US PATENT SUBCLASS 379 / 387
SUBSTATION OR TERMINAL CIRCUITRY

Current as of: June, 1999
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379 /   HD   TELEPHONIC COMMUNICATIONS

387SUBSTATION OR TERMINAL CIRCUITRY {7}
388  DF  .~> For loudspeaking terminal {2}
391  DF  .~> Sidetone control or hybrid circuit (e.g., induction coil) {1}
393  DF  .~> Hold circuit
394  DF  .~> Impedance matching or line equalizing
395  DF  .~> Amplifying
396  DF  .~> Visual signalling (e.g., lamp)
397  DF  .~> Wire distribution

DEFINITION

Classification: 379/387

SUBSTATION OR TERMINAL CIRCUITRY:

(under the class definition) Subject matter comprising electrical relationships of circuit elements of a terminal set or a group of such sets connected to a single line circuit.

SEE OR SEARCH THIS CLASS, SUBCLASS:

156+, for a key substation system.

177+, for a polystation line system.

199+, for a call limiting substation system.

419+, for the structure of a terminal.