Ch2 Set 03: Radio Systems: Classification, Communication

How can radio systems be classified?

By their location and size, as well as their signal transmission arrangements.

What do radio systems provide for different kinds of traffic?

Transmission channels that can be assigned to emergency or nonemergency communications.

What is direct radio communication?

Communication in which a radio signal travels directly from the transmitting radio to the receiving radio.

How do users take turns during direct radio communication?

One person finishes speaking before the next person presses the talk button and responds.

What shared-channel limitation exists for direct communication?

While one group is communicating, other groups farther away cannot use that same channel at the same time.

What are the purposes of repeated radio communications?

Strengthening signals between radios, increasing transmission distance, or increasing system capacity.

Why might pressing the push-to-talk button not immediately allow a firefighter to speak?

Heavy system use may delay access, and the radio may sound a tone until it is ready.

What is a dispatch channel used for?

Dispatching units, often on a channel dedicated to that function.

Who is assigned a command channel at an incident?

The Incident Commander, or IC.

What is a tactical channel used for?

Fireground operations.

How may channel assignments change as an incident grows?

Command and tactical channel assignments may expand as the incident becomes more complex and additional agencies participate.

What activities may use nonemergency radio channels?

Training, code enforcement, and administrative activities.

Who regulates the use of nonemergency radio channels?

The Authority Having Jurisdiction, or AHJ.

What major factors can limit radio communications?

Distance, physical barriers, dead zones, interference, and ambient noise.

What factors affect how far a radio signal can travel?

The power of the transmitting and receiving equipment and the height of the transmitting and receiving antennas.

How can radio coverage be increased?

By using repeaters.

What may static and broken radio messages indicate?

The receiving radio is near the limit of the transmission range.

How can physical barriers affect radio signals?

They can completely block, partially block, or reflect signals.

What communication problem may occur in tunnels, basements, or structures?

Firefighters may communicate with one another through talk-around but be unable to reach the IC or communications center.

How can a firefighter's body affect radio communication?

It can act as a physical barrier to the signal, especially inside a structure.

What adjustments may help overcome physical barriers to radio signals?

Turn your body 90 degrees, lift the radio higher, and raise the antenna into a straight, upright position.

What is a radio or cellular dead zone?

A remote area or location inside a structure where radio signals or cellular service are lost.

What equipment may be installed in a building to reduce dead zones?

Repeaters.

Where might reception improve when a firefighter is in a dead zone?

Near an outside wall, roof, window, or doorway.

When should radio checks inside buildings be performed?

During preincident planning by inspectors or other fire service personnel.

What is the purpose of radio checks during preincident planning?

To verify whether radios work in all areas of the building.

What communication alternatives may be needed in large metal or concrete buildings?

Runners or other communication methods if radios do not work.

Can direct radio communication still be possible within a dead zone?

Yes, nearby radios may still communicate directly even when other radio links are unavailable.

What radio-related sources may cause interference?

Other powerful radio signals, cellular towers or transmitters, and high-power radio sites.

What electrical or electronic equipment may cause radio interference?

Vehicle ignitions, electric motors, high-voltage transmission lines, computers, and equipment containing microprocessors.

How do manufacturers help reduce radio interference?

By designing transmitters, receivers, and repeaters that filter out interference.

What responsibility does the department or AHJ have when purchasing radio equipment?

Specify and purchase the best-quality radio systems available within its resources.

What is ambient noise, and how does it affect radio communications?

Background sound at the scene that can make messages difficult to hear or understand.

What technology may help reduce ambient noise during radio transmission?

Noise-canceling microphones.

Who is responsible for overcoming ambient noise when transmitting?

Each radio operator.

How can apparatus and equipment noise be reduced during radio communication?

Turn off audible warning devices when they are not needed and move away from noisy equipment when transmitting.

How can a firefighter reduce wind noise during radio transmission?

Move to a sheltered location or use the body or PPE as a wind barrier.

What general practice remains important when communicating in a noisy environment?

Follow established radio procedures at all times.