Over the years many interesting developments regarding radio-communication took place.
Instead of only morse-code, voice (SSB or AM), Telex (RTTY) or multi-channelsystems like Telex Over Radio (TOR) as professional or radio-amateur we now use many other, digital, systems. Several of those developments thanks to radio-amateurs.
To some these systems have exotic names or sound as such. To others it is common practice.

In case you enounter such an unkown sound, check it with the examples on following pages