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. 12, 1988
Filed:
Aug. 15, 1986
Yasuharu Yoshida, Tokyo, JP;
Masato Tahara, Tokyo, JP;
Manabu Yagi, Tokyo, JP;
Toru Matsuura, Tokyo, JP;
NEC Corporation, Tokyo, JP;
Abstract
In a demodulation system comprising a demodulator (22) which demodulates a quadrature amplitude modulated signal into first and second sets of output digital signals by the use of a reference carrier signal (CA), a specific phase control signal is produced in a transient state by discriminating a plurality of areas and a plurality of zones defined on a phase plane of the modulated signal. The areas are defined by dividing the phase plane by both a pair of quadrant reference axes and a pair of auxiliary reference axes phase shifted by .pi./4 (radians) relative to the quadrant decision axes. The zones are defined along and adjacent to the auxiliary reference axes. First and second detection signals (S.sub.1 and S.sub.2) are produced by a read-only memory (35) as results of discrimination of the areas and the zones, respectively. The specific phase control signal is switched to a normal phase control signal produced in a normal state in the known manner. Alternatively, the first and the second detection signals may be supplied to a transversal equalizer (21) for controlling imaginary part weighting control signals.