Chirp excitation of ultrasonic probe for high-rangeability gas flowmetering

Abstract

The adaptive signal processing based on pulse compression in conjunction with the ray rescue-angle orientation of the transducers is another important feature for achieving high-rangeability ultrasonic gas flowmetering. A technique for achieving the necessary broad bandwidth of the ultrasonic transducer, which has to be excited within a low-frequency band due to the increased absorption of ultrasound in gas with frequency, is described. A signal-processing system suitable for very low and high times-of-flight and their differences is also presented. Discussed is the use of a special filtering technique based on assessing the gradient of the time series (in ascending order) of times-of-flight which eliminates spurious times-of-flight observed in actual interrogations of the flow.<>