PM7346 datasheet(77/419 Pages) PMC

77 / 419 page

PM7346 S/UNI-QJET

DATASHEET

PMC-960835

ISSUE 6

SATURN QUAD USER NETWORK INTERFACE FOR J2, E3, T3

PMC-SIERRA, INC. PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA INC., AND ITS CUSTOMERS’ INTERNAL USE 56

FUNCTIONAL DESCRIPTION

9.1

DS3 Framer

The DS3 Framer (T3-FRMR) Block integrates circuitry required for decoding a

B3ZS-encoded signal and framing to the resulting DS3 bit stream. The T3-FRMR

is directly compatible with the M23 and C-bit parity DS3 applications.

The T3-FRMR decodes a B3ZS-encoded signal and provides indications of line

code violations. The B3ZS decoding algorithm and the LCV definition can be

independently chosen through software. A loss of signal (LOS) defect is also

detected for B3ZS encoded streams. LOS is declared when inputs RPOS and

RNEG contain zeros for 175 consecutive RCLK cycles. LOS is removed when

the ones density on RPOS and/or RNEG is greater than 33% for 175 ±1 RCLK

cycles.

The framing algorithm examines five F-bit candidates simultaneously. When at

least one discrepancy has occurred in each candidate, the algorithm examines

the next set of five candidates. When a single F-bit candidate remains in a set,

the first bit in the supposed M-subframe is examined for the M-frame alignment

signal (i.e., the M-bits, M1, M2, and M3 are following the 010 pattern). Framing is

declared, and out-of-frame is removed, if the M-bits are correct for three

consecutive M-frames while no discrepancies have occurred in the F-bits. During

the examination of the M-bits, the X-bits and P-bits are ignored. The algorithm

gives a maximum average reframe time of 1.5 ms.

While the T3-FRMR is synchronized to the DS3 M-frame, the F-bit and M-bit

positions in the DS3 stream are examined. An out-of-frame defect is detected

when 3 F-bit errors out of 8 or 16 consecutive F-bits are observed (as selected

by the M3O8 bit in the DS3 FRMR Configuration Register), or when one or more

M-bit errors are detected in 3 out of 4 consecutive M-frames. The M-bit error

criteria for OOF can be disabled by the MBDIS bit in the DS3 Framer

Configuration register. The 3 out of 8 consecutive F-bits out-of-frame ratio

provides more robust operation, in the presence of a high bit error rate, than the

3 out of 16 consecutive F-bits ratio. Either out-of-frame criteria allows an out-of-

frame defect to be detected quickly when the M-subframe alignment patterns or,

optionally, when the M-frame alignment pattern is lost.

Also while in-frame, line code violations, M-bit or F-bit framing bit errors, and P-

bit parity errors are indicated. When C-bit parity mode is enabled, both C-bit

parity errors and far end block errors are indicated. These error indications, as

well as the line code violation and excessive zeros indication, are accumulated

PM7346 Folha de dados(PDF) 77 Page - PMC-Sierra, Inc

PM7346 Folha de dados(HTML) 77 Page - PMC-Sierra, Inc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Folha de dados Download

Ligação URL