Research On Information Acquisition Of Fast Modulation Fourier Interferometer

Interferometric Atmospheric Sounding receives the radiation of Earth’s atmosphere, convert the interference signal through the interferometer’s modulation, obtain atmosphere temperature,humidity and gas components vertical distribution by the incident radiation’s spectral information which comes from the IFFT of interference signal. Interferometric Atmospheric Sounding with the advantages of high spectral resolution and high sensitivity is the important load of our meteorological satellites in the future. This paper based on infrared hyperspectral atmospheric sounder’s development, comprehensively expounds its information acquisition systems including the indicators determination, program design, noise analysis, system design and implementation and test results for a large dynamic range, fast moving mirror modulation Fourier interferometer.Firstly, this paper researches Interferometric Atmospheric Sounding and its information acquisition technology, analyzes the sources of noise in all aspects of information acquisition system and influence on detection sensitivity of the instrument. On this basis, determine the information acquisition system’s the technical solutions and related indicators; study the low-noise preamplifier, anti-aliasing filter key technologies and electromagnetic compatibility design; complete the information acquisition circuit design,and test its noise performance.Spectral noise induced by the random errors of mirror-velocity and sampling jitter in Fourier-transform spectroscopy is analyzed in this paper. A model based on Noise Equivalent Change in Radiance(NEdN) and Noise Equivalent Change in Temperature(NEdT) has been established as a function of the quality of the implemented instrumental devices. It shows that the mirror-velocity associated with the amplitude variations and the time delay of the anti-aliasing filter and the sampling jitter can lead to system noise. Then, simulate and calculate the noise impact of mirror-velocity and sampling jitter by MATLAB. It verifies the theoretical model, evaluates the noise of the actual instrument and provides the basis for mirror control, anti-aliasing filter design and noise calculation and improvement in Fourier-transform spectroscopy.This paper also introduces the interference signal acquisition circuit testing and data processing scheme, and the test results are analyzed. The results show that the noise of the preamplifier is less than detector noise, which can meet the low-noise design requirement. With the overall machine debugging,this system is implemented acquire the interference signal of target blackbody radiation, and the sensitivity of the system to achieve the basic performance requirements of the instrument. It provides a reference for further study of the Fourier transform infrared spectrometer.