iXBlue Gaps M5, Часто задаваемые вопросы

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Gaps M7 must not be declared as a standard USBL system because this is a pre-calibrated
system. In QINSY for example, Gaps M7 and M5 must be declared as a positioning system.
To get Gaps M7 and M5 nominal accuracy, the measurement of the sound velocity in the
water column is mendatory. If the sound velocity profile is not measured and not configured
into Gaps M7 and M5, this can lead to unaccuracy and even to non positioning. If no sound
velocity probe is available on the vessel, statistical sound velocity profiles can be used.
Contact iXblue to get a tatistical sound velocity depending on your location and season.
The different possibilities are :
•
increase beacon transmit level
•
reduce noise received by the Gaps (increase the horizontal distance between
Gaps and source of noise, increase Gaps depth)
If positions are jumpy, this probably comes from a multipath (reflective surface which is too
close from the Gaps M7 or M5 or the beacon) and/or difficult conditions for acoustic propa-
gation (shallow water or horizontal tracking). Increase Gaps M7 or M5 depth or place differ-
ently the beacon transducer. If a bias is observed in the positioning:
•
check beacon turn around time (in the beacon and in the Gaps web MMI)
•
check that a correct sound velocity profile has been configured into the Gaps
•
check the GPS lever arm and potential mounting misalignments.
Gaps M7 standard package comprises the Gaps M7 head, a 50 m cable and the Gaps M7
box. Beacons, other cable lengths, GPS antenna can be ordered separately.
Gaps M5 standard package comprises the Gaps M5 head, a 20 m cable and the Gaps M5
box. Beacons, other cable lengths, GPS antenna can be ordered separately.