Measured acoustic coefficient values correction method based on coordinate rotation

The ultrasonic relaxational absorption peak location based gas sensing techniques require to measure the acoustic velocity and absorption coefficient values at two fixed operating frequencies. Unfortunately, the inevitable errors resulted from the experimental equipment and environmental factors result in deviations in reconstructing the acoustic spectrums to affect the detection results. To overcome these errors, this paper proposes a coordinate rotation based method to correct the peak point locations. The method can address both the over-correction and under-correction issues of the existing temperature iterative correction algorithms, as well as the problem of iterative algorithm failure caused by two measured frequencies being too large or too small at the same time. The experimental results show that the method effectively reduces the error of frequency and acoustic attenuation coefficient measurement value, and optimizes the design and implementation process of gas sensor based on acoustic relaxation theory.