Application of the Wiener filtering algorithm for processing the signal obtained by the TDLAS method using the synchronous detection technique for the measurement problem of ¹³CO₂ concentration in exhaled air

Abstract

It has been shown clearly that using the synchronous detection technique with the pump current frequency modulation of a tunable diode laser emitting near 2 μm wavelength, combined with the application of the Wiener filtering algorithm for the experimental signal, ensures a two-times improvement in the measurement accuracy for the 13 CO 2 content in exhaled air, and, for the 13 CO 2 and 12 CO 2 concentrations ratio, more than seven times.

Improving the 13CO2 content measurement accuracy in exhaled air using the Kalman technique for filtering the experimental signal obtained by the tunable diode laser absorption spectroscopy method with the frequency modulation of the diode laser pump current

“…2. Application of the TDL pump current modulation with subsequent demodulation of the recorded signal using the synchronous detection technique [13][14][15].…”

“…The synchronous detection technique was used in [14]. The experimental signal from the synchronous detector was filtered using the Wiener and Savitsky-Golay filters.…”

Experimental observation of the vibration-rotation radiation curves of 12C16O2 and 13C16O2 absorption constants ranging from 4860 to 4880 sm−1 by the tunable diode laser absorption spectroscopy method

“…Earlier, this method was used to measure the content of 13 C 16 O 2 (636) in a mixture with 12 C 16 O 2 (626) in exhaled air. Performed studies have shown that one of the most promising ranges for measurements is the region near a wavelength of 2 µm (frequency range: 4860-4880 sm −1 ), which contains a number of absorption curves of these molecules, to a minimum extent overlapping, and the experimental arrangement does not require complex and expensive equipment [18][19][20]. To accurately measure the content of 13 C 16 O 2 and 12 C 16 O 2 in the analyzed mixture, knowledge of the absorption constantvalues and their pressure dependence, since the measurements can be carried out at different pressures, are necessary.…”

Interference fringe suppression in tunable diode laser absorption spectroscopy based on CEEMDAN-WTD

“…Kalman filter [14], wavelet transform [15], moving average [16], Wiener filter [17], and Gabor transform [18] have all been used to address noise suppression problems. Although these five methods reduce the influences of interference fringes on the detected signals, they are computationally intensive and not conducive to practical applications.…”