Almost thirty years ago amateur radio operators in Auckland and Wellington worked together to install a Wellington to Auckland link on the UHF band. Later known as the National System, the network now covers New Zealand from the Bay of Islands down to Balclutha with 28 connected repeater stations operating independent of telco infrastructure.
While still an invaluable AREC resource, the National System is an analog network using 20th century technology. Today the Internet has driven an increased demand for networked applications, increased availability of communications, and created expectations for services such as digital messaging, GPS, location, and applications such as job ticketing where tasks can be presented directly on radio screens.
AREC has risen to the challenge presented by our SLA partners to bring the organization’s communications resources into the 21st century with the development of an all-digital radio network. A trial system was established in Wellington for testing before gradually rolling out to other centres as funds permit. The ZL TRBO system is a DMR MARC affiliated network.
Choosing the right technology has not been an easy task. On one hand we were well aware of the P25 standard development in the whole of government space, on the other hand amateurs have their own D-STAR™ standard. A registered trademark of Icom Incorporated, D-STAR equipment provided by that company along with homemade adapters are popular and used by experimenters around the world.
For an effective network it is necessary to consider both the ease of linking as well as the availability of base station and subscriber radio equipment. In addition it would be difficult to justify to our funding agency the purchase of equipment available only from a single vendor. For these reasons and after much discussion the AREC Management team decided to build a network based on the ETSI DMR digital mobile radio standard. DMR equipment is available from Harris, Hytera, Kenwood, Kirisun, Motorola, Puxing, Selex, Sepura, Simoco, Tait, Yaesu Vertex, and various other vendors. Icom is a member of the DMR Association but does not market equipment as of August 2016.
The network operates at UHF which preserves the option of using the P25 system at VHF should the need arise in the future. It should be noted that amateurs are making limited use of P25 at VHF but this activity is not directly related to AREC.
Wide area linking of the present DMR network is occurring using either direct microwave at 5.8 GHz or telco provided Internet (cable, fibre, and temporary connections via cellular). It is hoped to gradually extend the direct linking to avoid reliance on telco services to improve resilience.
There are a number of talkgroups carried on the ZL-TRBO DMR network. These are:
ZL (TG530) is a nationwide talkgroup carried on all ZL TRBO DMR repeaters. This is the primary New Zealand wide talkgroup.
ZK (TG8) is a second nationwide talkgroup carried on all ZL TRBO DMR repeaters. It differs from ZL in that it is carried in timeslot 1 not timeslot 2, thus ZL and ZK can be in use simultaneously. It is intended primarily for wide area AREC use but is available for general use if TS1 is not busy. In an emergency overseas talkgroups may be removed from timeslot 1 to allow unimpeded use of the ZK talkgroup.
LCL (TG9) is carried only on a master repeater and its immediate peers. Currently there are only ZL2DMR Central and ZL3DMR Midland area masters, so LCL covers the South Island or North Island depending on your home repeater. In the longer term the North Island may split in to upper and lower north as the network grows.
WW (TG1) is the original World Wide talkgroup, primary language is English but you will hear contacts in other languages. It is should now only be used as a calling channel.
WWE (TG13) is the World Wide English language talkgroup. This is the preferred talkgroup for international contacts.
UAE1 (TG113) and UAE2 (TG123) are the so called ‘user access’ talkgroups. These are intended as overflow groups for WWE. They differ in that use of WWE keys up over a thousand repeaters worldwide and ties up the timeslot that it is carried in for the duration of the contact on all those repeaters. On the other hand UAE1 and UAE2 only key up the local repeaters at each end of the contact and free up the timeslot on the rest of the network. The idea is that you would make contact on WWE then change to UAE1 or UAE2 if you are going to have a long QSO. UAE1 and UAE2 are intended for English language contacts.
UAA1 (TG119) and UAA2 (TG129) are the equivalent user access groups for WW, QSOs in any language can occur in these groups.
DMRplus US (TG133)
DMRplus UK (TG143)
DMRplus South Pacific (TG153)
These DMRplus groups are being carried on a trial basis to support new technology in a wider range of connected devices for experimenters. DMR-MARC has formed a partnership with the DMRplus network.
A dedicated DMRplus reflector 4851 has been established in Wellington for the South Pacific. A second DMRplus reflector 4850 for New Zealand is also now in operation testing on TG530.
Both reflectors are running on a single IPSC2 instance on Centos Linux running on an IBM server. Support for Hytera repeaters, homebrew MMDVM repeaters and base stations, the upcoming DV4mobile, and the DV4mini is now possible. The IPSC2 program that powers the DMRplus network has been developed by Thorsten DG1HT, Kurt OE1KBC, and Hans-Jürgen DL5DI.