MT9074AP datasheet(39/122 Pages) MITEL

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Advance Information

MT9074

more than a millisecond or when more than

192 zeros have been received in a row. A

loss of signal condition will terminate when

an average ones density of at least 12.5%

has been received over a period of 255

contiguous pulse positions starting with a

pulse.

•

Remote Signalling Multiframe Alarm - (Y-bit)

of the multiframe alignment signal.

The alarm reporting latch (address 12H page 04H)

contains a register whose bits are set high for

selected alarms. These bits stay high until the

intermittent or sporadic alarm occurrences.

Automatic Alarms

In E1 mode the transmission of RAI and signalling

multiframe

alarms

can

made

function

automatically from control bits ARAI and AUTY

(page 01H, address 10H). When ARAI = 0 and basic

frame synchronization is lost (SYNC = 1), the

MT9074 will automatically transmit the RAI alarm

signal to the far end of the link. The transmission of

this alarm signal will cease when basic frame

alignment is acquired.

When AUTY = 0 and signalling multiframe alignment

is not acquired (MFSYNC = 1), the MT9074 will

automatically transmit the multiframe alarm (Y-bit)

signal to the far end of the link. This transmission will

cease when signalling multiframe alignment is

acquired.

Detected Events and Words

T1 mode

Severely Errored Frame Event

In T1 mode bit 5 page 3H address 10H toggles

whenever a sliding window detects 2 framing errors

events (Ft or ESF) in a sliding window of 6.

Loop Code Detect

T1.403 deﬁnes SF mode line loopback activate and

deactivate codes. These codes are either a framed

or un-framed repeating bit sequence of 00001 for

activation or 001 for deactivation. The standard goes

on to say that these codes will persist for ﬁve

seconds or more before the loopback action is taken.

In T1 mode MT9074 will detect both framed and

unframed line activate and de-activate codes even in

the presence of a BER of 3 x 10-3. Line Loopback

Disable Detect - LLDD - in the Alarm Status Word

(bit 0 address 11H of page 3H) will be asserted when

a repeating 001 pattern (either framed or unframed)

has persisted for 48 milliseconds. Line Loopback

Enable Detect LLED in the Alarm Status Word will be

asserted when a repeating 00001 pattern (either

framed

unframed)

has

persisted

for

milliseconds.

Pulse Density Violation Detect

In T1 mode bit 2 of address 11H on page 3H (PDV)

toggles if the receive data fails to meet ones density

requirements. It will toggle upon detection of 16

consecutive zeros on the line data, or if there are

less than N ones in a window of 8(N+1) bits - where

N = 1 to 23.

Timer Outputs

In T1 mode MT9074 has a one second timer derived

from the 20 Mhz oscillator pins. The timer may be

used

trigger

interrupts

for

T1.403/408

performance messaging.

E1 mode

Consecutive Frame Alignment Patterns (CONFAP)

Two consecutive frame alignment signals in error.

Receive Frame Alignment Signals

These bits are received on the PCM 30 and link in bit

positions two to eight of time slot 0 - frame alignment

signal. These signals form the frame alignment

signal and should be 0011011.

Receive Non Frame Alignment Signal

This signal is received on the PCM 30 and link in bit

position two of time slot 0 - non frame alignment

signal.

Receive Multiframe Alignment Signals

These signal are received on the PCM 30 and link in

bit position one to four of time slot 16 of frame zero

of every signalling multiframe.

Interrupts

The MT9074 has an extensive suite of maskable

interrupts, which are divided into four categories

based on the type of event that caused the interrupt.

Each interrupt has an associated mask and interrupt

bit. When an unmasked interrupt event occurs, IRQ

will go low and one or more bits of the appropriate

interrupt register will go high. After each interrupt

MT9074AP Datasheet(PDF) 39 Page - Mitel Networks Corporation

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