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PRACTICE 553-2201-193
1. QPC578 INTEGRATED SERVICES DIGITAL LINE CARD
Description
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1.01 The QPC578 Integrated Services Digital Line Card (ISDLC) is a
voice and data communication link between a Meridian SL-1 and the
Meridian
M2000/M3000
series of digital telephones. When a digital
telephone is equipped with the data option, an asynchronous ASCII
terminal or PC can be connected to Meridian
SL-1
through the digital
telephone. The ISDLC circuit pack supports voice only or simultaneous
voice and data service over a single twisted pair of standard telephone
wiring. This practice describes the ISDLC. For more information on
Meridian digital telephones, see 553-2201-110 and 553-2201-111 for the
M2000 series telephones, the 553-2201-115 for the M3000 telephone,+
and the 553-2201-113 for the M2317 telephone.
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1.02 Requirements. To use the ISDLC, the following Meridian SL-1
requirements must be met:
l Double Density Peripheral Shelves must be equipped (one shelf per
loop)
. Generic X11, Release 7 (or later) or Generic
X08.
Release 10
(or+
later) software must be running.
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l Quadruple Density loops must be defined in hardware
(SW5
set to
ON on the associated Peripheral Buffer) and software (OVL 17)
l At remote locations using Remote Peripheral Equipment (RPE),
ISDLC packs must be QPC578B. series C or higher.
1.03 The QPC578 ISDLC is equipped with eight identical line circuits.
Each line circuit provides a multiplexed voice, data and signaling path
to and from digital apparatus over a 2-wire full duplex 512 KHz Time
Compression Multiplexed (TCM) digital link.
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1.04 Time Compression Multiplexing. Once every 125
usecond.
the
ISDLC transmits a 23 bit message to a digital telephone. At the end of
the 23 bit message a 2.7 bit guard band delay is inserted. Then the
digital telephone begins transmitting a similarly formatted 23 bit
message to the ISDLC. Each 23 bit message consists of:
l
start (1 bit)
l
voice signaling (1 bit)
l voice
vahd
(1 bit)
l
PCM voice (8 bits)
l
data signaling (1 bit)
l
data valid (1 bit)
l
data (8 bits)
l
parity (1 bit)
l
stop (1 bit)
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6 Pages