DMR Tier 1
DMR Tier I terminals are intended for licence-free use in the European PMR446 band. Tier I products may not be used with infrastructure (i.e. without the use of repeaters). This part of the standard provides for consumer applications and low-power commercial applications, using a maximum of 0,5W ERP. These terminals use 16 hard-coded channels separated by 12,5kHz with 4-level FSK modulation at 3.6 kbit/s. The channels are hard-coded (non-programmable) as PMR446 may only operate on the following frequencies:
Although the DMR standard allows terminals to use continuous transmission mode (i.e. the terminal transmits on both slot 1 and 2). Tier I radios use TDMA due to the battery savings that come with transmitting only half the time instead of continuously.
The Motorola XT600d uses 6,25kHz FDMA and is therefore not DMR Tier 1 compliant. The Nitro product portfolio, currently sold in North America uses the 3,5GHz CBRS band and is also not DMR Tier 1 compliant (nor has anything to do with DMR). Currently, there is only one manufacturer of bona-fide DMR Tier 1 equipment. The overwhelming majority of PMR446 equipment available on the market is analogue.