Fiber Healthy

• 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, for example.

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 fiber-optic transmitters.

“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 certified contractors.

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 camera locations.

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 elementary schools.

“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.