TXC-06312BIOG Transwitch Corporation, TXC-06312BIOG Datasheet - Page 135

• Manufacturer Part Number: TXC-06312BIOG
• Manufacturer: Transwitch Corporation

Specifications of TXC-06312BIOG

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1 3 5 o f 2 02
12.3.2 Poisson Distribution of Errors
The degraded signal defect (dDEG) is cleared if DEG_RecoveryWindowSize consecutive
good intervals are detected. An interval is declared good if the number of errored blocks in
that interval is smaller than DEG_RecoveryErrorThreshold.
The parameters DEG_DetectionWindowSize and DEG_RecoveryWindowSize are
provisionable in the range 2 to 10.
The
DEG_RecoveryErrorThreshold are to be provisioned as a number of errored blocks in the
range of 0 < threshold <= Number of blocks in the interval.
If a Poisson distribution of errors is assumed, both the degraded signal and the excessive
error defects need to be detected based on the accumulated BIP errors during intervals of
configurable duration.
For each defect, two sets of configuration registers are provided: one for setting the defect,
one for clearing (to allow some hysteresis).
The monitoring intervals for the degraded signal defect (dDEG) can be configured in steps of
time base T. The value of time base T can be set to 500
DEG_Use125usCounter configuration.
The degraded signal defect (dDEG) is declared if the accumulated BIP error count since the
start of the detection interval is greater than or equal to DEG_DetectionErrorThreshold
errors. The interval duration is DEG_DetectionWindowSize * T.
The degraded signal defect (dDEG) is cleared if the accumulated BIP error count during the
clearing interval is less than DEG_RecoveryErrorThreshold errors. The interval duration is
DEG_RecoveryWindowSize * T.
The monitoring intervals for the excessive error defect (dEXC) can be configured in steps of
time base T. The value of time base T can be set to 500
EXC_Use125usCounter configuration.
The excessive signal defect (dEXC) is declared if the accumulated BIP error count since the
start of the detection interval is greater than or equal to EXC_DetectionErrorThreshold
errors. The interval duration is EXC_DetectionWindowSize * T.
The excessive signal defect (dEXC) is cleared if the accumulated BIP error count during the
clearing interval is less than EXC_RecoveryErrorThreshold errors. The interval duration is
EXC_RecoveryWindowSize * T.
The Poisson detector can be configured to work in BurstProtection mode, in that case the
configured error threshold needs to be exceeded during 2 consecutive intervals before the
defect is declared. This way one can protect the state machine against a burst of BER errors.
For B3 (POH) the BIP error counters have a overflow behaviour (instead of saturation). For
those counters a large DetectionErrorThreshold combined with a large DetectionWindowSize
can lead to an overflow and avoid correct detection of the DEG/EXC signal defects.
DetectionErrorThreshold and DetectionWindowSize (both for DEG and EXC detection) must
always be configured in such way no overflow of the BIP error counter can occur. For B2
(TOH) the BIP error counters have a saturating behaviour and are thus not vulnerable to this.
threshold
- Telecom Bus -
parameters
DEG_DetectionErrorThreshold
PRELIMINARY TXC-06312B-MB, Ed. 2
PHAST-12N Device
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DATA SHEET
TXC-06312B
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June 2005
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