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Public Safety DAS Monitoring Device & Installation

Dec 28, 2018

Public Safety DAS Monitoring Device & Installation

Systems ensure that emergency responders are able to use wireless communications while handling an emergency situation inside a building structure are known as Public Safety Distributed Antenna Systems (DAS). These systems are not only crucial for first responders to public safety scenarios, but also for building owners and others who need to ensure that all people under authority or in their structure are safe when a crisis occurs. A DAS monitoring device improves these systems one notch further to eliminate risk of downtime, because emergencies can occur any time.

Intrinsic Benefits of DAS, Explained.

Public Safety Distributed Antenna System enables a more efficient response to any emergency situation by ensuring that first responders can maintain communications with each other so that they can combine their efforts. Emergency communications are required during security threats, natural disasters, fires, and many more.

As a reliable Public Safety DAS could literally mean the difference between life and death during emergencies, institutions including such as the International Fire Code (IFC) and the National Fire Protection Association (NFPA) set regulations in this regard. They also work with local government to make sure that measures and requirements are in place to ensure that reliable, and efficient communication systems are in place for those impacted by an emergency, including emergency responders.

Any public safety DAS must meet system coverage specifications listed by the IFC and the NFPA. NFPA specifies that 99% of areas of crucial importance need to be covered as designated by the local fire department, while the IFC specifies that 95% of all areas need to be covered. The final say would come from your local authority having jurisdiction (AHJ).

Additionally, the NFPA specifies that 90% of general areas need to be covered. Although most areas normally used during office hours are generally covered by a DAS, those are not necessarily where first responders may need to be during an emergency. First responders are, for example, not always in conference rooms, break rooms, or offices. They are often trying to reach places where employees don't often go, such as elevator shafts, stairwells, basements and equipment rooms.

To implement these standards into a DAS, a close look is needed at materials used as well as the final designs and more effort is required. An all-inclusive RF (radio frequency) survey will also have to be done. When it comes to DAS coverage, radio frequencies including FirstNET used by public safety workers must be incorporated, and the layout and location of the building taken into account in order to make sure coverage is sufficient.

System Monitoring Alarm.

System monitoring alarms deliver real-time monitoring of systems to indicate that it is ready. DAS must be monitored for antenna network faults, battery capacity and power or battery failure.

System monitoring alarms need to be sent to a centralized point to be monitored, i.e. a central fire alarm panel. Although both the IFC and NFPA require alarm systems, their requirements are different. The local jurisdiction has the final word on monitoring requirements as well.

NEMA-4 Enclosure.

When there's a fire, it is likely that lots of water will be pumped into a structure and chances are that sensitive radio gear will get wet, compromising communication.

Both the IFC and NFPA specify that equipment supporting the public safety network has to be fitted inside NEMA-4 compliant enclosures, including power systems and radios. This will ensure that equipment continues operating in emergencies where its integrity may be compromised by emergency measures taken.

Battery Backup.

In a crisis, especially in buildings, power often fails or might need to be cut off to prevent hazards to emergency responders. To be up to spec., equipment that supports the public safety radio system has to be able to function for at least 24 hours on backup batteries.

Signal Strength.

Within the required coverage area, the minimum signal strength is -95 dB as specified by both the IFC and NFPA and should be the case for all public safety network frequencies.

If 700 and 800 MHz frequencies are to be used, it will not have the same signal strength as VHF and a greater density of antennas is needed to attain coverage at the needed signal strength.

Antenna Isolation.

The NFPA specifies that antenna isolation has to be 15 dB higher than the amplifier's gain.

To achieve proper antenna isolation, signal strength and coverage for a public safety DAS, a directional antenna might be more suitable than an omnidirectional one.

Frequency Updates.

Both IFC and NFPA specify that systems supporting radio coverage for public safety emergency responders have to support to frequency updates. To meet this requirement, current systems need to support 700 MHz, 800 MHz, VHF and UHF to comply.


The NFPA-72 and NFPA-1221 Public Safety DAS Annunciator System supplied by ensures client's Fire Inspection Readiness. This alert system is used by in-building public safety radio signal enhancement system installers. It provides FORM-C dry relay contacts to provide alarm signaling with any fire alarm installation. The system will operate with DAS installations that include multiple amplifiers, antennas and power source, and includes circuitry to detect communications faults (open or short circuits) with the DAS equipment.

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DAS monitoring & installation
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  • I’m glad to see public safety systems becoming more common and that there are organizations like the International Fire Code (IFC) and the National Fire Protection Association that set standards for them. Not being able to make a cell phone call is an inconvenience for you and me, but as this blog mentions, it’s a matter of life and death for first responders.

    Holly Martin on
  • These public safety DAS systems really took me by surprise. I didn’t know such devices existed until I started educating myself on cell phone signal boosters. I don’t know if cell phone signal boosters for the home or office are needed, but public safety ones sound like they’re essential. I don’t want any first responder to struggle to get in touch with their brothers and sisters when they go into action.

    Jesse Ayala on
  • I was talking to my gf the other day about firefighters (she’s a nurse) and gave her some of the basics on public safety DAS. She knows how important safety is for first responders and I told her how these can help keep them even safer. She was amazed at the technology.

    Murray Hayes on

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