A Modified Empirical Mode Decomposition Algorithm in TDLAS for Gas Detection

Abstract

Based on the research of the traditional empirical mode decomposition (EMD) method, we proposed a modified EMD algorithm for the detected signal processing in tunable diode laser absorption spectroscopy. The modified EMD algorithm introduced Savitzky-Golay filtering and cross-correlation operation into the traditional EMD algorithm and reconstructed the signal by using the cross-correlation coefficients effectively. Based on the modified EMD algorithm in theory, the second harmonic component analysis was simulated by comparing with some other filtering algorithms. The experiments system was performed for carbon monoxide (CO) concentration detection. Comparing the sensing performances without and with using EMD-FCR and other filtered methods, the experimental results show that the signal-to-noise ratio of the system was significantly improved from 7.32 to 14.31 dB by EMD-FCR corresponding to one absorption line of CO at 1567.32 nm, leading to the minimum detection limit of 2 ppm. The accuracy and stability of the system are both improved by proposing the modified EMD algorithm.

Mid-Infrared Tunable Laser-Based Broadband Fingerprint Absorption Spectroscopy for Trace Gas Sensing: A Review

“…An empirical mode decomposition (EMD) algorithm has been successfully used in WMS to remove optical fringes [27] and noise [163] by characterization of the signal profile. The procedure for employing EMD to decompose and reconstruct the WMS-2f signal is described in Figure 4a.…”

Mathematical Methods and Algorithms for Improving Near-Infrared Tunable Diode-Laser Absorption Spectroscopy

“…In this case, those algorithms that are most commonly used in general signal processing, like the least-squares method, cannot efficiently extract the precise desired signal. In recent years, some advanced algorithms have been proposed or introduced into TDLAS systems to process signals with low SNR, including wavelet transform (WT) [39,40], adaptive Savitzky–Golay algorithm [41], and empirical mode decomposition (EMD)-FCR algorithm [42]. These algorithms have been verified to be significant for practical issues.…”

“…The signal decomposition depends only on the characteristics of signal itself, which is the essential difference from WT. Meng et al [42] introduced the EMD algorithm into TDLAS signal processing, and proposed an improved algorithm that combines EMD, S–G filter, cross-correlation, and signal reconstruction (FCR), which is referred to as the EMD-FCR algorithm. This new method shows better applicability for second harmonic signal processing.…”

“…( b ) Relationship between the second harmonic intensity and gas concentration. This figure was obtained from [42].…”

Development and Integration of a CO Detection System Based on Wavelength Modulation Spectroscopy Using Near-Infrared DFB Laser

“…Carbon monoxide, which is odorless and colorless, is an important indicator gas of preventing spontaneous combustion of coal seam [1][2][3][4]. In order to avoid disasters and guarantee safety production in coal mines, CO concentration monitoring must be performed effectively in real time.…”