T1 Modem Bank
4
Line Build Out
After the T1 Modem Bank is installed, the carrier will determine the correct setting for Line Build Out (LBO).
However, certain determinations based on the following information will need to be entered into your computer.
• CSU mode Line compensation: Line attenuation can be set to one of the following: -0.0dB, -7.5dB, -15.0dB,
and -22.5dB. Your T1 installer will inform you of the correct setting.
• DSX-1 Mode Transmit line buildout: For line compensation, your T1 installer will select a cable length
between 0 and 655 feet based upon line length.
CSU Specification
Table 2 CSU Technical Description
Line Frequency 1.544 Mb/s +/- 200 b/s
Line Code AMI or B8ZS
Critical Circuitry Power Source Dry Span, CSU powered form local AC power source
Line Framing D4 or ESF
Line Loopback (LLB) Set Inband Code (00001) repeating binary pattern (per AT&T Pub 54016 and
ANSI T1.403)
Line Loopback (LLB) Reset Inband Code (001) repeating binary pattern (per AT&T Pub 54016 and ANSI
T1.403)
Line Build Out 0.0, -7.5, -15.0, or -22.5 dB of attenuation
Pulse Density and Consecutive Zeros
Enforcement In accordance with requirements of AT&T Pub 62411
T1 Cable Specification
Transmitting T1 signals requires two 24 AWG stranded unshielded twisted pair Category 5 cables. A 15’ cable
meeting these specifications is shipped with the T1 Modem Bank.