Audio compressor, expander, and noise reduction circuits for consumer and semi-professional use
CA 2030784 C · Owner: Cossette, Stanley Gene · Inventors: Cossette, Stanley Gene; Dolby, Ray Milton
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Three related embodiments of audio signal dynamic range circuits for consumer and semi-professional audio signal compressors; expanders, and compressor/expander noise reduction systems incorporate certain basic features of professional Spectral Recording (SR) while adapting SR for use with consumer recording media (particularly audio cassette tape) and reducing the cost and complexity of the SR circuitry. In addition the three embodiments, and particularly the preferred embodiment, provide substantial compatibility with the existing B-type and C-type consumer and semi-professional noise reduction systems. Subjective performance substantially equivalent to 16-bit PCM audio systems …
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 April 3, 1990 and granted August 10, 1999. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended April 3, 2010.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by April 3, 2012.
- 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.