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Table 2 Criteria for selection of an HPE filter cutoff

From: An approach for filtering hyperbolically positioned underwater acoustic telemetry data with position precision estimates

Criteria Stationary test Mobile test Rational for selection of a HPE filter cutoff of 8
1 2
Criterion 1 3–15 3–15 3 This criterion was met for stationary tests (Figure 4), but the mobile test would have required a very low HPE to attain below 1.77 m of average error as the unfiltered accuracy was lower (Figure 3). See review of the mobile test methodology in the Discussion.
Mean ≤1.77 m
Criterion 2 <7 <8 ≤15 An HPE of 8 did not meet the criteria for stationary tests, but only 1 of 625 positions (test one) and 1 of 134 positions (test two) remained. The mobile test criteria were met. Only 2 of 45,744 positions were problematic (<0.001%) for the combined stationary tests (Figure 4). The maximum point remaining was 17.7 m error.
Max error <15 m
Criterion 3 8.5 6.0 NA The criterion was met for stationary test one, which was the longer test that covered more variable weather conditions. The HPE 8 bin only was 95% confident in an HPE of 8.25 meters for test two but the estimate was based on data calculated within each bin and few points had an HPE of >6 for test two (3% of the data), which results in a less reliable 2DRMS prediction.
2DRMS ≤6 m
Criterion 4 8–10 3–15 None An HPE cutoff of 8 met the criteria for both stationary tests, and although the mobile test did not have a suitable range, the range from 5–10 was equally effective.
Percentage incorrectly retained vs. percentage incorrectly rejected 5–10