HAC data files

Echoview includes read and write support for selected HAC tuples.

This page covers:

About the HAC file format

The HAC data file format was developed as a standard format to allow interchange of raw and edited hydroacoustics data. The file format is independent of specific echosounders, software and computer platforms. For further information about the HAC file format refer to the following publications:

Compatibility considerations

The HAC format specifies which tuples can be included in HAC data files but leaves it to software developers to decide which tuples their product will read and write. This can result in compatibility problems between software, e.g. a product may write a technically correct HAC file that contains tuples that a technically correct reader does not support. Echoview reads and writes a set of tuple types from a number of tuple classes, that are of most importance to Echoview customers and are most commonly supported by other software products.

Some specific compatibility considerations with HAC files in Echoview are described below:

If you are using the HAC format to exchange data, please read the information on this page and contact Echoview for additional information or to request support for additional tuples.

Reading HAC files

A variable in Echoview is created for each supported channel tuple found in a .hac file with which one or more ping tuples are associated. The channel tuple identifies the type of channel as either Generic, EK500 or BioSonics (see Raw variables derived from HAC data files) and the ping and channel tuple together identify the type of data (Sv, TS, Angular position or Single targets).

Echoview can read the following HAC v1.0 tuple types:

20

Standard position

100

BioSonics model 102 echosounder

200

Simrad EK500 echosounder

1000

BioSonics model 102 channel (limited support, see Support for BioSonics model 102 tuples)

2000

Simrad EK500 channel

2001

Simrad EK500b

10000

Standard ping U-32

10001

Ping U-32-16-angles

10010

Ping C-32

10040

Ping C-16

10110

Event marker

65534

End of file

65535

HAC Signature

and the following HAC v1.3 tuple types:

901 

Generic echosounder tuple

1001

Biosonics 102 tuple (limited support, see Support for BioSonics model 102 tuples)

9001

Generic channel tuple

10011

Ping C-32-16 angles

65397

Private tuple 1

and the following HAC v1.4 tuple types:

10090

Split beam detected single target tuple, See note below

and the following HAC v1.5 tuple types:

2001

Simrad EK500 Channel tuple (2001) (Absorption of sound and Two-way beam angle)

and the following tuple types written by previous versions of Echoview:

900

Draft generic echosounder tuple

9000

Draft generic channel tuple

Notes:

Writing HAC files

Echoview can export SV, TS and angular position and split beam detected single target and dual beam variables to HAC files using tuple types from echosounder, channel and ping tuple classes. These data files can be re-imported into Echoview or imported into other programs that support HAC tuples. Exporting partial results (e.g. complex virtual variables) to HAC and creating a new EV file with the HAC data may lead to performance improvements with large and complex analyses.

See Exporting to HAC data files for details.

Supported tuple types

Echoview writes the following tuple types:

20

Standard position

901

Generic echosounder tuple v1.3 (see note below)

9001

Generic channel tuple v1.3 (see note below)

10000

Standard ping U-32

10001

Ping U-32-16-angles

10011

Ping C-32-16 angles

10040

Ping C-16

10090

Split beam detected single target tuple v1.4 (see note below)

65534

End of file

65535

HAC Signature

If Write compressed tuples is selected on the Export to HAC format dialog box then Ping-C (compressed) type tuples are written otherwise Ping-U (uncompressed) type tuples are written.

Notes:

Tuple

Parameter

Value written

901

Sound speed

  • The Sound speed value entered on the Calibration page for the Variable Properties dialog box (when enterable)

  • "Not available" (when not enterable)

 

Ping interval

Zero

 

Trigger mode

"not available"

9001

Frequency

  • The Frequency value on the Calibration page for the Variable Properties dialog box (when enterable)

  • "Not available" (when not enterable)

Sampling rate

  • Function of speed of sound (when Sound speed is enterable)

  • "Not available" (when Sound speed is not enterable)

Two-way beam angle

  • The Two-way beam angle value entered on the Calibration page for the Variable Properties dialog box (when enterable)

  • "Not available" (when not enterable)

Absorption coefficient

  • The Absorption coefficient value entered on the Calibration page for the Variable Properties dialog box (when enterable)

  • "Not available" (when not enterable)

Transmitted pulse length

  • The Transmitted Pulse Length value entered on the Calibration page for the Variable Properties dialog box (when enterable)

  • "Not available" (when not enterable)

Time-varied gain multiplier

  • For Sv variables - 20

  • For TS variables - 40

  • For angular position variables - "Not available"

Time-varied gain blanking mode

  • For Sv variables - "Not available"

  • For TS variables - "Not available"

  • For angular position variables - "Not applicable"

Time-varied gain range minimum

  • For Sv variables - "Not available"

  • For TS variables - "Not available"

  • For angular position variables - "Not applicable"

Time-varied gain range maximum

  • For Sv variables - "Not available"

  • For TS variables - "Not available"

  • For angular position variables - "Not applicable"

Alongship offset relative to sensor

The X - alongship offset value entered on the Location page of the Transducer Properties dialog box, for the transducer selected on the Calibration page for the Variable Properties dialog box

Athwartship offset relative to sensor

The Y - athwartship offset value entered on the Location page of the Transducer Properties dialog box, for the transducer selected on the Calibration page for the Variable Properties dialog box

Vertical offset relative to sensor

The Z - vertical offset value entered on the Location page of the Transducer Properties dialog box, for the transducer selected on the Calibration page for the Variable Properties dialog box

Transducer alongship angle offset main axis

The Alongship angle value entered/calculated on the Orientation page of the Transducer Properties dialog box, for the transducer selected on the Calibration page for the Variable Properties dialog box

Transducer athwartship angle offset main axis

The Athwartship angle value/calculated on the Orientation page of the Transducer Properties dialog box, for the transducer selected on the Calibration page for the Variable Properties dialog box

Pulse shape mode

"not available"

Bandwidth

"not available"

Transducer shape

"not available"

Calibration source level

"not available"

Calibration receiving sensitivity

"not available"

Calibration SL plus VR

"not available"

Bottom detection minimum level

"not available"

Transducer depth

The depth of the transducer below the water surface calculated as Z - vertical offset (entered on the Location page of the Transducer properties dialog box) minus Z - coordinate of the water level (entered on the Position page of the Platform properties dialog box).

Minor axis beam width

The Minor axis 3dB angle value entered on the Calibration page for the Variable Properties dialog box

Major axis beam width

The Major axis 3dB angle value entered on the Calibration page for the Variable Properties dialog box

Beam rotation

The Beam rotation value entered on the Orientation page of the Transducer Properties dialog box, for the transducer selected on the Calibration page for the Variable Properties dialog box

See also

Raw Variables derived from HAC data files
Calibration settings for HAC data

Export to HAC data file

Planning Group on HAC Data Exchange Format