Outlier Removal

Enhanced PTP User Guide (UG1602)

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1.1 English

The sync module scans incoming values for outliers, where the offset from the master differs significantly from other previously received values. These outliers can be partially or completely removed, so they do not feedback into the time synchronization:

  • Outliers are detected using methods such as Peirce’s criterion.
  • The number of values stored by using the outlier_filter_size option:
    • The default value gives the best accuracy of outlier detection.
    • Reducing this value lowers overheads, but also reduces accuracy.
  • The amount by which outliers feedback into the time synchronization is controlled using the outlier_filter_adaption option:
    • The default value of 1 means that outliers are used unchanged.
    • Reducing this value makes outliers have less effect.
    • Reducing this value to 0 so outliers have no effect is not recommended.