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. 14, 1987
Filed:
Apr. 10, 1986
Applicant:
Inventors:
Assignee:
Hitachi, Ltd., Tokyo, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H03C / ;
U.S. Cl.
CPC ...
332 / ; 332 21 ; 375 67 ;
Abstract
A quadrature phase modulator constructed by use of a simple digital circuit. Digital signals of sample data obtained by sampling outputs from a roll-off filter with a frequency four times a modulated carrier frequency are stored in an ROM, the outputs corresponding to all combinations of a plurality of successive bits of input data; the plurality of bits are set as an address, and a signal of an in-phase channel and a signal of a quadrature phase channel is alternately read from the ROM with a frequency equal to half the sampling frequency, then the obtained serial signals are subjected to a digital-to-analog conversion to obtain a quadrature phase modulated signal.