A. This is the generic class for multiplexing or duplexingsystems, methods, or apparatus.
(1)Note. Multiplexing includes for example, time division multiplexing(TDM) frequency division multiplexing (FDM), orthogonal and quasiorthogonalmultiplexing techniques, phantom connections and plural channeladaptive systems.
(2)Note. Selective or telemetering systems which may be analogousto multiplexing techniques are not classified here but elsewhere.(See References to Other Classes, below.)
(3)Note. The distinction between multiplexing and selectiveor telemetry is: in multiplexing, the information is unrestrictedas to content, e.g., a teletype-writer which uses an alphabet totransmit unlimited information, whereas in selective or telemetrydevices, the information is restricted as to content, e.g., a transducermeasuring a single parameter.B. This class includes elements and circuits forming subcombinationshaving a utility unique to multiplexing such as rotary distributorsused as multiplexers, synchronizers used to control distributionof multiplexed channels, bridge duplex circuits, resonant circuitshaving a special utility in a frequency division multiplexing system.
(1)Note. Multiplex modulators, per se, are not classified inthis class. See classification elsewhere. (See References to Other Classes,below.)