Data Sheet
June 2002
TMXF28155 Supermapper
155/51 Mbits/s SONET/SDH x28/x21 DS1/E1
475
Agere Systems Inc.
20 M13/M23 MUX/DeMUX Block Functional Description
(continued)
The B3ZS encoder block accepts data output from the M23 multiplexer and when M13_BIPOLAR = 1, performs
coding as follows: for each input data bit that is a 1, the encoder outputs a 1 (or pulse) on either its positive or neg-
ative output. The positive or negative output is chosen so that the resulting pulse is opposite in polarity to the last
nonzero output.
For each input data bit that is a 0, the encoder outputs zeros on both its positive and negative outputs, unless doing
so would cause three consecutive output periods of positive and negative zeros. In the latter case, the three con-
secutive input zeros are output as either [00V] or [B0V], where B is a pulse on either the positive or negative output
that is opposite in polarity to the last nonzero output, and V is a pulse that is the same polarity as the last nonzero
output. The choice of [00V] or [B0V] is made so that the polarity of consecutive V-pulses alternates (which is equiv-
alent to forcing the number of B-pulses between successive V-pulses to be odd).
When M13_BIPOLAR = 1, the user can force errors in the bipolar coding by setting M13_BIPOL_ERR (
Table 270
on page 218
) to 1. When this is done, the M13 transmits the next 1 as a bipolar violation.
20.10 DS3 R-to-T Loopback
The received DS3 signal can be looped directly back to the transmit DS3 output. If either M13_LOOP_R_TO_T = 1
(
Table 272 on page 219
), or both M13_AUTO_FLB = 1 (
Table 271 on page 218
) and M13_DS3_FLB_DET = 1
(
Table 263 on page 216
) (see
Section 20.7.6 FEAC on page 472
), the loopback is activated. (During loopback, the
SMPR_RDS3POS_DATA and SMPR_RDS3NEG_BPV input signals are looped to the M13_DS3POS_DATA and
M13_DS3NEG outputs, respectively.)
20.10.1 DS3 Transmit Path Interface
When cross connected to the DS3 device pins, the DS3 data out DS3POSDATAOUT (pin R22) and
DS3NEGDATAOUT (pin P22) are clocked out on the falling edge of DS3DATAOUTCLK (pin N22).
If the M13 DS3 interface is optioned for loop timing (M13_LOOP_TIME = 1), the DS3 data is clocked out on the ris-
ing edge of DS3DATAINCLK (pin J22).
20.11 M13/M23 Demultiplexer
20.11.1 DS3 LOC and LOS
SMPR_RDS3CLK is monitored for loss of clock, which is reported through bit M13_RDS3_LOC (
Table 237 on
page 209
). The user can configure which edge of SMPR_RDS3CLK retimes the data (M13_RDS3_EDGE = 1
(
Table 299 on page 227
) selects the rising edge; M13_RDS3_EDGE = 0 selects the falling edge).
The receive DS3 signal is also checked for loss of signal (LOS), which is reported through bit M13_RDS3_LOS
(
Table 237 on page 209
). An LOS defect, according to T1.231, is the occurrence of 175 ± 75 contiguous pulse
positions with no pulses of either positive or negative polarity at the DS3 input. An LOS defect is terminated upon
detecting an average pulse density of at least 33% over a period of 175 ± 75 contiguous pulse positions starting
with the receipt of a pulse. An LOS defect will not be terminated if, at the end of the pulse-position interval, any sub-
intervals of
100 pulse positions containing no pulses of either polarity were observed (T1.231).
B3ZS Decoder.
The receive DS3 device input can either be in the form of unipolar clock and data
(SMPR_RDS3CLK and SMPR_RDS3POS_DATA when M13_BIPOLAR = 0 (
Table 272 on page 219
)) or unipolar
clock, positive data, and negative data (SMPR_RDS3CLK, SMPR_RDS3POS_DATA, and
SMPR_RDS3NEG_BPV when M13_BIPOLAR = 1 and M13_BPV_IN = 0 (
Table 271 on page 218
)) or unipolar
clock, data, and bipolar violation indication (external input) (SMPR_RDS3CLK, SMPR_RDS3POS_DATA, and
SMPR_RDS3NEG_BPV when M13_BIPOLAR = 0 and M13_BPV_IN = 1).