DPMR = Digital Private Mobile Radio (a Common Air Interface protocol)
DMR = Digital Mobile Radio (a Common Air Interface protocol)
FDMA = Frequency Domain Multiple Access (a Channel Access Method)
TDMA = Time Domain Multiple Access (a Channel Access Method)
FDMA provides one 'communications path (voice or data)' per frequency/signal. Analog FM is an example of FDMA. So it P25 Phase 1. Thus, FDMA is uses with analog and digital systems.
TDMA is mulitple 'communications paths (voice or data)' per frequency/signal. DMR uses two-time-slot TDMA, to get two 'talk paths' per frequency/signal.
The DPMR protocol uses FDMA at 6.25 khz spacing.
MOTOTRBO uses the DMR protocol, which is TDMA at 12.5 khz spacing.
John Rayfield, Jr. CETma
W0PM
DPMR = MotoTRBO, I believe...not iDAS or NXDN.