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:
Apr. 27, 1999
Filed:
Jul. 12, 1996
Masayuki Doi, Tokyo, JP;
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
A QPSK demodulator that is smaller in size and lower in cost by restricting a storage capacity needed for a TAN.sup.-1 ROM to a minimum. Values of I and Q channel base band signals obtained by converting and quantizing a received signal are approximated to a nearest one of values on (2.sup.N-3 +1) segment lines represented by Q=(n/2.sup.N-3)I, where n=0, 1, . . . , 2.sup.N-3, with a phase accuracy of positive N bits. Data corresponding to the approximated segment line is previously stored in a TAN.sup.-1 ROM as phase arithmetic data. An address decoder converts each base band signal into an address. An arithmetic circuit obtains phase data, for obtaining a QPSK demodulated signal, by performing a predetermined arithmetic operation, which is commensurate with the size of I and Q channel base band signals, on phase arithmetic data stored in the TAN.sup.-1 ROM in association with the converted address.