The VK2RLE UHF 70cm repeater has been recently upgraded to use the open Digital Mobile Radio format, a standard as defined by the European Telecommunications Standards Institute (ETSI). The frequency remains the same 438.425 MHz with a minus 5 MHz transmit offset.
What is DMR? - DMR uses Time Division Multiple Access (TDMA) to provide two 30 ms "slots" per 12.5 kHz radio channel. Each time slot can carry independent voice conversations - this means the VK2RLE DMR repeater provides two simultaneous voice channels.
DMR provides better noise rejection and weak signal performance than analogue systems by using advanced Forward Error Correction (FEC) and codecs to remove noise and reconstruct signals that would otherwise be lost.
Talk Groups? - Each time slot can also have an almost unlimited number of "talk groups", which effectively function as discrete channels within that slot. Users on one talk group will not hear those on another.
DMR-MARC? - The VK2RLE DMR repeater is is linked to other DMR repeaters using the DMR-MARC network directly via Internet Protocol. This allows interconnection to more than five hundred interconnected DMR repeaters, across 44 countries, including Australia and New Zealand. A map of the DMR repeaters can be found here. There current status of the DMR-MARC repeaters in Australia, can be found here.
DMR Equipment - DMR transceivers are available from a number of manufacturers, with features ranging from the very simple to comprehensive, with prices start from about $150. The TDMA protocol used by DMR equipment means up to a 40% increase in battery capacity compared to conventional analogue equipment.
Tier 2 - The DMR standard has three tiers. Amateur radio utilises the DMR Tier 2 format. Tier 1 digital radio equipment is not compatible with DMR-MARC network.
Programming - Whilst there will be some variations in software between DMR equipment suppliers, the programming of DMR equipment is basically the same. A radio identification (or Radio ID) is required so your radio can be recognised by the DMR-MARC network. Request a Radio ID here. In addition to the frequency of your local DMR repeaters, programming of Digital Contacts (talk groups), Channel Information, Zone Information and Scan Lists will be required. Conventional analogue (FM) channels can also be programmed for repeater or simplex operation.
Time Slots and Talk Groups -The VK2RLE DMR repeater is configured the following talk groups;
Time Slot #1 -TG1 (World Wide), TG13 (world Wide English), TG100 (Tech Talk), TG113 (User Activated English 1), TG123 (User Activated English 2).
Time Slot #2 - TG5 (VK/ZL Region), TG505 (VK Region), TG5052 (VK2 Region).
Code Plugs - Copies of DMR radio program configuration files, otherwise known as code plugs, may also be available from fellow amateur radio operators.
Facebook - A Facebook page is available to help de-mystify DMR for Australian and New Zealand amateur radio operators. Find the Facebook page here.
Website - For further information and assistance on DMR equipment, repeaters and network can be found at the VK DMR Information website, found here.