ACC
- (ACCessory)
Adjacent-channel interference
When a receiver is tuned to a specific frequency and interference is received on a nearby frequency.
AF
- (Audio Frequency)
AFC
- (Automatic Frequency Control)
Automatically compensate frequency drift.
AFSK
- (Audio Frequency Shift Keying)
AGC
- (Automatic Gain Control)
Automatically optimize receiver amplifier gain.
ALC
- (Automatic Limiting Control)
Limits RF drive level to power amplifier during transmit to prevent distortion.
AM
- (Amplitude Modulation)
AMSAT
- (AMateur SATellite)
AMTOR
- (AMateur Teleprinting Over Radio)
A form of RTTY, radio teletype.
ANF
- (Automatic Notch Filter)
ANL
- (Automatic Noise Limiter)
Eliminates impulse and static noise peaks.
ANT
- (ANTenna)
Antenna ground system
Term used for a RF reference potential for some types of antennas. Most unbalanced or asymmetrical antennas need a good RF ground.
Antenna impedance
The impedance of an antenna at its resonance. Although an antenna’s impedance fluctuates with the frequency of operation, an antenna should be 50 Ohm most transceivers.
Antenna matching
When the antenna’s impedance at resonance is at optimum performance for your transmitter output circuit.
Antenna tuner
Device used to match an antenna to the output impedance of a transmitter.
APC
- (Automatic Power Control)
Current limiting of power amplifier to prevent damage to finals in high SWR conditions.
APRS
- (Automatic Position Reporting System)
In conjunction with a GPS and TNC provide position reporting.
ARES
- (Amateur Radio Emergency Service)
ARES is a public-service organization of the ARRL.
ARLHS
- (Amateur Radio Lighthouse/Lightship Society)
ARRL
- (The American Radio Relay League)
The United States of America section of IARU.
ASCII
- (American National Standard Code for Information Interchange)
A seven-unit digital code for the transmission of teleprinter data.
ATT
- (ATTenuator)
A network designed to reduce the amplitude of a signal.
ATV
- (Amateur Television)
Auto patch
Used in repeater operation for telephone interconnect.
Average power
Power measured on standard power meter.
Backscatter
Form of ionosphere propagation via the E and F layers allowing stations to hear other stations within the skip zones.
Balun
A simple transformer used to change an unbalanced input to a balanced output.
Band
A range of frequencies.
Bandwidth
Frequency needed for particular type of emission.
Bank
Memory bank
BCI
- (BroadCast Interference)
BFO
- (Beat Frequency Oscillator)
BNC
- (Bayonet Neill-Concelman)
A type of antenna connector
BPF
- (BandPass Filter)
Busy lockout
Inhibits transmit on a frequency in use.
Call sign
Sequence of letter and numbers used to identify amateur radio operators and issued by the National Communications Authority.
CAP
- (Civil Air Patrol)
Volunteer affiliate of the United States Air Force.
Carrier
An unmodulated transmitted signal.
Carrier frequency offset
(= Carrier Shift)
Distance between mark and space of the carrier for RTTY or similar communications.
CBR
- (Cross Band Repeater)
A repeater which receive incoming signal and re-transmit it in different bands - e.g. receives 144 MHz bands and retransmits 430 (440) MHz bands.
CCW
- (Counter ClockWise)
CH
- (CHannel)
Sequence of memory positions where frequency and related information is stored.
Conversion
Number of IF circuits in the receiver.
CPU
- (Central Processing Unit)
CQ
Radio communications term used to call others.
CTCSS
- (Continuous Tone Coded Squelch System)
Adds a continuous sub-audible low frequency tone to the transmitted carrier. Receivers set for the same low frequency tone can decode signal.
CW
1) Carrier Wave
2) ClockWise
CW filter
Used to narrow IF passband to improve reception in crowded band conditions.
Data communications
Transfer of data between two or more locations.
dBd
Unit of RF power as compared to a dipole antenna.
dBi
Unit of RF power as compared to an isotropic antenna.
dBm
Decibels measure, 1 mW with a load impedance of 600 Ohm
(0 dBm=1 mW).
DC
- (Direct Current)
DC ground
A connection point directly to chassis or battery ground to prevent build up of hazardous DC voltages.
Deviation
A measurement for a FM signals for the maximum carrier frequency changes either side of the carrier frequency.
Distress call
Signals a life-threatening situation. Most commonly referred to as an SOS or MAYDAY call.
Distress frequency
A frequency or channel specific for use in distress calling. Radio telephone distress frequencies are 2.182 MHz and 156.8 MHz. Survival craft use 243 MHz. Maritime distress frequencies are the same, while general aviation frequencies are 121.5 MHz.
Downlink
- (Uplink)
Frequency that repeater or satellite transmits on to a user.
DSP
- (Digital Signal Processor)
Used to improve the signal to noise ratio for clearer and more legible communications. Relatively new to the ham radio.
DTCS
- (Digital Tone Coded Squelch)
A Selective call system.
DTMF
- (Dual Tone Multi-Frequency (= touch-tone))
Used for transmit/receive numeric information such as phone number, PIN, remote radio control commands etc.
Dualwatch
Receiving two signals simultaneously.
Dummy load
A non radiating 50 Ohm load connected to the transmitter to replace
the antenna for testing purposes.
Duplex
An operation mode in which the transmit and receive frequencies are different.
Duplexer
A device which divides transmit and receive signals.
Duty cycle
The ratios of transmit to receive time.
Dxpedition
Trip to foreign land to "be DX."
ECTSY
- (ECTSY Radio Team)
A joint venture of CT1CSY and CT1ECT for FUN!
EBS
- (Emergency Broadcast System)
A system where at first an attention tone is transmitted over all station and the second tone followed with specific instruction regarding the receivable frequency in the national emergency.
EEPROM
- (Electrically Erasable and Programmable Read Only Memory)
EME
- (Earth-Moon-Earth)
Moon bounce communication.
EMI
- (Electro-Magnetic Interference)
Often called RFI (Radio-Frequency Interference).
Emission
Transmission of a signal.
Encryption
Transmitting cryptic form so that only certain people understand what has been sent.
Fading
Signal reduction due to atmospherics.
Field-Day
A radio operation with alternative power, like solar panels, generators, batteries, or any other source.
Filter
A circuit designed to pass only the desired frequency(s).
FM
1) Frequency Modulation
2) FM broadcast
FSK
- (Frequency Shift Keying)
FSTV
- (Fast Scan TV)
Graphics (and audio) communication using TV broadcast signals, requires a wide bandwidth.
Full duplex
An operation mode, which transmits and receives on different frequencies at the same time, as a telephone communication.
Ground Plane
A type of Omni-directional antenna.
Ground Wave
Electrical wave directly travelling from transmitter.
Grounding
Electrical connection to the earth.
Harmonic
Multiple of a fundamental frequency.
HF
- (High Frequency)
3–30 MHz range signals.
HPF
- (High Pass Filter)
IARU
- (The International Amateur Radio Union)
The watchdog and spokesman for the world Amateur Radio community, a federation of Regional Organizations and National Amateur Radio Societies founded im Paris, 1925.
IC
- (Integrated Circuit)
IF
- (Intermediate Frequency)
Internally converted frequency for amplification and other signal processing.
IF shift
A function that electronically shifts IF frequency from a center frequency.
ILLW
- (International Lighthouse/Lightship Weekend)
IMD
- (Inter-Modulation Distortion)
Distortion within RF circuits made with upper and lower adjacent channel signals.
ITU
- (International Telecommunications Union)
International organization within the United Nations System where governments and the private sector coordinate global telecom networks and services.
LF
- (Low Frequency)
30–300 kHz range signals.
Li-Ion
- (Lithium Ion)
Rechargeable battery which has better capacity than Ni-Cd, Ni-MH, etc., no memory effect after repeated non-full charge/discharge cycles.
LPF
- (Low Pass Filter)
LSB
- (Lower Side Band)
MARS
- (Military Affiliate Radio Service)
Memory bank
A set of memory channels organized into a group.
Memory effect
Rechargeable batteries such as Ni-Cd and Ni-MH types may be temporality getting less capacity as a result of repeated non-full charge/discharge cycles. It is called so since rechargeable batteries lose capacity as if "memorize" wrong full capacity level at less than full charge. Li-Ion batteries are free from this effect.
MF
- (Medium Frequency)
300 kHz–3 MHz range signals
MIC
- (MICrophone)
Modulation
Method of adding information to a radio frequency carrier
NB
- (Noise Blanker)
A function reducing pulse-type noises.
NBFM
- (Narrow Band FM)
Ni-Cd
- (Nickel-Cadmium)
Ni-MH
- (Nickel-Metal Hydride)
Notch filter
Sharp and narrow rejection filter for elimination of interfering signals.
NR
- (Noise Reduction)
DSP feature reduces unwanted signal noise.
Offset frequency
Frequency difference between transmits and receives.
OSC
- (OSCillator)
PA
- (Power Amplifier)
Parawatch
- (Dualwatch)
PBT
- (PassBand Tuning)
A function electronically reduce interference by narrowing IF bandwidth.
PEP
- (Peak Envelope Power)
RF power at maximum amplitude.
PLL
- (Phase Locked Loop)
Circuit to synthesize the different frequencies a radio will operate on.
Pocket beep
Beeping function when specific signal is received.
Priority watch
Reception mode, which by a selected frequency is always periodically, checked when VFO is set to different frequency.
PTT
- (Push To Talk)
PWR
- (PoWeR)
Reflected power
Non-radiated power dissipated as heat when the transmitter is mismatched to the antenna or load.
REP
- (Rede dos Emissores Portugueses)
The Portuguese section of IARU.
Repeater
Radio systems, which receive incoming signal and retransmit it for extended communication area. Normally put on geographically high locations for VHF/UHF hand portables.
RF
- (Radio Frequency)
RF ground
Connection of amateur equipment to earth ground to eliminate hazards from RF exposure and reduce RFI.
RFI
- (Radio Frequency Interference)
RIT
- (Receiver Incremental Tuning)
Fine-tuning receive frequency without changing displayed or memory frequency.
RTTY
- (Radio TeleTYpe)
RX
- (Receive)
S/N
- (Signal to Noise ratio)
SAR
- (Search And Rescue )
Scan
Continually sweeping frequencies looking for signals.
Scan Edge
End and start frequencies for a scanning range.
Scratch Pad Memory
Temporary frequency memories for quick access.
Semi Duplex
An operation mode in which transmits and receives is accomplished on different frequencies alternatively.
Sensitivity
Indicates how weak a signal the receiver will pick up.
Set mode
An operation mode used for radio. To set less frequently used control features.
Simplex
An operation mode where transmit and receive frequency is same.
Skywarn
Trained volunteer storm spotters for the National Weather Service.
SMA
- (Sub-Miniature a connector)
Type of antenna connector, used in VHF/UHF portable.
SP
- (Speaker)
Split
A mode in which the transmit and receive frequency is different.
SQL
- (SQueLch)
A function muting audio output for set conditions.
SSB
- (Single Side Band)
SSTV
- (Slow Scan TV)
Graphics communication using narrow bandwidth.
SWL
- (Short Wave Listener)
SWR
- (Standing Wave Ratio)
Measurement of forward versus reflected power output during transmit.
Spurious Emissions
Emissions, such as harmonics, removed in frequency from the main signal by at least 250% times He necessary bandwidht for the type of modulation used.
TCXO
- (Temperature Compensated Crystal Oscillator)
Heated crystal oscillator for better frequency stability.
TNC
1) Terminal Node Controller
Modem for data communication.
2) A type of antenna connector
TOT
- (Time Out Timer)
Time limiting function for continued repeater or other operations.
TS
- (Tuning Step)
Incremental steps
TSQL
- (Tone SQueLch)
Squelch function using sub-audible tones, selective call.
TVI
- (TeleVision Interference)
TX
- (Transmit)
UHF
- (Ultra High Frequency)
300 MHz–3 GHz range signals.
Uplink
- (Downlink)
Frequency that user transmits to the repeater or satellite.
Unwanted Emissions
An overall term for spurious emissions and out-of-band emissions.
USB
- (Upper Side Band)
UTC
- (Universal Time Coordinated)
An astronomical time based on the Greenwich meridian (zero degrees longitude).
VFO
- (Variable Frequency Oscillator)
An operation mode in which operator can change frequency freely.
VHF
- (Very High Frequency)
30–300 MHz range signals.
VOX
- (Voice Operated transmission)
A function automatically put the transmitter in transmit when talk into a microphone.
VSC
1) Voice Scan Control
2) Voice Squelch Control
Weather Alert
NOAA broadcast station transmitting alert signals.
WFM
- (Wideband FM)
WAC
- World Radiocommunications Conference
Treaty-level meetings held to revise the International Radio Regulations.
WARC Bands
A range of frequencies located to Amateur Service after 1979 WRC.