RTS CS9500, Руководство пользователя

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Usually, in the two pair approach, the center
two
wires on the
modular plug are the audio path.
To Phone
To Hybrid
One method for interfacing to some electronic phones. The
chokes
pass the DC voltage to the phone set when the hybrid is
active.
The "Superset" phones
use
a unique scheme that requires
only one pair for all three functions. How do they do it? The data
is amplitude shift modulated onto a 32 kHz "over voice"
and then the combined voice and data are AC coupled across the
power voltage.
The most advanced systems
use
a pure digital bit stream for both
voice and data. The phone set contains the CODEC for conversion
to and from the analog and digital domains. The pure digital
approach is
used in the System
85
and the digital version of
the NEC NEAX as well as in the new Northern Telecom
system.
Since most electronic phone systems use an analog talk path, a
hybrid can be connected to the system by inserting it in the analog
path by breaking the connection from the phone switching
equipment to the instrument. Usually, the
talk audio is found on
the center two wires of the line going to the phone. Looping this
through the hybrid gets the audio connected.
The operator is responsible for turning the hybrid on and off upon
initiation of each call. The hybrid's on and off remote may be
Telos
ON€
ELECTRONIC PHONE TUTORIAL