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:
Oct. 17, 1989
Filed:
Feb. 11, 1988
Yasuharu Yoshida, Tokyo, JP;
NEC Corporation, Tokyo, JP;
Abstract
An automatic level control circuit for a multi-level quadrature amplitude-modulated (QAM) demodulator having a QAM detector, which produces baseband in-phase (P) and quadrature (Q) signals in response to an input QAM camer wave, and two analog-digital (A/D) convertors which convert the Q and P signals into two parallel digital signals. Automatic level control of the input level of the baseband signal to the A/D convertor is maintained constant by the combination of a reference signal generator in a feed back loop with each A/D convertor. The A/D convertor produces a decoded digital signal and the reference voltage generator, in response to those signals, provides reference voltage to the A/D convertor that are optimized in response to variations in input signal level.