ref:vl-01.html - Dec '98 . / 21 Luglio 2007 -cod.34
Foreword
In a beautiful South Italian location, named Palinuro, there are several
fantastic caverns with deep and dangerous entrances:
some of them are located at minus 37-52 mt, 100' / 160'.
The problem was: how a large number of tourist with no diving experience
could enjoy them ?
How to show the beautiful deep-water caverns to old retired people or
young school children and their teachers ?
To reach the goal we manufactured a small size buoy in which a video transmitter device, batteries, control unit,
antenna were installed.
The transmission power is able to send clear colour images and the divers voice (on request ) up to 300 mt distance ( 1,000') with a low
power transmitter unit.
It is possible to increase the transmission range up to 1,500 mt ( 4,500') by
using a high power transmitter.
The buoy is connected to an underwater TV camera by a 80 mt - 240' - length floating cable,
with a diameter of only 7 mm.
On the cable the video signal is transmitted and, on request, the audio signals from the diver TV camera
to the buoy.
In case of need, and for special application, it is possible
to transmit extra signals or electrical power also from the buoy to the diver or to the TV camera housing.
The buoy is free to float near or far from the boat and the diver is able to operate connected to the boat crew by the
video link and a standard underwater phone.
The boat is free to cruise over the divers operational area or
to be moored in a favorable location without long-cable problems and
on-board winch.
In fact, the system eliminates the need for heavy and expensive motorized winch and avoids all problems
related to physical connection between the surface and the sea-bottom, sea
currents transport, surface waves and wind effect.
The survey boat is free to drift in any direction, change course,
rotate as required by the surface work activity without following
a floating cable, avoiding cable knots, diverting other boat
routes to prevent cable cutting by boat propellers.
Image and audio could be received also by standard TV sets
installed in hotels, on board of large cruising ships, divers supply
vessel, assistance vessels such as tugs, pontoons, mine-sweepers, fire
fighting units, anti-pollution boats, etc., and on the desk of diver's team
leader, survey inspectors, engineers, etc.
To reduce the buoy drag, particularly strong with high speed currents, a 5 Kg (10 lbs.)
chain was connected to the buoy hull.
Steel chain is an ideal ballast, easy to install, to remove, to modify in terms of buoyancy.
Cable could be manufactured neutrally or with a small negative or positive buoyancy in salt water.
Using a negative buoyancy cable in Mediterranean waters a number of small
size floating elements were fixed to increase the buoyancy lifting power.
The system allows the cable to be positive under the sea-surface, at approx. 10
mt distance from the sea-bed, avoiding boat propellers and all risk of
cutting when cable is floating on the surface.
On-Board Unit.
On board unit is a small electronic box installed in a plastic all-weather case.
From the unit it is possible to receive images from the buoy, and on request,
audio signals, through a small size antenna, and also check and charge batteries, etc.
System at work
Ideal application are all survey activities such as oil field underwater
element inspection, ship hull elements such as water
intake, propellers, rudder, stabilisation fins, and in general hull
survey, verification of damage and repaired areas, etc.
Great advantage of the real-time link is the possibility to modify the
underwater task in relation to requests or suggestions transmitted
by the surface team following in real-time the diver's activity.
The system is easy-to-use and to deploy: it's possible to work
from small size boats, inflated boats, sea-planes, choppers.
The light weight of the buoy, 3 Kg ( 6 lbs ) only, allows work from a
small size boat even in heavy weather conditions.
Finally the cost of the whole, with an innovative small size
colour TV camera, ranges around US $ 5,000 with a 20 mt ( 30' ) cable.
Technical specification
1 - ON-BOARD UNIT
Case dimension: cm 35 (L) x 27 (W) x 15 (H) - plastic box.
Weight in air: 10 Kg approx.
Video Channel Frequency: from 335 to 400 MHz - receiver device -
Bandwidth: 5 MHz - F.M.
Audio Channel - on request - Carrier Frequency: 6 MHz
Antenna: L/4 type - from 24.6 cm to 20.6 cm in length
Power input : 220 Volt or 110 Volt on request.
Output: # 2 video BNC - PAL or NTSC or SECAM standard
# 2 audio BNC on request
Video Colour screen: 4"
REMARKS:
Box contains a battery-charger suitable to be connected to the
buoy electronic box recharging buoy battery in 8 hours.
2- BUOY
Hull dimensions without antenna:
Diameter: 25 cm
Height : 45 cm
Height with antenna mast: 145 cm. ( L/4 type )
Stabilisation ballast: 5 Kg ( 10 lbs ) chain of 6 mt ( 18' ) in length.
Video Frequency transmitter device: MHz 335 - 355 - 380 - 400 -
Modulation: FM
Bandwidth: 5 MHz
d/B better than 25
Audio Channel Carrier Frequency: 6 MHz - Transmitter device -
d/B better than 65 dBm
Battery: 12 Volt - 2 Amp.
Endurance: 3 h.
Max. recharging time: 8 h.
On request: small size solar panel for fixed underwater surveillance installation.
3 - CABLE
Diameter: 7 mm - Buoyancy: 250 gr - negative - on 10 mt in length.
Diameter: 10 mm - positive buoyancy - 100 gr on 10 mt in length.
Standard length: 20 mt
Maximum length: 150 mt.
Material: special polyhuretane, stretch resistant.
Wires: # 3 x 0,5 mm diam. each plus # 1 coax. video cable.
Connector to the TV camera housing:
special 4 - pin type.
4 - UNDERWATER COLOUR CAMERA
Colour camera: cylindrical small size with special all-in-one built illiminator leads.
Housing material: aluminium.
Diameter: 6 cm. max
Length: 10 cm. approx.
Colour camera CCD: high resolution low-light level.
Max operating depth: 150 mt ( 450')
Illuminator: new high energy leads.
Lens: focal length: 3 - 4 - 6 mm.
Output: standard video signal.
Handgrip: included - M8 standard connection.
Lead illuminator: included.
System lay-out for diver's use
System lay-out - fixed installation
