At 03:04 AM 8/25/05, Dimitris Velissaris wrote:
We already tryied tests inside a big ship of our navy force.
Frequencies on vhf band (140-170 MHz) and we had contact until 6 heavy and closed door on the same horizontical level , after that nothing at all&.
Tranceivers was tk-2160 by Kewnwood company with a power output 5 Watt.
Best regards
Dimitris Velissaris
Technical Support
RadioCommunications Dpt.
ANCO S.A
44 Syngrou Ave
117 42 Athens - Greece
Tel : +0302109209217
Fax : +302109209345
URL : www.anco.gr
e-mail : [EMAIL PROTECTED]
Intership communications are usually VHF, and in-ship UHF.
In that case I'd use a UHF repeater with the duplexer antenna
port feeding a Radiax system that goes throughout the ship.
The Radiax cable will "leak" RF everywhere and allow inter-
compartment comms just fine.
Over the last 10 years a local company has installed over
20 miles of Radiax in the basements of buildings, in parking
garages, etc.... You put a small antenna at the far end,
and run it wherever you need signal. In a building you put
the radio in the basement and run Radiax up the elevator shaft
to an antenna on the roof. The building security folks can
talk anywhere on their handhelds plus for a few blocks around
the building.... The owner can tell stories about building
inspector after building inspector having to be educated that
this is one cable that you CAN'T put inside conduit... no
matter what.... It's made in plenum and regular type and you
had better order the right type the first time...it's not cheap.
Mike
Mike Morris WA6ILQ wrote:
At 12:56 PM 8/25/05, "Mark A. Holman AB8RU" <[EMAIL PROTECTED]> wrote:
I would say alot of holes to cut with a torch in those Ships,
True.
and they may been designed to stop water passage in
case of a hull breach
May ???? The walls are riveted steel and the doors are
called "water tight" for a reason.
I would ask the upper brass permission and discuss this
with Engineers B4 Cutting a hole for that cable.
I'd talk to a naval architect too. But most ships are
designed with extra space in the wiring ducts for a reason.
Mark AB8RU
The only reason I mentioned it was in case he didn't
know about radiax ... it's one solution for Faraday Cages.
I was on a tour of the SS Lane Victory
(http://www.lanevictoryship.com), supposedly the last
operational WW2 Liberty ship, a while back and one
of the other gentlemen on the tour was a radio engineer
from one of the larger cruise ships (the Lane is docked
right inbetween two sets of cruise ship berths in San
Pedro harbor, just south of Los Angeles... if you are
ever in the area it's worth the $4 for the tour....it's used
for a LOT of hollywood backdrops... most of the JAG
scenes that were not ship-specific were filmed on
board the Lane.)
Anyway, he told me then that in-ship comms are
handled on UHF specifically to avoid the marine channels.
They have five repeaters on adjacent channels - the 60w
transmitters feed a 5-port combiner and the receivers
are fed by a multicoupler. One repeater is ship mechanical
operations, a second is bridge personnel, and the
other 3 are run as community repeaters with multiple
tones and are used by the folks that handle the
passengers.. food service, housekeeping, etc.
All five repeaters feed out via one duplexer and the
combined signals split down several runs of 1/2 inch
Radiax run through out the ship. Anybody can be on
any channel and be heard throughout the ship.
So Radiax _can_ be run through a ship without impairing
the mechanical / physical structure... but it may have
been included in the overall ships design at the beginning...
I don't know, and have no way to contact him... the business
card he gave me got left in the shirt pocket, got washed in
the laundry and came out as wet confetti...
But the verbal block diagram I gave you above is not rocket
science, and not beyond a good system designer assembling
it with off-the-shelf components.
Mike WA6ILQ
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