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:
Sep. 19, 1978
Filed:
Aug. 20, 1976
Tadayoshi Katoh, Kawasaki, JP;
Eiji Itaya, Kawasaki, JP;
Fujitsu Limited, Kawasaki, JP;
Abstract
A carrier regeneration circuit regenerates the carrier from the QAM (Quadrature Amplitude Modulated) received signal, as produced and transmitted by a quadrature partial response modulation system wherein quadrature-related carriers (i.e., having a phase difference of 90.degree.) of the same frequency are amplitude modulated with two parallel signals which have been subject to partial response conversion. The carrier regeneration circuit comprises a probability decision circuit which decides the probability of generation of particular demodulated data code combinations, and a carrier regeneration control circuit which maintains the phase ambiguity of the regenerated carrier within an integer multiple of 90.degree.. The control circuit responds to the output of the probability decision circuit for selectively shifting the phase of the regenerated carrier by 45.degree..