Data Acquisition And Quantization Error Analysis Of Ground-based Multi-channel Digital Fully Polarized Microwave Radiometer

The microwave radiometer is a passive remote sensing instrument.Based on the information of the target radiation energy received by the antenna,we can obtain the relationship between the output voltage of the radiometer and the brightness of the observed target by the calibration equation,and then study the radiation characteristics of the observed targets.The fully polarized microwave radiometer is a new type of microwave remote sensor.It further extracts the full-polarization information of the observation target on the basis of the traditional microwave radiometer,and realizes the use of all information of the frequency,phase,amplitude and polarization of the electromagnetic wave in microwave remote sensing.The use of fully polarization information has great advantages in the detection and identification of surface roughness anisotropy properties and is therefore widely used in the measurement and research of ocean wind fields.7Radiometer data acquisition and processing is an important system component of microwave radiometers.The data acquisition and system control module collects and digitizes fully polarization information of the target received by the radiometer,and stores,manages,and displays it.Therefore,the research on the data acquisition and processing methods for radiometers provides a useful help for accurate measurement of target radiation information.This paper focuses on the data acquisition work of the multi-channel digital correlation type full-polarization radiometer developed by the Space Center.Based on the existing data acquisition functions of the digital correlator,the data acquisition work for the detection circuit is perfected,and then the quantization error and sensitivity of the digital correlator on fully polarization radiometer is analyzed.It mainly includes the following three aspects:(1)The design of the multi-channel data acquisition card based on FPGA is completed to acquire the information of the detection level.Including hardware design and programming,complete the construction and debugging of data acquisition system,collect experimental data and save.(2)Develop User-Control Software based on Qt.The functions include acquiring and saving data output from a digital correlator and a detector circuit,outputting images of four Stokes components,Image storage,read,zoom,grayscale adjustment and other functions.(3)Complete calibration of digital correlator in full-polarization microwave radiometer.Analyze the sensitivity of 8-bit quantization and the amount of error of analog correlation coefficient and digital correlation coefficient.The research content of this topic provides certain experience and technical basis for data acquisition and processing of the fully polarized microwave radiometer system.