5 Things to Know About Public Safety Distributed Antenna Systems

By Randy Montelius

Firefighters, police, and emergency medical technicians depend on their mobile radios to communicate with each other and with dispatchers during an emergency. Unfortunately, many building structures don’t allow adequate coverage for public safety radios to operate, which can significantly hinder response efforts.

A public safety distributed antenna system (DAS) can extend consistent RF coverage throughout the building and campus. This assures that radios work in stairwells, elevators, basements, and thick-walled or shielded areas that are typically difficult for outside RF signals to penetrate.

DAS systems use an external “donor antenna,” which receives and retransmits radio signals throughout the distributed antenna network. The network is made up of several repeaters connected by coax or fiber cable. The repeaters are specifically sized and spaced to provide even coverage without interference from each other or outside signals. 

The International Fire Code (IFC) and National Fire Protection Association (NFPA) codes now require these types of systems in commercial and institutional structures. Many building owners are also realizing the need for consistent, reliable public safety radio coverage to better safeguard employees, customers, and facilities during an accident or emergency.

As public safety distributed antenna systems continue to expand—especially in hospitals, manufacturing environments, public buildings, and distribution centers—there are five important things you should know.

1. In-Building Radio Coverage is Required

The two building code authorities, IFC and NFPA, now both require buildings to provide adequate radio signal throughout the facility. This can be a challenge in concrete and metal building structures. Some states like Florida also require all buildings 75 feet or taller to provide coverage for public safety radio systems; other states may be soon to follow in creating similar requirements.

2. Design & Equipment Must Be Approved

The authority having jurisdiction (AHJ) must approve a DAS before it’s installed. To gain approval, the AHJ will require a copy of the system design, which shows effective radiated power (ERP) readings that measure RF energy, a list of frequencies being used, and the qualifications of the team designing and installing the system.

Equipment must also be code compliant for use as an ERCES (emergency radio communication enhancement system) by the manufacturer.

3. Keep Coverage in Mind

The NFPA states that critical areas of the building, such as the fire command room, the fire pump room, stairwells, elevators, and any space deemed “vital” by the local AHJ, must provide 99% coverage. In general areas, common spaces, parking garages, and areas used during normal office hours, coverage must exceed 90%. This means the system must be specifically design and tuned to each space.

4. Backup & Continuous Monitoring are Necessary

To ensure that a DAS functions as expected during an emergency, it must be supported by 12 hours of battery backup.

It’s also required that the system be continuously monitored for signal booster malfunction, loss of power, battery charger breakdown, and loss of RF signal. The link between the DAS and fire alarm control panel must also be monitored.

5. Regular Testing is Essential

Just like with any life safety system, regular testing is critical to make sure each component of the DAS—from the cables and splitters to the antennas and repeaters—will perform when public safety officials need it most.

These checkpoints include:

1. Testing after the initial installation to verify that the system meets performance requirements.
2. Annual operational tests, which can be done in conjunction with an annual fire alarm system inspection.
3. A five-year quantitative test to verify that there have been no frequency changes and that coverage has not deviated by more than 5% from the original installation.

CEC is in a unique position to help organizations to design, deploy, and test distributed antenna systems. Our in-house expertise and experience in both RF radio systems and fire alarm systems set us up for success when it comes to public safety DAS projects. We also have the knowledge and resources to install the fiber network that serves as the backbone of these systems.

We’ll be talking about this topic during our upcoming Business Technology Conference on Oct. 21 in Cedar Rapids. Want to learn more about providing effective radio coverage using a distributed antenna system? Register now!

Vice President of Technology Randy Montelius joined CEC in 1982 and has held positions in field operations, service, sales, management, and engineering. Today, he applies his passion for technology as he helps employees solve complex business issues for customers.

Technologies:

Fire and Security | Two-Way Communications | Structured Cabling