HAM RADIO TERMS
Adjacent-channel interference
When a receiver is tuned to a specific frequency and
interference
is received on a nearby frequency.
AFC
(Automatic Frequency Control)
Automatically compensate frequency drift.
AFSK (Audio Frequency Shift Keying)
Automatically optimize receiver
amplifier gain.
ALC
(Automatic Limiting Control)
Limits RF drive level to power amplifier during
transmit to prevent
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.
Term used for a RF reference potential for some types
of antennas.
Most unbalanced or asymmetrical antennas need a
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 or 52 Ohms. For 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.
ARRL (The American Radio Relay League
The National Association for Amateur Radio in the US.
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)
FSTV, SSTV
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 (Band-Pass Filter)
Busy lockout
Inhibits transmit on a frequency in use
Call sign (your ham or stations I.D)
Sequence of letter and numbers used to identify
amateur
radio operators and issued by the FCC or R.A.
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
re-transmits
430(440) MHz bands or vice verse.
CCW (Counter Clock-Wise {Anti-clockwise})
CH (Channel{s})
Sequence of memory positions where frequency and
related
information is stored.
CI-V
Icom computer Control Interface allows multiple radio
control
simultaneously.
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
Carrier Wave
CW filter
Used to narrow IF pass band 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 .
(0dBm=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.
Radiotelephone 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 In the USA.
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.
Dual watch
Receiving two signals simultaneously.
Dummy load
A non radiating 50 . 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.
Dx’pedition
Trip to foreign land to be DX.
EBS (Emergency Broadcast System)
A system where at first an attention tone is
transmitted over
all station ad the second tone followed with specific
instruction
Regarding the receivable frequency in the national
emergency.
EEPROM (Electrically Erasable and Programmable Read
Only Memory)
ROM (Read Only memory)
RAM (Random Access 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.
Filter
A circuit designed to pass only the desired
frequency(s).
FM
Frequency Modulation a type of format I.E for the 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 traveling from transmitter.
Grounding
Electrical connection to the earth.
Harmonic
Multiple of a fundamental frequency; {Ghost
Frequency’s}.
HF (High Frequency)
1 to 30 MHz range signals.
HPF (High Pass Filter)
Hz (Hertz) a number of Cycle per seconds, Hz, Khz,
Mhz, Ghz.
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.
IMD (Inter-Modulation Distortion)
Distortion within RF circuits made with upper and
lower adjacent
Channel signals.
LF (Low Frequency)
30 to 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) ,A format of transmission.
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) Final amplified circuit in a
transmitter.
Para watch (=Dual watch)
PBT (Pass-Band 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.
Repeater
Radio systems, which receive incoming signal and
re-transmit
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 Tele-Type)
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.
Sky warn
Trained volunteer storm spotters for the National
Weather
Service.
SMA (Sub-Miniature a connector)
Type of antenna connector, used in VHF/UHF portable.
SP (S-Peaker)
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.
HFL High Frequency Listener
SWL (Short Wave Listener)
SWR (Standing Wave Ratio)
Measurement of forward vs. reflected power output
during
transmit.
TCXO (Temperature Compensated Crystal Oscillator)
Heated crystal oscillator for better frequency
stability.
TNC
1) Terminal Node Controller
Modem for data communication.
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 to 3 GHz range signals.
Uplink (.Downlink)
Frequency that user transmits to the repeater or
satellite.
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 to 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 weather
information and signals.
WFM (Wideband FM)
NFM Narrow band FM