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Emergency Responder Communication Systems : Comprehensive Overview

Updated: Jun 18

Emergency Responder Communication Systems, (ERCS's), are the systems we depend on everyday across the U.S. for emergency and critical incident response. These vital systems consist of critical two-way radio communications for coordinating emergency

Emergency communication systems are vital in establishing control

response resources at all levels of emergency and incident response. This includes: emergency and first responders involved in public safety, EMS and law enforcement. These systems are used within agencies and municipalities, but can also be used across jurisdictions (municipal, county, state, Federal) for proper Coordination, Command and Control and to provide Situational Awareness (SA) for vital emergency responder resources


In this article, we will specifically look at:


· The main goal of these systems

· The evolution of these systems

· Technology's Impact on Emergency Communications

· Design considerations

· System Vulnerabilities

· Effective Public Safety Communications Solutions

A well-designed emergency responder communication system should examine all aspects of capability, reliability and resiliency and can best be summarized by the below:


The main goal of an ERCS is to have reliable and resilient communications, at all times, for any emergency situation encountered, and to have effective communications at all levels of the disaster response.


Focusing on the “at all times” element is the most efficient way to ensure you will always have effective emergency response communications. While this may seem basic at its essence, having reliable and resilient communications, at all times, is not easy to achieve. This is because nearly all Emergency Communications Systems across the U.S. have vulnerabilities and weaknesses that can cause them to fail. This is illustrated by past history, as nearly every community that has experienced any form of major disaster has had communication failures identified as a main root cause for cascading events beyond the disaster. These cascading events greatly magnified and worsened the outcomes for those communities. Understanding the basic design of our emergency communication systems is key to understanding why these systems can fail if we are to provide communications that is reliable and resilient for all situations.

Much of what is in place today for public safety emergency communications has evolved from the mid 20th century designs of early two-way radio systems. Understanding these early systems provides a perspective of how our systems evolved and how that evolution has shaped the current systems that are in use today.

Emergency responders communicate using a variety of frequencies.

These early systems used both “Direct Wave” and “Ground Wave” and limited “Skip Wave” to carry the signals from the first responders to the head end control point of operations. The Direct Wave provided “line of site communications” (1-10 miles), while the Ground Wave could carry the signals from 10, up to 50 miles. The frequency ranges that these early systems used were in the High Frequency (HF) radio bands (think ham radio and CB) and used much larger antennas. Today you rarely see these larger antennas, however, we still have some residual emergency communications systems in those frequency ranges as there is still a remaining public safety radio segment in the 25-50 MHZ band.


The main problem with these early systems is that AM signals are very susceptible to noise, static, atmospherics and fading. This made communication difficult at times as transmissions could be become garbled which would create many problems. Fading would also occur as the signals could bounce off structures, with the Direct Wave, Ground Wave and Sky Wave signals all arriving at different times creating interference with each other and distorting what the receiver would hear. This led to many work arounds like “10 codes” and phonetic alphabets to help with understanding communications that were unclear. In the end, across the U.S., emergency two-way radio systems largely moved away from this older technology to newer technology and systems that didn’t have these issues. However, these older systems had one distinct advantage over the newer systems of today which is that they did not need any other intermediate communication systems (repeaters) in order to function.

Few other technologies have had a greater impact on emergency communications than the migration to Frequency Modulation (FM) communications in the 1950s and 1960s. In the 1950s and 1960s there was a mass movement away from Amplitude Modulated

Many emergency responder communication systems have evolved but still have vulnerabilities.

(AM) systems to Frequency Modulated (FM) communications which has the advantage of being much cleaner as it is not as susceptible to noise and atmospherics. The circuitry required for FM communications effectively removes noise making for much clearer communications. Also, FM communications allows for a wider range of audio which makes the signal much more understandable on the receiving end. However, to achieve this wider range of audio you need to operate at much higher frequencies (above 30 MHZ) in the radio spectrum. The propagation characteristics (how far a signal can travel) of these higher frequencies is very different from the propagation characteristics transmitted at the lower frequencies. In most instances, higher frequency FM communications can only be relied upon to provide “line of sight” communications. To extend the distances that an FM communication signal could travel, repeaters and towers were needed and added to the mix in order to have reliable communications beyond line of sight. This system of repeaters and towers in our Emergency Communications Systems is still widely used across the U.S. today.

As a result, nearly all public safety, law enforcement and emergency response communications occurs over a system of networks and some form of “line of sight” FM communications systems. These systems are designed to provide local and regional communications across metropolitan areas (generally up to 60 miles or more).


This typically includes some variation of the elements below:


1. Line of Sight FM communication systems across one or several bands of the VHF or UHF spectrum, typically in the frequency ranges of 150-174 MHZ, 450-470 MHZ, and 700/800 MHZ.


2. A network system of towers and repeaters across a metropolitan area or region that is usually connected by some form of “wired” communications network that connects the repeaters back to a centralized communications facility.


3. Mobile Radio Systems that are installed in public safety vehicles which also may connect to a multitude of critical devices in the vehicles themselves such as ruggedized computers and other systems.


4. Portable radios known as “handhelds” that emergency responders carry on their person. These handheld radios may transmit directly to the repeater towers or may connect to the mobile radio system in their vehicle which then connects them to the repeater network.


5. Centralized Operations/Dispatch Center-These facilities are often collocated at a 911 PSAP facility, where emergency calls from the public are also directed.

The design above in most cases consists of interdependent systems which is why most emergency communications systems are vulnerable to failure. An interdependent system is a system that depends on another system in order for it to function. Most of our emergency communication systems have many links in the chain that need to work in order for these systems to function. As a result, these systems are only as resilient as their weakest link. For example, any system that depends on a network of any kind is by definition an interdependent system. When a critical node in the network fails (for instance a repeater tower), the entire system can break down.


Repeaters and towers have a long history of failure in extensive emergency or disaster events, particularly natural disaster events. Yet our wide dependence on them in our emergency communications systems across the U.S. is nearly universal. Additionally, there are also hidden interdependent systems that are vulnerable to failure which on the surface may not be as obvious. For instance, any system that depends on any form of infrastructure (including roads) in order to function is also highly vulnerable to failure.


Examples of infrastructure dependent systems include:


1. As above, any system that depends on any form of network - including cellular

networks, repeaters and tower systems or the internet.


2. Any system that depends on the commercial power grid.


3. Any system that depends on roads, such as emergency command centers, mobile command vehicles, or mobile communication vehicles.

An emergency communication system that relies on networks is vulnerable.

4. Any system that depends on fossil fuel such as generators as these are not reliable for sustained operations without refueling. Systems depending on generators are also dependent on roads and the power grid for resupply. Likewise, mobile command vehicles and mobile communication vehicles also depend on refueling for sustained operations.


5. Any system that cannot be isolated from other systems is also vulnerable. The inability of a system to be isolated and protected makes it vulnerable to outside cyber attack from networks or grid systems.


Most of us involved in Emergency Communications Design and operations know intuitively that we have vulnerabilities in our critical communication systems. We attempt to mitigate these vulnerabilities by adding technology to solve known gaps. Many of our Public Safety Communications Systems across the U.S. have simply “evolved” into their current state as they were constructed by adding components piece by piece in an effort to add capability and solve problems within our systems. As a result, very few of these systems have been constructed with a comprehensive architecture where the entire system was designed holistically as very few communities have the financial resources to do so. These components that were added over time often make these systems more complex and can create additional potential points of failure.

So how do we solve the vulnerability problem? To have reliable and resilient communications for any situation, at all times, you need a system that is not dependent on any infrastructure whatsoever, and does not have the same vulnerabilities as our current mainline systems. Augmenting your main Emergency Communications System with such a capability is the most effective and affordable way to ensure you have communications for any situation you encounter.


The ideal system should at a minimum:


1. Not depend on any form of outside power or generator for sustained operations.


2. Be highly portable, easily deployable and tactically nimble.


3. Should not depend on any other infrastructure system in order operate including repeaters, towers, network systems, or roads.


4. Should provide protection from all hazards and critical incidents


About SemperComm® (“Always Communications”)


SemperComm’s Portable Command Center is the only system available today that does not need any infrastructure in order to operate and provides all the mission critical capabilities above. To learn more about our patented Portable Command Center

click here.


SemperComm® Systems is an Emergency Management consulting firm that provides emergency management services and emergency communications products. To learn more about how SemperComm® can meet your needs cl