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ices-publications / SONAR-netCDF4

The SONAR-netCDF4 convention for sonar data
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Is Gain applied correctly in Type 1 conversion equation? #75

Closed geoffmatt closed 2 years ago

geoffmatt commented 2 years ago

Not sure if this is an issue or not. In the Type 1 Conversion Equation there is a term: 10Log10(Pt * Lambda^2 / 16 pi^2) - G

This is exactly the same Transmit Receive factor we use in Echoview to calculate Power for Simrad EK systems, except that we have "2G" instead of G.

Now the EK systems are obviously not the same as the Simrad Omni systems, but I thought I'd check just in case this was a typo.

gavinmacaulay commented 2 years ago

The use of G instead of 2G was deliberate and follows the equations in:

Macaulay, G. J., Vatnehol, S., Gammelsæter, O. B., Peña, H., and Ona, E. 2016. Practical Calibration of Ship-Mounted Omni-Directional Fisheries Sonars. Methods in Oceanography, 17: 206–220,

where I had decided that the 2 didn't need to be there, so G for Simrad omnisonars has a different meaning to the G for Simrad echosounders (in hindsight that wasn't a good decision....).

geoffmatt commented 2 years ago

Understood. Does that mean you'll need a different Conversion Equation for Simrad echosounders? Either way this issue can be closed, as there was no error :)

gavinmacaulay commented 2 years ago

yep, simrad echosounder equations are given in the Type 3 section.