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 into a digital signal, in which a series of numbers is used to represent the amplitude of the original wave.
ADIF : Amateur Data Interchange Format, a standard specification for format of exported logbook files.
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
AFSK : Audio Frequency Shift Keying.
AGC : Automatic Gain Control – a feedback system to reduce fading by automatically adjusting gain
AGL : (Height) Above Ground Level, for antenna installations.
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.
AM : Amlpitude Modulation
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.
Analog (also analogue): a continuously varying signal.
ANC, ANR : Active noise control, active noise reduction. Also referred to as automatic noise cancellation or antinoise on some transceivers.
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.
Anti-VOX : Transceiver circuitry used in voice-operated (VOX) stations to prevent audio from the receiver’s speaker from actuating the voice-operated transmitter.
APRS : Automatic Position Reporting System, Automated Packet Reporting System.
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
ARISS : Amateur Radio on the International Space Station. A program that allows schools, with the help of an amateur club, to contact the amateur station on board the International space station.
ASL : Above Sea Level. Vertical height in metres or feet above sea level.
Attenuator : A resistive device to reduce the amplitude or power of a signal.
ATS : Automatic Transfer Switch, switches equipment to a backup power supply in event of power failure.
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.
Azimuth : The horizontal direction (angle) measured clockwise from North.
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.
Buffer Amplifier : An amplifier usually attached to an oscillator so as to reduce the drain on the oscillator output.
Bureau (also Burro) : An organization set up to process QSL cards between amateurs.
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).
Carrier Frequency : The centre frequency of a radio signal.
Carrier Power : The average power supplied to the antenna when no modulation is taking place.
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.
Color Code : Also spelt colour code. Coloured bands on resistors and other components that show their value.
Condenser : old name for Capacitor
Conductor : A material through which electricity flows easily.
Core : The material used in the centre of an Inductor coil.
CQ : Request for contact – specifically “calling any operator”
CQ Magazine : Published by CQ Communications.
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.
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 …….
DF : Direction finding. Also known as ARDF and “fox hunting”, the use of triangulation and directional antennas to find a hidden transmitter. May be done recreationally, or as a means of locating the source of problematic radio frequency interference.
Diplexer : A frequency splitting device used to couple two transceivers to either a single antenna or a dual band antenna.
Dipole : An antenna with two collinear elements, usually of equal length, with feedpoint in the centre. Commonly used as the driven elements for more complex antennas such as the yagi or log-periodic, a dipole on its own is omnidirectional if mounted for vertical polarisation but has a figure-8 directional pattern if mounted horizontally.
DPSK : Differential Phase Shift Keying – a form of BPSK
DRM : Digital Radio Mondiale. A system of digital broadcasting developed by a consortium of manufacturers, researchers, broadcasters and governments.
DSP : Digital Signal Processing. The digital processing of signals in filtering, noise reduction etc.
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.
Dual Band Antenna : An antenna designed to be used on two amateur Bands.
Duplex : Transmit and receive are on two different frequencies – often use in repeaters with a shift (difference) of 600Hz.
Duplexer : A device that allows an antenna to transmit and receive simultaneously.
DVM : Digital voltmeter.
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.
DXpedition : An expedition by amateurs to a location that may be geographically or physically remote and from where amateur contacts are rare.
Dynamic Range : How well a receiver can handle very strong signals wthout overloading.
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.
EHF : Extremely High Frequency – from 30GHz to 300GHz
Electron Tube : (Also known as an Vacuum Tube or a Thermionic Valve). A device that creates or modifies an electrical signal through the movement of electrons in a low pressure (vacuum) space.
Elevation (1) : The angle that an antenna – often a beam – makes with the horizontal.
Elevation (2) : How high an object/place/station is above sea level. Same as ASL (Above Sea Level)
Elmer : Slang for a person who helps newcomers get started in amateur radio.
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.
ERP : Effective Radiated Power.
Eu : Europe
FCC : Federal Communications Commission. The US government body that regulates the use of the radio spectrum.
F/D : The ratio of focal length to diameter of a parabolic dish antenna.
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.
Field Strength Meter : A devie used to measure the strength of an electromagnetic field.
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 frequency of the carrier signal is changed (modulated) in direct proportion to the instantaneous amplitude of an input signal, usually the voice of the operator. The resulting transmitted signal is of constant amplitude, with increasing amounts of power removed from the carrier and displaced to the sidebands as the modulating signal increases in amplitude.
Fox Hunt : Also known as ARDF (Amateur Radio Direction Finding). A contest to locate a hidden transmitter.
Frequency: The number of complete waves that pass a reference point per second. Expressed in Hertz (Hz)
FSK – 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.
Gel cell : A small sealed lead-acid rechargeable battery which uses a gel instead of a liquid electrolyte. Often used as backup power in applications such as alarm panel installations.
GHz : Gigahertz – one billion Hertz (1 000 000 000 Hz)
General coverage : The ability of a receiver to tune outside the amateur radio bands, typically over an extended continuous frequency range, to receive signals from non-amateur services such as shortwave broadcast or marine weather.
GMT : Greenwich Mean Time – the time at Greenwich UK. Related to 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)
Grey Line also Gray Line : a band around the earth that separates night from day.
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.
Ground (2): A common zero voltage reference point.
Ground-plane Antenna : a quarter wavelength vertical antenna with radials extending horizontally from its base.
Groud wave propagation : Propagation via radio waves that travel along the surface of the earth.
G-TOR (Golay – TOR) : A digital FSK mode that offers faster transfer rate than PACTOR. Rarely used by ham radio operators.
HAAT : Height Above Average Terrain.
Harmonic : Integer multiples of the fundamental frequency being generated, harmonics are 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.
Half Duplex : The ability for a transceiver to transmit and receive on two different frequencies, but ony one of these at any given time.
Half wave dipole : An antenna that is half a wavelength total, fed at the centre.
HASL : Height Above Sea Level. Often used for mountaintop stations such as repeaters and portable operations to describe their elevation. Measured in either feet or metres depending on the country.
hamfest : An event at which hams can buy sell and swap equipment. Often held in conjuction with lectures and demonstrations of equipment.
Harmonic (of a ham) : Slang term for the child of a ham.
Hellschreiber (Hell) : A digital mode for sending and receiving text using facsimile (fax) technology.
Henry :(H) The unit for inductance
HF : High Frequency. Frequencies in the range 3MHz to 30MHz, also known as shortwave.
High Pass Filter : A filter designed to pass high frequency signals.
hi hi : The morse equivalent of laughter.
Homebrew : Home built equipment.
Horizontal Polarization : An antenna which projects a radio signal in which the electric field is parallel to the surface of the earth OR a radio signal of which the electric field is propagated parallel to the surface of the Earth.
HT (1) : 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.
HT (2) : High Tension Voltage. Voltages over 500V
IARU : International Amateur Radio Union. An international society that works for and with national organisations to promote the interests of hams.
IF : Intermediate Frequency, at which signals are amplified and processed internally within a receiver.
IFK : Incremental Frequency Keying a variant of MFSK
Image frequency : A frequency separated from that of the desired received signal by twice the receiver’s intermediate frequency.
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.
Inductor : a coil of wire. Inductors are often used with capacitors in tuned circuits such as filters and oscillators. Some inductors are wound around a core of metallic material. This affects their inductance.
Interference : The interaction between a desired frequency and an undesired frequency.
Intermodulation : The undesired mixing of two or more frequencies, producing sometimes undesirable additional frequencies.
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.
Inverter : a device that converts a DC source to and AC output.
ITU : International telecommunication Union. The international organisation set up to standardise and regulate radio communications.
J-pole antenna : Vertical antenna composed of two parallel elements of differing widths. The longer element is connected to signal and the shorter to ground at an intermediate point; the elements are connected to each other at the base.
JT65-HF : An adaptation of JT65, for use on the HF bands.
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.
Key : A simple mechanical device used to send morse code
Keyer : An electronic circuit intended to interface an amateur CW transmitter to a paddle switch. While multiple variants exist, typically the keyer will send dit’s when the paddle is held in one position and dah’s in the opposite position. As the timing of the Morse dots and dashes is automatically controlled, code speed is more consistent than that sent manually using a straight key.
Kilo: Metric system multiplier x1000. Also Phonetic alphabet letter K
Kilohertz (KHz) : one thousand Hertz (Hz) or one thousand cycles per second.
Lead acid : A rechargeable battery type most commonly used in automobiles and marine applications. As some batteries can deliver large amounts of current instantaneously and contain sulphuric acid, these must be handled with caution.
LIon, Li-Ion : Lithium-Ion, a small but powerful rechargeable battery often factory-installed in laptop computers and handheld devices. As these cells are highly flammable if overheated, they are normally distributed only as part of pre-fabricated battery packs which internally include the requisite temperature sensors and charging circuits.
LSB : (1) Lower Sideband, used primarily in single sideband operation below 10 MHz
LSB : (2) Least Significant Bit, in transmitted digital data
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).
Megahertz: One million Hertz (HZ) – same as one million cycles per second.
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.
MP73N : A narrow band SSTV Mode
MUF : Maximum usable frequency. The highest frequency at which a skywave is reflected back to Earth at the ionosphere under current propagation conditions. Can vary rapidly depending on time of day and sunspot activity.
MW : Medium Wave, 300-3000 kHz. This range includes the 160 metres amateur band, the AM broadcast band and the 2182 kHz marine radiotelephone band.
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 directed 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 with 1.2 volts per cell.
NiMH : Nickel Metal Hydride, generally refers to a newer type of rechargeable battery with the same voltage as NiCad cells but increased capacity. NiMH cells do not exhibit the memory effects associated with partial discharge of NiCads, but do still need to be recharged before use if they have been stored for a month or more.
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”
Ohm : (<math> \Omega</math>) The unit for resistance
Ohm’s Law : Named after George Ohm :- V = IR. V = voltage, I = current, R = 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
Oscillator : Also known as a frequency synthesiser – A device that produces a signal at a particular frequency.
OCF : Off Centre Fed Dipole. A dipole that has sides of unequal length. These are multiband wire antennas
P5 : North Korea. For DX’ers, the most unattainable contact or a non-existent station. The rarest callsign prefix as one of two countries worldwide (the other is 7O Yemen) to have had no licensed radio amateur service at all since 2002.
Packet radio : An early digital radio mode developed in Canada in 1978.
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.
PEP : Peak envelope Power. The average power sent to the transmission line by the transmitter. Can be calculated by multiplying Peak Envelope Voltage (PEV) by 0.707
Period : The time in seconds taken for a complete wave to pass a reference point, period is the reciprocal of frequency.
PEV :Peak Envelope Voltage. The maximum voltage on a transmission line during transmission.
Phonetic Alphabet Specific, easily identifiable, non-confusable words are used instead of the letters of the alphabet.
Piezoelectric Effect : the ability of a substance to produce an electric charge when it is deformed physically.
PNP : A semiconductor device composed of an N layer sandwiched between two P layers.
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.
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.
PTT : Push to talk
QAM : Quadrature Amplitude Modulation. A method that allows simultaneous frequency and amplitude modulation of a signal.
Q Code Three letter codes used instead of sentences or phrases.
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.
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.
QSB : Fading (of signals). Used in signal reports eg “your signal is experiencing rapid QSB tonight”
QRSS : Very low speed operation – typically CW below one character per minute, 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
QTH : Home, home location, station location
Regulator : A device – often built to employ a Zener Diode as reference – which maintains a constant output voltage over a range of load currents and input voltages.
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.
Repeater council : A voluntary regional amateur organisation coordinating repeater frequency pair assignments to minimise interference. As no individual amateur group owns any given radio frequency, a council does not exercise legal authority to force individual repeater operators onto a specific frequency, height, location, power or directional pattern. Nonetheless, amateurs are obligated by national laws to avoid interference to other amateur stations and official regulatory agencies will resolve interference complaints between repeater operators by forcing uncoordinated repeaters to move off frequencies where their operation interferes with any coordinated repeater.
Resistance : The measure of how much an object (a resistor) opposes the flow of electric current.
Resistivity : The measure of how strongly a material (eg plastic) opposes the flow of electric current.
Resistor : A device that opposes the flow of electric current.
RF : Radio Frequencies : Frequencies that can pass through space as electromagnetic radiation.
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.
Ripple : The residual AC left over after rectification and filtering when an AC supply has been converted to DC’
RIT : Receive Incremental Tuning, Receive Independant of Transmit. The ability to shift the receive frequency of a transceiver away from the transmit frequency by a small amount.
RMS : Root Mean Square. Calculated by squaring each of the values on a signal, calculating the mean of the squares, and then taking the square root of the mean. approximately 0.707 of the peak value.
ROS Digital : An MFSK digital mode created in 2009.
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.
RTTY : Radioteletype.
RSV code : used to describe the readability, stength and video quality of SSTV transmissions
Rubber duck : Nickname for the flexible rubber antennas supplied with many handheld transceivers.
RX : Abbreviation for receive or receiver
Semiconductor : an element that is normally an insulator but which can, under certain physical conditions, be made to conduct.
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.
S meter : A meter on a receiver that displays the relative strength of an incoming signal.
SNP, SNPF : Shared non-protected pair, shared non-protected frequency. In repeater coordination, an input/output frequency pair on which no fixed/permanent repeater stations have been deployed. These frequencies remain available for temporary use only within a very limited coverage area by portable public service, emergency, search and rescue operations or short experiments. Individual temporary repeaters on these frequencies are not regionally-coordinated, so are not protected from mutual interference with other temporary repeaters on the same frequency.
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.
Sporadic E-Skip: Unexpected and unpredictable propagation using refraction in the E Layer.
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
Sunspot : A region on the sun where an electromagnetic “storm” is happening. These have an effect on propagation
Sunspot Cycle : A cycle of approximately 11 years in which the number of sunspots increases and decreases. The broader sunspot cycle is 22 years as the polarity of the sunspots reverses every 11 years.
Susceptance : the reciprocal of Reactance, measured in Siemens; symbol S
SWL : Shortwave listener. While SWL’s do not operate licensed transmitting stations, some are using equipment capable of receiving both radioamateur and broadcast signals. For both, SWL’s may submit reception reports in order to receive QSL cards. On VHF/UHF and above, one who can receive (but not transmit) is a scanner operator.
SWR : Standing Wave Ratio. The ratio of the height of a standing wave on a transmission line to the height of an adjacent node.
Telegraphy ; text based modes. Includes morse and RTTY.
Thermionic Valve : (Also known as an Electron Tube or a Vacuum Tube). A device that creates or modifies an electrical signal through the movement of electrons in a low pressure (vacuum) space.
THROB : An MFSK digital mode based on tone pairs.
TNC : Terminal Node Controller – a device used in packet radio that disassembles and re-assembles packets of data.
TOR (Teleprinting Over Radio): Used in three digital modes; AMTOR, PACTOR and G-TOR.
Toroid : A donut-shaped solid usually constructed of ferrite, used as the former for transformers and inductors’
Transceiver : A radio that has both a transmitter and a receiver, which either share common circuitry or a common housing or both.
Transient : A short spike or trough on a power line, usually lasting for a few microseconds.
Tuned Circuit : A capacitor and an inductor, usually in parallel. The circuit responds strongly at its resonant frequency and is used to select or tune in wanted signals.
TVI : Interference to television reception.
TX : Abbreviation for transmit or transmission
U : CW abbreviation for “you”
UFB : CW abbreviation for “Ultra Fine Business” or “excellent”
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.
UR : CW abbreviation for “your”
USB : (1) Upper Sideband, used primarily for single sideband operation above 10MHz
USB : (2) Universal Serial Bus, an interface to desktop PC peripherals
VA : Volt Amperes – measure of apparent power.
VAC : Volts Alternating Current.
Vacuum Tube : (Also known as an Electron Tube or a Thermionic Valve). A device that creates or modifies an electrical signal through the movement of electrons in a low pressure (vacuum) space.
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.)
VEC : Volunteer Examiner Coordinator
Vertical Polarization : Used to describe a transmission or antenna in which the electric field is propagated perpendicular to the surface of the Earth. Antennas intended for two-way radio communication with mobile stations (where vertical antennas are common) typically use vertical polarization, while broadcast TV/FM signals are most often horizontally polarised.
VFO : Variable Frequency Oscillator
Velocity Factor : the speed at which radio waves travel in a particular feedline, expressed as a fraction 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.
VLCA : Very limited coverage area. Typically used in reference to small portable repeaters deployed by emergency/disaster or public service groups to temporarily provide local communication within a relatively-small area.
VLF : Very Low Frequency 3 – 30 KHz
VMOS : Vertical metal-oxide semiconductor
VOX : Voice Operated Transmit
VSWR : Voltage standing wave ratio
VK : Australia
VXO : Variable crystal oscillator
VY : CW abbreviation for “very”
WAB : Worked All Britain.
WAC : Worked All Continents.
WAN : Worked All Neighbours. Used to refer to a powerful station in a densely-populated area where strong signals overload broadcast receivers in the immediate vicinity.
WAS : Worked All States. In the US, contacts with stations in each of the fifty US states.
WAVE : Worked All VE. Contacts with stations in each of the Canadian provinces.
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.
WAXE : Worked All XE / México.
WIA : Wireless Institute of Australia. The national organisation for Australian hams.
WKD : CW abbreviation for “worked”
WPM : Words per minute.
WRK : CW abbreviation for “work”
WSPR : Weak Signal Propagation Reporter.
WSJT : Weak Signal Joe Taylor – named after Joe Taylor who wrote the software.
WX : Weather. See weather spotting, APRS for transmission of current meteorological readings via amateur radio. Many 2 metre handheld transceivers are also capable of extended tuning to permit reception of forecasts over VHF bands assigned to other services, such as marine radio.
XCVR : Transceiver
XIT : The ability to shift the transmit frequency of a transceiver while maintaining a constant receive frequency.
XTAL : Crystal
XYL : Wife of an amateur operator. (A lady operator is referred to as YL – young lady.)
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 code Three letter codes for use in military radio instead of sentences or phrases. An extension (not a replacement) of the existing Q Code, these added codes are not in use by any of the civilian services (amateur radio, aviation, marine) currently using Q code.
Zero Beat : one or both of two signals are adjusted so that they are identical and in phase.
ZL : New Zealand.
Zulu : (z) Another term for Coordinated Universal Time (UTC). Also known as GMT (Greenwich Mean Time)
10 code: A series of abbreviations (originally 10-1 through 10-29) created by APCO, the US association of public safety communications officers, for use on 1950’s-era police radio. As many localities extended the series with their own non-standard codes, the same codes may have different meanings in different agencies (even between police and fire services in the same town). Ten codes are never used in amateur, marine or aviation radio as Q-codes already are in long-established international use but they may be heard in the unlicensed CB radio service and on local public-service frequencies.
11 metres: The 27MHz CB general radio service, nominally intended for local communications. As no license or callsign is required to transmit, quality of operating procedure employed on this band may be criticised as variable at best. Where existing citizen’s band procedure, code abbreviation and slang terminology are incompatible with amateur radio operating convention, users will find much needs to be re-learned upon leaving 11 metre CB to become licensed radio amateurs.
2, 6, 10, 20, 40, 80, 160 metres : See Bands.
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
92 code : A series of telegraphic abbreviations devised by Western Union in 1859 (originally as numbers 1 to 92). The later Philips Code added abbreviations for news wire service. While many of the codes are long forgotten, 19 and 31 (absolute and permissive) train orders continue in railroad use, the “30” as used by news editors at the end of a story remains widely known and “73” / “88” greetings are common in amateur radio.