We strongly recommend that calibration surveys are done at regular intervals. As a minimum, calibration must be done prior to each survey.
NoteCalibration must be taken seriously. To achieve the best results, the calibration must be planned and done carefully.
The calibration process requires a specific setup of the EK80 system, all gathering of data for calibration is performed following a specific pattern using Williamson turns. The data is stored in raw files and the calibration process is performed after the collection of data is finished.
A suitable location for velocity measurements calibration would be at a depth of 100 m, and a smooth seafloor. Variations
of up to 50 m depth and down to 200 m depth are tolerated. The vessel must have the space to move across the seafloor for a stretch of 3 nm or 5,5 km.
The setup of the EK80 system must be follow certain requirements. During the startup procedure of the EK80 system, a validation check of the calibration is performed. The EK80 system checks if the last calibration was performed using the same transceiver being currently present. If this is not the case a, a message box will appear with a request for a new calibration.
The calibration procedure relays on correct input from various instruments. KM Binary datagram provides essential information regarding roll, pitch and heading as well as angle-rates. The ratio of Speed Over Ground (SOG) from the GPS and SOG from the ADCP is used to correct the measurements from the ADCP. Average differences for pitch, roll and yaw are also used to correct the ADCP measurements.
Any adjustments to the EK80are done automatically by the calibration program. No gain adjustments are required.
NoteVelocity measurement calibration is always performed using replay data or reprocessing of calibration data.
If you have a EK80 system with several transceivers, you must calibrate one by one.
|
• |
If you add a new transducer to a previously calibrated EK80 system, this new channel must be calibrated. |
|
• |
If a calibrated transducer is moved from one transceiver to another, you must still calibrate the transducer on the "receiving"
transceiver. |
|
• |
If a calibrated transducer is removed, and then later reconnected to the same transceiver, the calibration data exist. A new
calibration is not required. |
A new calibration may also be required after an update of the EK80 software. Refer to the software release note.
The information provided by the calibration is entered into the EK80 software as operational parameters. This is done automatically.