IARU Region 2 Monitoring System
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USING THE ITU EMISSION CLASSIFICATIONS
|What follows is a brief list of the most common methods of transmitting information by HF/VHF radio and a simplified version of their ITU emission classification. If you have looked at the full table of ITU Emission Classifications you will know that describing the modulation scheme of a radio signal can be very complicated and would require a small radio laboratory in order to discover the exact method of modulation of an unknown signal. In addition the full classification includes the bandwidth of the emitted signal, but we will ignore that information as we are concerned only with the bandwidth of the received signal, not with the bandwidth that might have been intended by the operators of the transmitter.
Here we will concern ourselves only with the most common types of modulation and to the depth that suits the average Radio Amateur. Note that some of our usage is not quite according to the ITU rules, but these non-standard adaptions are more useful for our purposes.
There are many signals with other methods of carrying information, some of them quite sophisticated, but the ones described above are the most common, and the codes given here will serve for almost all intruders.