ACS-160 Series & STL-160 Series T1 Multiplexer Installation & Operation 4 – Setup & Configuration
Version 2.11, August 2011
4-18 Harris Corporation
Intraplex Products
3. To change either of the current settings, perform these steps:
a. Press down on the SET/NEXT switch until the display shows the desired setting. The green
light blinks, indicating a change is about to be made.
b. Press up twice on the SET/NEXT switch. The green light turns on continuously, indicating the
function on the display is active.
Table 4-7. Channel Service Unit (CSU) Configurations
Function Description
Off Disables the internal CM-5RB CSU for operation with an external CSU. The settings that follow
determine the configuration of the external CSU.
ATT With this position on, the CM-5RB module is compliant with AT&T Technical Reference 54016.
ANSI With this position on, the CM-5RB module is compliant with ANSI T1.403 ESF Data Link messages.
4.5.2 Framing and Line Code Configuration
If this installation includes a CSU, the frame format and line code settings must be identical on both
the multiplexers and the CSUs. Use ESF framing and B8ZS line code whenever possible.
1. Press down repeatedly on the GROUP switch until the display reads TSEL.
2. Press down repeatedly on the SET/NEXT switch to cycle through the available functions in the
TSEL group. The green (top) bi-level indicator light turns on when the display shows the currently
set selection for frame format (ESF or SF) and line coding (B8ZS or AMI). The red (bottom)
indicator light turns on when the display shows the configurations that are not selected for each
function.
3. To change either of the current settings, perform these steps:
a. Press down on the SET/NEXT switch until the display shows the desired setting. The green
(top) light blinks, indicating a change is about to be made.
b. Press up twice on the SET/NEXT switch. The green light turns on continuously, indicating the
function on the display is active.
Table 4-8. Framing and Line Coding Configurations
Function Description
SF Superframe format – An order frame format in which T1 frame (193 bits) are grouped into 12-frame
superframes, also referred to as D4. Generally, use the SF format only if the carrier’s network cannot
support ESF.
ESF Extended superframe format – A more recent frame format in which T1 frames are grouped into 24-
frame extended superframes. The ESF format provides better error detection than SF and is generally
recommended over SF. The only limitation of ESF is that some older carrier networks cannot support it.
The SF and ESF formats are mutually exclusive functions. ESF is the factory default framing format.
AMI Alternate mark inversion – A bipolar line code composed of (+) pulses, (-) pulses, and zeros. In an AMI-
encoded signal, every pulse has the opposite polarity of the pulse that precedes it, regardless of the
number of zeros between them. The major limitation of AMI is that it cannot support 64 kbps clear
channel capability.
B8ZS Bipolar with 8-zero substitution – A modified bipolar line code in which strings of eight zeros are
replaced by zero substitution codes. Thus, T1 signals using the B8ZS line code maintain sufficient ones
density, regardless of the number of zeros in the data, to support unrestricted 64 Kbps clear channel
capability. The only limitation of B8ZS is that some older channel service units (CSUs) and carrier
networks cannot support it.
The AMI and B8ZS line codes are mutually exclusive functions. B8ZS is the factory default line code.
PDE Pulse density enforcement – The data must meet the ones density requirements specified in AT&T
Technical Reference 54016 or ANSI T1.403 ESF Data Link messages, which requires that when AMI is
engaged, approximately 1 in every 8 bits must be a one and no more than 15 consecutive zeros can be
sent. If the data violates this requirement for ones density, the PDE puts ones in the output data to
ensure density compliance. (It also put errors in the data.)
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