HB3YAQLucerne
Radio terms.
Clearly explained.
What does squelch do? How do dB and dBm differ? Clear explanations with examples, common pitfalls and a path to practical learning.
32terms to explore
32 terms
A
ADIF
ADIF standardises exchange of amateur-radio log data between programs. Fields can include callsigns, UTC time, band, mode and confirmations.
Example & explanation →AGC
Automatic Gain Control adjusts gain according to signal level, reducing differences between weak and strong signals at the output.
Example & explanation →Aliasing
Aliasing makes different analogue frequencies indistinguishable after sampling. Unwanted signals may then appear inside the digital range of interest.
Example & explanation →AM
Amplitude modulation varies a carrier’s amplitude with the information signal. Conventional AM contains the carrier and two sidebands.
Example & explanation →
B
C
Coaxial cable
Coaxial cable carries a signal using an inner conductor and a concentric outer conductor. The dielectric and construction determine characteristic impedance, losses and propagation speed.
Example & explanation →Codeplug
A codeplug is a radio’s programmable configuration, including channels, contacts and zones. It is edited with programming software compatible with the hardware.
Example & explanation →Colour code
A colour code is a DMR identifier from 0 to 15. For normal operation, the channel must match the repeater or hotspot’s colour code.
Example & explanation →
D
D-STAR
D-STAR is an amateur-radio system for digital voice and data. DV operation uses callsign fields and a selected destination; a gateway can connect repeaters to the network.
Example & explanation →dB / decibel
Decibels express a ratio logarithmically. For power, use 10 · log₁₀(P₂/P₁), allowing gains and losses in a chain to be added.
Example & explanation →dBm
dBm expresses an absolute power level relative to 1 milliwatt, combining the logarithmic dB scale with a fixed power reference.
Example & explanation →Dipole
A centre-fed half-wave dipole has two conductor halves. Together they are approximately half a wavelength long; actual dimensions depend on construction and surroundings.
Example & explanation →DMR
Digital Mobile Radio is a family of digital radio standards. Amateur radio commonly uses DMR Tier II; channel configuration includes frequency, colour code, time slot and call destination.
Example & explanation →
F
G
Gain
Gain describes the ratio of output to input level. In a receiver it can occur before or after digitisation and is often expressed in dB.
Example & explanation →Ground plane
A simple ground-plane antenna consists of a vertical radiator and a conductive counterpoise, often radials. In the quarter-wave model, the radiator is approximately a quarter wavelength long.
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H
I
M
Q
R
S
Sample rate
Sample rate is the number of samples digitised per second. Together with filtering and the sampling method, it limits the usable frequency range.
Example & explanation →SDR
In a Software Defined Radio, software performs key signal-processing tasks such as filtering and demodulation. The analogue front end and converter still determine which signals can be processed.
Example & explanation →Simplex
In typical simplex voice operation, stations take turns transmitting and receiving on the same frequency. Only one station can speak intelligibly at a time.
Example & explanation →SNR / signal-to-noise ratio
Signal-to-noise ratio compares wanted signal power with noise power in the range being considered. It is often expressed in dB.
Example & explanation →Squelch
Squelch mutes audio when its opening condition is not met. With level- or noise-based squelch, the threshold determines when audio becomes audible.
Example & explanation →SSB · USB / LSB
Single Sideband transmits one sideband, usually with the carrier suppressed. USB is the upper and LSB the lower sideband relative to the carrier reference.
Example & explanation →SWR / standing wave ratio
SWR is the ratio of maximum to minimum voltage on a line with standing waves. It is related to reflection caused by an impedance mismatch.
Example & explanation →
T
Talkgroup
A talkgroup is a numbered group destination for digital calls. A DMR channel typically selects it as a digital group contact.
Example & explanation →Time slot
DMR TDMA divides a 12.5 kHz radio channel into two time slots. A suitably operated repeater can provide two separate call paths.
Example & explanation →