Research On Engineering Implementation Of Signal Detection And Processing Algorithm For Spectral Analysis

Tunable semiconductor laser absorption spectroscopy technology is widely used in the fields of atmospheric environmental pollution monitoring,industrial production,and chemical engineering due to its advantages of high sensitivity,high reliability,high spectral resolution,and short response time.In recent years,with the development and progress of science and technology,higher standards and requirements have been put forward for the detection speed and accuracy of the signal detection in the TDLAS system.Aiming at the TDLAS gas detection technology,combined with wavelength modulation spectroscopy,it focuses on preprocessing and demodulation of the electrical signal output by the TDLAS system,and builds a digital signal processing system based on the FPGA platform.In this system,wavelet filtering and related detection technology are the main signal processing methods,supplemented by multiple functional modules,to jointly complete the engineering realization of the FPGA-based digital signal detection algorithm.On this basis,by designing multiple sets of experiments,the effectiveness of the algorithm is simulated and verified.Main works of this paper are as follow:(1)In the context of TDLAS gas detection,this article first introduces the trace gas detection method based on laser absorption spectroscopy technology.Then,according to the characteristics of trace gas detection,the weak signal detection methods and the current research status at home and abroad are summarized,which lays a theoretical foundation for the construction of digital signal detection system.(2)Aiming at the wavelength modulation spectroscopy in TDLAS gas detection,combined with the advantages of FPGA,the overall design and logic design of various modules in the digital signal detection system have been completed on the FPGA platform.The system uses wavelet filtering and related detection algorithms to achieve preprocessing and second-harmonic correlation demodulation of the signal to be processed,combined with multiple functional modules,and finally completes the engineering realization of the FPGA-based digital signal detection algorithm.(3)After the establishment of the weak signal detection system is completed,the performance of the wavelet filter module and related calculation modules is tested by using simulated experimental data to design multiple sets of comparative experiments.After experimental testing and result analysis,under the condition that the wavelet base is db16,when the signal-to-noise ratio is greater than-5d B,the detection accuracy of the digital signal detection system is high,and it can quickly and accurately detect the amplitude of harmonic signals.In the signal filtering test,comparison experiments can show the effectiveness of the filtering algorithm and meet the basic requirements for weak signal detection.