Takeaways from Adam Baer’s Presentation at the University of Missouri
By John Morgensen, Construction Account Manager
Distributed Antenna Systems (DAS) and Emergency Radio Communication Enhancement Systems (ERCES) are often grouped together since they both amplify communications signals.
In many ways, that’s where the similarities end. The two systems operate differently and are governed by completely different regulatory bodies.
Cellular DAS amplifies the signals mobile phones use to communicate with cell towers, and are governed by carriers like T-Mobile, AT&T, and Verizon.
“You have to play by the carrier’s rules,” said Adam Baer, DAS technology specialist at Tech Electronics. “The cellular carriers pay a lot of money in FCC licensing to have those frequencies that those phones work on, so in the carrier world, it’s very important you play by their rules.”
ERCES is regulated by the authority having jurisdiction in the area, usually a fire marshal and FCC licensee. While they are not always enforced, regulations for radio coverage have been in the International Fire Code since 2009.
These regulations are in place to ensure that when first responders are on scene, they can maintain radio communications no matter where they are in the building. Often these systems are needed in large buildings or campuses but can also be required in smaller buildings with other obstructions like low E glass.
“It’s not just saving the firefighters, right? It’s saving the guy that’s in the room that’s having the medical issue, that’s getting that communication faster, getting the help they need,” said Baer. “So, it is helping the end user, the student, faculty, et cetera, but it’s also helping those first responders.”
Cellular DAS
Cellular DAS uses a donor antenna, usually placed on the roof of a building, to amplify signals to, and from cell towers. From there, the signal is sent through a bi-directional amplifier before being distributed throughout the building.
Installers must take care to ensure the antennas are aligned correctly with the corresponding cell towers for each carrier. A system will not be effective in amplifying cell signals if it is not reaching the cell tower of the carrier it is intended to amplify.
The Federal Communications Commission also regulates the maintenance and installation of some BDAs, and facility managers can even run into issues with the agency if an antenna or system is unregistered or incorrectly installed.
Baer said there are two different regulatory frameworks from the FCC, either Part 20 or Part 90 systems.
Part 20 systems are smaller, less powerful, and less likely to interfere with other nearby signals. As such, Part 20 systems can often be turned on and installed on the same day.
Part 90 systems are usually more powerful and cover a wider range of signals, increasing their potential to interfere with other nearby communications.
In the case of larger cellular DAS installations, like neutral host systems, Baer said installers will have to ratify a carrier retransmit agreement as well.
ERCES
ERCES installations operate similarly to DAS installations, although their goal is to amplify radio signals in and around a building for first responders, as opposed to cell signals.
While their operation and installation are similar, there are some key differences in regulations that need to be met, since ERCES installations are considered life safety systems in many jurisdictions.
During the construction process in jurisdictions that require these systems, an AHJ will ask for a survey of the radio signal strength, called a 20-Grid, which is performed throughout the building. The results of that survey will determine if a system is needed.
From there, a formal design can be completed to determine what equipment is required to improve the signal to meet code requirements.
Baer also noted that when facilities managers are looking for an ERCES partner, they will need one with an understand of both RF engineering and the life safety code requirements.
Many RF engineers aren’t as familiar with the codes, monitoring requirements, and topics like survivability.
Conversely, there are also legacy fire alarm companies that don’t understand RF, sweep testing, path loss, and oscillation. The goal is to partner with someone who understands both RF engineering and has in-depth knowledge and understanding of codes and AHJ requirements.
“You want to find that vendor that knows both right?” asked Baer. “There’s a lot of engineering groups out there, they know RF, they know how to use the spectrum analyzer, but they don’t necessarily understand code.”
Other Considerations
It’s important for facilities managers to understand what systems may be required in their buildings, and what the codes are for their area. Depending on where the facility is located, and which versions of the IFC their area uses, they could have different requirements from their AHJ.
“DAS has always been a bit of a black box, and this really helped to fill in those voids, those missing pieces to have a better understanding of the way the system works,” said Kenneth Keane, project manager and mechanical engineer with the University of Missouri.
For more information on how Tech’s experts can help you understand what systems are needed, and what will work best at your facility, schedule a consultation.
