What do the letters in something like J3E mean?
Every kind of transmission has a short code called an emission designator. It is made of letters and digits, and each position tells you something different. The licence uses the ITU system in Annex B.
The designator has three symbols (you will meet all three in the next lesson):
- The first symbol is the type of modulation of the main carrier.
- The second symbol is the nature of the signal(s) modulating the main carrier.
- The third symbol is the type of information sent (this one is beyond the RSK text).
This lesson is about the first.
The first-symbol letters
Modulation means changing a radio wave to carry information. The first symbol says how.
| Letter | Meaning |
|---|---|
| N | Unmodulated carrier |
| A | Amplitude modulated |
| F | Frequency modulated |
| G | Phase modulated |
| D | Amplitude and angle modulated |
| R | Single sideband, reduced or variable level carrier |
| H | Single sideband, full carrier |
| J | Single sideband, suppressed carrier |
| B | Independent sidebands |
| C | Vestigial sideband |
Making them stick
- N is for "none": no modulation at all.
- A, F, G are the classic three: amplitude, frequency, phase.
- D is the mix of amplitude and angle (frequency and phase together are called angle).
- R, H, J are all single sideband. They differ only in how much carrier is left: R keeps a reduced or variable carrier, H keeps the full carrier, and J suppresses the carrier.
- B has two independent sidebands; C has a vestigial (partly removed) sideband.
You now know
- The first symbol of a designator is the type of modulation of the main carrier.
- N unmodulated; A amplitude; F frequency; G phase; D amplitude and angle.
- R, H and J are single sideband with reduced, full and suppressed carrier.
- B is independent sidebands and C is vestigial sideband.