US 5,175,514 AGranted

Digital modulator and baseband signal generator for digital modulator

AssigneesSanyo Electric Co., Ltd., Tottori Sanyo Electric Co., Ltd.

InventorsToshinori Iinuma, Mitsufumi Yoshimoto, Hama: Mitsuji, Akio Kosaka

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Abstract

A digital modulator includes a signal source for a digital baseband signal and a signal source for carrier phase information. The digital baseband signal is converted into amplitude information of an I phase, a Q phase, an I' phase and a Q' phase by a mapping circuit. The carrier phase information is converted into four phase information with phases shifted by shift registers to be out of phase by .pi./4 from each other. The digital modulator includes four ROM, each ROM outputting a multiplication result of the corresponding amplitude information and carrier signal based on the corresponding one of the four amplitude information as a higher order address and the corresponding one of the four phase information as a lower order address. These outputs are added to each other in a digital manner and then converted into an analog signal which is supplied as a modulated signal.

Claims13

Dependent claims

A digital modulator comprising:

means for supplying a digital baseband signal,
means for supplying carrier signal information as digital data,
baseband signal converting means for converting said baseband signal into a plurality of digital amplitude information in phases different from each other,
phase information converting means for converting said carrier signal information into the same number of digital phase information as that of said amplitude information, which digital phase information are shifted by a predetermined amount from each other,
storing means of the same number as those of said amplitude information and phase information, each of said storing means storing data indicative of a multiplication result of the corresponding one of said amplitude information and said carrier signal at an address designated by the corresponding one of said plurality of amplitude information and the corresponding one of said plurality of phase information,
means for adding in a digital manner the plurality of data read from said plurality of storing means based on said plurality of amplitude information and said plurality of phase information, and
means for converting the output of said digital adding means into an analog signal and supplying the analog signal.

4 more elements

Dependencies are inferred from the claim text.