Table 5 User-defined transient noise removal parameters in Echoview®.
From: Sounding out life in the deep using acoustic data from ships of opportunity
Filter parameter | Unit | Description | Value used |
|---|---|---|---|
Exclude above depth | Metre | Nominal depth line. Filter is not applied between surface and this depth. Note that this depth line has been adjusted to preserve valid high scattering from biological sources. | 250 |
Exclusion threshold | dB re 1 m2 m−3 | The value of a time-varied threshold \(TVT(r)\) defined at 1 m range. See Table 3 for more details. Any \({S}_{v}(r)\) values below this calculated \(TVT(r)\) were preserved from the transient noise filter. | −150 |
Vertical size of smoothing window | Metre | Vertical window size used for smoothing. Corresponding horizontal smoothing window is one ping wide. | 20 |
Vertical size of context window (\(m\)) | Number | Vertical size of the context window (i.e. number of samples) used to identify noise. | 11 |
Horizontal size of context window (\(n\)) | Number | Horizontal size of the context window (i.e. number of pings) used to identify noise. | 51 |
Detection percentile (\(p\)) | Percentile | The value used to calculate percentile of \({S}_{v}\) samples in the context window. | 15 |
Detection threshold (\(\delta \)) | dB re 1 m2 m−3 | The transient noise removal threshold value. | 15 |
