mt9074ap1 Zarlink Semiconductor, mt9074ap1 Datasheet - Page 57

• Manufacturer Part Number: mt9074ap1
• Description: T1/e1/j1 Single Chip Transceiver With Wide Dynamic Range Liu
• Manufacturer: Zarlink Semiconductor

The following alarms are detected by the receiver in E1 mode. Each may generate a maskable interrupt:
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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 register is read. This allows the controller to record intermittent or sporadic alarm
occurrences.
Automatic Alarms
In E1 mode, the transmission of RAI and signaling multiframe alarms can be made to 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 signaling 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 signaling
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 or unframed)
has persisted for 48 milliseconds.
period of 193 contiguous pulse positions starting with a pulse. The loss of signal is reported in the Receive
Signal Status Word - page 3, address 16H bit 4.
Remote Alarm Indication (RAI) - bit 3 (A) of the receive NFAS;
Alarm Indication Signal (AIS) - unframed all ones signal for at least a double frame (512 bits) or two double
frames (1024 bits);
Channel 16 Alarm Indication Signal - all ones signal in channel 16;
Auxiliary pattern - 101010... pattern for at least 512 bits;
Loss of Signal - a loss of signal condition occurs when the receive signal level is lower than 20 dB or 40 dB
(by setting the bit ELOS on page 2) below the nominal signal level for 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 signaling Multiframe Alarm - (Y-bit) of the multiframe alignment signal.
Zarlink Semiconductor Inc.
MT9074
57
Data Sheet