Analysis of Experimentally Determined Transfer Function of Photoacoustic System Detection Part

Abstract

The microphone, amplifier and photoacoustic cell affect the transfer function of the gas-microphone detection of the photoacoustic measuring system. Experimental determination of the transfer function of the system detection part eliminates the influences of these components occurring due to the system design. Based on the measurements performed in an anechoic chamber where the swept sine signal was used as an excitation, the transfer function is determined. Two different acquisition cards were used for the signal detection. One of them was used to generate the excitation signal simultaneously with the microphone signal detection. The approximately flat transfer function up to 6 kHz is obtained with that card, which is not the case with the other acquisition card. In the latter case, the determined transfer function shows the oscillations in the regions where the signal to noise ratio is insufficient.