A Method of Improving the Signal-to-Noise Ratio of Fourier Spectrometer for Atmospheric Detection

Abstract

The invention relates to a method for increasing a signal and noise ratio of an atmospheric sounding Fourier infrared spectrometer. The method comprises the following steps of according to the working principle of the Fourier infrared spectrometer, sampling a zero-crossing pulse of an interference signal of the Fourier infrared spectrometer by a high-frequency clock, dividing the cycle of each zero-crossing pulse into a plurality of subpulses with equal time intervals, and using each divided subpulse as a triggering signal, so as to realize the oversampling of the infrared interference signal; converting the time coordinate information of the collected infrared interference signal sampling point into optical path difference coordinate information, and performing equal-optical path difference interpolation resampling and calculation on the sampling data crossing zero, and performing digital downsampling filtering on the resampled data. The method has the advantages that the data sampling frequency is improved, the digital filtering is realized, the aliasing noise and quantizing noise in the sampling can be eliminated, the noise introduced by an analog filtering device is avoided, and the signal and noise ratio of the spectrometer is increased.

Description

technical field [0001] The invention relates to a method for improving the signal-to-noise ratio of a spectrometer. In particular, it is a method for improving the spectral signal-to-noise ratio of atmospheric detection Fourier spectrometers with high spectral resolution and weak interference signals. Background technique [0002] The Atmospheric Detection Fourier Infrared Spectrometer is a time-modulated infrared interferometer with Michelson interferometer as the core, which modulates the light by the mechanical swing motion of the moving mirror. The Fourier spectrometer can only directly obtain the interference curve of the target object, and the energy in a certain spectral segment is obtained through the Fourier transform of the interferogram, so the signal-to-noise ratio of each spectral wavenumber and the signal-to-noise ratio of the entire interferogram relevant. In the actual inversion analysis of spectrometer data, the accuracy of the calculation result of the ab...

AI Technical Summary

Problems solved by technology

[0007] (1) Due to the limitation of the number and function of the analog filter chip and the limitation of special design software, the design of the analog filter is complicated and it is very difficult to adjust the parameters;

[0008] (2) The analog filter components themselves will also introduce noise;

[0009] (3) The spectral bandwidth of the atmospheric detection spectrometer is narrow, and the sampling frequency of the system is low, which makes the out-of-band noise easily aliased into the detection spectral band, increases the noise in the detection spectral band, and lowers the signal-to-noise ratio;

[0010] (4) The analog filter cannot filter out the quantization noise introduced by the sampling of the analog-to-digital converter

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