Glossary of Radio Terms

The Complete Guide to Two-Way Radios & Professional Mobile Radio (PMR)

Glossary of Radio Terms

A Reference Guide to Professional Radio Communication Terminology

Professional radio communications involve a wide range of technical terms, abbreviations and industry-specific language. While many of these expressions are used daily by engineers, system designers and communications professionals, they may be unfamiliar to organisations implementing a radio system for the first time.

This glossary provides clear, plain-English definitions of the most commonly used terms in professional radio communications. It is intended as a practical reference that readers can return to whenever they encounter unfamiliar terminology elsewhere in this guide.

Where appropriate, references are included to related concepts explored in earlier chapters.

A

Accessory Connector

The connection point on a two-way radio used for accessories such as
speaker microphones, earpieces and programming cables. Using the correct
accessory can improve comfort, safety and productivity.

AES Encryption

An advanced encryption standard used to protect digital radio
conversations from being intercepted. AES-256 is commonly used where
secure communications are essential.

Airwave

The secure radio network used by the UK emergency services. It is
separate from commercial business radio systems and is not available for
general business use.

Analogue Radio

A traditional two-way radio that transmits voice as a continuous signal.
While reliable, analogue radios offer fewer features than modern digital
systems.

Antenna

The part of a radio that sends and receives radio signals. The correct
antenna is essential for achieving the best possible coverage.

ATEX Radio

A specially certified radio designed for use in hazardous environments
where explosive gases, vapours or dust may be present. They are commonly
used in oil, gas, chemical and mining industries.

Audio Gain

The amount of amplification applied to transmitted or received audio.
Correct settings help ensure speech is loud and clear without
distortion.

Audio Accessory

An external device such as an earpiece, headset or speaker microphone
connected to a radio. Accessories can improve comfort, privacy and
communication quality.

Auto Roaming

A feature that automatically switches a radio to the strongest repeater
as the user moves between coverage areas. This keeps communication
uninterrupted across larger sites.
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B

Back-to-Back Repeater

A device used to link two radio systems together so users on different
frequencies can communicate. It is often used during temporary events or
migrations.

Base Station

A fixed radio installed in a control room, office or security desk. It
usually offers greater transmit power and better coverage than a
handheld radio.

Battery Eliminator

An accessory that powers a handheld radio directly from a vehicle or
mains supply instead of its battery. It is useful for permanent
installations.

Belt Clip

A clip that allows a handheld radio to be securely attached to clothing
or a belt. It keeps the radio easily accessible while leaving the user’s
hands free.

Bluetooth®

A wireless technology used to connect compatible radios to headsets,
earpieces and other accessories. It removes the need for cables.

Body-Worn Camera

A wearable camera used by security staff, enforcement officers and
frontline workers to record incidents. Many modern systems integrate
body-worn cameras with radio communications.

Broadband

High-speed internet provided through 4G, 5G or Wi-Fi networks. It is the
foundation of Push-to-Talk over Cellular (PoC) communication.

Business Radio

A two-way radio system designed for commercial organisations. Business
radios provide reliable instant communication without relying on mobile
phone calls.

Business Radio Licence

Authorisation issued by Ofcom allowing businesses to use licensed radio
frequencies. Licensed systems generally provide better coverage and less
interference than licence-free radios.

Busy Channel Lockout (BCL)

A feature that prevents a user from transmitting while another
conversation is already taking place on the channel. This helps reduce
accidental interruptions.

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C

Call Alert

A feature that sends an audible or visual notification to another radio
before starting a conversation. It is useful when trying to attract a
user’s attention.

Call Group

A predefined group of users who communicate together on the same channel
or talk group. Only members of that group hear the conversation.

Call Recording

The recording of radio conversations for training, compliance or
incident investigation. Many dispatch systems support automatic
recording.

Channel

A dedicated radio frequency or logical communication path used for
conversations. Different teams often operate on separate channels.

Channel Scan

A feature that automatically checks multiple channels for activity. The
radio stops scanning when it detects a transmission.

Charging Dock

A desktop charger designed to recharge handheld radios or spare
batteries. Multi-unit chargers are commonly used by organisations with
large fleets.

Cloud Dispatch

A cloud-based platform that allows operators to communicate with radios
from almost anywhere with an internet connection. It removes the need
for on-site dispatch hardware.

Cloud Management

The remote configuration and monitoring of communication devices over
the internet. It simplifies administration across multiple locations.

Codeplug

The programming file stored inside a professional radio. It contains
channels, frequencies, button functions and other settings.

Coverage

The geographical area where a radio system provides reliable
communication. Buildings, terrain and repeater locations all affect
coverage.

Cross-Band Repeater

A repeater that receives on one frequency band and retransmits on
another. It can extend communication between different radio systems.

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D

Dead Spot

An area where radio signals cannot be received reliably due to
buildings, terrain or other obstructions. Site surveys help identify and
reduce dead spots.

Digital Mobile Radio (DMR)

An internationally recognised digital radio standard used by businesses
around the world. DMR provides clearer audio, better battery life and
more features than analogue radio.

Digital Noise Suppression

Technology that removes background noise from radio transmissions. It
improves speech clarity in noisy environments such as factories and
construction sites.

Digital Voice Recording

The recording of radio conversations in digital format. Recordings can
be used for training, compliance and reviewing incidents.

Dispatch Console

A computer-based application used to communicate with radio users,
monitor activity and coordinate operations. It is commonly used in
security control rooms and transport centres.

Diversity Reception

A technology that uses multiple antennas or receivers to improve signal
quality. It helps reduce dropped or distorted communications.

Duplex

A communication method that allows transmitting and receiving on
separate frequencies. Most standard Push-to-Talk radios operate in
half-duplex rather than full duplex.

Dynamic Group Call

A feature that allows dispatchers to temporarily create communication
groups without reprogramming radios. It is useful during major incidents
or large events.

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E

Earpiece

A listening accessory that allows radio users to receive messages
discreetly. Earpieces are widely used by security staff, retail teams
and event personnel.

Echo Cancellation

Technology that removes unwanted echoes from voice transmissions. It
improves audio quality when radios are connected to dispatch systems or
broadband networks.

Emergency Alarm

A high-priority alert sent when a user activates the emergency button on
their radio. The alarm can notify other radios, dispatchers or control
rooms immediately.

Emergency Button

A dedicated button found on many professional radios that allows the
user to request urgent assistance. It can trigger an alarm, open the
microphone automatically or send the user’s location.

Emergency Call

A priority voice call that overrides normal radio traffic. It ensures
critical communications get through during emergencies.

Encryption

A security feature that prevents unauthorised users from listening to
radio conversations. Digital encryption is widely used by security
companies, utilities and critical infrastructure.

End-to-End Encryption

A method of securing communications from one radio directly to another.
The conversation remains encrypted throughout the entire transmission
path.

Event Radio Hire

The short-term rental of two-way radios for concerts, festivals,
sporting events, exhibitions and corporate functions. Hiring radios
provides reliable communications without the cost of purchasing
equipment.

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F

Failover

A backup process that automatically transfers communications to
alternative equipment if the primary system fails. It helps keep
businesses connected during faults.

False Alarm Protection

A feature that reduces accidental emergency button activations. This
helps prevent unnecessary disruption to radio users.

Firmware

The internal software that controls how a radio operates. Manufacturers
release firmware updates to improve performance, security and
functionality.

Fleet Management

The administration of multiple radios, users and communication groups
from a central platform. It simplifies programming, monitoring and
maintenance.

Frequency

The radio spectrum used for transmitting communications, normally
measured in MHz. Different frequencies are allocated for different
services and licence types.

Full Duplex

A communication method where users can talk and listen at the same time,
similar to a telephone call. Standard Push-to-Talk radios usually
operate in half-duplex mode instead.

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G

Geo-Fencing

A GPS feature that creates virtual boundaries around a location. Alerts
can be generated when a radio enters or leaves a defined area.

GPS (Global Positioning System)

Satellite technology used to determine the location of compatible
radios. GPS improves worker safety, asset tracking and fleet management.

Group Call

A communication sent to every user within a selected talk group. It
allows teams to coordinate efficiently without contacting each person
individually.

Guard Channel

A dedicated channel reserved for emergency or priority communications.
It is often monitored continuously by supervisors or control rooms.

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H

Half-Duplex

A communication method where users either transmit or receive but cannot
do both simultaneously. This is how most Push-to-Talk radio systems
operate.

Hands-Free Operation

The ability to use a radio without pressing the Push-to-Talk button by
using compatible accessories or VOX. It is useful when both hands are
needed for work.

Headset

An audio accessory that combines headphones and a microphone for clearer
communications. Headsets are commonly used in noisy environments and by
event staff.

Hotspot

A device or smartphone that provides internet access for broadband
communication devices. PoC radios can use hotspots where Wi-Fi is
unavailable.

Hybrid Communication

A solution that combines traditional two-way radio with broadband
technologies such as Push-to-Talk over Cellular. This provides flexible
communications across local and nationwide networks.

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I

Icom

A leading manufacturer of professional two-way radios used across
marine, aviation, business and industrial sectors. Icom products are
known for reliability and robust construction.

Incident Management

The process of coordinating people, communications and resources during
an emergency or operational incident. Modern dispatch systems help
organisations manage incidents more effectively.

Ingress Protection (IP) Rating

An internationally recognised rating that indicates a device’s
resistance to dust and water. Higher IP ratings provide greater
environmental protection.

Infrastructure

The fixed equipment that supports a radio network, including repeaters,
antennas, power supplies and networking hardware. Good infrastructure is
essential for reliable coverage.

Interference

Unwanted radio signals that reduce communication quality or block
transmissions. Proper system design helps minimise interference.

Interoperability

The ability of different radio systems or organisations to communicate
with one another. It is particularly important during large events and
emergency incidents.

Intrinsically Safe Radio

A radio specifically designed for hazardous environments where sparks or
excessive heat could create a risk. These radios are often ATEX
certified.

IP Site Connect

Motorola Solutions technology that links repeaters over an IP network to
provide wide-area communications across multiple locations.

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J

Job Ticket

A work order or task assigned to an employee that may be communicated
using two-way radios or dispatch software. Fast radio communication
helps teams complete jobs more efficiently.

Job Tracking

The monitoring of work progress using radio communications, dispatch
systems or GPS-enabled devices. It improves accountability and
operational visibility.

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K

Kenwood

A leading manufacturer of professional two-way radios used across
business, industry, transport and public services. Kenwood radios are
known for reliability, clear audio and durable construction.

Keypad Radio

A handheld radio fitted with a full or partial keypad for dialling, text
messaging and advanced programming. Keypad models are popular with
supervisors and control room staff.

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L

Latency

The small delay between pressing the Push-to-Talk button and another
user hearing your voice. Modern digital systems keep latency to a
minimum.

Licence-Free Radio

A two-way radio that operates on frequencies approved for public
business use without an individual Ofcom licence. They are ideal for
smaller sites but usually have lower power and shorter range.

Licensed Radio

A professional radio system operating on frequencies assigned by Ofcom.
Licensed systems provide greater coverage, reduced interference and
improved privacy.

Lithium-Ion Battery

The rechargeable battery technology used in most modern professional
radios. It offers long operating times, fast charging and low
maintenance.

Lone Worker

An employee working without direct supervision or immediate assistance.
Many professional radios include dedicated Lone Worker features to
improve safety.

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M

Man Down

A safety feature that detects when a radio has remained tilted or
motionless for a period of time. The radio can automatically send an
emergency alert if the user may be injured.

Marine Radio

A radio designed for communication on rivers, lakes and at sea. Marine
radios operate on dedicated maritime frequencies and are different from
standard business radios.

Mobile Radio

A two-way radio permanently installed in a vehicle such as a van, truck
or forklift. Mobile radios generally provide higher transmit power than
handheld units.

Motorola Solutions

One of the world’s leading manufacturers of professional communication
equipment. Its products are widely used by businesses, emergency
services and public sector organisations.

MOTOTRBO™

Motorola Solutions’ professional DMR radio platform. MOTOTRBO combines
digital voice, GPS, messaging, telemetry and advanced safety features.

Multi-Unit Charger

A charger capable of charging several radios or batteries at the same
time. It is commonly used by organisations with large fleets of radios.

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N

Narrowband

A radio technology that uses less bandwidth than older wideband systems.
Narrowband operation allows more efficient use of available radio
frequencies.

Network

A group of connected radios and supporting infrastructure that allows
users to communicate. Networks may cover a single building or multiple
locations across the country.

Noise Cancellation

Technology that reduces background sounds while preserving speech. It
improves communication in noisy environments such as factories,
warehouses and construction sites.

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O

Ofcom

The UK’s communications regulator responsible for licensing business
radio frequencies and managing the radio spectrum. Most licensed
business radio systems require Ofcom authorisation.

Ofcom Business Radio Licence

A licence issued by Ofcom permitting businesses to operate on assigned
radio frequencies. The licence helps reduce interference and provides
access to higher-powered systems.

Over-the-Air Programming (OTAP)

A feature that allows compatible radios to receive programming updates
remotely over the network. It removes the need to connect every radio
individually.

Over-the-Air Rekeying (OTAR)

A secure method of updating radio encryption keys remotely. It improves
security while reducing administration time.

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P

Paging

A feature that sends an alert tone or notification to a specific radio
or group of radios. It is commonly used to attract a user’s attention
before making a call.

Portable Radio

Another name for a handheld two-way radio. Portable radios are widely
used by security teams, warehouses, construction sites and event
organisers.

Power Output

The transmission power produced by a radio, usually measured in watts.
Higher power can improve communication range, although coverage also
depends on terrain and infrastructure.

Priority Call

A communication feature that gives selected users priority over normal
radio traffic. It helps ensure important messages are delivered quickly.

Private Call

A one-to-one conversation between two individual radios. Other users on
the network cannot hear the discussion.

Professional Mobile Radio (PMR)

A category of two-way radio systems designed for business, industrial
and public sector use. PMR equipment is built for reliable communication
in demanding environments.

Programming Cable

A cable used to connect a radio to a computer for configuration and
software updates. It is used when creating or modifying the radio’s
codeplug.

Push-to-Talk (PTT)

The operating method where a user presses a button to transmit and
releases it to listen. Push-to-Talk provides instant communication
without dialling a telephone number.

Push-to-Talk over Cellular (PoC)

A communication technology that uses 4G, 5G or Wi-Fi instead of
traditional radio frequencies. PoC enables instant nationwide or
international communications wherever network coverage is available.

Pseudo Trunking

A DMR feature that automatically assigns users to an available channel
without the need for a full trunked radio system. It improves channel
efficiency on busy networks.

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Q

Quality of Service (QoS)

A networking feature that prioritises voice traffic over other types of
data. It helps maintain clear and reliable communications on
broadband-based systems.

Queue Call

A feature available on some dispatch platforms that places incoming
requests into an organised queue. This helps operators manage high
volumes of radio traffic efficiently.

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R

Radio Check

A short test transmission used to confirm a radio is working correctly.
It is commonly carried out before the start of a shift or event.

Radio Frequency (RF)

The section of the electromagnetic spectrum used for wireless
communications. Two-way radios transmit and receive signals using
allocated RF frequencies.

Radio Hire

The short or long-term rental of two-way radios instead of purchasing
them. Radio hire is ideal for events, construction projects, seasonal
work and temporary operations.

Radio Programming

The process of configuring a radio with channels, talk groups,
frequencies and user settings. Programming ensures every radio operates
correctly on the intended system.

Radio System

A complete communication solution consisting of radios, repeaters,
antennas, software and supporting infrastructure. Systems can be
designed for a single site or nationwide operation.

Receiver

The part of a radio that receives incoming transmissions. Modern digital
receivers provide excellent sensitivity and clear audio.

Remote Speaker Microphone (RSM)

An accessory that combines a speaker and microphone into a single unit
worn on the shoulder or lapel. It allows users to communicate without
removing the radio from their belt.

Repeater

A fixed device that receives, amplifies and retransmits radio signals to
extend communication range. Repeaters are commonly used to provide
reliable coverage across large buildings and wide geographical areas.

Roaming

A feature that allows compatible radios to move automatically between
repeater sites without losing communication. Roaming is particularly
useful for organisations operating across multiple locations.

Rugged Radio

A radio designed to withstand harsh environments, including impacts,
vibration, dust and water. Rugged models are popular in construction,
logistics and utilities.

RSSI (Received Signal Strength Indicator)

A measurement showing how strong a received radio signal is. It can be
used to assess coverage and troubleshoot communication issues.

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S

Scan List

A group of channels programmed into a radio for automatic scanning.
Users can monitor several departments without manually changing
channels.

Security Radio

A professional two-way radio used by security personnel to coordinate
patrols, respond to incidents and communicate discreetly. Many include
emergency and lone worker features.

Selective Calling

A feature that allows one radio to contact another specific radio or
group without broadcasting to every user. This helps keep communications
organised.

Simplex

A communication method where radios communicate directly with one
another without using a repeater. Simplex is ideal for smaller sites
where coverage is sufficient.

SIM Card

A card used in Push-to-Talk over Cellular radios to access mobile data
networks. It enables nationwide communications using 4G or 5G coverage.

Site Survey

A technical assessment carried out before installing a radio system. It
identifies coverage requirements, potential interference and the best
locations for equipment.

Speaker Microphone

An external accessory combining a microphone and loudspeaker in one
unit. It allows users to keep their radio securely attached to a belt or
vest.

Spectrum

The range of radio frequencies available for wireless communications.
Ofcom manages the allocation of spectrum within the UK.

Subscriber Unit

A general term for an individual radio connected to a communication
system. Subscriber units include handheld and vehicle-mounted radios.

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T

Talk Group

A virtual communication group that allows selected users to communicate
together without involving the entire network. Talk groups improve
organisation and efficiency.

Telemetry

The remote monitoring and transmission of equipment or sensor data over
a communication network. It can be used to monitor machinery, alarms and
infrastructure.

Time Division Multiple Access (TDMA)

A digital technology used by DMR systems that allows two conversations
to share a single radio frequency. This doubles channel efficiency
without requiring additional spectrum.

Transceiver

A device that combines both a transmitter and receiver into a single
unit. Every modern two-way radio is a transceiver.

Transmission

The act of sending voice or data from one communication device to
another. Clear transmissions are essential for safe and efficient
operations.

Trunked Radio System

A radio system that automatically allocates available channels to users.
Trunking improves efficiency for organisations with large numbers of
radio users.

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U

UHF (Ultra High Frequency)

A section of the radio spectrum commonly used for business
communications. UHF performs well indoors and in built-up environments.

User ID

A unique digital identity assigned to each radio on a communication
network. It allows users and dispatchers to identify who is
transmitting.

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V

Vehicle Charger

A charger designed to power or recharge radios while travelling in a
vehicle. It is commonly used by transport and field service teams.

VHF (Very High Frequency)

A section of the radio spectrum often used in open rural environments
where signals can travel longer distances. VHF is also widely used in
marine communications.

Voice Activation (VOX)

A feature that automatically transmits when the user speaks, removing
the need to press the Push-to-Talk button. VOX is useful when both hands
are occupied.

Voice Announcement

An audible prompt that confirms channel changes, battery status or other
radio functions. Voice announcements improve usability without looking
at the display.

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W

Walkie Talkie

A common name for a handheld two-way radio. Modern professional walkie
talkies offer digital audio, GPS, encryption and advanced safety
features.

Warehouse Radio

A two-way radio system used to improve communication between warehouse
staff, supervisors and forklift operators. Reliable communications help
improve efficiency and safety.

Wide Area Network (WAN)

A network connecting multiple sites across a large geographical area.
WAN connectivity is often used to link radio infrastructure and dispatch
systems.

Wi-Fi

A wireless networking technology that provides internet access for PoC
radios and cloud-based communication systems. It can reduce reliance on
mobile data indoors.

Worker Safety

A collection of radio features designed to protect employees working in
hazardous or isolated environments. These may include Lone Worker, Man
Down, GPS tracking and emergency alerts.

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Z

Zone

A collection of channels grouped together within a radio. Zones make it
easier for users to organise communications by site, department or
operation.

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The Complete Guide to Two-Way Radios & Professional Mobile Radio (PMR)