AT&T DS1/DMi/ISDN-PRI On-Premises Cabling, Direct Under 1310 Feet, DS1 Transmission and Cabling

DS1 TRANSMISSION AND CABLING 3-3

●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

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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-PremisesMetallic-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-PremisesMetallic-Cable Configurations, shows this configuration.