Section 363-772-100
Revision 01
Page 2
A. PRODUCT OVERVIEW
1. DESCRIPTION AND FEATURES
1.01
The PG-Flex FRL-772 Remote Terminal (RT)
Line Unit is the remote end of the PG-Flex
carrier system that uses two pairs of unconditioned
copper wire as a carrier for up to 12 independent
subscriber channels between a Central Office Terminal
(COT) and the RT. The FRL-772 RT Line Unit uses
PairGain’s High-bit-rate Digital Subscriber Line (HDSL)
technology to provide the equivalent of 1.544 Mbps
digital transmission rates, plus signaling over two copper
pairs without the need for repeaters, loop conditioning,
or pair selection.
1.02
The FRL-772 RT Line Unit resides in a PairGain
RT Enclosure; one FRL-772 RT Line Unit is
required for the system.
1.03
Revision History of this practice.
Revision 01 - February 12, 1996
a) Initial release.
1.04
FRL-772 RT Line Unit features:
•
Distributed subscriber carrier system
architecture
•
Proven PairGain HDSL (2B1Q) technology
operates on unconditioned copper pairs
Bridge Taps
No Pair Selection
No Repeaters
2. APPLICATIONS
2.01
PG-Flex is a small capacity universal subscriber
carrier system supporting up to 24 subscriber
channels, including POTS and ISDN services. The
system is based on HDSL transmission technology and
the remote power is powered from the central office.
Using two 24 gauge unconditioned copper pairs, the
remote terminal may be located up to 12.3 kft from the
central office terminal. Standard 19- or 23-inch shelves
contain multiple systems; circuit cards may be hot-
swapped without affecting other systems installed in the
shelf. POTS channel units use 64-kbps
µ
-Law PCM
encoding to allow Group 3 facsimile or high-speed
modem operation on all channels.
2.02
System Flex Configuration. A PG-Flex
system, shown in Figure 2 consists of:
•
Central
Office Terminal (COT). Two
complete systems may be installed in a 19-
inch COT Shelf and four complete systems
may be installed in a 23-inch COT Shelf.
Each system requires one COT Line Unit
and up to three (23-inch shelf) or six (19-
inch shelf) Channel Units. A common Alarm
Unit or Pair Gain Test Controller Interface
Unit in each shelf provides an interface for
maintenance alarm relays and metallic
access to the remote subscriber lines.
•
Remote Terminal (RT). The RT Enclosure
provides a weatherproof housing for the
PG-Flex remote electronics and subscriber
terminations. The enclosure accepts one
common RT Line Unit and up to four
Channel Units. The Remote Terminal
communicates with, and is line-powered
from, the COT over two pairs of 19- to 26-
gauge twisted-pair telephone wire. Each pair
carries both power and HDSL signaling.
2.03
HDSL Transmission. PG-Flex utilizes HDSL
transmission technology between the COT and
RT and provides up to 24 DS0s, plus signaling, over two
copper pairs without the need for repeaters, loop
conditioning, or pair selection. Adaptive equalization,
scrambling, and a four-level 2B1Q line coding scheme
increase range and minimize crosstalk.
2.04
The line interface is a two-pair, 784-kbps full-
duplex 2B1Q transmission format. The dual
HDSL lines provide 24 64-kbps channels with signaling,
and an embedded operations channel for management
control. The signal characteristics on the carrier pairs
comply with TR-NWT-001210, Generic Requirements for
High-bit-rate Digital Subscriber Line (HDSL) Systems.
2.05
For the system configuration depicted in Figure
2, the maximum distance between the COT and
the RT is 12.3 kft (3.8 km), assuming the HDSL lines are
24 gauge. Table 1 shows the maximum distance
between the COT and RT for various gauge wire. Due to
the nature of HDSL transmission technology, the HDSL
lines do not require any special conditioning and may
include unterminated bridge taps, but cannot include
load coils.
2.06
Subscriber Drop Testing. For subscriber drop
testing from the central office, PG-Flex is able to
select and connect any subscriber drop to a metallic test
pair at the RT. PG-Flex extends this connection back to
the COT where technicians can switch it onto a test
access bus, or to the corresponding subscriber line on
the COT channel card.
2.07
Test access is achieved by p116 V on
the subscriber’s COT tip lead for 1.5 seconds,
then removing the +116 V. Depending on the
configuration of the PG-Flex system, the selected
subscriber drop (assuming a working metallic bypass
