- By Mark S. Wilson
- Jan 01, 2012
Miami-Dade County Public Schools is the fourth largest
school district in the United States,
composed of 392 schools, 345,000 students and
more than 40,000 employees. Located at the
southern end of the Florida peninsula, the
school district stretches across more than
2,000 square miles of diverse and vibrant communities
ranging from rural and suburban to
urban cities and municipalities.
Watching over this large organization is a surveillance system that is
constantly morphing and expanding. The system has used a variety of
transmission schemes and camera technologies under the scrutiny of
Dwayne Mingo, the district’s project manager on the Facilities Operations
Capital Task Force.
“Today, fiber optics is tying everything together,” Mingo said.
“Throughout the district, we are using more than 2,000 fiber-optic
transmitters and receivers. However, it hasn’t always been that way.”
As with many legacy installations, it was copper coaxial cable handling
images from the cameras to their IDF (intermediate distribution
frame) and from the IDFs to the MDF (main distribution frame).
However, as the school district knew, coax has its limitations, including
restricted transmission distance, signal degradation over long
cable runs and interference, to name a few.
With Southern Florida being the lightning capital of the United
States, the latter was a significant concern. Fiber-optic cabling, with its
interference immunity, increased inherent security, robust cabling distances
and huge bandwidth capability, would serve the schools better,
the district realized.
Working with Infinova, the team decided to explore using the
organization’s dark fiber. Dark fiber, what some call unlit fiber,
refers to unused optical fibers available in buildings and throughout
local, regional and national networks. There is an estimated 80
million dark fibers installed in North America, thanks to the dotcom
bubble of past years, new construction practices and technological
advances in getting more traffic through the installed base.
Often on the IT side, installers have almost always included
extra fiber strands when installing structured cabling backbones
between telecommunications closets and separate buildings,
Mingo and his team decided to use those existing available fiber
links, cutting the initial investment and reducing what installers
call long cable pulls. Instead of continuing to use expensive 25-pin
copper wire, all the cameras were connected to their IDFs using
that fiber-optic cabling.
Planning for IP
Two different contractors had been hired to do the installation.
One was to create infrastructure, while another would do the actual
install of the video system. When the video installers showed up,
they found out that the electrical contractors had installed smaller
wall boxes at the schools than needed for the surveillance system’s
“There were thousands of these boxes, and it would cost several
hundred thousand dollars to replace them,” Mingo said. “And the
transmitter and receiver modules only came in one standard size.
We had two choices. We could replace the wall boxes with the correct
size for standard fiber-optic transmitters or go to litigation.”
It turned out that there was a third option. If the transmitter
module could be customized to reduce it in size, the receiver module
could remain the same and both would fit in the smaller wall
boxes. The customization provided by Infinova saved the project
and the budget.
At the time, all cameras were analog. For instance, even the
PTZs, Infinova’s V1748, were analog. This specific model was
selected because it provided a 26x optical zoom and wide dynamic
range. The day/night camera’s variable speed capabilities range
from a smooth, fast pan motion of 240 degrees per second to a
low speed of 0.5 degrees per second. The system is capable of 360
degrees rotation and has an “auto flip” feature that allows the
camera to rotate 180 degrees and reposition itself for uninterrupted
viewing of any subject that passes directly beneath the
PTZ dome. This particular model also saved the school district
up to $500 per PTZ.
In addition, Mingo had obtained an advanced replacement policy,
garnered local support and all work was being done by trained
Both fixed and PTZ cameras were deployed throughout the
schools with PTZs typically used on perimeters and high-occupancy
locales. For instance, PTZs are outside, watching over parking
lots and fields, and inside, covering areas such as auditoriums,
breezeways and cafeterias. Cameras provide remote access to the
schools’ police department and downtown administration.
They are controlled by the local operations staff and the principals
at the schools but can be overridden by the school police.
However, as the team started discussing a migration to IP cameras,
installers started pulling Cat-5 cabling to the IDF junctions
and to the edge device of the cameras using video baluns at all new
Once the decision was made to go IP, all the installer would
need to do is to replace the fiber-optic cards for encoders and
switch the edge analog camera for an edge IP camera. Fiber optics
would continue to connect the IDFs to the MDF. The team decided
to use its video management system (VMS) to interconnect the
main IDF controllers to the MDF using DVRs as encoders.
Then, once the first batch of IP cameras was installed, the state
of Florida informed the district that a law required that they store
30 days of recorded data at all times, from all cameras. Since IP
cameras cause a logarithmic increase in storage space, they also
create a similar increase in storage costs.
The schools had no choice. Out came the IP cameras to be rereplaced
by the analog cameras. Cat-5 cabling was ousted for fiberoptic
cabling between the IDFs and MDFs.
Results are Positive
Nonetheless, everything worked out in the end.
“Our users are very satisfied,” Mingo said. “They especially like
having color video, and we have been able to apprehend people
undertaking malicious acts. Knowing such people are being seen,
prosecuted and convicted makes our staff and parents feel safer. It
also sends a message to other would-be lawbreakers.”
According to Mingo, all senior and junior high schools are now
installed, and the team is well on its way implementing video at the
“We find analog to be very cost-effective for our school district,”
Mingo said. “Analog cameras are less expensive, yet provide us
with the clarity of images we need. The added cost of storing IP
camera images for 30 days is just too expensive for us.
“With such a big system and the problems that can occur with
such a big operation, we need to rely on trustworthy vendors. We
are lucky that our vendors have stepped to the plate for us with
both engineering help and field installation.”
This article originally appeared in the January 2012 issue of Security Today.