Digital Mobile Radio (DMR) is an international digital radio standard developed by the European Telecommunications Standards Institute (ETSI), and first ratified in 2005. More than a decade ago, vendors and users of radio systems recognized that the existing analog trunking standards required updates with modern techniques to provide:
Improved voice quality
Improved functionality such as Location information)
Improved security (i.e. Authentication and Encryption)
Improved channel efficiency (2 slot TDMA)
MotoTRBO is Motorola's flavor of DMR. NexEdge is a Kenwood/Icom digital format, completely different technology.SO different Digital Radio has different radio standard 'mode'
The only reason why the majority of ham repeaters are Motorola is because only they support the IP Connect that allows them to be linked via the internet easily.
Hytera and other manufacturers build DMR equipment as well.
The DMR standard also specifies the use of TDMA technology. TDMA stands for Time Division Multiple Access. TDMA provides two logical channels and each 12.5-kilohertz channel space (see diagram below). This provides a useful doubling of capacity within the same analog channel space.