Method and device for detecting a ringtrip
CA 2274525 A1 · Owner: Telefonaktiebolaget Lm Ericsson · Inventors: Bokinge, Bo
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A ringtrip detector comprises a reference counter for controlling a battery current generator, which shapes the ring signal a zero pass detector for , detecting zero passes in a voltage at a node which is proportional to the , telephone line current and two other counters. The zero passes of the voltage create a pulse at both the positive and the negative zero crossing of the zero pass detector. The reference counter is gated into a memory when these pulses , appear. The zero passing of the previous and the present ring cycle are stored in the memory. A counter decides the difference between the previous and the present ring cycles zero passes. If the zero pass difference between the …
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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 November 18, 1997. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended November 18, 2017.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by November 18, 2019.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
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.