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DMR (Digital Mobile Radio)
The most common use of the Digital Mobile Radio (DMR) communication mode in ham radio is where an analog voice signal is converted to an AMBE +2 Vocoder compatible digital signal. This signal is then sent to a DMR repeater that is connected to the internet. It is then sent to a distant repeater that is connected to the internet which retrieves the digital signal and transmits it to its local destination. The received signal is then decoded by the DMR targeted listener to an analog voice signal which can be a remote party somewhere else in the world.
There are several modes for DMR including simplex which may have a communication distance of only a few hundred yards. Simplex may also be used in unlicensed operation because of its short transmission distance.
The site listed below will provide significant detail on how DMR works and how to get started In DMR.
The Quaboag Valley Amateur Radio Club (QVARC) 