US PATENT SUBCLASS 455 / 570
.~.~.~ Noise suppression or echo cancellation

Current as of: June, 1999
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455 /   HD   TELECOMMUNICATIONS

73  DF  TRANSMITTER AND RECEIVER AT SAME STATION (E.G., TRANSCEIVER) {9}
550  DF  .~ Radiotelephone equipment detail {17}
569  DF  .~.~ Hands-free or loudspeaking arrangement {1}
570.~.~.~ Noise suppression or echo cancellation

DEFINITION

Classification: 455/570

Noise suppression or echo cancellation:

(under subclass 569) Subject matter wherein any undesired electrical disturbance occurring in signal paths between loudspeaker and microphone circuitry is reduced or prevented.

SEE OR SEARCH CLASS

370, Multiplex Communications,

278, and 282+ for transmit/receive interaction control in a wireless and in a general duplex communication system, respectively, particularly subclasses 286+ for echo cancellation.

379, Telephonic Communications,

389+, for loudspeaker with circuitry for voice control of transmission direction, subclasses 391+ for sidetone control, and subclasses 406+ for echo suppression in a telephone substation or terminal circuitry.