Keep a reference nearby

Radio terms explained

A short explanation can make an unfamiliar instruction easier to follow. These definitions introduce the terms you will meet around the site. Equipment manuals and current operating rules provide the detail for a particular station.

Access tone: A low audio tone sent with your voice to let a repeater recognize your transmission. The required setting is listed by the repeater operator; it does not make the conversation private.
Activation: Operating from a qualifying place in a program such as POTA or SOTA. The program defines what makes an outing count.
ALC: Automatic level control: a radio circuit that limits drive or output. Follow the radio and digital-mode software instructions when setting audio levels; excessive drive can distort a transmitted signal.
AM: Amplitude modulation: a way of carrying information by varying signal strength. AM is used for broadcast radio and some amateur voice activity.
Antenna analyzer: An instrument that sends a small test signal and measures how an antenna system responds. Disconnect the transmitter before attaching it.
APRS: Automatic Packet Reporting System: a system for sharing short reports such as station position, weather and messages. Some reports travel through radio and internet-connected gateways.
Band: A range of radio frequencies. Names such as 20 meters describe approximate wavelength; that amateur band is near 14 MHz. Your license determines where and how you may transmit.
Bandwidth: The range of frequencies a signal occupies. Your complete signal needs to fit within the frequency and emission limits that apply to your license.
Beacon: A station that sends a recognizable signal to help others check reception or propagation. Some beacons run on schedules or assigned frequencies.
Calibration: A procedure that checks or corrects an instrument against known references. For antenna measurements, the cable and adapters used during calibration affect what the result includes.
Callsign: The identifying letters and numbers assigned to a licensed radio station or operator. Operators exchange callsigns during contacts and use them to identify on the air.
CAT control: Computer-aided transceiver control: a connection that lets software read or change radio settings such as frequency and mode.
Coax: Coaxial cable: a feed line with a center conductor surrounded by insulation and an outer shield. It is commonly used between radios and antennas.
Contact / QSO: A radio exchange between stations. Operators often record the other callsign, time, frequency and mode in a log.
Contest: An organized operating event with rules about which contacts count and what information stations exchange.
CQ: A general call inviting any station to answer. On an ordinary local FM repeater, giving your callsign and saying you are listening is more common.
CW: Continuous wave: the mode commonly used to send Morse code by switching a radio signal on and off. Operators hear the pattern as short and long tones.
Digital modes: Methods that encode information so software or other electronics can recover it. Some carry typed conversations, while others exchange short reports or position data.
Doppler shift: A change in received frequency caused by motion between stations. Satellite operators may adjust tuning as a satellite approaches and moves away.
Downlink: The signal traveling from a satellite to a station on Earth. Listening to this signal is a useful first step in satellite radio.
DX: A shorthand for distant radio communication. What counts as distant depends on the band and how the signals travel.
DXCC: DX Century Club: an ARRL award program based on confirmed contacts with designated geographic entities. An entity is not always the same thing as a political country.
EIRP: Equivalent isotropically radiated power: power after accounting for antenna gain relative to an ideal antenna that radiates equally in every direction, and relevant losses.
Emission: The kind of radio signal a station transmits. FCC permissions can distinguish voice, data, images and other emission types within a band.
ERP: Effective radiated power: power after accounting for antenna gain relative to a half-wave dipole and relevant feed-line losses. A transmitter power setting alone does not establish ERP.
Feed line: The cable or line carrying radio energy between the radio and antenna. Cable type, length and connections affect loss and measurements.
Firmware: Software stored in a device such as a radio. Before updating it, read the device instructions and back up settings where supported.
FM: Frequency modulation: a way of carrying information by varying a signal frequency. FM voice is common on local handheld and repeater radio.
Frequency: How many cycles a radio wave completes each second. Tuning changes the frequency your radio receives or transmits.
FT4: A digital mode for short, structured contacts with faster transmit and receive sequences than FT8. It is often used where contact speed matters.
FT8: A digital mode for short, structured contact exchanges that software can decode from weak signals. It is not intended for a free-form typed conversation.
Gateway: A station or service that passes information between systems, such as a radio message network and the internet.
Grid square: A short code from the Maidenhead locator system that describes a position on Earth. Longer codes identify smaller areas.
Ham radio: Radio used by licensed individuals for personal communication, learning and experiments. A ham is an amateur radio operator.
HF: High frequency: the radio range from 3 to 30 MHz, often called shortwave. Some HF signals can travel far beyond the horizon through the ionosphere.
Hz: Hertz: one cycle per second, the unit used to describe frequency.
Impedance: How a circuit opposes alternating current, including radio signals. Many radios and coax cables are designed around a 50-ohm impedance.
Ionosphere: A region high in the atmosphere containing electrically charged particles. It can bend some radio waves back toward Earth and make long-distance HF contacts possible.
JTTY: A newer digital mode for keyboard conversations and contest exchanges, available in WSJT-X development versions. Check the current release documentation and frequency recommendations before using it.
kHz: Kilohertz: one thousand cycles per second. One MHz equals 1000 kHz.
Line of sight: A path that is relatively unobstructed between stations. Hills and buildings can reduce coverage, especially for local VHF and UHF operation.
Logging: Keeping a record of radio contacts. A log may include callsign, date, time, frequency and mode. An entry alone does not mean the other operator has confirmed it.
LSB: Lower sideband: an SSB setting that uses frequencies below the suppressed carrier. It is commonly used for amateur voice on 80 and 40 meters.
MHz: Megahertz: one million cycles per second. For example, 14.074 MHz is the same frequency as 14,074 kHz.
Mode: The method used to carry information over radio. Voice, Morse code and computer-decoded messages use different modes, with different equipment and bandwidth needs.
Net: An organized on-air gathering, often at a scheduled time. A net-control operator may invite each station to check in and take a turn.
Offset: A frequency difference. For a repeater, it is the difference between your transmit and receive frequencies. In digital-mode software, an audio offset places your signal above or below the radio dial setting.
Packet radio: A way of sending digital information in small, addressed groups called packets. Amateur uses include position reporting and message forwarding.
PCB: Printed circuit board: a board with conductive tracks that connect electronic components.
PEP: Peak envelope power: a way of specifying transmitter power at the peaks of a modulated signal. It is different from average power.
Portable operating: Using a radio station away from its usual fixed location, often with a temporary antenna and battery power.
POTA: Parks on the Air: a program for making contacts from listed parks or contacting the operators there. Check the program rules and the park rules before an outing.
Propagation: How radio waves travel from a transmitter to a receiver. Frequency, terrain, time of day and conditions high in the atmosphere can change what you can hear.
PSK: Phase-shift keying: a way of encoding digital information in a radio signal. PSK31 is one amateur mode used for typed conversations.
QSL: Confirmation of a radio contact. It can be a card or an electronic record, depending on the service or award rules.
Repeater: A station that receives a signal and retransmits it, usually on a different frequency. A well-placed repeater can let small radios communicate over a larger area.
Resonance: In an antenna, resonance is where the reactive parts of its input impedance cancel. A resonant antenna can still need matching to the radio and feed line.
RF: Radio frequency: the part of the electromagnetic spectrum used for radio signals. In station instructions, RF usually means the signal going to or coming from the antenna.
RF exposure: The radio-frequency energy reaching a person. A station assessment considers factors such as power, antenna gain, distance and how long the station transmits.
RST: Readability, strength and tone: a traditional signal-report system. Voice reports generally use readability and strength; the tone part is used for Morse signals.
RTTY: Radio teletype: a digital method for sending text, traditionally using a pair of tones. Operators use it for conversations and contest exchanges.
Satellite pass: The period when a moving satellite is within view of a location. Tracking predictions give times and directions; they do not prove the satellite radio is operating.
Schematic: A diagram that uses symbols to show electrical connections. It describes the circuit, rather than the physical placement of every part.
SDR: Software-defined radio: a radio in which software handles much of the signal processing. A public web receiver lets you listen through a remote antenna using your browser.
Sideband: A group of frequencies produced when a radio signal carries information. Single-sideband voice uses either the upper or the lower sideband.
Signal report: A description of how well a station is being received. On local voice radio, plain language such as clear but weak is often more useful to a beginner than a number.
Simplex: Direct radio communication between stations on the same frequency, without a repeater relaying the conversation.
SNR: Signal-to-noise ratio: how a signal compares with background noise in a specified measurement bandwidth. Reports made with different methods may not be directly comparable.
SOTA: Summits on the Air: a program for contacts from qualifying summits and for contacting those operators from elsewhere.
Spectrum: A range of frequencies. A spectrum display shows where signals are present and their relative strength at a particular moment.
Spot: A report that a station was heard or is operating on a particular frequency. A spot can become outdated when the station changes frequency or stops.
SSB: Single sideband: a voice mode common on the HF amateur bands. Choose the correct upper or lower sideband setting so speech sounds intelligible.
SSTV: Slow-scan television: sending still pictures over radio. A picture takes time to build up and is usually decoded with software.
SWR: Standing wave ratio: a measure of mismatch on an antenna feed line at the point being measured. A ratio closer to 1:1 means less reflection there. Low SWR alone does not show how well an antenna radiates.
TNC: Terminal node controller: hardware or software that handles packet-radio information between a computer and a radio.
UHF: Ultra high frequency: 300 to 3000 MHz. It includes the 70-centimeter amateur band used by many handheld radios and repeaters.
Uplink: The signal traveling from a station on Earth to a satellite. Its frequency may be different from the downlink.
USB: In radio mode settings, USB means upper sideband. On computer connectors and cables, USB means Universal Serial Bus. The surrounding instructions tell you which meaning applies.
UTC: Coordinated Universal Time: the shared time reference used in radio logs and schedules. It avoids confusion between local time zones.
VHF: Very high frequency: 30 to 300 MHz. The 6-meter, 2-meter and 1.25-meter amateur bands are here. Terrain and antenna height often affect local coverage.
VNA: Vector network analyzer: an instrument for measuring how radio-frequency circuits reflect or pass a test signal. A NanoVNA is a small version commonly used for antenna experiments.
Waterfall: A scrolling display of radio activity. Position shows frequency, color usually shows signal strength, and the scrolling direction shows time.
WSPR: Weak Signal Propagation Reporter, pronounced whisper. Stations send short beacon messages, and receivers report where those signals were heard. It is used to study radio paths, not for a conversation.

Read further

For operating procedures and technical background, see the ARRL new ham resources, RSGB introduction to amateur radio and All About Circuits textbook. The WSJT-X User Guide explains its digital modes. Check the US band plan reference and current FCC rules before transmitting.

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