852-GS Ultra-Miniature Imaging Sonar
Doc No: 430-048-0B
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drift, the sonar image will be coherent, allowing the operator to continue to work. Note that the absolute
heading will not be exact during this time as the sonar does not differentiate between induced drift and real
movement. After a few minutes, re-calibrate the motor to re-align the sonar and the transducer. This will reset
the accumulated drift that occurred during the warm-up period. It is recommended to periodically re-calibrate
the motor to re-align the sonar and transducer to remove offset that have occurred via induced drift.
Manual Gyro Calibration
The information below describes the manual biasing mode which may be necessary in
strong magnetic field
environments.
Do not calibrate the gyro until the internal temperature of the sonar has stabilized which will be approximately
30-60 minutes underwater.
The procedure below is followed:
•
Suspend sonar operations and mount the sonar on a level stable surface or settle the ROV on a flat
bottom.
•
Select “
Options => Calibrate Gyro
”.
•
The message “
Calibrating Gyro
” will appear. Calibration takes approximately 30 seconds. The
calibration time can be set in the .ini file.
•
Once the message disappears, commence standard operation.
Note
: When using manual biasing, it is
ESSENTIAL
that the sonar is completely stationary and at constant
temperature. Any movement will cause undesirable drift in the gyro.
3.5.6.
Options => Enable Gyro Auto Bias
RealTime only
Puts the sonar into auto bias mode where the sonar will continuously re-bias the gyro in real time. Disabling
this mode necessitates periodic manual calibration. See Section 3.5.5 Options => Calibrate Gyro.
