Improvement of Resolution of Absolute Type Displacement Sensor Utilizing Standing Wave on Transmission Line

Abstract

In this paper, we describe how to improve the resolution of an absolute type displacement sensor utilizing standing wave on a transmission line. This sensor is based on the phenomenon that the node of standing wave is produced every half-wavelength on the transmission line driven by a signal source. We show theoretically that the resolution is dependent on the frequency of the signal source and establish experimentally that the resolution also depends on the frequency jitter of it chiefly.
By our experiments, we have been able to confirm that it is possible to improve the resolution by using the signal source with higher frequency and lower frequency jitter. Finally, we have confirmed that the resolution of this sensor is improved to 4μm, i.e., 1ppm in the displacement of 4m.