We use the XXX ITU classification of emissions code to classify all the transmission modes used by non-amateur stations in the amateur radio bands whose modulation technique is unknown.
In this category, different types of transmissions are grouped, like transmissions intended to be received by another station, and transmissions sent with other purposes, sometimes unknown.
In this last group we include certain jammers, whose type of transmission is unknown. A jammer is an intentional transmission of a signals with the purpose of disturbing the transmission of another radio signal in such a way as to make interpretation by the receiver difficult or impossible, by interfering it or canceling it. This is not a specific transmission mode, since different modes as well as simple audio signals and even music can be used for this function. In the same way, its bandwidth varies depending on the signal or the portion of radio spectrum to disturb. They are very often used in military scenarios, and sometimes for political purposes to disrupt broadcasting stations.
