Elements of design and a field application of a TDR-based soil moisture and electrical conductivity monitoring system are described with detailed presentation of the time delay units with a resolution of 10 ps. Other issues discussed include the temperature correction of the applied time delay units, battery supply characteristics and the measurement results from one of the installed ground mea...

A method for measuring the length of an optical fiber by use of an optical fiber ring laser pulse source is proposed and demonstrated. The key element of the optical fiber ring laser is a gain-switched Fabry-Perot laser diode operated in a self-injection seeding scheme. This method is especially suitable for measuring a medium or long fiber, and a resolution of 0.1 m is experimentally achieved....

Based upon a framework of time-frequency analysis, a path towards systematic and comprehensive implementation of condition based maintenance (CBM), or maintenance only upon evidence of need, is outlined for both electrical and mechanical systems. Specifically, metrics are proposed for helicopter drivetrain systems and electrical cable. Using principles of time-frequency analysis, metrics for he...