PHASE-AMPLITUDE MULTIPLE DIGITAL MODULATION SYSTEM

• US 3,805,191 A
• Filed: 02/08/1972
• Issued: 04/16/1974
• Est. Priority Date: 02/10/1971
• Status: Expired due to Term

• Current Assignee: Hidetaka Yanagidaira, Kazuo Kawai, Sotokichi Shintani
• Original Assignee: Hidetaka Yanagidaira, Kazuo Kawai, Sotokichi Shintani
• Inventors: Kawai, Kazuo, Shintani, Sotokichi, Yanagidaira, Hidetaka
• Primary Examiner(s): Brody, Alfred L.
• Application Number:
  US05/224,451
• Time in Patent Office: 798 Days
• Field of Search: 332/9R,9T,21,22,40,41,42,17,11R,10 178/66R 179/15BM 325/320
• US Class Current: 332/145
• CPC Class Codes: H04L 27/362 Modulation using more than one carrier, e.g. with quadrature carriers, separately amplitude modulated H04L27/366 takes precedence

Abstract

A digital modulation system for modulating the phase and the amplitude of a carrier in accordance with multi-value digital code units so as to produce a phase-amplitude modulated wave, so that respective pointed ends of signal vectors corresponding to possible multi-values of the phase-amplitude modulated wave are positioned at respective centers of regular hexagons predetermined so as to correspond to possible multi-values of the multivalue digital code units from a plurality of regular hexagons, which are closely positioned to one another without leaving any space in a honeycombed fashion near the original point of a polar coordinate on the polar coordinate plane.

Claims

1. A multiple digital modulation system for producing a phaseamplitude modulated wave, comprising:

a carrier generator for generating a carrier wave of constant frequency, terminal means for receiving multi-value digital code units to be transmitted, a phase splitter coupled to said carrier generator for developing three reference carriers having the same phase difference from one another and the same frequency as the carrier wave, a code converter coupled to said terminal means for converting the multi-value digiTal code units to corresponding combinations of N control code units, three amplitude-modulators respectively receptive of said three reference carriers for respectively amplitude-modulating said reference carriers in accordance with said combinations of said N control code units to develop three amplitude-modulated waves respectively having the same frequencies as the reference carriers, and a combiner receptive of all of the amplitude-modulated waves for combining them to develop one of a plurality of phase-amplitude modulated waves, each having a vector representation in the phase-amplitude plane wherein the end points of signal vectors corresponding to said plurality of the phase-amplitude modulated waves are positioned at respective centers of regular hexagons predetermined so as to correspond to possible multi-values of the multi-value digital code units from a plurality of regular hexagons, which are closely positioned to one another without leaving any space in a honeycombed fashion near the origin point of the polar coordinates on the polar coordinate plane.

2. A multiple digital modulation system according to claim 1, in which each of said amplitude modulators comprises attenuator means for producing three level-adjusted reference waves, and three AND gate circuits respectively receptive of said three level-adjusted reference waves and controlled by said control signals.

3. A multiple digital modulation system according to claim 1, further comprising second input means for receiving a high speed pulse train and a high speed digital signal synchronous therewith, and signal conversion means coupled to the second input means and said terminal means for successively distributing successive bits of said high speed digital signal to convert same to N parallel low speed digital signals each having a frequency of 1/N of the frequency of said high speed pulse train and synchronous therewith wherein the simultaneous parallel bits of said low speed digital signals correspond to said multi-value digital code units.

4. A phase and amplitude modulation system for use in the transmission of a serial digital information signal to effect a system information capacity substantially equal to the maximum capacity for a given noise characteristic representable by a circular vector having a given diameter in a phase-amplitude plane, said system comprising:

coding means receptive of a serial digital information signal comprising a first plurality of bits and developing therefrom one of a second plurality of signals each corresponding to a different combination of said first plurality of bits and each having a predetermined different vector representation in a phase-amplitude plane wherein the minimum distance between the end points of any two vectors is equal to the diameter of a given circular noise vector and wherein each of said end points is disposed at the center of one of a plurality of regular hexagonal sections of said plane, said hexogonal sections completely filling a portion thereof thereby defining a substantially maximum vector density for a given separation in said portion of said plane; and

phase and amplitude modulating means receptive of said signals having different vector representations for amplitude and phase modulating a carrier signal with the vector represented signals, said phase and amplitude modulating means comprising means for developing said carrier signal, phase-splitting means receptive of said carrier signal for developing three phase signals each corresponding to a delayed version of said carrier signal and all having the same phase difference therebetween and means for combining said signals having different vector representations and said three phase signals to develop an amplitude and phase modulated carrier signal having a substantially maximum vector density in said portion of said amplitude-phase plane for the given noise characteristic wherein the information capacity of said amplitude and phase modulated carrier siGnal is proportional to said vector density;

whereby the system information capacity is substantially equal to the maximum information capacity for said given noise characteristic.

5. A phase and amplitude modulation system according to claim 4, wherein said coding means comprises means receptive of said serial digital information signal for developing a plurality of parallel amplitude signals each representative of an amplitude value for one of said three phase signals and wherein said amplitude and phase modulating means further comprises means for combining the plurality of amplitude signals and said three phase signals to develop said amplitude and phase modulated carrier signal.

6. A method of phase and amplitude modulating a carrier wave for use in the transmission of a serial digital information signal to effect an information capacity substantially equal to the maximum capacity for a given noise characteristic representable by a circular vector having a given diameter in a phase-amplitude plane, said method comprising:

receiving a serial digital information signal comprising a first plurality of bits;

developing therefrom one of a second plurality of signals each corresponding to a different combination of said first plurality of bits and each having a predetermined different vector representation in a phase-amplitude plane wherein the minimum distance between the end points of any two vectors is equal to the diameter of a given circular noise vector and wherein each of said end points is disposed at the center of one of a plurality of regular hexagonal sections of said plane, said hexagonal sections completely filling a portion thereof thereby defining a substantially maximum vector density for a given separation in said portion of said plane;

developing a carrier signal, phase splitting said carrier signal into three phase signals each corresponding to a delayed version of said carrier signal and all having the same phase difference therebetween;

amplitude and phase modulating said carrier signal with the vector represented signals by combining said three phase signals and said signals having different vector representations to develop therefrom an amplitude and phase modulated carrier signal having a suhstantially maximum vector density in said portion of said amplitude-phase plane for the given noise characteristic wherein the information capacity of said amplitude and phase modulated carrier signal is proportional to said vector density;

whereby the information capacity is substantially equal to the maximum information capacity for said given noise characteristic.