DS3173N datasheet(82/232 Pages) DALLAS

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active and none of the last sixteen consecutive F-bits has been errored, or when the DS3 framer updates the data

path frame counters. Multiframe alignment OOF is programmable (on or off).

A Severely Errored Frame (SEF) condition is declared when three or more out of the last sixteen consecutive F-bits

have been errored, or when a manual resynchronization is requested. An SEF condition is terminated when an

OOF condition is absent.

A Loss Of Frame (LOF) condition is declared by the LOF integration counter when it has been active for a total of T

ms. The LOF integration counter is active (increments count) when an OOF condition is present, it is inactive (holds

count) when an OOF condition is absent, and it is reset when an OOF condition is absent for T continuous ms. T is

programmable (0, 1, 2, or 3). An LOF condition is terminated when an OOF condition is absent for T continuous

ms.

A Change Of Frame Alignment (COFA) is declared when the DS3 framer updates the data path frame counters

with a frame alignment that is different from the current data path DS3 frame alignment.

A Loss Of Signal (LOS) condition is declared when the B3ZS encoder is active, and it declares an LOS condition.

An LOS condition is terminated when the B3ZS encoder is inactive, or it terminates an LOS condition.

An Alarm Indication Signal (AIS) is a DS3 signal with valid F-bits and M-bits. The X-bits (X1 and X2) are set to one,

the P-bits (P1 and P2) are set to zero, all C-bits (CXY) are set to zero, and the payload bits are set to a 1010 pattern

starting with a one immediately after each DS3 overhead bit. An AIS signal is present when a DS3 frame is

received with valid F-bits and M-bits, both X-bits set to one, both P-bits set to zero, all C-bits set to zero, and all but

seven or fewer payload data bits matching the DS3 overhead aligned 1010 pattern. An AIS signal is absent when a

DS3 frame is received that does not meet the aforementioned criteria for an AIS signal being present. The AIS

integration counter declares an AIS condition when it has been active for a total of 10 to 17 DS3 frames. The AIS

integration counter is active (increments count) when an AIS signal is present, it is inactive (holds count) when an

AIS signal is absent, and it is reset when an AIS signal is absent for 10 to 17 consecutive DS3 frames. An AIS

condition is terminated when an AIS signal is absent for 10 to 17 consecutive DS3 frames.

A Receive Unframed All 1’s (RUA1) condition is declared if in each of 4 consecutive 2047 bit windows, five or less

zeros are detected and an OOF condition is continuously present . A RUA1 condition is terminated if in each of 4

consecutive 2047 bit windows, six or more zeros are detected or an OOF condition is continuously absent.

An Idle Signal (Idle) is a DS3 signal with valid F-bits, M-bits, and P-bits (P1 and P2). The X-bits (X1 and X2) are set

to one, C31, C32, and C33 are set to zero, and the payload bits are set to a 1100 pattern starting with 11 immediately

after each overhead bit. In C-bit mode, an Idle signal is present when a DS3 frame is received with valid F-bits, M-

bits, and P-bits, both X-bits set to one, C31, C32, and C33 set to zero, and all but seven or fewer payload data bits

matching the T3 overhead aligned 1100 pattern. In M23 mode, an Idle signal is present when a T3 frame is

received with valid F-bits, M-bits, and P-bits, both X-bits set to one, and all but seven or fewer payload data bits

matching the overhead aligned 1100 pattern. An Idle signal is absent when a DS3 frame is received that does not

meet aforementioned criteria for an Idle signal being present. The Idle integration counter declares an Idle

condition when it has been active for a total of 10 to 17 DS3 frames. The Idle integration counter is active

(increments count) when an Idle signal is present, it is inactive (holds count) when an Idle signal is absent, and it is

reset when an Idle signal is absent for 10 to 17 consecutive DS3 frames. An Idle condition is terminated when an

Idle signal is absent for 10 to 17 consecutive DS3 frames.

A Remote Defect Indication (RDI) condition (also called a far-end SEF/AIS defect condition) is declared when four

consecutive DS3 frames are received with the X-bits (X1 and X2) set to zero. An RDI condition is terminated when

four consecutive DS3 frames are received with the X-bits set to one.

A DS3 Framing Format Mismatch (DS3FM) condition is declared when the DS3 format programmed (M13, C-bit)

does not match the incoming DS3 signal framing format. A DS3FM condition is terminated when the incoming DS3

signal framing format is the same format as programmed. Framing errors are determined by comparing F-bits and

M-bits to their expected values. The type of framing errors accumulated is programmable (OOFs, F & M, F, or M).

An OOF error increments the count whenever an OOF condition is first detected . An F & M error increments the

count once for each F-bit or M-bit that does not match its expected value (up to 31 per DS3 frame). An F error

increments the count once for each F-bit that does not match its expected value (up to 28 per DS3 frame). An M

error increments the count once for each M-bit that does not match its expected value (up to 3 per DS3 frame).

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