01 — The radio spectrum
02 — Modulation modes
AM — Amplitude Modulation
The strength of the radio wave varies to carry audio. Simple, widely compatible, and used by the majority of international shortwave broadcasters. Standard on all CB radios.
SSB — Single Sideband
A stripped-down form of AM that removes the carrier and one sideband, focusing all power into useful signal. More efficient and longer range, but tuning must be precise — a few Hz off sounds like "Donald Duck".
LSB — Lower Sideband
One of the two SSB modes. Convention below 10 MHz — used on CB radio and lower amateur bands. When someone says "I'm on LSB", they're using the sideband below the carrier frequency.
USB — Upper Sideband
The upper SSB mode. Standard above 10 MHz — shortwave amateur and utility stations. Increasingly common on CB. Cleaner on the high end of a band.
CW — Continuous Wave (Morse)
The oldest radio mode — turning a carrier on and off to send Morse code. Extremely efficient; can punch through noise and interference that would bury voice signals completely.
FM — Frequency Modulation
The frequency of the wave varies with audio rather than the amplitude. Cleaner sound but shorter effective range on shortwave. More common on VHF, but narrow-band FM appears on some shortwave stations. Standard on UK CB.
03 — Essential technical terms
Frequency & wavelength
Frequency (MHz or kHz) counts wave cycles per second. Wavelength is the physical length of one cycle. They're inversely related — higher frequency means shorter wavelength. Shortwave occupies 3–30 MHz (10–100 metre wavelengths).
BFO — Beat Frequency Oscillator
A circuit inside your receiver that generates a local tone, letting you hear SSB and CW signals properly. Without it, SSB sounds like unintelligible garble. Essential for serious shortwave listening.
S-meter
Signal Strength meter — shows how strong the received signal is, typically S1 to S9 (with S9+dB for very strong signals). S9 is considered a full-strength signal.
Squelch
A threshold circuit that mutes the speaker when no signal is present, so you're not listening to constant static. Turn it up until noise disappears, then back off slightly so weak signals can break through.
Propagation
How radio waves travel. Shortwave signals bounce off the ionosphere — a charged atmospheric layer — allowing them to travel thousands of miles. This is called "skywave" propagation and is what makes shortwave remarkable.
Ionosphere & band timing
The ionosphere has layers (D, E, F1, F2) that reflect different frequencies based on time of day and solar activity. Lower bands (3–10 MHz) work best at night; higher bands (15–30 MHz) suit daytime listening.
QRM / QRN / QSB
Q-codes used by operators worldwide. QRM = man-made interference. QRN = natural static (lightning, etc). QSB = signal fading. A legacy of Morse telegraphy, still in everyday spoken use on shortwave and amateur radio.
DX
Short for "distance" — long-distance contacts or stations. DXing is the pursuit of hearing or contacting stations as far away as possible. Prized by shortwave listeners and CB enthusiasts alike.
04 — CB radio specifics
| Channel | Designated use |
|---|---|
| Ch. 9 | Emergency & roadside distress (internationally recognised) |
| Ch. 14 | UK general calling channel (commonest in Britain) |
| Ch. 19 | Truckers' calling channel |
| Ch. 1–40 | Full UK CB allocation at 27 MHz — FM & AM |
Calling channel
A shared channel where operators listen to make initial contact, then move to a quieter channel to chat. Don't hold long conversations on a calling channel.
Break / Breaker
"Break" is said to politely interrupt a conversation. "Breaker 1-9" signals someone wants to use channel 19. A core piece of CB etiquette.
Skip / Sporadic-E
Atmospheric conditions occasionally bounce CB signals hundreds of miles. Exciting when it happens, but frustrating when distant stations override local traffic.
05 — Getting started
Antenna matters most. Even a modest radio performs dramatically better with a good antenna. For shortwave, a simple long wire (10–20 metres) strung outdoors will outperform any whip or built-in antenna significantly.
Time your listening. For shortwave, late evening and night-time opens the lower bands (49 m, 31 m) for long-haul stations from the Americas, Asia, and Africa. Daytime suits higher bands (16 m, 13 m).
Use a frequency schedule. Sites like EIBI and HFCC publish up-to-date shortwave broadcasting schedules. Shortwave isn't dead — BBC World Service, Radio Romania International, China Radio International, and many others still broadcast.
On CB, listen first. Spend time monitoring a channel before transmitting so you understand local conventions, active times, and who's around. UK CB uses both FM and AM — ensure your set supports both.
Recommended receivers. For shortwave listening, the Tecsun PL-880 and Sangean ATS-909X are strong portable options. For CB, the President range and Midland Alan 42 are popular UK choices. Always ensure CB sets are UK type-approved.