Calibration settings for Simrad EK500 telegrams logged with Simrad Ex500

This page describes the settings, necessary to an Echoview calculation, on the Calibration page of the Variable Properties dialog box for acoustic variables derived from Ex500 data files.

We recommend you assess the suitability of the settings available on the Calibration pages for each acoustic variable. Some settings will be used to calculate data point values or ranges, others may be used during analysis or display of the data. The tables below show which settings are used for calculating data point values and ranges and which are used for other calculations. The tables also detail the parameters that are read from the data file and used to calculate range values.

Quantitative calculation/analysis requires calibrated data which is achieved using correct calibration setting values (rather than default values). An ECS file enables you to modify calibration settings for variables in a fileset.

Changes in calibration settings used for range calculations may shift ping data in the depth dimension but will not automatically adjust the position of regions and lines. You should review any existing regions and lines to ensure they are still valid. For more information refer to Range calculation effects on regions and lines.

Notes:

• Data file values that have been used since the data was loaded or the ECS file was added, saved or removed are displayed in black text. Default values that have been used are displayed in orange text. Data file or ECS values that have been read but not used are displayed in grey text. Read About calibration settings for further information.
• This data may have one calibration source however calibration settings available under the calibration source may not be available (or used) by every raw variable.

Table legend:

Y	Setting is used in calculating data point values or ranges as indicated by the column heading.
	Setting is not used in calculating data point values (when green background) or ranges (when blue background) but may be used for other purposes, see Additional uses of Calibration settings. Pink backgrounds distinguish settings used for data values with Echoview's calibration correction overriding your echosounder's calibration settings.
	Setting is not available for this variable

• Simrad sample variables logged with Ex500
  • Sv and TS from Power (W telegrams) and B telegrams logged with Ex500
  • Sample Sv and TS variables (V and P telegrams) logged with Ex500
• Simrad echogram and echo trace (Q and E telegrams) variables logged with Ex500
• Specific Simrad Ex500 setting details

Simrad sample variables logged with Ex500

Sv and TS from Power (W telegrams) and B telegrams logged with Ex500

Sample Sv and TS variables (V and P telegrams) logged with Ex500

It is possible to apply calibration correction to Sample Sv and Sample TS variables. How the settings are used depends on whether calibration correction has been applied.

Setting	Data values without calibration correction (Settings for calibrated data)		Data values with calibration correction (Logging settings)		Data point range
	Sample Sv (V)	Sample TS (P)	Sample Sv (V)	Sample TS (P)	All acoustic variables
Calibration page of Variable Properties dialog box
ApplyCalibrationCorrection	To use data values without calibration correction, set ApplyCalibrationCorrection = False		To use data values with calibration correction, set ApplyCalibrationCorrection = True
AbsorptionCoefficient AbsorptionCoefficientLogging			Y	Y
SoundSpeed SoundSpeedLogging			Y	Y	Y
TransmittedPower TransmittedPowerLogging			Y	Y
TwoWayBeamAngle TwoWayBeamAngleLogging			Y
Ek5SvGain Ek5SvGainLogging			Y
Ek5TSGain Ek5TSGainLogging				Y
Wavelength WavelengthLogging See also: Note.			Y	Y
PulseDuration PulseDurationLogging			Y	Y
Frequency
Specific Simrad Ex500 settings
SimradStartSampleRange *					Y
SimradSampleResolution +					Y
From data file
Number of data points					Y

Simrad echogram and echo trace (Q and E telegrams) variables logged with Ex500

It is possible to apply calibration correction to echogram and echo trace variables. How the settings are used depends on whether calibration correction has been applied.

Setting	Data values without calibration correction (Settings for calibrated data)			Data values with calibration correction (Logging settings)			Ranges
	Sv (Q)	TS (Q)	Single targets (E)	Sv (Q)	TS (Q)	Single targets (E)	Data point range (Q)	Target range (E)
Calibration page of Variable Properties dialog box
ApplyCalibrationCorrection	To use data values without calibration correction, set ApplyCalibrationCorrection = False			To use data values with calibration correction, set ApplyCalibrationCorrection = True
AbsorptionCoefficient AbsorptionCoefficientLogging				Y	Y	Y
SoundSpeed SoundSpeedLogging				Y	Y	Y	Y	Y
TransmittedPower TransmittedPowerLogging				Y	Y	Y
TwoWayBeamAngle TwoWayBeamAngleLogging				Y
Ek5SvGain Ek5SvGainLogging				Y
Ek5TSGain Ek5TSGainLogging					Y	Y
Wavelength WavelengthLogging See also: Note.				Y	Y	Y
PulseDuration PulseDurationlogging				Y	Y
SimradDraftLogging				Y	Y	Y
Frequency
MajorAxis3dBBeamAngle MinorAxis3dBBeamAngle						Y
From data file
Start range							Y
Stop range							Y
Number of data points							Y
Target range								Y

Notes:

• Echoview Software recommends logging data with transducer depth set to 0 on the Ex500 as the embedded draft that is otherwise created reduces the number of samples in the echogram telegram, see logged draft warning for more information.
• Not all telegram types can be logged by all Ex500 echosounders.

• Wavelength in the Ex500 is calculated from the nominal frequency using a sound speed of 1470 meters per second (Haakon Solli, Simrad, pers. com.) - this does not appear in Simrad user manuals. Changing the sound speed on the Calibration page does not change wavelength.
• Settings available under the calibration source may not be available to or used by every raw variable.
• Warning: Telegrams that are dependent on each other may be affected by the settings that they have in common. Calibration changes to one variable will affect the other variable of paired variables. An example of paired variables are Sv Q telegrams and Sv Q telegrams with expanded bottom.

See also

About calibrated data

Specific Simrad Ex500 setting details

Start sample range

This is the SimradStartSampleRange displayed on the Calibration page of the Variable Properties dialog box.

Note that for EK500 v. 5.3 and higher, this must be 0 meters. For EK500 v. 5.2 and earlier, use the start depth of the "super layer".

Sample resolution

This is the SimradSampleResolution displayed on the Calibration page of the Variable Properties dialog box.

The sample resolution can be determined from the nominal frequency of the transceiver card. The following table provides sample resolution for common Simrad transducers according to the Simrad EK500 manual (V5.3).

Note that the sample resolution is constant in distance even if a sound speed profile is entered. The algorithm used by Simrad to calculate sample values at fixed distances, given data sampled at fixed time intervals, is not documented in the EK500 manual. Contact Simrad for details.

If it is desirable to process at a different sound speed than the sound speed that the data were logged with then it is necessary to change the sample resolution.

There is a simple relationship between sample resolution and sound speed, when the Ex500 was run with a constant sound speed over the data depth range:

New sample resolution = old sample resolution * new sound speed/old sound speed

Simrad Transducer type	Frequency (kHz)	Sample resolution (cm)		Simrad Transducer type	Frequency (kHz)	Sample resolution (cm)
12-16	11.990	40		200-30G	200.000	2
E-12_60	11.990	40		200-35E	200.000	2
18-11	17.986	25		710-30	714.286	1
63BA	17.986	25		710-36	714.286	1
27-26	27.027	15		38/200	37.878	10
27-26/21-E	27.027	10		38/200	200.000	2
38-12x20F	37.878	10		50/200	49.020	8
38-26/22-E	37.878	10		50/200	200.000	2
38-7	37.878	10		ES18	17.986	25
49-26	49.020	8		ES38-12	37.878	10
50-18P	49.020	8		ES38-B/D	37.878	10
50-10x17	49.020	8		ES38-5	37.878	10
70-24	70.422	5		ES70-11	70.422	5
120-25	119.047	3		ES120-7	119.047	3
120-35/25-E	119.047	3		ES120-4x10	119.047	3
200-7	200.000	2		ES120-2.5x10	119.047	3
200-28E	200.000	2		ES120H	119.047	3
120-2/50	119.047	3

Apply Simrad TVG range correction

The Ex500 series of echosounders apply a correction to the time-varied gain calculated for each sample point to compensate for electronic delays in filter circuits.

If applied, the time-varied gain applied at each sample depth, when calculating Sv from power, is calculated using a corrected range, rather than the actual range to the sample.

See EK500 Power to Sv and TS for further details.

The reason for this type of range correction is discussed in Simmonds and MacLennan pp. 118. Also see About Time Varied Gain.

If range correction is not applied, the time-varied gain, applied in calculating Sv, is calculated using the range of each sample.

See also

About calibration settings Entering calibration settings
Simrad data files
Raw variables derived from Simra Ex500 data
Simrad EK500 Power to Sv and TS
Simrad angular position calculations
Simrad Ex500_cal_page
Simrad Ex500_ecs_Cal_info