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:
Aug. 31, 1999
Filed:
Aug. 04, 1997
Masahiro Tsujishita, Tokyo, JP;
Kenichi Taura, Tokyo, JP;
Tadatoshi Ohkubo, Tokyo, JP;
Yoshiharu Ohsuga, Tokyo, JP;
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
A digital receiver uses a local oscillator to down-convert an orthogonal frequency-division multiplexed signal that has been modulated by differential phase-shift keying, and performs further processing to obtain a differentially demodulated array of phase values. According to a first aspect of the invention, the digital receiver detects a carrier offset, applies a corresponding phase correction to the values in the array, then shifts the entire array by an amount corresponding to the carrier offset. As a result, the local oscillator need be tuned only in a frequency range equal to the subcarrier spacing. According to a second aspect of the invention, the local oscillator is tuned within a range equal to the subcarrier spacing multiplied by a certain integer, the array is shifted by a multiple of this integer, and the phase correction is eliminated.