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General BDA Information
The Coverage Problem
1st Responder Radio signals are attenuated by:
• Concrete, Metal and other building
materials
• Low-E Glass
• Below-Ground Structures
• Other obstructions
• RF Interference
What is a BDA?
BDA: Bi-Directional Amplifier, aka Signal Booster is a powered, active device that boosts the signal level of the first responder radios (Uplink & Downlink). It is often referred to as the “head end.”• Also known BDAS
What is a DAS?
DAS: Distributed Antenna System is a network of passive or active antennas, cabling and other components installed with the purpose of distributing the signal throughout the structure.
First Responder Radio Coverage Code Requirements
NFPA 1, 11.10 Two-Way Radio Communication Enhancement Systems
11.10.1 In all new and existing buildings, minimum radio signal strength for fire department communications shall be maintained at a level determined by the AHJ.
NFPA Coverage Requirements
• Critical Area Coverage – 99% (NFPA 1221 9.6.7.4)
Critical areas, such as :
• Emergency Command Center(s)
• Fire Pump Room(s)
• Exit Stairs
• Exit Passageways
• Elevator Lobbies
• Standpipe Cabinets
• Sprinkler Sectional
• Valve Locations
shall be provided with 99 percent floor area radio coverage.
• General Area Coverage – General building areas should have 90%
(NFPA 1221 9.6.7.4) coverage required in General areas.
NFPA 72 Requirements for grid testing
· 24.5.5: A minimum signal strength of -95dBm per testing grid for each floor. Use a testing procedure where a grid is overlaid onto a floor area to provide 20 grid cells. Grid cells are provided with definite minimum and maximum dimensions. For most buildings, using a minimum grid dimension of 20 ft. (6.1 m) and a maximum grid dimension of 80 ft. (24.4 m) will suffice to encompass the entire floor area. Where a floor exceeds 128,000 ft2 (11,890 m2), which is the floor area that can be covered by the maximum grid dimension of 80ft. (24.4 m), it is recommended that the floor be subdivided into sectors, each having an area of less than or equal to 128,000 ft2 (11,890 m2), and that each sector be tested individually with 20 grid cells in each sector.
· 24.5.2.2.1: Critical areas, such as the fire command center(s), the fire pump rooms(s), exit stairs, exit passageways, elevator lobbies, standpipe cabinets, sprinkler sectional valve locations, and other areas deemed critical by the authority having jurisdiction, shall be provided with 99 percent floor area radio coverage.
· 24.5.2.3.1: A minimum inbound signal strength of -95 dBm, or other signal strength as required by the authority having jurisdiction, shall be provided throughout the coverage area.
Typical Deployment Process
1. VERIFY LOCAL REQUIREMENTS
1. VERIFY LOCAL REQUIREMENTS
1. VERIFY LOCAL REQUIREMENTS
Review AHJ requirements
• Not all have a BDA written
specification
• Frequencies that need to be covered?
• Fire Only? Or Fire & Police? EMS? Other?
• Repeater locations?
• Additional requirements?
2. SIGNAL Strength SURVEY
1. VERIFY LOCAL REQUIREMENTS
1. VERIFY LOCAL REQUIREMENTS
Once the building is substantially
complete, BDA NOW, a qualified and FCC
licensed vendor will perform the
signal survey to check the current
radio signal levels inside the
building.
3. MEASURE SIGNALS
1. VERIFY LOCAL REQUIREMENTS
4. DOCUMENT LEVELS
BDA NOW will measure the
incoming signal levels by
monitoring the AHJ radio
repeater talk-out frequency, and take signal strength readings in 20 grids per floor plus any areas deemed critical by Code or local guidelines
4. DOCUMENT LEVELS
4. DOCUMENT LEVELS
4. DOCUMENT LEVELS
Signal readings are
documented/noted on print or
floor plan and forwarded to
the system design engineer
5. BDA REQUIRED?
4. DOCUMENT LEVELS
5. BDA REQUIRED?
If the measurements
show that the levels are
below the required
minimum, then a signal
amplification system (BDA
system) shall be required by code.