Design Of A Dual Calibration Millimeter-wave Radiometer Signal Acquisition And Processing System

Millimeter-wave radiometer is a kind of passive receivers,which detects targets by comparing the intensity of thermal radiation in different locations.This project improves the structure of the millimeter-wave radiometer and combines two calibration methods towards external calibration and periodic internal calibration,aiming to improve the brightness temperature sensitivity and promote the target resolution further.In this paper,the signal acquisition and processing system,an important part of the millimeter-wave radiometer,mainly realizes the functions of front-end numerical control,data acquisition,data processing,scanning control,and human-computer interaction.This part coordinates the operation of the millimeter-wave radiometer,hence its research and development work have great practical engineering value.In this paper,the design of signal acquisition and processing system for the millimeter-wave radiometer is done,and the specific work includes the following:1.This paper combines the internal and external calibration methods,and proposes a processing algorithm for the front-end output signal to reduce the influence of channel gain changes and system noise on the brightness temperature sensitivity,thereby improving the brightness temperature sensitivity of the system.2.Taking the system structure and requirements into consideration,this paper focuses on the design scheme of the signal acquisition and processing system with FPGA and ARM processor.FPGA is employed to realize data acquisition and the advantages are its flexibility and parallel operation.The superiorities of ARM processor are low power consumption,high reliability and abundant standard peripherals,and ARM processor mainly realizes data transmission,processing and system control.3.The hardware design and program development of signal acquisition and processing system are finished.System hardware design includes device selection,schematic drawing,PCB layout drawing and debugging,etc.And program development includes the coding and verification of FPGA and ARM processor programs.In this paper,the programs of FPGA are coding based on the Verilog language,and the core module' logic functions are verified by using the ChipScope tool.The program of ARM processor is based on the standard peripheral libraries provided by the manufacturer.And the codes of some system functions,such as data processing,network data transmission and reception,host computer instruction analysis,and servo system scan control,are programmed by myself.In addition,in this paper,the design of touch screen interface for human-computer interaction is completed.4.In this paper,the key modules in the signal acquisition and processing system is tested,a test platform according to the design scheme is built,and the joint adjustment of the millimeter-wave radiometer is realized.In the process of joint adjustment,the millimeter-wave radiometer works normally and can be controlled by the host computer software,the relevant data can also be displayed in real time on the host computer and touch screen.At the same time,the brightness temperature sensitivity of the millimeter-wave radiometer is tested,and the results show that it can satisfy the design requirements.