Because RFL™ and Hubbell® have a policy of continuous product improvement, we reserve the right to change designs and specifications without notice.
4.6 SETTING CM4, T1 FRAME FORMAT AND LINE CODE (TSEL Group)
The TSEL (T1 Select) Group is used to set T1 frame format and line code. The functions available in
the TSEL group are explained in Table 4-2.
Table 4-2. TSEL group
Function Description
SF
ESF
Superframe Format. An older format in which 193-bit T
1
frames are grouped into 12-frame superframes.
Also referred to as "D4." Generally, SF is only us
ed in applications where the carrier's network
cannot support ESF.
Extended Superframe Format. A 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 t
o
ESF is that some older carrier networks
cannot support it.
Note: The SF and ESF frame formats are mutually exclusi
v
e functions. ESF is the factory-default framing
format.
AMI
M-DACS-T1 RFL Electr
o
nics Inc.
B8ZS
Alternate Mark Inversion. A bipolar line code comp
o
sed of positive pulses, negative pulses, and zeroes.
In an AMI-encoded signal, every pulse h
as the opposite polarity of the pulse that preceded it, regardless
of the number of zeroes between them. The major limitation of AMI is that it cannot support
64-Kbps clear-channel capability, due to the possibility of an excessive number of zeros.
Bipolar With Eight-Zero Substitution. A modified bipolar li
n
e code in which strings of eight zeroes are
replaced by zero substitution code. This allows T1 signals usi
ng the B8ZS line code to maintain a
sufficient ones density, regardless of the number of
zeroes in the data. B8ZS supports unrestricted
64-Kbps clear-channel capability. The only limitation
of B8ZS is that some older carrier networks
cannot support it.
Note 1: The AMI and B8ZS line codes
are
mutually exclusive functions. B8ZS is the factory-default line
code.
RFL This is the standard FDL mode which allows remote configuration, status
inquiries, and diagnostics. This mode does not provide CSU functionality.
ANSI ANSI CSU standard T1.403 is followed
If framing is SF, the CM4 can respond to line loop-up and loop-down commands.
ATT AT&T CSU standard TR54016 is followed.
If framing is SF, the CM4 can respond to line loop-up and loop-down commands.
Note: The RFL, ANSI and ATT line codes are mutually exclusive
functions. RFL is th
e factory-default line
code.
July 18, 2008 4-6 (973) 334-3100
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