Design And Development Of Data Processing And Control Unit For Multi-frequency Microwave Radiometer

This multi-frequency microwave radiometer (MWR) is used for remote sensing sounding of ocean geophysical parameters on the offshore oil platform. It will provide long time series of geophysical parameters such as the sea-surface temperature, near-surface wind speed and direction. The data processing and control unit is one of the most important parts of the ground-based MWR. It takes charge of operating mode control, data acquisition and digitizing, state control of the radiometer system and communication with the remote computer system. The main contents include:(1) This paper presents the principle of sounding ocean dynamic environment by microwave radiometer, technical specifications and system composition of the multi-frequency microwave radiometer. And the receiver adjustment and system specification testing are completed. The linearity of receiver is better than 0.9999, the nonlinear error is smaller than 0.6 k and the radiometric resolution is better than 0.2 k, all of the specifications have met the requirements of the system.(2) According to the requirements of MWR real-time calibration, a high accurate temperature measuring unit was designed based on Platinum resistance transducers and the accurate measuring of system internal ambient temperature is realized. The results show that the temperature error of the temperature measuring unit is smaller than 0.015 k and the consistency among multi channels is smaller than 0.01 k, which has ensured high system radiometric resolution.(3) A data processing and control unit of MWR was designed and realized, and its scheme design based on FPGA according to the analysis of data acquisition, automatic gain control (AGC), state control and remote communication is presented. Furthermore, the hardware architecture of FPGA, software design flow and design cycle were described in detail. Finally, all the design has been successfully simulated with Modelsim and Chipscope and provided the foundation for MWR system integration.Comparing to the traditional design, the design based on FPGA has reduced the number of devices and optimized the circuit structure. And the design methods of concentrative power supply and unified management by the data processing and control unit have increased the integration density and reliability. At the same time, the FPGA technology has implemented the design of low power consumption and system miniaturization, and made the system easily used and transplanted, with strong adaptability and extensibility, which have met the requirements of multi-frequency microwave radiometer quite well.