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Basic public safety communications and interoperability

By Capt. Eddie Reyes
Sponsored by Cisco Systems

I am honored that PoliceOne.com and Cisco Systems have chosen me to contribute monthly columns focused on law enforcement communications technology. Next to helping others, training is a very big part of what I believe in. So I'm very excited about sharing the wealth of information I have managed to gather in the past 16 years of being a police officer, the last five really focusing on communications technology projects.

I thought that since this was my inaugural article, I would start with the basics and establish a solid foundation on communications projects upon which we will be building more comprehensive and robust solutions.

One of the myths I have uncovered is that most communications subject matter experts know all the basics. I have been surprised by some real veterans in this field who still share with me that they learned something I thought was common knowledge.

Therefore, let's start with some key points in the world of public safety communications and interoperability:

Key Points

• Focus on operability before interoperability. That is, optimize your agency's radio system first before attempting to become interoperable with another.

• Effective human interaction between agencies is critical before embarking on any interoperability solution.

• Remember that there are three basic interoperability solutions that cost nothing or very little:


    1. Pre-program all mobile and portable radios with national interoperability channels in all frequencies (usually no infrastructure involved or required)
    2. Share radio frequencies with neighbors on compatible radio systems (conventional or trunked radio systems); and
    3. Drop most radio codes and adopt plain English communications for day-to-day transmissions. Remember, in an emergency, an agency will "play like they practice". Encourage mutual aid regularly using radio communications.

Public Safety Communications

This is the most used tool in any public safety agency's arsenal yet the tool that is least formally trained with and often suffers the most amount of criticism after any major event.

Today's public safety radio systems can be very complex and very expensive to upgrade and/or replace, so it's no wonder that whenever you talk with political leaders or department heads about public safety radio systems they will tell you that they can't afford them or are too difficult to manage. Because today's first responders are challenged with greater events, they have come to rely on sophisticated safety features commonly provided by most radio vendors, such as emergency notification, "caller identification", and multiple channels or talk groups for a single incident.

By understanding a few simple terms that the public safety radio community often takes for granted, a decision maker with limited understanding of the complex issues at the surface level, can make very informed decisions. There are three primary reasons why public safety agencies cannot communicate seamlessly still today.

First, there are four distinctive frequency bands that are used primarily by public safety across the United States and most radio manufactures only produce single band radios. Therefore, an agency with a VHF low radio system will usually only be able to communicate with another agency using radios in the same range (providing common frequencies have been pre-programmed in the radios).

The four primary public safety bands are:

1. VHF Low which operates in the 30 - 40 MHz range (commonly referred to as "Low Band");

2. VHF High which operates in the 152 - 162 MHz range;

3. UHF which encompasses 406-512 MHz;

4. 800 MHz operations.

It should be known that the public assumes that public safety across disciplines and jurisdictions can talk to each other seamlessly during a mutual aid event. The reality is that in many jurisdictions today, a police department and fire department from the same municipality are on different radio systems and often cannot communicate with each other via radio during the event.

The second primary reason public safety agencies cannot communicate seamlessly is that still today, even when agencies are using radio systems in the same frequency range, some radio manufacturers are not compatible with others and first responders are unable to communicate.

Therefore, a bridging device, or gateway, is needed to connect disparate radio systems that are operating in the same frequency range. I will dedicate another article entirely to gateways later as some can be very complex and are often misunderstood.

My experience has shown that lack of formal training with these devices is a major culprit. Some regions have adopted a cache of radios as a solution. Like any other solution, caches of radios have many pros and cons.

The biggest positive attribute is that it will serve well when first responders from other agencies arrive without a radio to assist in a mutual aid event.

The negative attributes are:

1. If there are no bridging devices, this means one more radio for a first responder to carry;

2. It takes time to know how to operate a new radio and feel comfortable with it, so most first responders are not comfortable with a new radio; and

3. If the incident is an emergency, unless there are plenty of charged batteries ready for use, it may be a few hours before the cached radios can be deployed for use.

Deciding on a cache of radios is not as easy as you may think because there are many issues and options to consider. I spearheaded a major radio cache procurement process in the National Capital Region (NCR) and was surprised by the complexity of this process. I will dedicate another article to cache radios later.

Finally, when all the technical barriers are removed and the radios are able to communicate with one another, if agencies have not adopted a common language ("plain English") for all first responders in the area, there may still exist a failure to communicate at the human level, as proprietary radio codes can make a very busy scene even more confusing.

It is strongly recommended that public safety agencies adopt plain English radio communication for day-to-day use so that it becomes seamless to communicate with other first responders at a mutual aid event.

Political leaders and department heads must first make a sincere commitment to attain the best possible radio system for their municipality or agency and accept that the public expects them to communicate with their neighbor during a major event.

Different Types of Radio Systems and Features.

Radio system planners may need to conduct a wide range of comparative analyses to determine the type of system that is most appropriate for their environment and requirements. Planners in public safety agencies need to consider, in addition, the special requirements imposed by their mission and operations:

• Simplex or line-of-sight

This type of radio communication does not rely on any infrastructure or major costs, such as repeaters or tower antennas.

In this mode of communication, first responders simply communicate from one radio to another providing that the exact frequencies have been pre-programmed in each of the radios (mobile and portable). This is commonly referred to as "talk-around" mode.

The significant drawback to this type of radio operation is that it only provides radio coverage in a very limited area, such as one city block. While this is inefficient for dispatch operations, simplex operations are used extensively for fire ground, and often for law enforcement special operations, where in-building signal penetration, or operational security is critically important.

Both conventional and trunked radio repeater systems often provide a talk around capability that operates on frequencies that bypass the repeater infrastructure.

• Conventional Radio System

A conventional radio repeater system is simply a system where a radio repeater, installed in a location with line of sight to a large geographic area is shared among a number of users.

A repeater system extends the line of sight operating range of communications beyond that achievable directly between users on the ground. Conventional radio repeater systems can be either analog or digital.

A conventional radio repeater system typically consists of one or more channels, each made up of a pair of frequencies (input & output) and a user selects the frequencies being used by changing channels on his or her radio.

Conventional radio repeater systems are inefficient when used by a large number of users.

• Trunked Radio System

A trunked radio repeater system operates using the same fundamental principles that a conventional system does, with the exception that a computer connected to a control channel controls operating frequencies.

The system automatically recognizes a user's radio and assigns privileges based on information contained in a database.

When a user presses the push-to-talk button on a radio, the radio "requests" permission to transmit. If granted, the system allocates frequency resources and directs the user radio to available frequencies.

In a trunked radio system, when a user selects a channel, the user is actually selecting a set of privileges that he is authorized to communicate with. The computer retains this information in a database. A group of users with common privileges is commonly referred to as a "trunk group".

The user's request to participate in trunk group is automatically conveyed to the system via the control channel, and all other group participants are also automatically directed to operate at the proper frequencies.

Trunked radio systems make orders of magnitude more spectrally efficient, supporting many more users via fast computer control of the same frequency resources. They are also generally much more complex and costly to operate than conventional radio repeater systems.

I hope this information has been beneficial and I look forward to hearing from you with any comments or concerns you may have in your region.

Special thanks to Mr. Phil Harris from the National Law Enforcement and Corrections Technology Center-Northeast in Rome, NY (NLECTC - NE)

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