The choice of calibration offset is of particular relevance in determining the accuracy of the TS to Sv and Sv to TS operators.
If you need to choose a calibration offset as part of your echosounder calibration process, see Using Echoview in the calibration process.
Simrad Ex500 echosounders associate one gain with Sv data and another with TS data (the Sv Gain and TS Gain respectively).
The calibration offset to use in converting:
from Sv to TS is (TS Gain - Sv Gain)
from TS to Sv is (Sv Gain - TS Gain)
See EK500 Power to Sv and TS and Sv to TS and TS to Sv for the underlying formulae.
Simrad Ex60 echosounders associate:
The calibration offset to use in converting
from Sv to TS is (2 x Sa correction)
from TS to Sv is (-2 x Sa correction)
See Ex60 Power to Sv and TS and Sv to TS and TS to Sv for the underlying formulae.
To the best of our knowledge, generally no calibration offset is required for TS/Sv conversion with Sv and TS data derived from echosounders other than the Simrad Ex500 and Simrad Ex60. However, if you have used different calibration offset values for the parent TS and Sv variables, you may have to consider the impact of that on subsequent TS/Sv conversions with the data.
See Sv to TS and TS to Sv for the underlying formulae.
Calibration settings for Sv to TS and TS to Sv virtual variables
Sv to TS and TS to Sv
Using Echoview in the calibration process