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. 05, 1988
Filed:
Jul. 07, 1986
Yasuharu Yoshida, Tokyo, JP;
NEC Corporation, Tokyo, JP;
Abstract
In a demodulator for use in demodulating a quadrature amplitude modulated signal into a first and a second digital signal by the use of a reproduction of a carrier wave, a pull-in phase is detected by a pull-in phase discriminator (55) after establishment of synchronization. The reproduction of the carrier wave is momentarily phase shifted in a phase modulator (65, 65') with reference to the pull-in phase and is produced as a phase shifted carrier signal. The resultant pull-in phase is momentarily corrected to avoid abnormal demodulation. Detection of the pull-in phase is possible either by monitoring a demodulating analog signal and the first and the second digital signals or by monitoring only the first and the second digital signals. The phase modulator may be either a two-phase modulator or a n.pi./2-phase one where n is a natural number between unity and three, both inclusive.