ASL Environmental Sciences data files

Echoview can read data files produced by ASL Environmental Sciences instruments configured as Acoustic Zooplankton Fish Profilers (AZFP), including sixth-generation and earlier formats. These files may include raw acoustic samples along with instrument configuration and supporting metadata.

Echoview reads and uses unique frequency values stored in AZFP data files. Calibration data associated with duplicated frequency values is not used. When supported calibration metadata is available, Echoview can calculate derived acoustic variables such as Sv and TS using standard AZFP processing equations. For further information, see AZFP Sv and TS.

Pitch and roll data may be available in AZFP data files when recorded by the instrument. Echoview reads this data directly from the file and makes it available for use in analysis.

Averaged AZFP data

Some AZFP deployments record averaged ping-burst data. When present, Echoview can read this averaged data from the data file and determine sample ranges using parameters such as bin size, number of bins, samples per bin, digitization rate, and sound speed stored in the file.

StartRange = -0.5 × BinSize

StopRange = StartRange + (BinSize × Num_Bins × Samples_bin)

where:

BinSize = (SoundSpeed/2)/AZFP_Digitization_rate)

Num_bins, Samples_bin, SoundSpeed, AZFP_Digitization_rate are read from the data file.

Further information may be found in "Appendix G AZFP Data and Calibration" within the AZFP Operator's manual or contact ASL Environmental Sciences.

File naming convention

ASL Environmental Sciences data files are named in the following way, YYMMDDHH_PPx

where:

YY = Year

MM = Month

DD = Day

HH = Hour

PP = Phase

x = Follows an alphabetical sequence from 'A' to 'Z', resetting after 26 increments. This pattern allows for up to 99 sequential phases, though most deployments typically use phases 01 to 12. The instrument assigns a new letter each time it restarts within the same hour.

An example data file named 26031522_01A.aps6 is interpreted as recorded on March 15th 2026 at 2200 hours, and is the first file created from Phase 1. The time zone is based on the time zone settings on the machine that synched the AZFP instrument's clock.

AZFP legacy data files (.azfp, .nnx)

When an AZFP .XML or .cfg file is present in the data folder, Echoview is able to read AzfpDetectionSlope, AzfpEchoLevelMax, AzfpTransmitVoltage, AzfpTransmitVoltageResponse, SoundSpeed and TwoWayBeamAngle.

AZFP .XML files occur with AZFP data files on the SD card of the AZFP device and may be copied manually. Data files (*.nnx) are set to the phase number (nn), which can range consecutively from 01 to 99. The third character (x) follows an alphabetical sequence from 'A' to 'Z'. resetting after 26 increments. This pattern allows for up to 99 sequential phases, though most deployments typically use phases 01 to 12. the instrument assigns a new letter each time it restarts within the same hour. Refer to the AZFP Software Manual for more detailed information.
AZFP .cfg files occur when AZFP software is used to 'extract' data files from the AZFP device. The data files take the form *.nnn where n can be an integer in the range 0 to 9 and the text component can include a date/time.

Values for Sv, TS can be calculated with data read from an AZFP binary data file. ASL Environment Sciences files can be verified by Echocheck. However, note that Echocheck does not currently enforce the same file extension validation rules as Echoview, meaning some files may appear as valid in Echocheck but remain unsupported in older versions of Echoview.

Note: When .XML or .cfg files are missing, Echoview may default calibration values that may be unsuitable for the data. Use an Echoview ECS file to specify correct calibration values.

AZFP sixth-generation data files (*.aps6)

Echoview supports *.aps6 raw data files produced by ASL Environmental Sciences sixth-generation instruments, configured as Acoustic Zooplankton Fish Profiler (AZFP6), Ice Profiling Sonar (IPS6) and Shallow Water Ice Profiler (SWIP6) systems. The APS6 file format includes instrument configuration and calibration-related metadata within the file header. To provide redundancy, the metadata is also written to an associated *.xml file.