Patent Number: 6,294,896

Title: Method and apparatus for measuring complex self-immitance of a general electrical element

Abstract: A device measures complex self-immittance of a general element at a discrete frequency by implementing "sine/cosine correlation" in software. An active source excites the element with a periodic voltage or current having fundamental period equal to the reciprocal of the desired measurement frequency. Linear circuitry senses two signals; one proportional to the periodic voltage or current excitation, the other proportional to the periodic current or voltage response. Identical low-pass or band-pass filter-response functions process each signal to remove higher-order harmonics. The resulting band-limited signals are each sampled in synchronism with the excitation, digitized, and inputted to a microprocessor or microcontroller which performs the appropriate calculations.

Inventors: Champlin; Keith S. (Minneapolis, MN)


International Classification: G01N 27/02 (20060101); G01R 31/36 (20060101); H01J 007/00 (); G01N 027/46 ()

Expiration Date: 09/25/2018