Terminology Guide
Four acronyms, one goal: keeping first-responder radios working inside your building. Here's what each term actually means, which are systems and which are components, and which are just two names for the same thing.
If you only remember one thing: ERRCS and ERCES are the system; BDA and DAS are the components inside it. And ERRCS and ERCES are two names for that same system, coined by two different code bodies. Here's how it breaks down:
ERRCS (Emergency Responder Radio Coverage System) and ERCES (Emergency Responder Communication Enhancement System) describe the identical thing: an in-building system that guarantees fire, police, and EMS radios work everywhere inside a structure. The only reason there are two acronyms is that two code bodies govern the same buildings.
The International Fire Code (Section 510) — the basis for the Houston Fire Code — uses ERRCS, so it appears on permits and plan review. NFPA 1225 uses ERCES, so it appears on the acceptance and annual test reports. Same building, same -95 dBm requirement. A full breakdown is on the ERCES page.
Inside every ERRCS / ERCES are two key pieces of equipment that people often mix up:
The BDA (bi-directional amplifier) is the powered box that takes the weak signal from a rooftop donor antenna and amplifies it — in both directions, so responders can both hear and be heard. It is the engine of the system. The DAS (distributed antenna system) is the network of interior antennas and cabling that carries that amplified signal to every floor, stairwell, elevator, and basement. It is the delivery network. The BDA makes the signal strong; the DAS makes it reach everywhere. See BDA installation and public safety DAS for each.
"DAS" also shows up in the cellular world, and the two are not interchangeable. A public safety DAS carries first-responder radio frequencies and is required by fire code. A cellular DAS carries carrier signal (Verizon, AT&T, T-Mobile) for phones and data and is a tenant-convenience upgrade, not a code requirement. A cellular DAS does not satisfy an ERRCS. BDA Houston deals with the public safety side.
At a Glance
The fastest way to keep the four terms straight.
The whole in-building radio coverage system, as named by the IFC and Houston Fire Code. What your permit requires.
The same system, as named by NFPA 1225. What your acceptance and annual test reports reference.
The bi-directional amplifier that boosts the signal. The engine of the system.
The distributed antenna network that spreads the boosted signal through the building. The delivery network.
Common Questions
A BDA (bi-directional amplifier) is the amplifier that boosts the emergency responder radio signal in both directions. A DAS (distributed antenna system) is the network of antennas and cabling that distributes that boosted signal throughout the building. The BDA is the engine; the DAS is the delivery network. A complete system uses both, along with a donor antenna and battery backup.
Yes. ERRCS (Emergency Responder Radio Coverage System) is the term used by the International Fire Code and the Houston Fire Code. ERCES (Emergency Responder Communication Enhancement System) is the term used by NFPA 1225. They describe the same in-building public safety radio system — the difference is only which code body names it.
Not exactly. ERRCS (or ERCES) is the whole system — the code-defined requirement for in-building radio coverage. A BDA is one component inside that system. A building needs an ERRCS; the BDA and DAS are the equipment that delivers it. People often say "BDA system" as shorthand for the entire ERRCS, which is where the confusion comes from.
Houston plans and permits, based on the Houston Fire Code (Section 510), use ERRCS. The acceptance and annual maintenance test, performed to NFPA 1225, uses ERCES. The equipment list on both will reference the BDA and DAS components. All of these describe the same project.
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