Security Sales & Integration October 2022 - 23

SMARTS & PARTS
Fire Side Chat by Shane Clary
Examining
BDA Installation
Procedures
Part of this
testing is to
determine if
the uplink and
downlink can,
throughout
a building,
maintain the
required signal
strength for
communications
within and
outside of the
building.
▶ THIS MONTH'S ARTICLE continues the
discussion on bi-directorial amplifi ers (BDA), or
emergency responder communications enhancement
system (ERCES). As jurisdictions adopt
the next editions of either the International Fire
Code or NFPA 1, Fire Code, the requirements
for these systems will increase. While these systems
are not a fi re alarm system and do not use
a fi re alarm control unit to operate, a fi rm that
has a one of their primary services as the design,
installation and servicing of fi re alarm systems
should at this time be looking at the addition of
these systems to their off erings.
Th e primary document that is to be used is
NFPA 1225, Standard for Emergency Services
Communications. Th e fi rst edition that has been
Shane Clary, Ph.D., is an
SSI Industry Hall of Famer
and has more than 45
years of security and fi re
alarm industry experience.
He serves on a number of
NFPA technical committees,
and is Vice President of
Codes and Standards
Compliance for Concord,
Calif.-headquartered Bay
Alarm Co.
securitysales.com
published by the NFPA is the 2022 version. In
addition to NFPA 1225, the designer or installer
needs to know what the requirements of the jurisdiction
is that the building is located within. Th e
AHJ may not be the fi re department on all occasions.
Th ese systems are used by all emergency
responders, including law enforcement and emergency
medical.
Th ere are four bands of frequencies that have
been set aside by the FCC for use by public safety
agencies. Th ey are VHF (150-174MHz), UHF
(450-512MHz) and the 700/800MHz bands.
Th ey may also now be the bands that the new
FirstNET system uses. One needs to know the
frequencies that are being used. Th is information
should be made available by the AHJ.
Th ere are a number of new terms that one needs
to be aware of for these systems. Th e AHJ will reference
these terms within their agency's specifi cations.
Th e system must meet these requirements.
I have already touched on frequencies. Th is is
the fi rst item within the predesign that needs to
be checked off . Depending on the manufacturer
of the product that you may be installing, it
may require several BDAs to be installed within
a structure. Once these are known, the site survey
may proceed.
smclary@bayalarm.com
Th is is conducted for each frequency at typically
within 20-foot grids within each building, per
fl oor. In addition, critical areas such as stairwells,
fi re command rooms, fi re pump rooms electrical
rooms and the like also need to be included.
Th e signal that is received during the survey
needs to be either no lower than -90dBm or have
a delivered audio quality (DAQ) of 3.0 or greater,
with the preferred minimum being 3.4. Th e
DAQ method is becoming the preferred method
of determining if a system will be required. DAQ
is defi ned within 1225 as " A measure of speech intelligibility
of land mobile units. "
Part of this testing is to determine if the uplink
and downlink can, throughout a building, maintain
the required signal strength for communications
within and outside of the building. Th e
downlink is the signal from the base station to the
portable radios. Th e uplink is the signal from the
portable radios to the base station.
One should become familiar with Chapter 18
and the associated annex to this chapter within
1225 on the specifi c requirements for the conducting
of a site survey. All product manufacturers
also provide training on how to conduct a
proper site survey.
Part of the survey is to spot the location of the
donor antenna. Each DBA that is to be installed
within a building will require a donor antenna.
Th e donor antenna will in most cases be mounted
on the roof and have a direct line-of-site view of
the radio systems transmitting site.
If a jurisdiction does utilize more than one
band, a donor antenna for each band will be
required, and may be directed toward diff erent
locations. Th e AHJ or license holder should have
the locations of each of their transmitting sites.
It is important that the donor antennas do not
cross each other.
Th e connection from the donor antenna to the
BDA will in most cases utilize a two-hour fi re resistive
coaxial cable. Depending on the size of the
structure and number of fl oors, the DBA may not
be mounted directly near the fi re alarm control
unit or on the grade fl oor.
While multiple BDAs and donor antennas may
be required, the distributed antenna system (DAS)
within the building uses the same antennas for all
frequencies. Th e connections to these antennas
may be through the use of coax or fi ber. Th e location
of these antennas is based on the survey that
was conducted and the fi nal design of the system.
OCTOBER 2022 Security Sales & Integration 23
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Security Sales & Integration October 2022

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