| 主权项 |
1. A method for detecting a gas (G) in a gas detector (1), the gas detector (1) having a reflecting wall (3) and a wave generating and sensing means (2) at a distance d opposite the reflecting wall (3), wherein the method comprises a continuous process of:
generating (S1) acoustic waves by means of the wave generating and sensing means (2), transmitting (S2) the acoustic waves (Wt) through the gas (G) towards the reflecting wall (3), wherein the acoustic waves (Wr) are reflected towards the wave generating and sensing means (2) from the reflecting wall (3), thereby creating constructive and destructive interference between the acoustic waves (Wt, Wr) propagating in opposite directions, the constructive and destructive interference being dependent of a wavelength of the acoustic waves (Wt, Wr), which wavelength is dependent of the gas (G), detecting (S3) the acoustic waves (Wr) by the wave generating and sensing means (2), wherein a motional resistance of the wave generating and sensing means (2) is changed due to a change of the wavelength of the acoustic waves (Wt, Wr), and indicating (S4) a presence of the gas (G) by determining a change of a magnitude of an output signal of the wave generating and sensing means (2), wherein the change of the magnitude of the output signal is related to the change of the motional resistance; the method further comprising compensating (S6) for temperature changes in the gas detector (1); wherein the compensating (S6) comprises moving a reflecting surface (8) of the reflecting wall (3) along an axis (X) transverse to the reflecting surface (8), thereby adjusting the distance d between the reflecting wall (3) and the wave generating and sensing means (2). |
