Patent ID: 7575371

Claim:
A temperature sensor and extensometer for monitoring an electrical conductor, comprised of one or more acoustic generators attached along said conductor where the said acoustic generators emit one or more acoustic signals consisting of a sinusoid of finite extent in time and having a narrow range of acoustic frequencies, where the said acoustic signals travel in the said conductor as longitudinal or torsional acoustic waves, where the frequency of said acoustic signals are selected to ensure that the acoustic signals are launched in said conductor as both the lowest order longitudinal acoustic wave and the lowest order torsional acoustic wave, where one or more acoustic detectors are attached along said conductor, where an electronic timer measures the time between the launching of one or more said acoustic signals by said acoustic generators and the detection of one or more said acoustic signals by said acoustic detectors, where a signal processor computes the travel time of a first acoustic signal between two locations on said conductor where the travel time has a first temperature dependence, and computes the travel time of a second acoustic signal between two locations on said conductor where the travel time has a second temperature dependence, such that the difference or ratio of travel times can be used to calculate the temperature along the region of said conductor wherein the acoustic signals traveled, and the travel times can be used to calculate the distance traveled by the acoustic signals.