Changes in recent versions

The underlying raw converted data structure used by echopype (the EchoData object) has undergone revisions over time. While in most echopype releases these changes are relatively small, versions 0.8.0 and 0.6.0 incorporated significant changes, with implications for backward compatibility. Here we describe the main changes in each of these major releases. Please refer to What’s new for more complete details on specific changes that impacted the data structure.

v0.7.1 to v0.8.0 changes

Changes introduced in version 0.8.0 were carried out to incorporate missing variables that are mandated by SONAR-netCDF4 v1 and to implement adaptations to the convention in a more consistent fashion across variables and instrument types. Some of these changes modified or reverted decisions implemented in version 0.6.0 (below) that were later found to have large impacts on performance and usability.

Highlights include:

• Remove beam and ping_time dimensions from a whole netCDF4 group or individual variables when they were determined to be not required for specific instrument types. The beam dimension is now dropped from all Sonar/Beam_groupX groups except for EK80 complex samples, where both backscatter_r and backscatter_i exist and the beam dimension represents different sectors of split-beam transducers. The ping_time dimension is retained only with variables that are known to potentially vary with time in the instrument types supported by echopype.

• In Sonar/Beam_groupX groups: Standardize the use of transmit_frequency_start and transmit_frequency_stop, where they were previously missing or the names being used (frequency_start and frequency_end) were not the ones specified by the convention.

• In the Platform group: Implement variables absed on the convention more consistently across instrument types:

  • Assign default values to variables when no such variables are found in the raw data file

  • Revise the dimensions of each variable to be consistent across instrument types, with dimensions deemed unnecessary dropped from some variables.

• In the Provenance group: Add new attributes combination_* to the “combined” EchoData object, mirroring the convention-based attributes conversion_*.

• In the Vendor_specific group: Move filter coefficients and decimation factor from attributes to variables in EK80, to facilitate consistent provenance tracking during combine_echodata operations.

• Improve the presence and use of variable attributes throughout EchoData groups.

Note

Version 0.8.0 does not incorporate the capability to read files converted by previous versions of echopype. We recommend using open_raw to re-convert the raw data files.

v0.5.x to v0.6.0 changes

In order to enhance the compliance of echopype-generated datasets to the SONAR-netCDF4 version 1 convention, a number of changes were introduced in echopype v0.6.0 that create incompatibilities with the data structure used in previous versions.

To ease the transition, the open_converted function is able to open files previously converted using echopype v0.5.x (0.5.0 to 0.5.6) into the v0.6.0 data format, encapsulated in the EchoData object.

Key changes involved renaming and restructuring a couple of groups, and renaming some coordinates and data variables, as summarized below:

Type	v0.5.x	v0.6.0	Rationale and notes
Group	Beam	Sonar/Beam_group1	Convention compliance
Group	Beam_power	Sonar/Beam_group2	Convention compliance
Group	Vendor	Vendor_specific	Convention compliance
Coordinate	frequency	channel	Accommodate channels with duplicated frequencies. The new variable frequency_nominal was introduced
Coordinate	range_bin	range_sample	Better intuitive understanding of data
Coordinate	quadrant	beam	Convention compliance. This Beam_groupX coordinate was added when it did not exist.
Coordinate	location_time	time1	Convention compliance. In Platform group
Coordinate	mru_time	time2	Convention compliance. In Platform group
Variable	heave	vertical_offset	Convention compliance. In Platform group
Variable	src_filenames	source_filenames	Convention compliance. In Provenance group. Also converted from global attribute to variable

Other changes included:

• Adding previously missing, mandatory convention variables. When no data are available to populate them, these are filled with null (NaN) values.

• Moving variables from one group to another, particularly from the Beam groups to Platform and Vendor. These variables were not typically not part of the convention.

• The Beam_groupX beamwidth_receive_athwartship and beamwidth_transmit_athwartship variables were consolidated into beamwidth_twoway_athwartship because the EK60 and EK80 echosounders do not store one-way transmit or receive beam widths. Likewise for beamwidth_receive_alongship and beamwidth_transmit_alongship.

More details, including Pull Requests and discussions related to these changes, can be found in the Release notes.

v0.5.x data format

Below we provide a sample of the v0.5.x data format via a printout of the previous EchoData object.

Compare this with the v0.6.0 EchoData object to see the changes listed in the table above.

EchoData: standardized raw data from Internal Memory

• top: (Top-level) contains metadata about the SONAR-netCDF4 file format.

  <xarray.Dataset>
  Dimensions:  ()
  Data variables:
      *empty*
  Attributes:
      conventions:                 CF-1.7, SONAR-netCDF4-1.0, ACDD-1.3
      keywords:                    EK60
      sonar_convention_authority:  ICES
      sonar_convention_name:       SONAR-netCDF4
      sonar_convention_version:    1.0
      summary:                     EK60 raw file s3://ncei-wcsd-archive/data/ra...
      title:                       2017 Pacific Hake Acoustic Trawl Survey
      date_created:                2017-07-28T18:16:19Z
      survey_name:                 

  xarray.Dataset

  • Dimensions:
  • Coordinates: (0)
  • Data variables: (0)
  • Attributes: (9)

    conventions :

    CF-1.7, SONAR-netCDF4-1.0, ACDD-1.3

    keywords :

    EK60

    sonar_convention_authority :

    ICES

    sonar_convention_name :

    SONAR-netCDF4

    sonar_convention_version :

    1.0

    summary :

    EK60 raw file s3://ncei-wcsd-archive/data/raw/Bell_M._Shimada/SH1707/EK60/Summer2017-D20170728-T181619.raw from the 2017 Pacific Hake Acoustic Trawl Survey, converted to a SONAR-netCDF4 file using echopype.

    title :

    2017 Pacific Hake Acoustic Trawl Survey

    date_created :

    2017-07-28T18:16:19Z

    survey_name :

  
  
• environment: (Environment) contains information relevant to acoustic propagation through water.

  <xarray.Dataset>
  Dimensions:                 (frequency: 3, ping_time: 529)
  Coordinates:
    * frequency               (frequency) float64 1.8e+04 3.8e+04 1.2e+05
    * ping_time               (ping_time) datetime64[ns] 2017-07-28T18:16:19.31...
  Data variables:
      absorption_indicative   (frequency, ping_time) float64 0.002822 ... 0.03259
      sound_speed_indicative  (frequency, ping_time) float64 1.481e+03 ... 1.48...

  xarray.Dataset

  • Dimensions:
    • frequency: 3
    • ping_time: 529
  • Coordinates: (2)
    • frequency
      (frequency)
      float64
      1.8e+04 3.8e+04 1.2e+05

      units :

      Hz

      long_name :

      Transducer frequency

      valid_min :

      0.0

      array([ 18000.,  38000., 120000.])

    • ping_time
      (ping_time)
      datetime64[ns]
      2017-07-28T18:16:19.313999872 .....

      axis :

      T

      long_name :

      Timestamps for NMEA position datagrams

      standard_name :

      time

      array(['2017-07-28T18:16:19.313999872', '2017-07-28T18:16:22.143000064',
             '2017-07-28T18:16:24.962999808', ..., '2017-07-28T18:41:23.292000256',
             '2017-07-28T18:41:25.949000192', '2017-07-28T18:41:28.597000192'],
            dtype='datetime64[ns]')

  • Data variables: (2)
    • absorption_indicative
      (frequency, ping_time)
      float64
      0.002822 0.002822 ... 0.03259

      long_name :

      Indicative acoustic absorption

      units :

      dB/m

      valid_min :

      0.0

      array([[0.00282171, 0.00282171, 0.00282171, ..., 0.00282171, 0.00282171,
              0.00282171],
             [0.00985526, 0.00985526, 0.00985526, ..., 0.00985526, 0.00985526,
              0.00985526],
             [0.03259379, 0.03259379, 0.03259379, ..., 0.03259379, 0.03259379,
              0.03259379]])

    • sound_speed_indicative
      (frequency, ping_time)
      float64
      1.481e+03 1.481e+03 ... 1.481e+03

      long_name :

      Indicative sound speed

      standard_name :

      speed_of_sound_in_sea_water

      units :

      m/s

      valid_min :

      0.0

      array([[1480.62597656, 1480.62597656, 1480.62597656, ..., 1480.62597656,
              1480.62597656, 1480.62597656],
             [1480.62597656, 1480.62597656, 1480.62597656, ..., 1480.62597656,
              1480.62597656, 1480.62597656],
             [1480.62597656, 1480.62597656, 1480.62597656, ..., 1480.62597656,
              1480.62597656, 1480.62597656]])

  • Attributes: (0)

  
  
• platform: (Platform) contains information about the platform on which the sonar is installed.

  <xarray.Dataset>
  Dimensions:        (location_time: 2165, frequency: 3, ping_time: 529)
  Coordinates:
    * location_time  (location_time) datetime64[ns] 2017-07-28T18:16:21.4759997...
    * frequency      (frequency) float64 1.8e+04 3.8e+04 1.2e+05
    * ping_time      (ping_time) datetime64[ns] 2017-07-28T18:16:19.313999872 ....
  Data variables:
      latitude       (location_time) float64 dask.array<chunksize=(2165,), meta=np.ndarray>
      longitude      (location_time) float64 dask.array<chunksize=(2165,), meta=np.ndarray>
      sentence_type  (location_time) <U3 dask.array<chunksize=(2165,), meta=np.ndarray>
      pitch          (frequency, ping_time) float64 dask.array<chunksize=(3, 529), meta=np.ndarray>
      roll           (frequency, ping_time) float64 dask.array<chunksize=(3, 529), meta=np.ndarray>
      heave          (frequency, ping_time) float64 dask.array<chunksize=(3, 529), meta=np.ndarray>
      water_level    (frequency, ping_time) float64 dask.array<chunksize=(3, 529), meta=np.ndarray>
  Attributes:
      platform_type:       Research vessel
      platform_name:       Bell M. Shimada
      platform_code_ICES:  315

  xarray.Dataset

  • Dimensions:
    • location_time: 2165
    • frequency: 3
    • ping_time: 529
  • Coordinates: (3)
    • location_time
      (location_time)
      datetime64[ns]
      2017-07-28T18:16:21.475999744 .....

      axis :

      T

      long_name :

      Timestamps for NMEA datagrams

      standard_name :

      time

      array(['2017-07-28T18:16:21.475999744', '2017-07-28T18:16:21.635000320',
             '2017-07-28T18:16:22.168999936', ..., '2017-07-28T18:41:29.893000192',
             '2017-07-28T18:41:31.143000064', '2017-07-28T18:41:31.301000192'],
            dtype='datetime64[ns]')

    • frequency
      (frequency)
      float64
      1.8e+04 3.8e+04 1.2e+05

      units :

      Hz

      long_name :

      Transducer frequency

      valid_min :

      0.0

      array([ 18000.,  38000., 120000.])

    • ping_time
      (ping_time)
      datetime64[ns]
      2017-07-28T18:16:19.313999872 .....

      axis :

      T

      long_name :

      Timestamps for position datagrams

      standard_name :

      time

      array(['2017-07-28T18:16:19.313999872', '2017-07-28T18:16:22.143000064',
             '2017-07-28T18:16:24.962999808', ..., '2017-07-28T18:41:23.292000256',
             '2017-07-28T18:41:25.949000192', '2017-07-28T18:41:28.597000192'],
            dtype='datetime64[ns]')

  • Data variables: (7)
    • latitude
      (location_time)
      float64
      dask.array<chunksize=(2165,), meta=np.ndarray>

      long_name :

      Platform latitude

      standard_name :

      latitude

      units :

      degrees_north

      valid_range :

      (-90.0, 90.0)

      Array Chunk Bytes 16.91 kiB 16.91 kiB Shape (2165,) (2165,) Count 2 Tasks 1 Chunks Type float64 numpy.ndarray

    • longitude
      (location_time)
      float64
      dask.array<chunksize=(2165,), meta=np.ndarray>

      long_name :

      Platform longitude

      standard_name :

      longitude

      units :

      degrees_east

      valid_range :

      (-180.0, 180.0)

      Array Chunk Bytes 16.91 kiB 16.91 kiB Shape (2165,) (2165,) Count 2 Tasks 1 Chunks Type float64 numpy.ndarray

    • sentence_type
      (location_time)
      <U3
      dask.array<chunksize=(2165,), meta=np.ndarray>

      Array Chunk Bytes 25.37 kiB 25.37 kiB Shape (2165,) (2165,) Count 2 Tasks 1 Chunks Type numpy.ndarray

    • pitch
      (frequency, ping_time)
      float64
      dask.array<chunksize=(3, 529), meta=np.ndarray>

      long_name :

      Platform pitch

      standard_name :

      platform_pitch_angle

      units :

      arc_degree

      valid_range :

      (-90.0, 90.0)

      Array Chunk Bytes 12.40 kiB 12.40 kiB Shape (3, 529) (3, 529) Count 2 Tasks 1 Chunks Type float64 numpy.ndarray

    • roll
      (frequency, ping_time)
      float64
      dask.array<chunksize=(3, 529), meta=np.ndarray>

      long_name :

      Platform roll

      standard_name :

      platform_roll_angle

      units :

      arc_degree

      valid_range :

      (-90.0, 90.0)

      Array Chunk Bytes 12.40 kiB 12.40 kiB Shape (3, 529) (3, 529) Count 2 Tasks 1 Chunks Type float64 numpy.ndarray

    • heave
      (frequency, ping_time)
      float64
      dask.array<chunksize=(3, 529), meta=np.ndarray>

      long_name :

      Platform heave

      standard_name :

      platform_heave_angle

      units :

      arc_degree

      valid_range :

      (-90.0, 90.0)

      Array Chunk Bytes 12.40 kiB 12.40 kiB Shape (3, 529) (3, 529) Count 2 Tasks 1 Chunks Type float64 numpy.ndarray

    • water_level
      (frequency, ping_time)
      float64
      dask.array<chunksize=(3, 529), meta=np.ndarray>

      long_name :

      z-axis distance from the platform coordinate system origin to the sonar transducer

      units :

      m

      Array Chunk Bytes 12.40 kiB 12.40 kiB Shape (3, 529) (3, 529) Count 2 Tasks 1 Chunks Type float64 numpy.ndarray

  • Attributes: (3)

    platform_type :

    Research vessel

    platform_name :

    Bell M. Shimada

    platform_code_ICES :

    315

  
  
• nmea: (Platform/NMEA) contains information specific to the NMEA protocol.

  <xarray.Dataset>
  Dimensions:        (location_time: 22037)
  Coordinates:
    * location_time  (location_time) datetime64[ns] 2017-07-28T18:16:19.3140003...
  Data variables:
      NMEA_datagram  (location_time) <U73 '$SDVLW,5050.149,N,5050.149,N' ... '$...
  Attributes:
      description:  All NMEA sensor datagrams

  xarray.Dataset

  • Dimensions:
    • location_time: 22037
  • Coordinates: (1)
    • location_time
      (location_time)
      datetime64[ns]
      2017-07-28T18:16:19.314000384 .....

      axis :

      T

      long_name :

      Timestamps for NMEA datagrams

      standard_name :

      time

      array(['2017-07-28T18:16:19.314000384', '2017-07-28T18:16:20.896000000',
             '2017-07-28T18:16:20.995999744', ..., '2017-07-28T18:41:32.515999744',
             '2017-07-28T18:41:32.616000000', '2017-07-28T18:41:32.401999872'],
            dtype='datetime64[ns]')

  • Data variables: (1)
    • NMEA_datagram
      (location_time)
      <U73
      '$SDVLW,5050.149,N,5050.149,N' ....

      long_name :

      NMEA datagram

      array(['$SDVLW,5050.149,N,5050.149,N', '$INHDT,268.8,T', '$INHDT,268.8,T',
             ..., '$INHDT,270.9,T', '$INHDT,270.9,T',
             '$GPDTM,W84,,0000.0000,N,00000.0000,E,,W84'], dtype='<U73')

  • Attributes: (1)

    description :

    All NMEA sensor datagrams

  
  
• provenance: (Provenance) contains metadata about how the SONAR-netCDF4 version of the data were obtained.

  <xarray.Dataset>
  Dimensions:  ()
  Data variables:
      *empty*
  Attributes:
      conversion_software_name:     echopype
      conversion_software_version:  0.5.6
      conversion_time:              2022-05-26T18:01:56Z
      src_filenames:                s3://ncei-wcsd-archive/data/raw/Bell_M._Shi...
      duplicate_ping_times:         0

  xarray.Dataset

  • Dimensions:
  • Coordinates: (0)
  • Data variables: (0)
  • Attributes: (5)

    conversion_software_name :

    echopype

    conversion_software_version :

    0.5.6

    conversion_time :

    2022-05-26T18:01:56Z

    src_filenames :

    s3://ncei-wcsd-archive/data/raw/Bell_M._Shimada/SH1707/EK60/Summer2017-D20170728-T181619.raw

    duplicate_ping_times :

    0

  
  
• sonar: (Sonar) contains specific metadata for the sonar system.

  <xarray.Dataset>
  Dimensions:  ()
  Data variables:
      *empty*
  Attributes:
      sonar_manufacturer:      Simrad
      sonar_model:             ER60
      sonar_serial_number:     
      sonar_software_name:     
      sonar_software_version:  2.4.3
      sonar_type:              echosounder

  xarray.Dataset

  • Dimensions:
  • Coordinates: (0)
  • Data variables: (0)
  • Attributes: (6)

    sonar_manufacturer :

    Simrad

    sonar_model :

    ER60

    sonar_serial_number :

    sonar_software_name :

    sonar_software_version :

    2.4.3

    sonar_type :

    echosounder

  
  
• beam: (Beam) contains backscatter data and other beam or channel-specific data.

  <xarray.Dataset>
  Dimensions:                         (frequency: 3, ping_time: 529,
                                       range_bin: 3957)
  Coordinates:
    * frequency                       (frequency) float64 1.8e+04 3.8e+04 1.2e+05
    * ping_time                       (ping_time) datetime64[ns] 2017-07-28T18:...
    * range_bin                       (range_bin) int64 0 1 2 3 ... 3954 3955 3956
  Data variables: (12/30)
      channel_id                      (frequency) <U37 'GPT  18 kHz 009072058c8...
      beam_type                       (frequency) int64 1 1 1
      beamwidth_receive_alongship     (frequency) float64 10.9 6.81 6.58
      beamwidth_receive_athwartship   (frequency) float64 10.82 6.85 6.52
      beamwidth_transmit_alongship    (frequency) float64 10.9 6.81 6.58
      beamwidth_transmit_athwartship  (frequency) float64 10.82 6.85 6.52
      ...                              ...
      data_type                       (frequency, ping_time) float64 3.0 ... 3.0
      count                           (frequency, ping_time) float64 3.957e+03 ...
      offset                          (frequency, ping_time) float64 0.0 ... 0.0
      transmit_mode                   (frequency, ping_time) float64 0.0 ... 0.0
      angle_athwartship               (frequency, ping_time, range_bin) float64 ...
      angle_alongship                 (frequency, ping_time, range_bin) float64 ...
  Attributes:
      beam_mode:              vertical
      conversion_equation_t:  type_3

  xarray.Dataset

  • Dimensions:
    • frequency: 3
    • ping_time: 529
    • range_bin: 3957
  • Coordinates: (3)
    • frequency
      (frequency)
      float64
      1.8e+04 3.8e+04 1.2e+05

      long_name :

      Transducer frequency

      standard_name :

      sound_frequency

      units :

      Hz

      valid_min :

      0.0

      array([ 18000.,  38000., 120000.])

    • ping_time
      (ping_time)
      datetime64[ns]
      2017-07-28T18:16:19.313999872 .....

      long_name :

      Timestamp of each ping

      standard_name :

      time

      axis :

      T

      array(['2017-07-28T18:16:19.313999872', '2017-07-28T18:16:22.143000064',
             '2017-07-28T18:16:24.962999808', ..., '2017-07-28T18:41:23.292000256',
             '2017-07-28T18:41:25.949000192', '2017-07-28T18:41:28.597000192'],
            dtype='datetime64[ns]')

    • range_bin
      (range_bin)
      int64
      0 1 2 3 4 ... 3953 3954 3955 3956

      long_name :

      Along-range bin (sample) number, base 0

      array([   0,    1,    2, ..., 3954, 3955, 3956])

  • Data variables: (30)
    • channel_id
      (frequency)
      <U37
      'GPT 18 kHz 009072058c8d 1-1 ES...

      array(['GPT  18 kHz 009072058c8d 1-1 ES18-11',
             'GPT  38 kHz 009072058146 2-1 ES38B',
             'GPT 120 kHz 00907205a6d0 4-1 ES120-7C'], dtype='<U37')

    • beam_type
      (frequency)
      int64
      1 1 1

      long_name :

      type of transducer (0-single, 1-split)

      array([1, 1, 1])

    • beamwidth_receive_alongship
      (frequency)
      float64
      10.9 6.81 6.58

      long_name :

      Half power one-way receive beam width along alongship axis of beam

      units :

      arc_degree

      valid_range :

      (0.0, 360.0)

      array([10.89999962,  6.80999994,  6.57999992])

    • beamwidth_receive_athwartship
      (frequency)
      float64
      10.82 6.85 6.52

      long_name :

      Half power one-way receive beam width along athwartship axis of beam

      units :

      arc_degree

      valid_range :

      (0.0, 360.0)

      array([10.81999969,  6.8499999 ,  6.51999998])

    • beamwidth_transmit_alongship
      (frequency)
      float64
      10.9 6.81 6.58

      long_name :

      Half power one-way transmit beam width along alongship axis of beam

      units :

      arc_degree

      valid_range :

      (0.0, 360.0)

      array([10.89999962,  6.80999994,  6.57999992])

    • beamwidth_transmit_athwartship
      (frequency)
      float64
      10.82 6.85 6.52

      long_name :

      Half power one-way transmit beam width along athwartship axis of beam

      units :

      arc_degree

      valid_range :

      (0.0, 360.0)

      array([10.81999969,  6.8499999 ,  6.51999998])

    • beam_direction_x
      (frequency)
      float64
      0.0 0.0 0.0

      long_name :

      x-component of the vector that gives the pointing direction of the beam, in sonar beam coordinate system

      units :

      1

      valid_range :

      (-1.0, 1.0)

      array([0., 0., 0.])

    • beam_direction_y
      (frequency)
      float64
      0.0 0.0 0.0

      long_name :

      y-component of the vector that gives the pointing direction of the beam, in sonar beam coordinate system

      units :

      1

      valid_range :

      (-1.0, 1.0)

      array([0., 0., 0.])

    • beam_direction_z
      (frequency)
      float64
      0.0 0.0 0.0

      long_name :

      z-component of the vector that gives the pointing direction of the beam, in sonar beam coordinate system

      units :

      1

      valid_range :

      (-1.0, 1.0)

      array([0., 0., 0.])

    • angle_offset_alongship
      (frequency)
      float64
      -0.18 -0.08 -0.05

      long_name :

      electrical alongship angle of the transducer

      array([-0.18000001, -0.08      , -0.05      ])

    • angle_offset_athwartship
      (frequency)
      float64
      0.25 0.0 0.37

      long_name :

      electrical athwartship angle of the transducer

      array([0.25, 0.  , 0.37])

    • angle_sensitivity_alongship
      (frequency)
      float64
      13.89 21.97 23.12

      long_name :

      alongship sensitivity of the transducer

      array([13.89000034, 21.96999931, 23.12000084])

    • angle_sensitivity_athwartship
      (frequency)
      float64
      13.89 21.97 23.12

      long_name :

      athwartship sensitivity of the transducer

      array([13.89000034, 21.96999931, 23.12000084])

    • equivalent_beam_angle
      (frequency)
      float64
      -17.37 -21.01 -20.47

      long_name :

      Equivalent beam angle

      units :

      sr

      valid_range :

      (0.0, 12.566370614359172)

      array([-17.37000084, -21.01000023, -20.46999931])

    • transducer_offset_x
      (frequency)
      float64
      0.0 0.0 0.0

      long_name :

      x-axis distance from the platform coordinate system origin to the sonar transducer

      units :

      m

      array([0., 0., 0.])

    • transducer_offset_y
      (frequency)
      float64
      0.0 0.0 0.0

      long_name :

      y-axis distance from the platform coordinate system origin to the sonar transducer

      units :

      m

      array([0., 0., 0.])

    • transducer_offset_z
      (frequency)
      float64
      0.0 0.0 0.0

      long_name :

      z-axis distance from the platform coordinate system origin to the sonar transducer

      units :

      m

      array([0., 0., 0.])

    • gain_correction
      (frequency)
      float64
      22.95 26.07 26.55

      long_name :

      Gain correction

      units :

      dB

      array([22.95000076, 26.06999969, 26.54999924])

    • gpt_software_version
      (frequency)
      <U6
      '070413' '070413' '070413'

      array(['070413', '070413', '070413'], dtype='<U6')

    • backscatter_r
      (frequency, ping_time, range_bin)
      float32
      15.79 26.34 26.27 ... -159.5 -158.4

      long_name :

      Backscatter power

      units :

      dB

      array([[[  15.7923155,   26.340124 ,   26.269571 , ..., -145.34105  ,
               -146.65805  , -139.60266  ],
              [  15.7923155,   26.340124 ,   26.269571 , ..., -145.08235  ,
               -146.19945  , -134.15825  ],
              [  15.7923155,   26.340124 ,   26.269571 , ..., -141.47234  ,
               -142.30722  , -146.36407  ],
              ...,
              [  15.7923155,   26.340124 ,   26.269571 , ..., -158.02899  ,
               -148.25728  , -143.49489  ],
              [  15.7923155,   26.340124 ,   26.269571 , ..., -135.67516  ,
               -145.0941   , -131.0186   ],
              [  15.7923155,   26.340124 ,   26.269571 , ..., -134.85204  ,
               -136.62764  , -132.78246  ]],
      
             [[  17.379778 ,   26.72817  ,   27.175013 , ..., -151.70265  ,
               -155.86534  , -161.45085  ],
              [  17.379778 ,   26.72817  ,   27.175013 , ..., -163.59099  ,
               -162.27399  , -161.35678  ],
              [  17.379778 ,   26.72817  ,   27.175013 , ..., -155.99469  ,
               -147.63405  , -154.08972  ],
      ...
              [  17.379778 ,   26.72817  ,   27.175013 , ..., -145.42336  ,
               -144.48264  , -146.96378  ],
              [  17.379778 ,   26.72817  ,   27.175013 , ..., -145.67029  ,
               -149.93881  , -147.42238  ],
              [  17.379778 ,   26.72817  ,   27.175013 , ..., -150.23277  ,
               -150.35037  , -152.79623  ]],
      
             [[  12.417487 ,   18.073559 ,   18.050041 , ..., -180.3593   ,
               -160.2632   , -163.3558   ],
              [  12.417487 ,   18.073559 ,   18.0618   , ..., -183.04034  ,
               -162.48564  , -157.74677  ],
              [  12.417487 ,   18.073559 ,   18.050041 , ..., -166.00157  ,
               -167.4009   , -170.03491  ],
              ...,
              [  12.417487 ,   18.073559 ,   18.0618   , ..., -169.77621  ,
               -155.05397  , -162.21518  ],
              [  12.417487 ,   18.073559 ,   18.0618   , ..., -157.81732  ,
               -167.87126  , -162.45036  ],
              [  12.417487 ,   18.073559 ,   18.050041 , ..., -158.89915  ,
               -159.53413  , -158.37     ]]], dtype=float32)

    • sample_interval
      (frequency, ping_time)
      float64
      0.000256 0.000256 ... 0.000256

      long_name :

      Interval between recorded raw data samples

      units :

      s

      valid_min :

      0.0

      array([[0.000256, 0.000256, 0.000256, ..., 0.000256, 0.000256, 0.000256],
             [0.000256, 0.000256, 0.000256, ..., 0.000256, 0.000256, 0.000256],
             [0.000256, 0.000256, 0.000256, ..., 0.000256, 0.000256, 0.000256]])

    • transmit_bandwidth
      (frequency, ping_time)
      float64
      1.574e+03 1.574e+03 ... 3.026e+03

      long_name :

      Nominal bandwidth of transmitted pulse

      units :

      Hz

      valid_min :

      0.0

      array([[1573.66552734, 1573.66552734, 1573.66552734, ..., 1573.66552734,
              1573.66552734, 1573.66552734],
             [2425.1496582 , 2425.1496582 , 2425.1496582 , ..., 2425.1496582 ,
              2425.1496582 , 2425.1496582 ],
             [3026.39160156, 3026.39160156, 3026.39160156, ..., 3026.39160156,
              3026.39160156, 3026.39160156]])

    • transmit_duration_nominal
      (frequency, ping_time)
      float64
      0.001024 0.001024 ... 0.001024

      long_name :

      Nominal bandwidth of transmitted pulse

      units :

      s

      valid_min :

      0.0

      array([[0.001024, 0.001024, 0.001024, ..., 0.001024, 0.001024, 0.001024],
             [0.001024, 0.001024, 0.001024, ..., 0.001024, 0.001024, 0.001024],
             [0.001024, 0.001024, 0.001024, ..., 0.001024, 0.001024, 0.001024]])

    • transmit_power
      (frequency, ping_time)
      float64
      2e+03 2e+03 2e+03 ... 250.0 250.0

      long_name :

      Nominal transmit power

      units :

      W

      valid_min :

      0.0

      array([[2000., 2000., 2000., ..., 2000., 2000., 2000.],
             [2000., 2000., 2000., ..., 2000., 2000., 2000.],
             [ 250.,  250.,  250., ...,  250.,  250.,  250.]])

    • data_type
      (frequency, ping_time)
      float64
      3.0 3.0 3.0 3.0 ... 3.0 3.0 3.0 3.0

      long_name :

      recorded data type (1-power only, 2-angle only 3-power and angle)

      array([[3., 3., 3., ..., 3., 3., 3.],
             [3., 3., 3., ..., 3., 3., 3.],
             [3., 3., 3., ..., 3., 3., 3.]])

    • count
      (frequency, ping_time)
      float64
      3.957e+03 3.957e+03 ... 3.957e+03

      long_name :

      Number of samples

      array([[3957., 3957., 3957., ..., 3957., 3957., 3957.],
             [3957., 3957., 3957., ..., 3957., 3957., 3957.],
             [3957., 3957., 3957., ..., 3957., 3957., 3957.]])

    • offset
      (frequency, ping_time)
      float64
      0.0 0.0 0.0 0.0 ... 0.0 0.0 0.0 0.0

      long_name :

      Offset of first sample

      array([[0., 0., 0., ..., 0., 0., 0.],
             [0., 0., 0., ..., 0., 0., 0.],
             [0., 0., 0., ..., 0., 0., 0.]])

    • transmit_mode
      (frequency, ping_time)
      float64
      0.0 0.0 0.0 0.0 ... 0.0 0.0 0.0 0.0

      long_name :

      0 = Active, 1 = Passive, 2 = Test, -1 = Unknown

      array([[0., 0., 0., ..., 0., 0., 0.],
             [0., 0., 0., ..., 0., 0., 0.],
             [0., 0., 0., ..., 0., 0., 0.]])

    • angle_athwartship
      (frequency, ping_time, range_bin)
      float64
      -3.0 -3.0 -4.0 ... 19.0 54.0 33.0

      long_name :

      electrical athwartship angle

      array([[[  -3.,   -3.,   -4., ...,   46., -103.,  -18.],
              [  -3.,   -3.,   -4., ...,  -13., -126.,   -2.],
              [  -3.,   -3.,   -4., ...,    6.,   17.,  -61.],
              ...,
              [  -3.,   -3.,   -4., ...,  107., -103.,  112.],
              [  -3.,   -3.,   -4., ...,   30.,  123.,   33.],
              [  -3.,   -3.,   -4., ...,   -9.,  -15.,   15.]],
      
             [[  -1.,   -2.,   -2., ...,  -37.,  -65., -117.],
              [  -1.,   -2.,   -2., ...,  -38.,   47., -100.],
              [  -1.,   -2.,   -2., ...,   11.,   23.,   32.],
              ...,
              [  -1.,   -2.,   -2., ...,   13.,   13.,   32.],
              [  -1.,   -2.,   -2., ...,    4.,   31.,   24.],
              [  -1.,   -2.,   -2., ...,  -11.,  -42., -104.]],
      
             [[  -2.,   -3.,   -3., ...,  122.,  -30.,   -7.],
              [  -2.,   -3.,   -3., ..., -120.,   81.,    9.],
              [  -2.,   -3.,   -3., ...,   -2.,   51., -105.],
              ...,
              [  -2.,   -3.,   -3., ...,  107.,  -32.,  -20.],
              [  -2.,   -3.,   -3., ...,  -13.,  -99.,  -39.],
              [  -2.,   -3.,   -3., ...,   19.,   54.,   33.]]])

    • angle_alongship
      (frequency, ping_time, range_bin)
      float64
      3.0 2.0 3.0 3.0 ... 51.0 93.0 -27.0

      long_name :

      electrical alongship angle

      array([[[   3.,    2.,    3., ...,  -90.,  -78.,  -29.],
              [   3.,    2.,    3., ...,   90., -101.,  -70.],
              [   3.,    2.,    3., ...,   49.,   75.,  105.],
              ...,
              [   3.,    2.,    3., ...,  118.,   77.,  -63.],
              [   3.,    2.,    3., ...,  -55.,  116.,   18.],
              [   3.,    2.,    3., ...,   -1.,  -46.,  -42.]],
      
             [[   0.,    0.,   -1., ...,  -42.,    7., -103.],
              [   0.,    0.,   -1., ...,   93.,  -76.,   86.],
              [   0.,   -1.,   -1., ...,  -60.,    9.,   33.],
              ...,
              [   0.,   -1.,   -1., ...,   19.,   47.,   64.],
              [   0.,    0.,   -1., ...,   25.,   -2.,    4.],
              [   0.,   -1.,   -1., ...,   63.,  -10.,  -14.]],
      
             [[  -1.,   -1.,   -1., ..., -122.,  -30., -100.],
              [  -1.,   -1.,   -1., ...,  118.,   61.,    9.],
              [  -1.,   -1.,   -1., ...,  109.,   42.,  120.],
              ...,
              [  -1.,   -1.,   -1., ...,   88.,    3.,  -71.],
              [  -1.,   -1.,   -1., ...,   47.,  109.,   70.],
              [  -1.,   -1.,   -1., ...,   51.,   93.,  -27.]]])

  • Attributes: (2)

    beam_mode :

    vertical

    conversion_equation_t :

    type_3

  
  
• vendor: (Vendor specific) contains vendor-specific information about the sonar and the data.

  <xarray.Dataset>
  Dimensions:           (frequency: 3, pulse_length_bin: 5)
  Coordinates:
    * frequency         (frequency) float64 1.8e+04 3.8e+04 1.2e+05
    * pulse_length_bin  (pulse_length_bin) int64 0 1 2 3 4
  Data variables:
      sa_correction     (frequency, pulse_length_bin) float64 0.0 -0.7 ... -0.3
      gain_correction   (frequency, pulse_length_bin) float64 20.3 22.95 ... 26.55
      pulse_length      (frequency, pulse_length_bin) float64 0.000512 ... 0.00...

  xarray.Dataset

  • Dimensions:
    • frequency: 3
    • pulse_length_bin: 5
  • Coordinates: (2)
    • frequency
      (frequency)
      float64
      1.8e+04 3.8e+04 1.2e+05

      units :

      Hz

      long_name :

      Transducer frequency

      valid_min :

      0.0

      array([ 18000.,  38000., 120000.])

    • pulse_length_bin
      (pulse_length_bin)
      int64
      0 1 2 3 4

      array([0, 1, 2, 3, 4])

  • Data variables: (3)
    • sa_correction
      (frequency, pulse_length_bin)
      float64
      0.0 -0.7 0.0 0.0 ... 0.0 0.0 -0.3

      array([[ 0.  , -0.7 ,  0.  ,  0.  ,  0.  ],
             [ 0.  ,  0.  , -0.52,  0.  ,  0.  ],
             [ 0.  ,  0.  ,  0.  ,  0.  , -0.3 ]])

    • gain_correction
      (frequency, pulse_length_bin)
      float64
      20.3 22.95 22.9 ... 27.0 27.0 26.55

      array([[20.299999, 22.950001, 22.9     , 23.      , 23.      ],
             [24.      , 26.      , 26.07    , 26.5     , 26.5     ],
             [25.5     , 26.799999, 27.      , 27.      , 26.549999]])

    • pulse_length
      (frequency, pulse_length_bin)
      float64
      0.000512 0.001024 ... 0.001024

      array([[5.120e-04, 1.024e-03, 2.048e-03, 4.096e-03, 8.192e-03],
             [2.560e-04, 5.120e-04, 1.024e-03, 2.048e-03, 4.096e-03],
             [6.400e-05, 1.280e-04, 2.560e-04, 5.120e-04, 1.024e-03]])

  • Attributes: (0)