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:
Jan. 22, 1991
Filed:
Oct. 05, 1989
Dennis E Burke, Elmhurst, IL (US);
Other;
Abstract
An improved multilevel FSK demodulator, according to the invention, is provided that down-converts the IF frequency back to baseband quadrature via dual mixers. The improved multilevel FSK demodulator uses time-delay demodulation. This method requires a .+-.90.degree. phase difference between 2 modulated signals to produce a maximum demodulated output amplitude at the maximum frequency deviation. Since the IF frequencies have been down-converted back to baseband quadrature, these 2 signals are only 'out of phase' by an amount .DELTA.t that is equal to 90.degree./d.omega.. For a .DELTA..omega.of 4 MHz, this gives a .DELTA.t=62.5 nonoseconds. As a result, it is easy to achieve a delay line using multiple tap positions for 62.5 nonoseconds total delay.