Circuit for the acquisition of a carrier signal by applying a substitute pilot to a synchronous demodulator
CA 2178198 C · Owner: Zenith Electronics Corporation · Inventors: Mycynek, Victor G.; Krishnamurthy, Gopalan; Sgrignoli, Gary J.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A synchronous demodulator is controlled by a phase locked loop for tuning to a pilot in a television signal. A start-up interval is commenced upon initiation of tuning (either after power-up or a channel change) during which a substitute signal at the pilot frequency is supplied to the phase locked loop to rapidly bring the VCO close to its lockup frequency. Thereafter the IF signal is supplied. The start-up interval is defined by an AFC Defeat signal from a microprocessor and controls an IF switch. The substitute signal is from a crystal oscillator.
Read the whole patent
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 December 15, 1994 and granted May 2, 2000. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended December 15, 2014.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by December 15, 2016.
- 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
Timeline From CIPO dates
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.