3.0 Registers
CX28394/28395/28398
3.9 Receiver Registers
Quad/x16/Octal—T1/E1/J1 Framers
Table 3-12. Receive PRBS Test Pattern Measurements (2 of 2)
FRAMED
ZLIMIT
RPATT
10
Test Pattern Measurements
Inversion
No
Framed 220
1
1
1
1
1
1
0
0
1
1
1
1
Framed 223
11
Yes
Framed 211 with 7 zero limit
Framed 215 with 7 zero limit (non-std)
Framed 220 with 14 zero limit (QRSS/QRS/QRTS)
Framed 223 with 14 zero limit (non-std)
00
No
01
No
10
No
11
No
ZLIMIT
PRBS Zero Limit—Determines the number of consecutive zeros allowed within the selected
PRBS test pattern. Refer to Table 3-12 for test pattern measurement options.
RPATT[1:0]
PRBS Test Pattern—Selects one of four PRBS test pattern lengths used to measure received bit
error ratio during out of service testing. Refer to Table 3-12 for test pattern measurement
options. PRBS test patterns used by RPATT [addr 041] and TPATT [addr 076] are defined in
the ITU standards O.151 and O.152 to use either inverted or non-inverted data. Standard data
inversion is used for selected PRBS test patterns unless ZLIMIT is enabled, in which case the
test pattern always uses non-inverted data.
042—Receive Loopback Code Detector Configuration (RLB)
Unused bits are reserved and should be written to 0.
7
6
5
4
3
2
1
0
—
—
—
—
DN_LEN[1]
DN_LEN[0]
UP_LEN[1]
UP_LEN[0]
DN_LEN[1:0]
Loopback Deactivate Code Length—Selects the number of loopback pattern bits from LBD
[addr 044] that are compared to received data. This is done in order to determine whether a
Loopback Deactivate Code [LOOPDN; addr 048] has been detected. LOOPDN is recovered if
the received data pattern contains fewer than 63 bit errors in a 24 ms period, or lost if 64 or
more bit errors are detected in a subsequent 24 ms period. F-bits that overwrite or are inserted
into the loopback pattern are not counted as bit errors. Accurate code detection is provided on
lines with up to 1E-3 BER.
DN_LEN
LBD Length
4 bits
00
01
10
11
5 bits
6 bits
7 bits
3-40
Conexant
100054E
CONEXANT [ CONEXANT SYSTEMS, INC ]
