A BDA system, or bi-directional amplifier, is a radio frequency amplifier which boosts signals in 2 directions, and therefore can also be called an emergency radio signal booster. An in-building BDA system ensures compliance with NFPA-1221, NFPA-72, and FFPC SB 1190, enabling constant clear 2-way emergency responder radio communications transmissions.

The Florida Fire Prevention Code mandates compliance with the NFPA code family in new construction and existing buildings. NFPA-1221, Standards for Installation, Maintenance, and Use of Emergency Services Communications systems, Mandates in-building emergency responder radio signal minimum coverage requirements.  Two types of building areas are defined: critical areas and general building areas. Critical areas include emergency command centers, fire pump rooms, exit stairs, exit passageways, elevator lobbies, standpipe cabinets and other areas deemed critical by the AHJ. Critical areas must have 99% coverage, while general building areas must have 90% coverage.

According to the NFPA definition, an AHJ, or authority having jurisdiction,  is an organization, office, or individual responsible for enforcing requirements of code or standard, or for approving equipment, materials, an installation, or a procedure. In the State of Florida, the AHJ can be a local fire department or FCC license holder.

Existing high-rise buildings as defined by the Florida Building Code are not required to comply with minimum radio strength for fire department communications and two-way radio communication enhancement systems as required by the Florida Fire Prevention Code until January 1, 2025. However, by January 1, 2024, an existing high-rise building that is not in compliance with the requirements for minimum radio strength for fire department communications must apply for an appropriate permit for the required installation with the local government agency having jurisdiction and must demonstrate that the building will become compliant by January 1, 2025.