Odokiyenko O. Structural synthesis and practical realization of radiometers with compensation of temperature gain fluctuations

The object of the study is radiometric signal processing. The subjects of the research are algorithms and structural schemes for processing radiometric signals in modulation radiometers with an unstable gain in the pre-detector part. The analysis of deficiencies which reduce efficiency of the radiometers applications in various problems solution was performed in this research. One of these problems is the shift of the radiometric signal parameter estimates that is caused by the fluctuations of the gain in the predetection part of the receiver. These fluctuations are caused, for example, by temperature fluctuations of the environment or by heating of individual elements of the radiometer when it is in the operating mode. That is why it is mandatory to consider this factor while designing perspective radiometers The optimization problem statement is mathematically formulated, and the optimal and quasioptimal algorithms for estimating noise temperature of the radiation source in the modulation radiometer are presented for the first time. These algorithms contain the operations of received signals adaptive decorrelation as operations of the interval integration during the corresponding modulation periods in different receiving channels of noise hindrance and hindrance mixed with useful radiation, as well as total integration. This allows to compensate the trend of an unstable gain coefficient of the receiving input. The paper presents both simulation results and field tests of the receiver, which implements a synthesized algorithm of signal processing. A number of long-term (several hours) measuring of the atmosphere parameters (within the clear and clouded sky) proved reliability of the obtained results and conclusions.