Apparatus and method for supervising derived channel communications
CA 2249575 C · Owner: Eakes, James W. · Inventors: Hughey, Stephen A.; Darr, Roger Raymond; Eakes, James W.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A supervisory signal (18) for a derived channel data reporting system is implemented as a tone having a frequency capable of transmission using a telephone signal communicating network (31) including networks incorporating , digital equipment at an attenuated level. The tone preferably has a frequency of from 200 Hz to 300 Hz, and is capable of operating in conjunction with biphase modulated (BPSK), frequency shift keyed (FSK) and multi-tone modulated (MLT) polling systems. Such frequencies are effectively communicated by conventional digital loop carrier systems despite a limited frequency range, and are of a sufficient magnitude to be detected by the derived channel data reporting …
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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 March 19, 1997 and granted July 2, 2002. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended March 19, 2017.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by March 19, 2019.
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Timeline
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Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.