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OC-3
Laser Installation Free Space Laser
System Beats High Cost of Fiber When a large BC
Government Ministries moved a department
to a new office in Surrey, one of their
biggest problems was to maintain the
performance of their 100 Mbps computer
network.
Because of
deep underground parking lots in all the
buildings in the vicinity, installing the
fiber-optic cabling necessary to provide a
100 Mbps link was going to be very
expensive.
CoastWorks
used an infrared laser system developed by
LightPointe, to provide the most cost
effective data link available for high
transmission rates.
An
overview of
project,
the
yellow line indicates the link. The
distance is 290 metres.
Telephoto
view of Guildford Commercial Centre from
Guildford Court.
Red circle
is the location of Laser 1.
Note that
there is a clear line of sight over the
parking lot of the Sheraton Hotel, next
door.
It is
unlikely that this line of sight will be
interrupted in the next 10 years.
The
view is looking towards Guildford Court
(BCAL) from Guildford Commercial
Centre.
Red
circle indicates location of Laser 2.
This is the new shorter, stiffer mast
that was installed following the
January 30 windstorm.
Ben, the
roofing contractor, preparation to install
the roof Jack to the pass conduit
containing cables to the laser
system.
Three
concrete cores had to be drilled in order
to run the fiber-optic cables, antenna
cables and power to the roof.
This
building was very difficult to work in
because of extreme security.
A
custom non penetrating roof mount was
designed and built out of aluminum for
stiffness and long service life.
The
Equipment cabinet at MOE - this was the
only location that was permitted that
would give a short antenna cable run (20
m) and security. Our preferred location
was in the stairwell just below the roof
but this was not permitted by the
landlord. The location of this cabinet
required a change to the lease with
Ministry of Environment. There is now a
new property management group looking
after the building.
Eight
strand fiber runs directly to the roof to
connect to the laser. Eight strand fiber
runs from this point back to the server
room below, which is just over 100 m away.
Media converters are used to link to the
Cisco Aironet 11 Mbps backup radio via
Ethernet and to the switch in the server
room. The OC-3 Laser link is optical from
switch to switch.
The MOE
server room where fiber terminates. The
run to the equipment cabinet above was
over 100 m so 8 strand multi-mode fiber
was run from this room to the equipment
cabinet in the previous picture.
The fiber
cabling and administrative hurdles in this
building made this a very slow (12 days)
frustrating installation.
Charles
Middleton, from the Environment office in
Victoria, came over to setup the redundant
roll-over from laser to radio.
This
was a new building with a very
cooperative landlord, making the
installation much easier for the
crew.
The
finished cabinet at Guildford court (BCAL)
Fiber runs from this cabinet to the wiring
closet on the second floor and to the
laser on the outside of this penthouse(3 m
away).
A separate
15 amp circuit from the uninterruptible
power circuit was run to the cabinets in
each building.
Power is
additionally protected in each cabinet
with APC battery backup power supplies
capable of powering the radio and laser
systems for 24 hours.
The
battery backup systems also provide surge
protection for the equipment.
Chris (The
Optic Terminator), showing off his wiring
art to Mike. This was CoastWorks first
laser installation. The biggest lesson
learned was to get all the cabling and
permissions done well ahead of installing
the equipment.
Aiming the
lasers using the telescopic sights is not
the best way to zero in on the signal. The
tone generated in test mode, and picked up
through ear phones is best. The sight on
one laser was more than 30 degrees off. We
found that closing your eyes while moving
from side and up and down was the best way
to discover the signal; the fine
adjustment screws are then turned to get
the strongest signal.
We have
learned to trust our ears rather than our
eyes when it comes to sighting in the
lasers over long distances.
The main equipment
used for this installation is:
LightPointe - Laser
System - FlightPath 155/600
Cisco Aironet BR
500 (Cisco 340) series 11 Mbps 2.4 GHz DSS
radios
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