Picture a firefighter on the third floor of a climate-controlled self-storage building, keying their radio to call for help. If the building blocks the signal, nobody hears them.
That’s the problem a Bi-Directional Amplifier (BDA) system solves. In a recent post, we looked at why BDA so often surprises owners late in a project. This time we’ll cover how the system works, what inspectors usually look for, and how Access Control Technologies (ACT) can help you get it right the first time.
Emergency radios have to work in both directions: the dispatcher needs to reach the crew inside, and the crew needs to reach the outside. A BDA system handles both.
A donor antenna, usually on the roof, picks up the public safety radio signal outside.If only one direction works, the system has failed. A crew that can hear dispatch but can’t answer is still cut off.
Today’s building materials are good for durability and energy efficiency, but bad for radio signals. Concrete, steel framing, low-E glass, and below-grade levels all weaken signals. Self-storage buildings add more: long interior corridors, steel partitions, and hundreds of metal unit doors in a single building.
That’s why BDA now comes up on many kinds of projects: multifamily, self-storage, mixed-use, industrial, and commercial.
Requirements vary by jurisdiction. Your local Authority Having Jurisdiction decides which code edition applies and what local amendments add. Most requirements usually include:
Coverage: a minimum signal strength across a set share of the building, with higher coverage required in critical areas like stairwells and fire command centers.The specifics depend on your AHJ, and they’re much easier to plan for at the design stage than to fix once walls are closed.
1. Early review during design. We help your team find out whether a BDA system is likely to be required. We also plan for the details that cause trouble later: cable pathways, roof penetrations, equipment space, and power. Bringing us in during design is what keeps BDA from becoming a change order.
2. Signal testing. We measure actual signal strength in the building so the design is based on real conditions, not guesses.
3. System design and coordination. We design a system for your building and your jurisdiction, and help coordinate the documentation your AHJ needs to see.
4. Installation. The same team that handles your low-voltage, structured cabling, access control, cameras and gates installs your BDA system. That means fewer trades on site and one partner coordinating the critical systems.
5. Testing and commissioning. We test the completed system against the requirements and help you get the documentation together for occupancy.
6. Long-term service. BDA systems need periodic testing and maintenance to stay compliant. ACT’s service and maintenance programs keep your BDA on schedule alongside your other property systems.
For more than two decades, ACT has designed, installed, and serviced the technology self-storage and commercial properties rely on every day. We’re often already on site for gates, access control, cameras, and low voltage, so adding BDA to our scope means one less contractor to manage, one less schedule to coordinate, and one less surprise at final inspection.