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US6388575B1
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Addressable underground marker
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Self leveling underground marker
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Passive electrical marker for underground use and method of making thereof
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Omnidirectional passive electrical marker for underground use
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Probe for sampling differential electromagnetic fields
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Method and apparatus for connecting to a circuit in a jack without interrupting the circuit
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Method and apparatus for analyzing resistive faults on telephones cables
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Method and apparatus for detecting digital carrier signals on telephone cables
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Method and apparatus for achieving two-way long range communication over an optical fiber
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Method and apparatus for achieving communication at all locations along a ping pong communications channel
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Method for locating conductive faults in telephone and similar cables
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Methods of communicating over metallic conductors having multiple grounds
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CA1255756A
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Methods of communicating over metallic conductors having multiple grounds
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