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Definitions
RAC
am (amplitude modulation) - a radio transmission mode in which the strength of the speech signal controls the strength of the transmitter signal. This normally resuilts in two sidebands containing the modulation energy.
AMSAT - Radio Amateur Satellite Corporation - an amateur radio organization promoting and developing amateur radio satellite service. Over two dozen satellites are now in operation, many as a result of AMSAT effort.
APRS (Amateur Packet Reporting System) - a system which supports plotting of station positions on screen maps
ASL (above sea level) - a method of measuring antenna height
access code - one or more numbers and/or symbols that are keyed in with a telephone key pad to activate a repeater function e.g autopatch, link etc
antenna separation - the physical spacing between transmit and receive antennas, when separate antennas are used
autopatch - a device that interfaces a repeater to the telephone system to permit repeater users to make telephone calls. Often called a "patch"
band (amateur radio frequency band) - the range of contiguous frequencies over which amateurs may communicate
band-opening - a condition that results in greater-than-normal communication range on the VHF and UHF bands
band-plan - a voluntary system of frequency allocations in each amateur radio band
break - the word used to interrupt a conversation on a repeater , often to indicate that there is an emergency
CAS (carrier activated switch) - see COR
COR (carrier-operated relay) - a device that causes the repeater to transmit in response to a received signal
CTCSS (Continuous Tone-Coded Squelch System) - This is a sub-audible tone transmitted by your radio in addition to your voice signal. When it is equipped with a CTCSS decoder, a repeater will not function unless it hears the CTCSS tone and the "carrier" signal from your transmitter. Different CTCSS tones are in use for different repeaters or areas. These may be applied to input or output frequencies, or both. CTCSS tones are used to minimize the effects of co-channel interference due to band-openings causing reception of distant signals
carrier - your unmodulated (no speech) transmitter signal
cavity resonator - a sharply tuned circuit using the physical dimensional resonance of one or more tuned cavities
channel - the pair of frequencies (input and output) used by a repeater
channel spacing - the frequency spacing between adjacent frequency allocations - may be 50, 30, 25, 15 or 12.5kHz, depending upon the convention in use in the area of the repeater
clear - indicates the end of a contact
closed repeater - a repeater whose access is limited to a select group (see also open repeater)
co-channel interference - the interference resulting when a repeater receives signals from a distant repeater on the same frequency pair
controller - the control system within a repeater which may include turning the repeater on-off, timing transmissions, sending the identification signal, controlling the autopatch and CTCSS encoder/decoder
control operator - the amateur radio operator who is designated to control the repeater
courtesy tone - an audible indication that the repeater user may go ahead and transmit
coverage - the geographic area within which the repeater provides communications
cross-band - the process of transmitting on one band and receiving on another
DTMF - see tone pad
desense (desensitization) - the reduction of receiver sensitivity due to overload from a nearby transmitter
digimodes (digital modes) - the various digital transmission modes, including packet, RTTY (radio teletype), etc
digipeater (digital repeater) - a packet radio repeater
dropping out - the situation, while using a repeater, when your signal does not have enough strength to keep the repeater triggered.
duplex - a mode of communication in which you transmit on one frequency and receive on another frequency (see also half and full duplex)
duplexer - highly selective filter which allows a repeater's transmitter and receiver to share one antenna
EIRP (effective radiated power referred to isotrope) - ERP plus 2.14 dB to correct for reference to isotrope
ERP (effective radiated power) - radiated power, allowing for transmitter output power, line losses and antenna gain
fm - see frequency modulation
frequency coordinator - an individual or group responsible for assigning channels to new repeaters with minimal interference to existing repeaters
frequency modulation - a method of modulation, where the strength of the signal is constant, but the frequency varies with the strength of the voice, and the rate of change varies with the frequency of the voice
full duplex - a mode of communication in which you transmit on one frequency while you simultaneously receive on another frequency
full quieting - a received signal that contains no noise
gateway - a link or bridge between one communication network and another. Can be repeater to satellite
HAAT (height above average terrain) - a method of measuring antenna height
half duplex - a mode of communication in which you transmit at one time on one frequency and receive at another time on another frequency
hand-held - a portable transceiver small enough to fit in the hand, clipped to your belt, or in your shirt pocket
handle - slang for your name (not recommended)
helical resonator - a compact resonant filter circuit to block multiple interfering signals
horizontal polarization - the antenna elements are horizontal (used at vhf/uhf for weak signal CW/SSB operation)
Hz (Hertz) - a unit of frequency measurement equal to one cycle per second
ID (identification) - the means by which a station identifies its call sign by Morse code or speech
input (frequency) - the frequency of the repeater's receiver
intermod (intermodulation distortion or IMD) - interference that results when strong signals from nearby transmitter(s) mix with the desired signal in a radio receiver
isolation - the difference in level (measured in dB) between a transmitted and received signal due to filtering
isotrope - a theoretical antenna with zero dimensions and a spherical radiation pattern. Gain is -2.14 dB from dipole
jamming - the action of deliberate illegal interference with a repeater operation
kHz (kilohertz) - a unit of frequency measurement equal to 1,000 cycles per second (Hertz)
kerchunk - to key up a repeater without identifying
key pad - see tone pad
key up - to turn on the repeater by transmitting on its input frequency
linking - the process of connecting repeaters in a permanent network, or one controlled by access codes
MHz (megahertz) - a unit of frequency measurement equal to 1,000,000 cycles per second (Hertz)
machine - a slang expression meaning a repeater system
magnetic mount (mag-mount) - an antenna with a magnetic base that permits quick installation and removal from a metallic surface, including an automobile body
microwave - the region of the radio spectrum above 1 gigahertz (GHz)
modem (modulator-demodulator) - an interface device for use between computers. See TNC
negative offset - the repeater input frequency is lower than the output frequency
NiCd (or NicCad) - a nickel cadmium battery that may be recharged many times; often used in handheld transceivers
NiMH - new technology nickel metal hydride battery that has advantages over NiCd, but is more expensive
odd split - unconventional frequency separation between input and output frequencies.
offset - see separation
open repeater - a repeater whose access is not limited
OSCAR (Orbiting Satellite Carrying Amateur Radio) - Acronym describing amateur satellites. A number applies to a specific satellite e.g. OSCAR-16 or AO-16.
out - indicates the end of a contact
output frequency - the frequency of the repeater's transmitter (and your receiver)
over - the word used to indicate the end of a voice transmission
positive offset - the repeater input frequency is higher than the output frequency
ptt (push to talk) - the use of the microphone button or control line to key the transmitter on
packet - the most popular form of digital mode communications, in which computers communicate via radio to exchange data "packets"
pacsat (PACket SATellite) - amateur radio satellite used to store and forward digital (packet radio) messages.
PL - Private Line (trademark of Motoroal Inc) see CTCSS
Q signals or codes - abbreviations developed for use on Morse code transmissions. Not recommended for phone.
radio direction finding (RDF) - the art and science of locating a transmitter
raster - the vertical spacing of television scanning lines. Used also as slang for channel spacing
repeater - an automatic relay station, generally in a high location, which is used to increase the range of mobile and handheld FM transmitter/receivers
repeater directory - a repeater list for a particular area (RAC publishes one for Canada and neighbouring states)
reverse patch - when a call is received on its incoming telephone line this special autopatch rings over the air and may be answered by tone access
rubber duck(y) - slang term for the flexible rubber-covered antenna supplied with handheld radios
ssb (single-sideband) - a type of AM transmission which occupies half the spectrum of a standard AM signal
sked (schedule) - a prearranged (scheduled) contact between two stations
separation (split) - the difference, in kHz, between the repeater's transmit and receive frequencies. Conventional separations by amateur band are: 29 MHz - 100 kHz; 50 MHz - 1 MHz; 144 MHz - 600 kHz; 220 MHz - 1.6 MHz; 440 MHz - 5 MHz; 902 MHz - 13 MHz; 1270 MHz - 12 MHz.
simplex - a mode of communication in which you take turns to transmit and receive on the same frequency. A frequency set aside for non-repeater use.
squelch - a circuit within a radio that keeps the speaker silenced (squelched) until the signal level exceeds a certain point, set by the squelch control. Normally you set the squelch to just block out noise and allow signals to pass.
sub-audible tone - see CTCSS
TNC (Terminal Node Controller) - the interface circuitry that goes between the computer and radio for digimode (normally packet) communications
tail - the brief signal transmitted by a repeater transmitter after someone stops talking.
time-out - to cause the repeater, or a repeater function, to turn off because you have transmiited too long
timer - a device which measures the length of each transmission and causes the repeater, or a repeater function, to turn off, after a transmission has exceeded the preset time.
tone pad - an array of 12 or 16 numbered keys that generate the standard telephone dual-tone multi-frequency (DTMF) dialing signals
touch tone - trade mark of AT&T. See DTMF
triggering - to activate a repeater by transmitting on its input frequency (see also key up)
translator (linear translator) - a device used to directly convert and retransmit a block of received frequencies
transponder - the term used for a linear translator in a satellite. Inverting transponder transmits received upper sideband as lower sideband. Non-inverting transponder transmits received upper sideband as upper sideband
vhf (very high frequency) - the region of the radio spectrum between 30 and 300 megahertz (MHz)
vertical polarization - the antenna elements are vertical (used at vhf/uhf for FM and repeater operation)
uhf (ultra high frequency) - the region of the radio spectrum between 300 and 1000 MHz or 1 GHz