurement to obtain surface reflectance,and introduces the reflectivity measurement system of direct method.The measurement system consists of a spectral radiance meter and a spectral irradiance meter,which can simultaneously measure the surface radiance and the total sky illuminance,calculate the target reflectivity,and have a calibration coefficient self-calibration function.In view of the functional requirements of the reflectivity measurement system of the direct method,the control module design of the measurement system is carried out.It mainly includes:design of main control circuit of measuring instrument,complete control of other modules such as detection module and motion module;design motion control module to realize horizontal cutting of observation optical path in standard self-calibration process;design standard board self-cleaning function for clearing standard Residual dirt on the surface of the board and inside the protective box;design the local host computer and the remote data center host computer to realize the control and data communication of the measurement system.The paper carried out the laboratory spectral calibration and the calibration of the responsiveness based on the standard radiation source,and determined the spectral calibration coefficient and the radiation reflectance ratio calibration coefficient of the measurement system.In order to verify the control module function and observation accuracy of the measurement system,an outdoor comparison verification test was carried out.Using the measurement system to observe the diffuse reflection reference plate,calculate the relative deviation between the reflectance measurement data and the reference plate reflectance calibration data,and verify that the measurement system can achieve high-precision reflectivity automatic observation.Based on the self-calibration function of the measurement system,the reflectivity of the diffuse reflection reference plate is measured,and the relative deviation between the reflectance measurement data and the calibration data is calculated,and the effectiveness of the self-calibration function is preliminarily verified.