Bt8370/8375/8376
Fully Integrated T1/E1 Framer and Line Interface
3.8 Receiver Registers
FRAMED
PRBS Framed—When set, PRBS test pattern bits are not checked during framing bit positions.
In T1 mode, F-bit locations are not searched. In E1 mode, time slot 0 and time slot 16 (if CAS
framing is selected) are not searched. CAS framing is selected by setting RFRAME[3] to 1 in
the Primary Control register [CR0; addr 001]. If FRAMED is disabled, the PRBS pattern
receiver searches all time slots for the test pattern. FRAMED, ZLIMIT, and RPATT establish
the test pattern measurement type as listed in Table 3-11.
Table 3-11. Receive PRBS Test Pattern
FRAMED
ZLIMIT
RPATT
00
Test Pattern
Inversion
No
11
15
20
23
11
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
Unframed 2
Unframed 2
Unframed 2
Unframed 2
01
Yes
No
10
11
Yes
No
00
Unframed 2 with 7 0 limit
15
01
No
Unframed 2 with 7 0 limit (non-std)
20
10
No
Unframed 2 with 14 0 limit (QRSS/QRS/QRTS)
23
11
No
Unframed 2 with 14 0 limit (non-std)
11
00
No
Framed 2
15
01
Yes
No
Framed 2
20
10
Framed 2
23
11
Yes
No
Framed 2
11
00
Framed 2 with 7 0 limit
15
01
No
Framed 2 with 7 0 limit (non-std)
20
10
No
Framed 2 with 14 0 limit (QRSS/QRS/QRTS)
23
11
No
Framed 2 with 14 0 limit (non-std)
ZLIMIT
PRBS 0 Limit—Determines the number of consecutive zeros allowed within the selected
PRBS test pattern. Refer to Table 3-11 for test pattern measurement options.
RPATT[1:0]
PRBS Test Pattern—Selects one of four PRBS test pattern lengths used to measure the
received bit error ratio during out of service testing. Refer to Table 3-11 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.
Bt8370/8375/8376 uses the standard data inversion option for the selected PRBS test pattern
unless ZLIMIT is enabled, in which case the test pattern always uses non-inverted data.
N8370DSE
Conexant
3-49
CONEXANT [ CONEXANT SYSTEMS, INC ]
