Due to its high resolution, large flux, and high signal-to-noise ratio, Fourier Transform Infrared Spectroscopy (FTIR) is often used to monitor atmospheric environment. The preamplifier, as the key module of the FTIR optical receiver system, determines the accuracy, SNR and other key parameters of the subsequent signal directly. This paper presents a high gain and wide dynamic range preamplifier based on high performance integrated op amp. Using a low noise op amp IV conversion and multi-level Butterworth type active filter, a very weak signal input, multi-file Gain low noise and high SNR preamplifier circuit was designed. Experiments show: the preamplifier can make the signal of the atmospheric FTIR monitor meet the SNR and quality requirements.
Two optical payloads on the GF-5 satellite have produced by Beijing Institute of Space Mechanics and Electricity. The full-spectrum spectral camera has the characteristics of wide spectral range, high spatial resolution and high accuracy of radiation calibration. It has reached the domestic leading and international advanced technology level, which has greatly improved China's high-precision observation capability. This paper designs a video circuit for the visible near-infrared spectrum of the camera. The circuit implements timing control and driving of the detector, as well as analog to digital conversion and processing of the analog signal. It completes the acquisition of 8 channels of analog signals, and outputs 14 bits of quantized bits and 30 Mbps of single channel data. The system achieves high signal-to-noise ratio (SNR) through high-stability power supply, high-speed drive level shifting and high-precision (2ns/step) timing control. Under the given simulation test conditions in the laboratory, the measured signal-to-noise ratio of the visible light channel reached 307, and good image data was obtained in the external scene imaging and in the space.
Fourier Transform Infrared spectroscopy technique, featured with large frequency range and high spectral resolution, is becoming the research focus in spectrum analysis area, and is spreading in atmosphere detection applications in the aerospace field. In this paper, based on FTIR spectroscopy technique, the principle of atmosphere interference signal generation is deduced in theory, and also its mathematical model and simulation are carried out. Finally, the intrinsic characteristics of the interference signal in time domain and frequency domain, which give a theoretical foundation to the performance parameter design of electrical signal processing, are analyzed.