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:
Nov. 14, 1989
Filed:
Apr. 04, 1988
Applicant:
Inventor:
Manabu Yagi, Tokyo, JP;
Assignee:
NEC Corporation, Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H04L / ; H04L / ;
U.S. Cl.
CPC ...
332103 ; 329304 ; 375 39 ; 375 67 ; 375 86 ;
Abstract
A digital signal transmission system adopting a quadrature amplitude modulation and demodulation principle and feasible for large capacity data transmission in which a number of levels are used. Each of a modulating and a demodulating device of the system is constructed to shift the phase difference between two carrier waves by a suitable angle of .DELTA..theta. radian from .pi./2 radian. The tuning phase in the demodulating device is limited to one so as to allow a bit error rate characteristic to remain constant.