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Expired Canadian patentCanada

Plural frequency method and system for identifying metal objects in a background environment using a target model

CA 2180585 C · Owner: Shoemaker, Donald K. · Inventors: Shoemaker, Donald K.

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Abstract From the Canadian patent

A system for detecting metal targets located in a background environment such as the ground evaluates metal targets by processing components of signals at two or more different frequencies. A component of the received signal induced by the ground can be eliminated by subtracting signal components measured at two different frequencies. The received signal can be processed to account for changes in the background response with frequency. The type of an unknown target can be identified by processing background excluded components to produce data characterizing the target type.

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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.

Why it's free to use

  • Filed July 5, 1996 and granted September 12, 2000. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended July 5, 2016.
  • A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by July 5, 2018.
  • We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
FiledJuly 5, 1996
GrantedSeptember 12, 2000
Term endedJuly 5, 2016
Patent numberCA 2180585 C
Classification (IPC)G01V3/11 +1 more

Timeline

Timeline From CIPO dates

1997199920012003200520072009201120132015Application filedJuly 5, 1996Patent grantedSep 12, 2000Term endedJuly 5, 2016

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Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.