cx29600 Mindspeed Technologies, cx29600 Datasheet - Page 74

• Manufacturer Part Number: cx29600
• Description: Optiphytm - M155 Sts-3 Sonet/sdh Multiplexer
• Manufacturer: Mindspeed Technologies

2.0 Functional Description
2.4 SONET/SDH Framer and Overhead Processor
2.4.3.10 Error Threshold
2-30
2.4.3.12 APS Switch
2.4.3.11 Threshold
2.4.3.9 Actual Bits
Requirement
Detect Time
Observed
This column is the number of frames observed multiplied by 19,224 bits/frame
(amount covered by the B2 BIP). Since two to three times the number of bits that
is required are observed, the accuracy of BER estimation is improved.
This column is the BER multiplied by the actual number of bits observed. This is
the threshold that is wired in the circuit. If this threshold is exceeded by the
number of incoming B2 errors accumulated during the frames’ observed period,
then the set criteria for the BER alarm (SD or SF) has been reached. For clearing
thresholds, the accumulated number of B2 errors during the observation period
must be below the threshold to clear the SD or SF alarm. The clearing threshold is
automatically set to 1/10 of the setting threshold by the set/clear circuit.
This column is the number of frames observed multiplied by 125 µsec per frame.
This is the maximum amount of time that it takes to declare that the programmed
BER is being received. If the threshold is exceeded at any time, the alarm is set
immediately; not at the end of the window period. This is to meet the requirement
in Synchronous Optical Network, ANSI T1.105 that an actual incoming BER
higher than the programmed threshold is detected in the amount of time listed for
the actual BER rather than in the time for the threshold BER.
This column lists the APS switch initiation objective from Synchronous Optical
Network, ANSI T1.105. This is the time that an APS switch operation should
commence from onset of the incoming BER. At worst, the current window is
missed when the incoming errors start, thus requiring a maximum of two times
the threshold detect time to set an SD or SF alarm. This still provides ample time
for interrupt response and software processing to initiate the APS operation
within the required time. The tightest requirement is at the 10
Mindspeed Technologies
™
CX29600 Data Sheet
-3
29600-DSH-001-B
threshold.
CX29600