Dictionary of Ham Radio Terms

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A
AC : Alternating Current

ADC : Analogue to Digital Converter. Also known as A/D and A-to-D. A device that samples an analogue wave and converts it inot a digital signal, in which a series of numbers id used to represent the amplitude of the original wave.

Admittance : The reciprocal of impedance of a component in a series or parallel tuned circuit.

AF : Abbreviation for Audio Frequency. AF is in the range 20Hz to 20 000Hz

AFC : Automatic Frequency Control - used to prevent drift in FM receivers

AGC : Automatic Gain Control - a feedback system to reduce fading by automatically adjusting gain

ALC : Automatic Level Control - a feedback system in the transmitter output amplifier used to prevent overload.

 Ampere :(A) The unit used for measurement of current. Usually abbreviated to Amps

Amplitude : the height of a wave from the average or median position.

AMSAT : The name for amateur radio satellite organizations world-wide, but in particular the Radio Amateur Satellite Corporation.

Analog (also analogue): a continuously varying signal.

 Antenna: a device to either radiate radio signals or to receive them from another station.

Antenna Switch " A switch used to change the output of a transceiver from one antenna to another.

Antenna Tuner : A device used to match the output impedance of a transmitter to that of an antenna.

Amplifier : A device that is used to increase voltage, current or power.

AMTOR : A specialised form of RTTY protocol. An acronym for AMateur Teleprinting Over Radio or AMateur Teletype over Radio.

ARC : Amateur Radio Club (also ARA, ARS - Amateur Radio Association, Amateur Radio Society) - usually prefixed by the name of the community or region served

ARDF : Amateur Radio Direction Finding

ARES : Amateur Radio Disaster Services, Amateur Radio Emergency Services

ARRL : The American Amateur Radio League - the national ham radio association for the USA

APRS : Automatic Position Reporting System, Automated Packet Reporting System.

 Attenuator : A resistive device to reduce the amplitude or power of a signal.

ATV : Amateur Television - "moving picture" ham TV transmissions.

Az/El : used to describe an antenna rotator that can change both the Azimuth (horizontal) and the Elevation (vertical) direction of the antenna.

B
Balun : A passive electronic device that converts between balanced and unbalanced electrical signals using some form of electromagnetic coupling.

Balanced Line : parallel conductors at equal and opposite potentials. Neither conductor is at ground potential.

Bandpass (also Passband): the range of frequencies that a certain filter allows to pass.

Base Station : A ham station that has a fixed location

 Bandpass Filter : a filter designed to pass a certain range of frequencies.

Band : The portions of the Electromagnetic Spectrum that are allocated to ham radio operators.

Baud : The rate of transmission - in symbols per second, of digital data. The number of times a transmitted digital signal changes per second. In the one special case where data is transmitted one bit at a time serially, the baud rate will match the bps rate.

 Beacon : A station that transmits signals either continuously or on a timed basis, for location and propagation purposes.

BFO : Beat Frequency Oscillator. An oscillator that is mixed with an incoming signal at the detector to produce an Audio Frequency (AF) tone for CW reception. In SSB operation, the beat frequency oscillator must replace the carrier which was suppressed when the signal was originally transmitted.

Bird : Slang term for an amateur or communications satellite.

Boat Anchor : A slang term used to describe obsolete ham radio gear - often applied to old transceivers.

BNC : A push-and-turn locking coaxial connector commonly used with VHF/UHF transceivers, as well as oscilloscopes and test equipment.

BPS : Bits per second, the rate at which digital data is transmitted. The number of characters transmitted per second will be a sub-multiple of this figure (for instance, if a character is sent with 8 data bits, 1 start bit, 1 stop bit, the number of actual characters transmitted per second would be one tenth the bps rate).

BPSK : (Binary Phase Shift Keying). A digital modulation method for transmitting data.

Bureau (also Burro) : An organization set up to process QSL cards between amateurs.

C
Callsign A unique identifier for each radio amateur and licensed radio station throughout the world

Capacitor : A passive electronic component composed of two conducting plates separated by a dielectric (insulating material).

Capacitive Hat : Also known as a capacity hat. A system of wires, or at VHF and above a solid metal disk, added to the top of a vertical antenna to reduce its inductance and increase its bandwidth.

Carrier Frequency : The centre frequency of a radio signal.

Cavity filter : A very narrow RF filter used to pass one single frequency, common in repeater operations where the receiver must be protected from overload by a transmitter on the same band on the same antenna tower.

Circular Polarization: A method of polarizing the antenna such that the emmitted electric field rotates around the axis of the antenna

CLOVER : A PSK mode that allows full duplex communications.

CNDX : Abbreviation for Conditions

Coaxial Cable : Cable that has a central conductor and an outer shield as the second conductor. Known as coaxial because the cable is cylindrical and the conductors share the same central axis.

Conductor : A material through which electricity flows easily.

CQ : Request for contact - specifically "calling any operator"

Cross Modulation : distortion caused by two or more carriers interfering with each other.

CTCSS : Continuous Tone-Coded Squelch System - a sub-audible tone that is frequently used on repeaters. The signal "opens" the repeater for use.

Current : The flow of electricity through a conductor - usually associated with electron movement, but current is actually the transfer of charge between atoms.

CW : Continuous wave - used in Morse code transmissions.

CW Abbreviations Used by CW operators to reduce the length of transmissions by shortening words or phrases to a 2 or three letter code.

D
DAC : Also known as D/A and D-to-A. Digital to Analogue converter. A device that converts digital signals into analouge signals.

dB : Decibel - the ratio of two power measurements.

dBd : dB relative to a dipole. Also known as dBD

dBi : dB relative to a theoretical isotropic (point) source.

 dBm: The power compared to a 1 milliwatt (1mW) source, expressed in decibels (dB)

dBo : Optical gain. An unofficial term used by some amateurs working with transmission of data using light.

dBuv : a measure of voltage compared to one microvolt. 0dBuv = one microvolt.

 De or DE : "this is" or "from" - for example an operator may use VL2TK de VK4ZW .......

Dipole : An antenna with two sides, usually of equal length.

 Dish : A highly directional antenna, parabolic in shape. Often used at microwave frequencies.

Domino EX : a digital mode that uses a variant of MFSK known as IFK for transmission of information.

DTMF Dual Tone Multi Frequency - the allocation of a unique tone pair to each button on an appliance (made up of two frequencies - high and low) that allows a computer to recognize the tone. Originally used on a wide scale in landline telephony to allow tone dialling using a small keypad on a telephone or handset, but has been used in amateur radio to remotely control repeaters, autopatch, IRLP or Echolink nodes.

Dummy Load : An artificial antenna that does not radiate. A non-inductive power resistor, a dummy load is connected in place of the transmitting antenna and used when aligning transceivers.

Duplex : Transmit and receive are on two different frequencies - often use in repeaters with a shift (difference) of 600Hz.

DXCC : DX Century Club

DX : Distance or distant station. Originally "distant exchange", from landline telephony. On HF radio, normally used to refer to a station on another continent or in an exotic location.

E
Earth : A circuit connection to a ground rod driven into the ground or system of wires buried below the surface of the ground.

EIRP : Effective Isotropic Radiated Power. The sum of transmitted power and antenna gain, minus any transmission line losses.

Electromagnetic Waves : The waves emitted by an antenna, having two dimensions, electric and magnetic.

EHF : Extremely High Frequency - from 30GHz to 300GHz

EME : Earth Moon Earth - bouncing a signal off the moon to a remote station that would not normally be accessible.

EMF : Electromotive Force - Voltage.

EMI : Electromagnetic Interference.

eQSL : Electronic QSL - a website for sending and receiving QSL's online.

F
F/D : The ratio of focal length to diameter of a parabolic dish antenna.

Feedline : The wire or cable that joins a transmitter or receiver to an antenna. Also known as a transmission line.

FET : Field-effect transistor, a semiconductor in which current between source and drain is controlled by voltage applied to a high-impedance gate

Field day : An annual event in which portable stations are deployed, contacts made and new or prospective operators encouraged to get on the air.

Filter : An electric circuit (often called a network) that allows certain frequencies to pass but rejects (attenuates) other unwanted frequencies.

FM (Frequency Modulated or Frequency Modulation): The shape of the carrier signal is changed (modulated) by the frequency of another signal, usually the voice of the operator.

Frequency: The number of complete waves that pass a reference point per second. Expressed in Hertz (Hz)

Frequency Shift Keying: A digital mode in which the signal is broken into "chunks". Each chunk is then shifted in frequency slightly above or below the central carrier. Effectively, frequency modulation used to carry a digital signal.

 Fuse : A device that self destructs when too much current passes through it - used for circuit protection.

G
Gain : How much more effective an antenna is as a radiator than a half wave dipole (dBd) or a theoretical point source (dBi). A more directional antenna is considered to have higher gain.

Ground : A direct connection from electrical equipment to the Earth - often achieved by driving a conducting spike into the ground, and connecting equipment to it.

GMT : Greenwich Mean Time - the time at Greenwich UK. Also known as Zulu and UTC.

GOTA : (1) Get On The Air - a station available for supervised public use at Field Day events,

GOTA : (2) Guides On The Air - a programme sponsored by YL organisations to introduce Girl Guides to amateur radio (see also: Jamboree on the Air)

G-TOR (Golay - TOR) : A digital FSK mode that offers faster transfer rate than PACTOR. Rarely used by ham radio operators.

H
 Harmonic : Integer multiples of the fundamental frequency being generated; present if a signal is not perfectly sinusoidal or is undergoing intermodulation distortion. Harmonics located outside the desired band for transmission are normally removed with low-pass filters to avoid interference to other radio services.

Hellschreiber (Hell) : A digital mode for sending and receiving text using facsimile (fax) technology.

Henry :(H) The unit for inductance

Hertz : Hz - The unit of measure for frequency.

HF : High Frequency. Frequencies in the range 3MHz to 30MHz.

High Pass Filter : A filter designed to pass high frequency signals.

Horizontal Polarization : An antenna or radio signal in which the electric field is propagated parallel to the surface of the Earth.

HT : Handheld Transceiver or HandiTalkie. Usually refers to transceivers that operate in the 2m and  70cm amateur bands; these are self-contained hand-held radios which include an antenna and battery and transmit at low power.

I
IFK : Incremental Frequency Keying a variant of MFSK

Ionosphere : a region in the atmosphere that contains ionised gasses that refract (bend) radio waves and direct them back to earth.

 Inductance : A measure of how well a coil stores energy in the form of a magnetic field.

 Interface: usually refers to a circuit used to connect the sound card of a computer to a transceiver to allow digital modes to be used.

Insulator : A substance through which electricity does not pass easily - known as a dielectric in capacitors

IRLP Internet Radio Linking Project. A method of cross-world linking of repeaters so that very basic equipment can be used to communicate with hams in other countries.

ITU : International telecommunication Union. The international organisation set up to standardise and regulate radio communications.

J
JOTA : Jamboree On The Air - an annual event in which scouts worldwide can communicate with each other and radio amateurs using ham radio equipment.

K
K : The symbol used in CW (Morse) and digital modes for "please respond" or "any station respond". The KN prosign is used to invite a specific station only to respond.

Kilohertz : one thousand Hertz (Hz) or one thousand cycles per second.

L
LID : In amateur radio, used to denote a poor or inept operator; a term originally from landline telegraphy.

Loading coil : An inductor placed in series with an antenna element in order to lower the antenna's resonant frequency. May be used singly or in conjunction with a capacity hat.

LPDA : Log Periodic Dipole Array. A multiband Antenna

M
Mayday: A most urgent distress call (français: «m'aidez» - help me) solely for use in life-threatening emergencies. The CW equivalent is SOS. Lesser incidents are signalled using "pan-pan" (français: «panne» - mechanical breakdown, typically a ship drifting helplessly or an aircraft's emergency landing) or "security" (français: «sécurité» - safety, for warnings such as reports of icebergs in shipping lanes).

Microphone : A device that converts voice into electrical signals.

Microwave : signals above 1GHZ in frquency.

 Microwave Bands : Division of the range of frequencies above 1GHz into a series of bands.

Mobile: A mode of operation in which a station may operate from a moving vehicle (mobile) or a ship at sea (maritime mobile). In CW, mobile and maritime mobile operators may identify using /M and /MM respectively. As a class of transceiver, mobile units fall between hand-held (5W or less) and base stations in both physical size and transmitted power. These units typically operate from the vehicle's battery and often transmit 50 watts or more using a vertical antenna mounted to use the metal vehicle body as a ground plane.

Mode : The way electromagnetic waves are changed so that transmission of information is possible.

Modulation : The process of adding information to a carrier signal.

Modulator : A device that adds information to a carrier signal.

Morse Code The code used by CW operators instead of voice communications

N
NB: Narrow band. Also noise blanker.

NBFM : Narrow band FM

Negative : no, incorrect

Negative copy : unsuccessful transmission

Negative Feedback A process in which a portion of the amplifier output is returned to the input, 180 degrees out of phase with the input signal.

Negative Offset : Used in repeater systems where the repeater input frequency is lower than the output frequency.

 Net : a scheduled and structured on-air meeting of amateurs - often run and controlled by clubs. A structured net designates one station to act as net controller; that station is responsible for inviting other stations to check in (by sending their call signs) and then sequentially assigns each station a window of time in which to send traffic to other stations on the net. Intent is to avoid message collisions which otherwise may be caused by multiple stations attempting to send simultaneously.

NiCad : Nickel Cadmium, generally refers to a type of rechargeable battery.

NiMH : Nickel Metal Hydride, generally refers to a newer type of rechargeable battery.

Noise : Unwanted elecromagnetic energy that can interfere with signal transmission or reception.

NPN : A type of bipolar transistor that has a layer of P-type semiconductor material sandwiched between layers of N-type semiconductor material.

NVIS : near-vertical-incidence-skywave, a propagation mode where signals are reflected back down from directly overhead. Useful for relatively short-distances, overcoming the limitations of the usual "skip-zone" distance"

O
Ohm : ($$ \Omega$$) The unit for resistance

OLIVIA : A digital mode using multiple FSK carriers; intended for operation under QRP or weak-signal conditions.

OM : Abbreviation meaning Old Man - any male operator, regardless of age or marital status.

OSCAR : Orbiting Satellite Carrying Amateur Radio

OCF : Off Centre Fed Dipole. A dipole that has sides of unequal length. These are multiband wire antennas

P
PACTOR : An FSK mode that combines packet and AMTOR technologies.

 Parabolic Antenna : An antenna in the shape of a dish with a parabolic cross section.

Parallel circuit : usually used to describe a tuned circuit in which the capacitive and inductive elements are parallel to each other.

Period : the time it taks in seconds for a complete wave to pass a reference point.

Phonetic Alphabet Specific, easily identifiable, non-confusable words are used instead of the letters of the alphabet.

 Pi pad  : one of the possible configurations used in Attenuators

Polarization : Used to describe the orientation of the electric field produced by an antenna compared to the surface of the Earth.

Portable: A mode of operation in which a station may be moved for rapid deployment from a temporary location, but is not able to operate while mobile. In CW, portable operators may identify using /P. Portable stations differ from mobile stations in that large antennas or other structures must be folded or stowed away in order to move the station to a new location. While well-suited to field day or emergency/disaster operations, portable stations normally do not have a mobile station's ability to continue transmission while in motion.

Power : The rate of energy consumption. Calculated by multiplying voltage by  current, P = VI

Propagation : How well a signal is transferred from the sending station to the receiving station, as a function of the path type (ground wave, sky wave reflection or direct line-of-sight) and related atmospheric conditions.

 PSK : Phase Shift Keying - a digital mode.

Q
Q Code Three letter codes used instead of sentences or phrases.

 Q of a circuit The quality factor of a resonant circuit - the ratio of stored power to dissipated power in the Reactance and Resistance of the circuit.

QCWA : Quarter Century Wireless Association, a radioamateur club with local chapters in which membership is offered solely to operators who were first licensed twenty-five or more years ago.

QRM : Man made noise. Can be used to indicate noise interfering with an amateur station or an amateur station interfering with other spectrum users.

QRN : Electromagnetic noise from natural sources interfering with amateur transmissions.

QRP : Low power operations - usually understood to mean power at or below 5 watts. From QRP, a code requesting that a station reduce its transmitted power.

QRPp : Very low power operation - at or below 1 Watt.

QPSK : Quadrature Phase Shift Keying. Also known as Quadraphase Phase Shift Keying. A method of modulating a carrier in digital transmissions by changing its phase four times, with each change being represented by two binary digits.

QRSS : Very low speed operation - typically CW below one character per second, intended for machine-assisted reception under extreme QRP or noisy/weak signal conditions. Bandwidth used is a small fraction of 1 Hz. From QRS, a code requesting "send more slowly".

QSL : Confirmation of receipt of transmission

R
 Repeater : A transceiver - often comprised of separate transmitted and receiver linked by controlling hardware. A repeater picks up a radio signal and re-transmits it, allowing weak stations to be heard from further away than normally possible.

RFI : Radio Frequency Interference (also BCI - broadcast interference, TVI - television interference). Normally resolved by installation of filters at the transmitter, the affected receiver(s) or both.

RSGB : Radio Society of Great Britain - national amateur radio organisation of UK.

RSQ code Used to describe the readability, strength and quality of digital modes.

 RST code Used to describe the readability, strength and tone of voice or CW transmissions.

RSV code used to describe the readability, stength and video quality of SSTV transmissions

RX : Abbreviation for receive or receiver

S
Series circuit: Usually used to describe tuned circuits in which the capacitive and inductive elements are in series with each other.

Signal to Noise Ratio S/N : the ratio of signal power to noise power. The better the S/N ratio, the better the quality of the signal and the easier it is to decode.

Simplex : Transmit and receive on the same frequency - most often used when communicating directly (not used when operating via voice repeaters).

Skip : Skip is a radio phenomenon in which signals are reflected or refracted by the atmosphere and return to earth in unexpected places, far away from the normal reception zones. In between transmitter and receiver there is a zone where no transmissions can be heard

Skip Distance : The shortest distance, for a fixed frequency, between transmitter and receiver.

Skip Zone : The distance between the point of no reception and the closest point of reception.

Split operation : Direct communications where transmit and receive are offset from each other in frequency - most often used by DXpedition stations which must accommodate large numbers of incoming calls.

SSB : Single Sideband. A transmission mode used mainly in the HF bands.

SSTV : Slow Scan Television - still picture ham transmissions.

Standing Wave: The vector sum of two waves - in ham radio, this most usually refers to the forward and reflected waves in a feedline

SWL : Shortwave listener. While SWL's do not operate licensed transmitting stations, in some cases they will be using equipment capable of receiving both radioamateur and broadcast signals. For both, SWL's may submit reception reports in order to receive QSL cards. A similar capability exists on VHF/UHF and above for scanner operators; one need not already be the operator of a licensed station to merely listen and observe on any of the radioamateur bands.

SWR : Standing Wave Ratio. The ratio of the height of a standing wave on a transmission line to the height of an adjacent node.

T
THROB : An MFSK digital mode based on tone pairs.

TOR (Teleprinting Over Radio): Used in three digital modes; AMTOR, PACTOR and G-TOR.

 T pad  : one of the possible configurations used in Attenuators

 Transmission Line : Also known as feedline.

TX : Abbreviation for transmit or transmission

U
UHF : Ultra High Frequency. Frequencies in the range 300MHz to 3 000MHz

UHF connector : A threaded co-axial RF connector (PL-259, SO-239) originally designed in the 1930's for use at frequencies in the 30-300MHz range. (These frequencies are now considered to be VHF.) Most commonly used in amateur radio stations to make RG-8 or RG-213 cable connections to HF transceivers.

V
 Volt : (V) The unit of electric potential difference (Voltage) between two points.

VA : Volt Amperes - measure of apparent power.

VAC : Volts Alternating Current.

Varactor Diode : a component whose capacitance decreases as the reverse bias voltage is increased.

VCO : Voltage-controlled oscillator

VE : Volunteer Examiner, in countries in which government radio inspectors no longer conduct examinations for prospective new licensees but delegate this task to a few experienced radio amateurs. (Also: VE as a callsign prefix refers to the Dominion of Canada - so "W/VE stations" would indicate the continent of North America.)

Vertical Polaraization : Used to describe a transmission or antenna in which the electric field is propagated perpendicular to the surface of the Earth.

VFO : Variable Frequency Oscillator

Velocity Factor : the speed at which radio waves travel in a particular feedline, expressed as a percent of the speed of light

VHF : Very High Frequency. Frequencies in the range 30MHz to 300MHz

VIS : Vertical Interval Signalling. Digital encoding of the transmission mode in the vertical sync portion of an SSTV image.

 VLF : Very Low Frequency 3 - 30 KHz

VMOS : Vertical metal-oxide semiconductor

VOX : Voice Operated Transmit

VSWR : Voltage standing wave ratio

VXO : Variable crystal oscillator

W
WARC, WRC : World (Administrative) Radio Conference. Run by the International Telecommunications Union.

WARC Bands : Agreed to at the 1979 WARC, they consist of the 30m ( 10.100Mhz - 10.150MHz), 17m (18.086MHz - 18.186MHz) and 12m (24.890MHz - 24.990MHz) amateur bands.

Waveguide : A hollow tube, typically square in cross-section, used to carry microwave signals.

Wavelength : The distance in metres between corresponding points on a wave.

WIA : Wireless Institute of Australia. The national organisation for Australian hams.

WSPR : Weak Signal Propagation Reporter.

WSJT : Weak Signal Joe Taylor - named after Joe Taylor who wrote the software.

X
XCVR : Transceiver

XTAL : Crystal

XYL : Wife of an amateur operator

Y
Yagi : A directional antenna consisting of a dipole and at least two additional elements, a slightly longer reflector and one or more slightly shorter directors. Invented in 1926 by Hidetsugu Yagi and Shintaro Uda.

YL : Abbreviation for Young Lady, any female operator regardless of age or marital status.

Z
Zero Beat : one or both of two signals are adjusted so that they are identical and in phase.

Zulu : (z) Another term for Greenwich Mean Time (GMT). Also known as UTC

0-9
30: End of message

33: Love sealed with friendship and mutual respect between one YL and another YL. (coined by Clara Reger W2RUF, adopted officially by YLRL in 1940)

73: Goodbye, best regards.

88: Love and Kisses