05850624 is referenced by 134 patents and cites 41 patents.

An electronic compass (10) for use in a boring tool (12) which will provide an orientation of the boring tool relative to the earth's magnetic field. In addition, a more straightforward left or right deviation from an initial bearing can be determined. The invention can correct for pitch angle and roll angle variation as well. The magnetic field is sensed by an axial magnetic field (12), a radial magnetic field sensor (18) and a plane-normal magnetic sensor (24) which are preferably magnetoresistive sensors.

Title
Electronic compass
Application Number
8/544940
Publication Number
5850624
Application Date
October 18, 1995
Publication Date
December 15, 1998
Inventor
John C Wisehart
Stillwater
OK, US
Jian Jin
Perry
OK, US
Michael F Gard
Perry
OK, US
Agent
Sidley & Austin
Assignee
The Charles Machine Works
OK, US
IPC
G01C 17/38
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