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:
Jul. 09, 1996
Filed:
Jul. 18, 1995
Takashi Okada, Kanagawa, JP;
Tadashi Shirato, Tokyo, JP;
Nippon Telegraph and Telephone Corporation, Tokyo, JP;
Abstract
A digitized quadrature modulator receives an I-channel input digital signal and Q-channel input digital signal, and quadrature modulater the I-channel and Q-channel input digital signals by digital signal processing. The modulator has a digital filter (504) for shaping the spectrum of the I-channel and Q-channel input digital signals to provide I-channel and Q-channel output signals. The output signals have a predetermined phase shift between the I-channel and the Q-channel so as to compensate a phase difference based upon the quadrature modulation by the digital signal processing. Complementers (505a, 505b) for taking the complement of the I-channel and Q-channel output signals to provide I-channel and Q-channel complement signals. A multiplexer (505c) multiplexer the I-channel and Q-channel output signals from the digital filter and the I-channel and Q-channel complement signals from the complementers to provide a quadrature modulated output signal.