DS1 TRANSMISSION AND CABLING
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Monitoring of the input DS1 or, when necessary, adding pulses (1s) to ensure that the ones-
density requirements are met
Removing bipolar violations (which implies incompatibility with B8ZS line coding)
Termination of a DS1 or regeneration of received data using an office repeater
Provisions for supplying DC power to a DS1 to power line repeaters
A fault-locating jack to aid in testing repeaters on the DS1
Jacks for manually looping the NCTE and aiding in maintenance testing
A DC-triggered remote (toward the far end) loopback relay
Other optional features include inband loopback control and the ability to pass bipolar violations.
The most frequently used NCTEs are the 551V and the 551V ST. Other vendor-provided NCTEs
may have distance limitations different from those for the 551V and 551V ST.
NOTE: The 551V has a maximum transmit distance (toward a Generic 1 or Generic 2) of 85
feet. Therefore, when this type of NCTE (the 551V) is used, the DS1 should be optioned or
administered accordingly. The 551V ST has a maximum transmit distance (toward a Generic 1
or Generic 2) of 655 feet. Exact distance settings are usually determined at installation time and
by configuring the NCTE’s user-selectable option switches. Switch option selection must be
coordinated with the particular switch DS1.
For most types of NCTEs the critical circuitry (such as, network protection and ones-density
enforcement) are normally line-powered from the CO using a 60-mA current loop. If power from
the CO is not available, then power must be provided locally. The type of power required (120 VAC
or –48 VDC) generally depends on installation/engineering specifications and on the NCTE being
used; refer to the installation and/or user’s manuals for the particular NCTE. The NCTE's
noncritical circuits (such as, error monitoring, alarming) are always powered locally.
On-Premises Cabling
When both endpoints are within the same building, cabling between them can be categorized into
three distance ranges. The equipment required depends on the range. For these categories, it is
assumed that all cabling remains inside and is not exposed to foreign potentials such as lightning, and
thus does not need to be appropriately protected. Since all equipment is on customer premises, the
customer is responsible for maintaining the equipment. Figure 3-1, On-Premises Metallic-Cable
Configurations, shows the various possible on-premises metallic cabling configurations.
Direct — Under 1310 Feet
If two DS1s are separated by no more than 1310 feet (or no more than 655 feet to the same DSX-1
cross-connect point), then they may be connected directly without the need of additional equipment.
The cross-connect point is generally not required and the connection may consist of a single
continuous 1310 foot cable. Figure 3-1-A, On-Premises Metallic-Cable Configurations, shows this
configuration.
