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which contains the transceiver electronics and the scannermirror is on the
Bell 212 mounted between the skids. Inside the helicopter there are three
racks for airborne computer, workstation, gps-reciever, MMI and laserelectronics.
Bell 212 has to have higher skid to carry the system . There is also changes
in powerdistribution and antennainstallations required.
get longer operationtime an extra tank for fuel is to prefer.
installation in a helicopter witch already is modified can be done by two man
on half a day.
surveyoperations the helicopter cruises at a speed between 30 and 60 knots.
The swathwidth is always 100m. Due to the distance between the lasershots we
have different speeds. Our most common setting is 4m shotdistance which gives
a speed at 60 knots. In shallow areas we sometimes uses 3m distance witch
gives us a speed at 30 knots.
•The altitude is between 150 and
300m, but an altitude over 200m is to prefer.
It is only when we have a low cloudceling we fly at 150m.
system can operate in either search or ident mode. In search mode the helicopter
cruises at a constant speed and coarse. And the pattern under the helicopter
look s like .... If the operator sees something interesting the helicopter can
hover over that area and search it time after time. The operator can also move
the square relative to the helicopter. That is used for navy operations to
follow a target.
•For survey operations there is only one operator and one
pilot required. Of coarse there is
ground staff taking care of the helicopter, but for the certain operation
there is only two persons needed
HawkEye system works with a 200Hz laser.
laserbeam is transmitted through a mirror system to the scanning mirror which
sends the pulses down to the watersurface.
The laserpulse contains of 80%IR
and 20%green light. The IR component of the pulse is reflected in the
watersurface back to the helicopter. The green light penetrates the
watervolume and is reflected at the bottom.
There are three detectors for the
returning pulses, one for the IR and two for the green light. The reflected
pulses are digitized and the time between the IR and the green pulse is
measured. With that time the depth can be determined.
scannermirror has encoders witch gives very accurate angles for the beam.
These angels are used to calculate the position of the lasershots relative to
the helicopter. In order to stabilize the mirror for helicopter motions the is
an IRS system connected to the mirror.
The helicopter it self is
positioned with DGPS. We have two possibilities to get differential
corrections. One is through our IALA standard radiobeacons and our other
possibility is through the national EPOS service. The EPOS service is
transmitted on the FM band.
bestäms med hjälp av tidsskillnaden mellan den reflekterandeytreflexen och den
Tider som mäts är t(0) =
tid då ljuset lämnar lasern
t(1) = tid då ljuset
t(2) = tid då ljuset
3-D picture shows the sunken Russian fishfactory ”Wapper”.
is located south of Falsterbo. The wreck has been hit once or twice by ferries.
mission was to detect the shallowest part of the wreck which we found to be
tracks over the wreck gave the result shown on the 3-D picture.
the other picture we see a stranded ship of the same type as the ”Wapper”