3.0 Registers
CX28394/28395/28398
3.12 Transmitter Registers
Quad/x16/Octal—T1/E1/J1 Framers
TLOFC–TLOFA
Transmit Loss Of Frame Criteria—Determines the number of frame errors that the online
framer must detect before declaring loss of frame alignment [TLOF; addr 048]. Refer to
TFRAME [addr 070] to find which frame bits are monitored during the selected framer mode.
T1/E1N TLOFC–A
Reframe Criteria
Three consecutive FAS errors
Two out of four frame bit errors
Two out of five frame bit errors
Two out of six frame bit errors
0
1
1
1
100
001
010
100
NOTE(S): All other TLOFC–A combinations are invalid.
TZCS[1:0]
Transmit Zero Code Suppression—Selects ZCS and Pulse Density Violation (PDV)
enforcement options for TPOSO/TNEGO outputs. B8ZS and HDB3 replace transmitted
sequences of 8 zeros or 4 zeros with a recoverable code and are standard T1 and E1 line code
options, respectively (see Table 3-20).
Table 3-20. Transmit Zero Code Suppression
Zero Code Substitution
(Sent left to right)
TZCS
T1/E1N
T1DM
ZCS
AMI
PDV
None
00
01
X
0
1
1
1
X
X
X
1
None
HDB3
B8ZS
UMC
AMI
None
000V or B00V
000VB0VB
10011000
on PDV errors
01
None
10
None
11
X
Enforced
AMI
Alternate Mark Inversion. Bipolar line code forces successive ones to alternate their output pulse polarity. Analog and
digital dual-rail outputs are always AMI encoded, although certain AMI codes are modified to include zero
suppression.
HDB3
B8ZS
PDV
Prior to transmission, 4 consecutive zeros are substituted by 000V or B00V code, where B is an AMI pulse and V is a
bipolar violation. ZCS encoder selects the code which will force the BPV output polarity opposite that of the prior BPV.
Prior to transmission, 8 consecutive zeros are substituted by 000VB0VB code, where B is an AMI encoded pulse and
V is a bipolar violation.
Enforcer overwrites transmit zeros that would otherwise cause output data to fail to meet the minimum required pulse
density per ANSI T1.403 sliding window. Note that the enforcer will never overwrite a framing bit and is not applicable
during E1 mode. Note that each PDV enforced one causes a nonrecoverable transmitted bit error.
UMC
Unassigned Mux Code. DS0 channels that contain 8 zeros are substituted with the 10011000 code, per Bellcore
TA-TSY-000278. Note that the receiver's ZCS decoder cannot recover original data content from UMC encoded signal.
NOTE(S): PRBS, inband loopback, and YB2 alarm insertion occur after PDV enforcement. Therefore, output data might violate
minimum pulse density requirements while these functions are active.
3-60
Conexant
100054E
CONEXANT [ CONEXANT SYSTEMS, INC ]
