Research On A New Type Of Periodic Calibration Microwave Radiometer And Its Measurement & Control System

The periodic calibration microwave radiometer can effectively overcome the system gain fluctuation, so it is applied in more and more fields. The periodic calibration microwave radiometer usually uses two noise reference sources for calibration. Its hardware is complicated, long-term stability of the low-temperature reference source is difficulty to obtain. Therefore, the periodic calibration radiometer using active noise source is proposed. This study is based on the periodic calibration microwave radiometer with active noise source, first of all, we improve its hardware; then, we proposed a new calibration cycle according to the characteristics of the active noise source; finally the upper data control and processing software is designed to modify the program of radiometer and process the output data of radiometer further.The hardware structure of the new type periodic microwave calibration radiometer is introduced firstly. In accordance with the lack of radiometer hardware, a new numerical control circuit is designed. The numerical control circuit has integrated multi-channel radiometer switch driver, multi-channel analog acquisition, SD card and so on. The system software is developed to control the calibration of radiometer and store the data.Then, we make analysis of sensitivity of the radiometer and carry out experiments with the improved radiometer. Experiments show that the outputs of the active noise source have interaction when the switch changed between the high and low temperature calibration noise sources. According to this characteristics, new calibration cycle is proposed, which can improve the performance of radiometer.Finally, upper data control and processing software of the radiometer is designed. The software is multi-functional, including modifying the key parameters of the program easily, selecting the radiometer's output data, automatically saving date and charting data, calculating the stability of radiometer and querying historical data according to the input of the time.The improved radiometer is flexibly, convenient to process data, and has good performance which meets the initial design requirements.