05264795 is referenced by 105 patents and cites 79 patents.

An improved locator system is provided which transmits digital and analog information over an electromagnetic field that is radiating from an underground source. The locator system includes a transmitter that modulates its output signal by turning its output signal on and off in response to a sequence of digital words. The transmitter also modulates an analog signal onto the transmitted signal. The modulated analog signal can include an audio frequency or voice signal. The improved locator system also includes a receiver that senses and detects the transmitted digital or analog signal impressed on the radiated electromagnetic field. The receiver also demodulates the transmitted audio frequency signal and provides an audio output signal to an operator.

Title
System transmitting and receiving digital and analog information for use in locating concealed conductors
Application Number
7/539851
Publication Number
5264795
Application Date
June 18, 1990
Publication Date
November 23, 1993
Inventor
Alan J Rider
Reston
VA, US
Agent
Richards Medlock & Andrews
Assignee
The Charles Machine Works
OK, US
IPC
H04B 13/02
G01V 3/165
G01V 3/11
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