Patent Number: 6,529,007

Title: Temperature compensation for ground piercing metal detector

Abstract: A hand tool has a ground-piercing probe, which is manually insertable inthe soil. The probe has a chamber in which an inductor is positioned andconnected to metal detection circuitry. A pulse generator applies currentpulses to an inductor for inducing eddy currents in a buried targetobject. After the pulse terminates, the decaying coil voltage is sampledat different times to detect both the presence and range of the object, aswell as the type of metal in the object. The coil voltage samples areapplied to signaling circuitry, which provides an audible signal which isa series of bursts of an audio tone. The pitch of the audio tone signalsthe presence, range and bearing of the buried metal object, while thepulse rate of the bursts signals the metal type. Signal variationsresulting from temperature changes when the probe is inserted into soilare compensated for by detecting a signal proportional to the coil currentduring the pulse and subtracting a scaled portion of that signal fromvoltage samples.

Inventors: Ott; Ellen (Akron, OH), Ott; James H. (Akron, OH)

Assignee:

International Classification: G01V 3/15 (20060101); G01V 003/11 (); G01V 003/165 ()

Expiration Date: 03/02015