US PATENT SUBCLASS 375 / 261
.~.~ Quadrature amplitude modulation

Current as of: June, 1999
Click HD for Main Headings
Click for All Classes

Internet Version by PATENTEC © 1999      Terms of Use


375 /   HD   PULSE OR DIGITAL COMMUNICATIONS

259  DF  SYSTEMS USING ALTERNATING OR PULSATING CURRENT {4}
260  DF  .~ Plural channels for transmission of a single pulse train {2}
261.~.~ Quadrature amplitude modulation {4}
262  DF  .~.~.~> Maximum likelihood decoder or viterbi decoder
263  DF  .~.~.~> Partial response
264  DF  .~.~.~> Multilevel
265  DF  .~.~.~> Trellis encoder or Trellis decoder

DEFINITION

Classification: 375/261

Quadrature amplitude modulation:

(under subclass 260) Subject matter in which the transmitted signal can be represented as the superposition of two modulated signals, each being obtained by pulse amplitude modulation of a signal sequence on a sinusoidal carrier, the two signal sequences being generated in synchronization at the same rate, and the two carriers being of the same frequency but 90 degrees apart in phase.

SEE OR SEARCH THIS CLASS, SUBCLASS:

298, for quadrature amplitude modulation transmitters.

316+, for quadrature amplitude modulation receivers.

SEE OR SEARCH CLASS

370, Multiplex Communications,

20, for independent signals on quadrature carriers.

455, Telecommunications, 60, for analog transmission via plural phases of one carrier.