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PRACTICE 553-2201-183
4. CHARACTERISTICS
FUNCTIONAL
Common Features
4.01
The following features are provided:
l
6000
balanced terminating impedance
Unique Features
.A.::
.
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.:
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l -48 V through a battery feed resistance and ground
l supervise the loop current to determine on-hook/off-hook status
l ringing current to the loop
l isolation of foreign potentials on the loop from the transmission and
signaling circuit
l conversion from a
2-
to a 4-wire transmission path
l analog-to-digital and digital-to-analog conversion of transmission
signals
l common multiplexing’ circuit to interface with the peripheral bus
signaling channel .
l retime the digital signals received from the peripheral bus
l decode address information received from the peripheral bus to
enable individual line circuits during selected time slots
l control the disconnection timing of ringing current to the loops to
avoid switching during current peaks.
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4.02 The various special versions of the
500/2500
line pack have
additional features as follows:
4.03
QPCl92
and QPC292 OPX Line packs:
l serve lines up to a maximum loop resistance of 1400
R
l
serve Dataphone sets
l have line-to-line insertion loss of 1
dB.
4.04 QPC494 and QPC558 Message Waiting Line packs:
l provides connection of -150 V in a steady or 1 Hz flash rate to
activate the Message Waiting lamp on the telephone
l provides for one Message Waiting lamp per line
l maintain all Message Waiting lamps off and do not allow phones to
ring during power-up sequence.
Page 4-l
8 Pages
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