700-712-100-01, Revision 01
Overview
UTU-712 and ETU-762 List 1
May 10, 1999
1
O
VERVIEW
PairGain
®
HiGain-ETSI™ offers High-bit-rate Digital Subscriber Line (HDSL) Line Termination Units (LTUs),
Network Termination Units (NTUs), Universal Termination Units (UTUs), and ETSI Termination Units (ETUs).
The units are shelf and enclosure mounted, providing full-duplex transmission of up to 2.048 Mbps data over
one or two twisted pairs of copper wire. Public carriers and private network providers can use these units to offer
low-cost service with fiber-optic quality using the local copper loop without installing repeaters or conditioning
the outside plant. The units comply with European Telecommunication Standards Institute (ETSI) specifications
ETR152 and TS 101 135 for this type of system.
This practice describes the PairGain
®
HiGain-ETSI™ RS UTU-712 List 1 and ETU-762 List 1 Rate Selectable
HDSL line and desktop units. The terms for these units are defined as follows:
•
LTU and NTU are defined by the European Telecommunication Standards Institute (ETSI) to distinguish
between the two units in an HDSL system. An LTU is generally located at the Exchange Office end of the
circuit and acts as the master unit. The NTU is located at the customer site and acts as the slave unit.
•
UTU is defined by PairGain. These are programmable HDSL line units that can be configured as an
LTU (master) or an NTU (slave). The UTU default configuration is NTU (slave). The UTUs do not provide
line power to other HDSL units. All other aspects of UTU functionality are identical to LTUs or NTUs. The
UTU-712 has an Nx64k interface and must be locally powered from a -36 Vdc to -72 Vdc power supply.
•
ETU is defined by PairGain. These are programmable HDSL line units housed in plastic enclosures with
interface and power connectors for convenient use as integrated desktop units. The ETUs can be configured
as an LTU or an NTU. The ETU default configuration is NTU. The ETU-762 does not provide or receive line
power; it must be locally powered. All other aspects of ETU functionality are identical to LTUs or NTUs. The
ETU-762 has an Nx64k interface and contains a power supply that accepts 100 to 240 volt, 50 or 60 Hz,
AC power.
•
HiGain-ETSI RS (rate selectable) is defined by PairGain. HiGain-ETSI RS is a single pair High-bit-rate
Digital Subscriber Line (HDSL) solution that offers extended reach capabilities through the use of
industry-leading multi-rate DSL technology. The UTU-712 and ETU-762 deploy HDSL in networks using a
single pair of copper wire running at speeds between 64 kbps and 768 kbps. The HDSL line rates are either
menu selected in time slot increments of 64 kbps or derived automatically from the Terminal Transmission
(TT) clock received at the Nx64k serial data port from the Network Data Terminal Equipment (DTE) .
Transmission ranges vary according to the rate selected. Depending on noise environment, ranges of
up to 8.5 km (5.3 miles) are possible at the lowest-selectable HDSL line rates (64 and 128 kbps).
These HDSL units are configured as Data Communications Equipment (DCE) and respond to data, clock, and
control signals from Data Terminal Equipment (DTE).
+
R
ATE
S
ELECTABLE
HDSL U
NIT
F
IRMWARE
Version 4.0 is the current rate selectable HDSL unit firmware release.
Unless otherwise specified:
•
LTU refers to an LTU-configured UTU or ETU.
•
NTU refers to an NTU-configured UTU or ETU.
•
The term “line and desktop units” refers to UTUs and ETUs, respectively.
Rate selectable units are not backward compatible with standard HDSL or management unit
firmware. The installed firmware must be designed for rate selectable units.
Rate selectable units must have the same payload rates available. An LTU set for a rate of
768 kbps will not function with an NTU whose maximum available rate is 256 kbps.
