System Design of Millimeter Wave Atmospheric Ozone Radiometer

Stratospheric ozone concentration has an important impact on global climate change and ecological environment. Hyperspectral millimeter wave radiometer with spectral analysis capability is a passive microwave remote sensor used to detect atmospheric trace gases. It can effectively detect the vertical profile of atmospheric ozone and has very important application value in the field of space earth science. In this paper, a new hyperspectral millimeter wave ozone radiometer system for detecting stratospheric ozone absorption lines is developed. The system structure includes RF receiver and digital spectrum analyzer. The RF receiver part uses a superheterodyne structure to obtain a 142.175 GHz ± 100 MHz bandwidth signal. The digital spectrum analysis part uses a high-performance analog-to-digital converter to sample the input analog signal at 5×10⁸ sample·s^–1. The quantization bit is 14 bit and the 3 dB bandwidth of the input signal is 200 MHz. The signal power spectrum is obtained by high-performance Field Programmable Gate Array (FPGA), and the number of detection channels is 16384, and the spectral resolution reached 12.2 kHz. This paper introduces the design scheme, device selection and test method of the key modules of the radiometer system. It is concluded that the system sensitivity and various indicators can meet the requirements of atmospheric ozone inversion, and the correctness of the system design is verified by conducting atmospheric detection experiments and comparing the experimental results with the simulation results of Atmospheric Radiative Transfer Simulation Software (ARTS). The radiometer system meets the application requirements of stratospheric ozone concentration monitoring, early warning and climate change research.