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When the external sensor is used and connected to the device (
Calc. distance from = External log
), the calibration is
used to get the best possible distance measurements. The sensor principle of operation is based on pulse counting.
The sensor calibration factor equals the number of pulses which the speed sensor will produce while swimming a 100m
distance.
A typical value is 1590 pulses on a 100 m distance. In most cases this value will be between 1400 and 1600 pulses on a
100 m distance.
Pulses value can be altered by type of DPV, mounting position, and influence of for example “propeller suction” effect.
Devices are calibrated to be used with Seacraft scooters, which construction allows for optimal sensor placement, and
minimizes interferences. While for general orientation underwater factory setting will be fine with most types of DPV’s,
for more precise applications- as for example mapping- we recommend speed log calibration with whole set-up used.
This calibration factor depends also on the exact sensor position on the DPV. To get best results, mark the sensor
position on the DPV body and perform the calibration procedure as described below:
-
Mark the START and STOP point on a straight, known distance (100-1900 meters)
-
Go to
SETUP -> Log/Speed -> Calibrate log
(make sure
Active log
is set to
EXT
)
-
Enter the known calibration distance in the field
log at: …
-
Below, you will see the actual calibration factor
log 100 m: 1590
. Make sure, the arrow points to this line, and
press the lower button.
-
The screen will show the message
Press START and swim exactly …. m
-
Go to START, set the favorite speed on your DPV, press START (lower button) on the navigation console, and
swim as straight as possible to the STOP point. The screen display will show the pulse counter, which should
increase with time.
-
When you reach the STOP point, press the lower button again. The new log calibration factor will be shown on
the screen.
Caution:
The calibration procedure will fail, if the pulse count recorded during the procedure is far too low. In this case,
the previous value will be shown in the calibration factor field (
log 100 m: ….
)
The calibration procedure needs values in meters. No other units are available. 1 N.M. (Nautical Mile, U.S.) equals 852.0
meters. 100 feet equals 30.48 meters. 100 meters equals 328.08 feet.
Summary of Contents for ENC II
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