Table 6 User-defined background 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 |
|---|---|---|---|
Vertical size of averaging cell (\(M\)) | Number | The vertical size of the averaging cell (i.e. number of samples). This cell height defines the range interval for noise estimation (see Eq. 7). | 15 |
Horizontal size of averaging cell (\(N\)) | Number | The horizontal size of the averaging cell (i.e. number of pings). This cell width defines the ping interval for noise estimation. | 10 |
Vertical overlap of averaging cell | % | The percentage vertical overlap of the averaging cell. | 0 |
Maximum noise threshold (\(Nois{e}_{max}\)) | dB re 1 W | The upper limit of background noise levels. Any noise estimates greater than this threshold was replaced with the ‘value used’. | −100 |
Minimum SNR threshold (\(Minimu{m}_{SNR}\)) | dB re 1 | Acceptable SNR for background noise corrected data. Corrected \({S}_{v}\) data with corresponding SNR values below this threshold were set to ‘−999’. This low SNR threshold was empirically determined to preserve weak scattering signal. | 0.1 |
