05231355 is referenced by 91 patents and cites 38 patents.

The present invention generally relates to a system for use in determining the location and orientation of concealed underground objects and, more particularly, to an improved locator system having a unique and improved interface with an operator. In accordance with one embodiment of the invention, a magnetic field detector for locating concealed underground objects is provided. The magnetic field detector includes a housing having an upper housing portion and a lower housing portion. A receiver is disposed within said housing for receiving magnetic field signals from the concealed underground objects. A swivel joint couples the upper housing portion and the lower housing portion to permit relative rotational motion.

Title
Locator transmitter having an automatically tuned antenna
Application Number
7/539552
Publication Number
5231355
Application Date
June 18, 1990
Publication Date
July 27, 1993
Inventor
Lester R Querry
Reston
VA, US
Alan J Rider
Reston
VA, US
Agent
Richards Medlock & Andrews
Assignee
The Charles Machine Works
OK, US
IPC
H03J 3/02
H04B 5/00
G01V 3/165
G01V 3/11
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