The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 21, 1995
Filed:
Oct. 15, 1993
Raymond B Montagne, Mountain View, CA (US);
Apple Computer, Inc., Cupertino, CA (US);
Abstract
A method and apparatus for demodulating a pulse width modulated (PWM) signal previously modulated with either a first or second data value comprises sensing an actual duration of the first period of the bit cell, and generating an actual first signal value that is proportional to the actual duration of the first period of the bit cell. Using the actual first signal value and an expected first signal value, a first adjustment amount is determined and used for adjusting the actual first signal value. Then, an actual duration of the second period of the bit cell is sensed. The adjusted actual first signal value is further adjusted by a second adjustment amount to produce a final adjusted signal value, the second adjustment amount being proportional to the actual duration of the second period of the bit cell. Finally, a signal is generated which alternatively has a first value or a second value in correspondence with the final adjusted signal alternatively being greater than or not greater than a reference value. Alternative embodiments of the method and apparatus include an accurate as well as an approximate determination of the first adjustment amount.