Mobile Communications specializes in providing in building communication solutions to commercial and public safety customers. Providing good quality RF signal throughout your building or campus represents significant challenges in today's day and age.
Our solutions could be as simple as adding some two-way radio repeaters or combiners. they could also be as complex as installing a distributed antenna system (DAS). We will customize a solution for your exact needs.
In-building systems are customized solutions – rarely do they work “out of the box”. A number of factors including system signal strength at the “donor” antenna, building construction, size, layout, coverage requirements, end user equipment, covered networks, and similar issues.
The in building team at mobile communications has extensive design experience and utilizes state-of-the-art software to meet your design objectives. We offer a complete turnkey solution for your two-way radio system and in building application needs. We will design, install, and maintain your two-way radio and in building amplification system. In many jurisdictions two-way radio communications for public safety is mandated by state and local laws.We will make sure that your facility complies with all of these rules and regulations.
The Case for Public Safety In-Building Communications (DAS)
Courtesy of our partners at Tessco.
The following is a list of seven things you should know about the in-building Public Safety code and how these requirements may impact your next DAS project.
NFPA systems require 99 percent coverage in critical areas as designated by the local fire department, and 90 percent coverage in general-use areas. The IFC requires 95 percent coverage of all areas. Think about it... your typical DAS design will provide coverage in the areas that are most likely occupied during a normal day (offices, conference rooms, public and common areas); however, first-responders often find themselves in stairwells, elevators, equipment rooms, parking structures and basements. Adding the first-responder requirement to your project adds another layer of effort, including a more comprehensive initial RF survey which of course impacts your final design and bill of materials. Additionally, you need to incorporate the radio frequencies used by local Public Safety personnel (UHF/VHF 700 MHz and 800 MHz) and assess the building's construction and layout to ensure acceptable coverage.
In the event of a fire, there are usually a lot of hoses aimed on a building. That means lots of water on sensitive radio gear. It won't take long before communication is lost. The NEMA specification reads: "Watertight and weatherproof. Must exclude at least 65 GPM of water from a one-inch nozzle delivered from a distance not less than 10 feet for five minutes." Get the picture? Both IFC and NFPA require all equipment, such as radios and power systems, supporting the Public Safety network to be housed in NEMA 4-compliant enclosures. While NEMA 4 enclosures are nothing new, there is an added expense in material cost and an added installation effort that includes proper mounting and conduit installation.
System Monitoring Alarms
Essentially these alarms provide real-time monitoring of the system's readiness. The code covers alarm requirements for power/battery failures, antenna malfunctions, and battery capacity (alarm generated at 70 percent remaining power). This will surely impact your solution design, as well as the networking or the backhaul of this information to a centralized monitoring point. Both the IFC and NFPA require some level of alarming, but they do differ. Your local jurisdiction will have the final say on the requirement.
-95 db Minimum Signal Strength
The minimum signal strength, within the coverage area, for both the IFC and NFPA is -95 db regardless of the frequency. Your analysis and design must reflect both coverage area and signal strength. Also, you need to consider the frequencies to be used. 700 MHz and 800 MHz frequency will not have the same signal strength as legacy VHF. 700/800 MHz will possibly need a greater antenna density to achieve coverage, at a minimum, 95 db.
In the event of a building emergency, there's often a power failure or power is cut off to prevent further danger to first-responders. The code requires the equipment supporting the Public Safety radio system to remain operational, on a battery backup, for no less than 24 hours. There are several ways to meet this requirement. Selecting the proper solution for your design will take a bit of time and research. Remember to think holistically when selecting components as your power requirements can vary from AC to 12 volts or -48 volts DC.
Future Frequency Changes
Systems supporting the Public Safety emergency-responder radio coverage need to support future frequency requirements. Current platforms will need to support UHF,VHF, 700 MHz and 800 MHz. Both the IFC and NFPA promote this requirement. Future-proofing your DAS deployment to cover the adoption of new frequencies should be a design consideration.
While the IFC does not specify a requirement, the NFPA does stipulate an antenna isolation requirement of 15 db higher than the gain of the amplifier. While your DAS design will probably incorporate a 15-db separation, your Public Safety coverage may require more antennas as you factor coverage and signal strength for a Public Safety solution. To ensure proper isolation, a directional antenna rather than an omnidirectional antenna may be required for proper coverage and signal strength and antenna isolation.