What is Single Sideband (SSB) Radio?
SSB provide sailors with long range communications with no ongoing contract, costs or connection charges. There are four levels of GMDSS Certificate of Competence, however only two are relevant for SSB;
- Long Range Certificate (LRC), for vessels under 24m
- General Operator Certificate (GOC) for any sized vessels
- Medium Frequency (MF)
- High Frequency (HF)
Marine HF Radio
High Frequency (HF) lies between MF and VHF and is the frequencies 3 MHz to 30 MHz. HF radio waves can refract of the ionosphere giving us hundreds or even thousands of miles range.
HF Radio Propagation
Low frequencies follow the curvature of the earth. This is known as Ground Wave. Higher frequency radio waves can refract off the Ionosphere wich is known as Sky Wave. Sky Wave can result in dead zones (where no signal is received) when close to a transmitting station and MF or VHF will therefore be more appropriate for short range communication. A good rule of thumb for daytime use is to assume about 100 miles range per MHz of frequency:-
| MF/HF Frequency | Daylight Range | Range in Darkness |
|---|---|---|
| 2 MHZ | 200 NM | 500 NM |
| 4 MHZ | 400 NM | 800 NM |
| 6 MHZ | 600 NM | 1200 NM |
| 8 MHZ | 800 NM | 1600 NM |
| 12 MHZ | 1200 NM | 2400 NM |
| 16 MHZ | 1600 NM | Fade Out |