ESTIMATION OF PERFORMANCE STABILITY OF ACOUSTO-OPTICAL SPECTROMETERS FOR MICROWAVE SWITCHING RADIOMETERS

摘要

Performance characteristics of the acousto-optical spectrometers (AOS) for the millimeter-wave radiometers are discussed. The main attention is given to the longterm stability of the acousto-optical spectrometer's characteristics. As to long-term frequency stability it was found that the main part of the frequency scale drifts does not depend on the channel number. So a simple method of the AOS's frequency scale drifts correction by using the data from measuring of a single reference signal's frequency was developed and applied. Long–term amplitude stability estimations are based on the Allan variance method. The Allan dispersion plots were measured for two types of AOS backends of millimeterwave switching spectroradiometers: (1) AOS-80, including laser diode module, for radioastronomical studies of interstellar gas in molecular lines, and (2) AOS- 500 – wideband spectrometer, intended for atmosphere ozone radiation researches. The results obtained are discussed and conclusions about choosing of millimeter wave receiver’s parameters in order to optimize the observation efficiency are made.