Glossary of Amateur Radio Terms #

Welcome to the amateur radio glossary! Here you’ll find definitions for common terms used in the amateur radio community and throughout this book. Understanding these terms will help you communicate effectively with other hams and better comprehend technical discussions.

A #

Amateur Radio #

A radio communication service used by licensed operators for personal communication, technical exploration, emergency communication, and public service. Governed by the FCC in the United States, amateur radio operators (hams) use various frequency bands and modes to communicate locally and globally.

APRS (Automatic Packet Reporting System) #

A digital communication system that allows amateur radio operators to transmit position data, weather information, and short text messages. It provides real-time tactical communications with mapping capabilities. Discussed in Section 3.6.

ARES (Amateur Radio Emergency Service) #

A volunteer organization for emergency communications. Discussed in Section 7.3.

B #

Beacon #

An amateur station that transmits communications for the purpose of observing propagation or related experimental activities. These stations typically send out periodic signals to help operators understand radio wave propagation characteristics.

Band Plan #

A voluntary guideline for using different modes or activities within an amateur radio band. While not legally binding, band plans help operators efficiently share limited spectrum resources.

C #

CTCSS (Continuous Tone-Coded Squelch System) #

A sub-audible tone transmitted along with voice audio to open the squelch of a receiver. Often called “PL” (Private Line), it helps prevent interference and unwanted repeater activations.

CW (Continuous Wave) #

Another term for Morse code transmission. Despite its name, it’s not truly continuous but a method of communication using on-off keying of a radio signal.

It was originally called Continuous Wave to differentiate it from the raspy square waves generated by spark-gap transmitters. Over time, it came to be associated with Morse Code, although spark-gap transmitters also used Morse Code.

D #

Digital Mobile Radio (DMR) #

A digital voice and data radio technology that uses time-division multiple access (TDMA) to allow two voice channels in a single 12.5 kHz channel bandwidth.

Doppler Shift #

An observed change in signal frequency caused by relative motion between a satellite and an Earth station. As a satellite approaches, the frequency appears higher; as it moves away, it seems lower.

DTMF (Dual-Tone Multi-Frequency) #

A method of signaling that uses pairs of audio tones to send commands, often used in repeater systems and internet-linked radio networks.

When first used, Western Electric called it TouchTone (TM), but since other manufacturers couldn’t call it by its trade-marked name, they referred to it as DTMF.

F #

Frequency Coordinator #

A volunteer or volunteer group recognized by local amateur operators who recommends transmit/receive channels and other parameters for auxiliary and repeater stations.

H #

HF (High Frequency) #

The radio frequency band between 3 and 30 MHz, known for long-distance communication through ionospheric propagation.

I #

IRLP (Internet Radio Linking Project) #

A system that connects amateur radio systems via the internet using Voice Over Internet Protocol (VoIP), allowing worldwide communication through linked repeaters.

L #

LEO (Low Earth Orbit) #

A satellite orbit relatively close to Earth’s surface, typically between 100 and 1,200 miles above the planet.

M #

Modulation #

The process of combining speech or data with a radio frequency carrier signal. Different types include AM (Amplitude Modulation), FM (Frequency Modulation), and SSB (Single Sideband).

P #

Packet Radio #

A digital communication mode where information is transmitted in small packets of data, similar to how internet data is transmitted.

Part 97 #

Shorthand for the Code of Federal Regulations, Title 47, Chapter I, Part 97. Part 97 defines the Amateur Radio service and sets the rules and regulations which govern it.

Propagation #

The way radio waves travel from a transmitting antenna to a receiving antenna. Different bands and frequencies have different propagation characteristics.

R #

RACES (Radio Amateur Civil Emergency Service) #

An amateur radio service specifically for civil defense communications during national emergencies, operating under governmental authority.

Repeater #

An amateur radio station that receives signals on one frequency and simultaneously retransmits them on another frequency, extending communication range.

RF (Radio Frequency) #

Electromagnetic waves used for wireless communication, typically ranging from 3 kHz to 300 GHz.

S #

Simplex #

A communication mode where stations transmit and receive on the same frequency.

Space Station #

An amateur radio station located more than 50 km above Earth’s surface, typically a satellite.

SSB (Single Sideband) #

A type of amplitude modulation that carries information on a single sideband of the carrier frequency, allowing more efficient use of radio spectrum.

SWR (Standing Wave Ratio) #

A measure of how well a load (like an antenna) is matched to a transmission line, indicating the efficiency of power transfer.

T #

Telecommand #

A one-way transmission to initiate, modify, or terminate functions of a device at a distance.

Telemetry #

A one-way transmission to report measurements collected at a distance.

Third Party Communications #

A message transmitted by a control operator of an amateur station to another amateur station’s control operator on behalf of another person.

U #

ULS (Universal Licensing System) #

The FCC database where licenses are recorded. An amateur radio license is valid as soon as it appears and is active in the ULS.

V #

Vanity Call Sign #

A custom call sign chosen by a licensed operator. See Section 8.1.

VHF (Very High Frequency) #

The radio frequency band between 30 and 300 MHz.

VoIP (Voice Over Internet Protocol) #

A method of delivering voice communications over the internet using digital techniques.

Special Codes and Abbreviations #

73 #

A traditional ham radio sign-off meaning “best regards” or “goodbye”.

88 #

A friendly sign-off meaning “love and kisses”, often used between hams who know each other well.

CQ #

A general call meaning “seeking contact with any station”.

QRM #

Interference from other radio stations.

QRN #

Atmospheric or natural static interference.

QRZ #

“Who is calling me?”

QSL #

Acknowledgment of receipt or understanding.

QSY #

Changing to a different frequency.