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User Guide
246
Selection method Configures one of the packet selection method to be used to
filter PTP samples to compute wander performance metrics.
The selection method configured in this field constitutes a
not linear filter applied to the timing input before it is trans-
ferred to the wander metric calculation block. This filtering is
used to discard samples and avoid unrealistic wander
results. For example the filter could be used to discard pack-
ets with potentially more delay variation. The selection meth-
ods supported by the test units are defined in ITU-T G.8260
and they are listed below:
• Minimum: Selects the packet with smaller end-to-end
delay within the filtering window.
• Maximum: Selects the packet with larger end-to-end delay
within the filtering window.
• Percentile: Uses a percentile value expressed in % to con-
figure the packets to be processed by the MTIE / TDEV
block (Max. percentile). Packets with an end-to-end delay
larger than the configured percentile are not taken into
account.
• Band: Uses two percentile values expressed in % to con-
figure the packets to be processed by the MTIE / TDEV
block (Max. percentile, Min. percentile). Samples with a
delay smaller than Min. percentile or larger than Max. per-
centile are ignored by the MTIE / TDEV block.
Selection window
length
Configures the length of the not linear sample selection filter
in seconds. Longer selection filters may potentially generate
more accurate results but they involve an increase in the test
period or at least in the amount of time required to get the
first results
Min. percentile Minimum allowed percentile in Band selection modes.
Max. percentile Maximum allowed percentile in Percentile and Band selec-
tion modes.
Table 9.10: Wander Test Configuration Parameters
Setting Description
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