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:
May. 27, 1997
Filed:
Feb. 21, 1996
Barry W Carlin, Cincinnati, OH (US);
Mark J Dapper, Cincinnati, OH (US);
Michael J Geile, Loveland, OH (US);
USA Digital Radio Partners, L.P., Linthicum, MD (US);
Abstract
The invention provides a method and apparatus for demodulating a composite AM DAB waveform which contains digitally modulated carriers and which employ (1) a mixer for converting a received signal into two signals (the first of these two signals represents an in-phase component and the second of these two signals represents a quadrature component); (2) two analog-to-digital converters for converting the two signals into digital signals; and (3) two fast Fourier transform elements for extracting data separately from the two digital signals. Complementary digital carrier signals are recovered from the quadrature component, and non-complementary digital carriers are derived from a sum of the complementary data and the output of the in-phase component FFT process. Leakage of the AM signal through a highpass filter is prevented from interfering with the demodulation of the complementary carrier signals' use of separated demodulation channels.