Pneumatic frequency selection filter in the prior stage of the air pressure transducer

To use frequency selection filter with electrical components, the signal from the transducer should have the detailed information with enough signal-to-noise ratio. In the measurement of air pressure, if the small variation is added to the big amplitude of slowly varying signal, there needs to eliminate the low frequency component in front of the transducer to avoid saturation. To achieve that, the concept of balancing tube was suggested and analyzed as pneumatic high pass filter. The simple method to adjust and find the cutoff frequency of the high pass filter is shown and validated. One application of this measurement technique in physiological monitoring using air mattress and balancing tube is summarized.