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. 01, 2008
Filed:
Dec. 24, 2003
Takehiko Kobayashi, Kodaira, JP;
Takehiko Kobayashi, Kodaira, JP;
Hitachi Kokusai Electric Inc., Tokyo, JP;
Abstract
A demodulator of a differential detection system for a π/4 shifted QPSK or DQPSK modulation wave in digital communication. The demodulator includes a differential detector connected to receive orthogonal components of the modulation wave, a corrector connected to receive an output of the differential detector for correcting a deviated distribution of signal points on a constellation, and a slicer/decoder connected to receive an output of the corrector. The slicer/decoder decodes a received bit from the signal points after the deviated distribution is corrected. The corrector has average calculators connected to receive respective outputs of the differential detector, and subtractors connected to receive the associated outputs of the differential detector and also to receive associated outputs of the average calculators for subtracting an average value of the outputs of the differential detector from the outputs of the differential detector.