Opening version 2 EV files in Echoview version 3 and higher

Echoview version 3 and higher can open EV files created by Echoview 2.

Warning: Once an EV file is saved with Echoview 3 or higher, it can no longer be read by earlier versions. For this reason Echoview Software recommend that you keep a backup of all your version 2 EV files before modifying them with version 3 or higher.

Echoview version 3 and higher includes functionality that requires the manual translation of some Echoview 2 concepts into the new Echoview concepts. Once the new concepts are understood, we believe that they will provide a simple and logical approach that allows functionality to develop further in the future. In some cases these changes were required because echosounder manufacturers have provided us with updated information about interpretation of their data formats. While all users will need to use "transducers" in Echoview 3 or higher, most of the version 2 to version 3 correction will only apply to a few users.

Please take the time to review the list below and determine whether you are likely to be affected by the changes. Echoview version 3 and higher will detect that it is opening an EV file that needs special attention and display a message that describes the relevant changes even if it cannot automatically make the changes. We recommend that you compare some Echoview 3 or higher results with Echoview 2 results to confirm that relevant changes have been made.

To check which version of Echoview was last used to save an EV file, you must:

Open the EV file
On the View menu, click EV File Properties
Click the Notes tab
Check the version number in the EV File Saved by box

Please contact support@echoview.com if you have any questions relating to converting your Echoview 2 EV files to version 3.

Transducers

Version 3 or higher makes use of "transducer" objects that are a very close analog to real world acoustic transducers. Depending on your application you will need to understand at least a little about transducers and how they are used in Echoview (Transducer geometry).

In earlier versions of Echoview, the transducer draft correction and beam width were set as variable properties for every variable that was associated with the physical transducer. In version 3 or higher, they are transducer properties. As a consequence, when loading an EV file from earlier versions, Echoview will create one transducer for each unique combination of draft correction and beam width, and associate each variable in that EV file with the appropriate transducer (see About calibration settings).

All users should review the new transducer geometry material. If you are operating with a simple arrangement of downwards looking vertically orientated transducers then you will need to know only the basics of transducer geometry (how to set a draft), however if you have horizontal or non-vertical transducer orientations and wish to take these into account, then you will need to learn transducer geometry in some detail.

Range dependent variable settings

Three settings which describe range dependent variables are affected by the change from version 2.25 to version 3 or higher. Each of them is influenced by a Time-Varied Gain term which was defined by an initial value and a start depth. The three settings affected are:

Context	Superseded setting	Maintained setting
Time Varied Threshold	TVT start depth (m)	Sv at 1 m (dB re 1m-1)
Background Noise	Background noise start depth (m)	Background noise at 1 m (dB re 1m-1)
Data Generator	TVG start depth (m)	Sv at 1 m (dB re 1m-1)

In each case the Superseded setting is replaced by the location of the transducer face and the Maintained setting is unchanged.

Particular care is required by Simrad users who have Q and/or E telegram data that includes a "logged draft" because the logged draft calibration setting must also be set to enable range to be calculated. (Logged draft is a more general form of the 'start depth" used in Version 2.) See Logged draft warning for more details.

Changes to analysis variables

The names of some analysis variables have changed. The order of all columns in exported files remains unchanged, but the label heading each column may have changed. If you are producing scripted output with version 2.25 (or earlier) EV files this will affect the output of those scripts.

Corrected behavior

Some defects in version 2.25 were identified which will affect the interpretation of data loaded in the now corrected version 3 or higher.

Simrad Ex60 Sa correction bug fixed

Sa correction, a calibration parameter for Simrad Ex60 raw data was not correctly used in Echoview 2.25. All results generated with Echoview 2.25 based on Ex60 raw data (with a non-zero Sa correction) will have an error in Sv, NASC and related variables such as PRC_NASC. This error in interpretation of Sa correction was discovered only in final checking of the version 3 release. It is essential that you understand the error and make adjustments to results, or reprocess data in Echoview if necessary. If the value of Sa correction was copied from the Ex60 data file and entered in 2.25, then version 3 or higher will interpret it correctly. If, you used a "work around" in 2.25, then you will need to remove your work around value and enter the correct Sa correction from the Ex60 in version 3 or higher. Contact Echoview support for more information about the consequences of this bug or if you have questions about any aspect of Ex60 raw data handling in Echoview.

BioSonics range correction

The range of samples in BioSonics data files was incorrectly calculated by one sample thickness. All samples in version 3 or higher are effectively one sample thickness nearer to the transducer than they were in version 2.25. Lines and regions will not move. As a consequence, some samples of bottom echo-trace may have moved above the defined exclude-below line. This may influence integration results. Single targets may also move outside of fish track regions

It is possible to reposition the regions using the Region Editor. Lines may be reposition by overwriting each line individually with a new line relative to the old. See Creating, renaming and deleting lines.

BioSonics reduced power level correction

Some BioSonics echosounders are equipped with an option to operate at a reduced power level. Echoview Version 3 or higher reads the reduced power level from the data file and calculates SV and TS taking into account the reduced power level.

Version 2.25 of Echoview did not automatically correct for the reduced power level and it was necessary to include an offset to compensate for the reduced power level. If such a calibration offset was entered in a version 2.00 EV file, then the offset must be manually removed when the EV file is opened in version 3 or higher.

Single target maximum beam compensation filter expanded

In version 2.25 there is a 10 dB limit to the Beam compensation filter (found on the Data page of the Variable Properties dialog box). This has been relaxed to 35 dB. (This was relaxed in version 2.25 but when no beam compensation filter was applied, an internal limit of 12 dB was applied regardless - this being the range of validity for the beam compensation function implemented in Echoview).

There may be some benefit in detecting targets with a beam compensation greater than 12dB for the purposes of fish tracking but it must be remembered that the compensated Target Strength will be unreliable. For this reason the beam compensation filter setting can now be extended to 35 dB and the internal limit of 12 dB has also been relaxed.

This will affect version 2.25 EV files with split-beam single target detection variables (where no beam compensation filter was applied) when they are opened in version 3. In version 2 these were effectively filtered at 12 dB maximum beam compensation (even if you entered a larger value in the operator settings) but in Version 3 they will be filtered at the setting you have entered. You will most likely find that more single targets are displayed because more will pass the filtering. These additional targets may affect the results of fish track analyses (additional targets may be included in fish track regions) and single target analyses. Since the TS of single targets detected with beam compensation settings greater than 12 dB may be incorrect, you may wish to consider changing the beam compensation filter to a maximum of 12 dB for the purpose of exporting single target analyses.

Fish track layer allocation was wrong

When exporting an analysis of fish tracks by cells, fish tracks are considered to be in the cell in which the last target within that track is found. There was an error in version 2.25 which allocated the interval based on the last target but the layer based upon the target nearest the transducer. This has been corrected.

Any version 2.25 EV files containing fish tracks may, as a consequence allocate those same tracks to slightly different cells on occasion when an analysis of fish tracks by cells is exported. This is most likely to happen with tracks where the last target and that nearest the transducer are far apart (the track angles downwards to the right on an echogram).

Calibration offset for HAC generic tuples now applied correctly

In all versions prior to Echoview 3.00 the calibration offset was subtracted from the recorded data. It is now added, as all calibration offsets in Echoview are. If you load a version 2.25 EV file with an affected calibration offset the sign will be changed and a message box will inform you of such. No further action is necessary.

CSIRO RAW format nautical mile conversion constant correction

Vessel log distances were converted to nautical miles using a constant of 1852 meters per nautical mile. This is now 1852.0000118 meters per nautical mile which will result in very minor discrepancies in distance measurements which may be observed in exports.