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Digital-voice repeaters
DMR, D-STAR and Fusion repeaters: what changes and what coordination still means.
DMR, D-STAR and Fusion repeaters: what changes and what coordination still means.
A digital-voice repeater still receives on one frequency and retransmits on another, so everything in Repeater hardware and duplexers and Repeater antennas and coverage applies: the same duplexer, antenna, feed line and site. Part 97 defines a repeater by what it does (it retransmits another amateur station on a different channel), not by its mode. What is new is the modem and the network behind the controller: a digital repeater decodes the signal, and usually connects to the internet to link to others. The modes themselves are in DMR, D-STAR and Yaesu System Fusion; this article is about being the repeater.
A radio works only with its own system: a DMR radio cannot use a D-STAR repeater.
Some repeaters serve analog FM and one digital mode from one site, either by switching automatically or by running separate channels. That saves a tower and an antenna, but analog and digital users cannot decode each other's transmissions unless the repeater is built to convert between them (Yaesu says WIRES-X lets C4FM stations talk to analog FM stations). In practice: listen for a while before you transmit, and expect a digital signal to sound like a buzz or hiss on an FM radio.
Coordination. Part 97 does not require it, though most repeater owners coordinate, and if two repeaters interfere and only one is coordinated, the other's licensee has primary responsibility for resolving it (97.205(c)). That is true for digital repeaters too. Coordinators set their own policies, including whether to assign pairs to digital use, so ask yours. ARRL says it is not itself a frequency coordinator. Its repeater directory lists digital repeaters, but a directory listing is not coordination.
Identification. Part 97.119(a) says each station must transmit its call sign on its transmitting channel at the end of each communication and at least every 10 minutes during one. Under 97.119(b) the call sign must be sent with an emission authorized for that channel: by CW, by phone in English, or, in the cases the rule lists, by RTTY or image emission. The rule has no separate paragraph for digital voice. It does not say whether call signs carried in a digital header or network registration count, so do not assume it. The conservative habit is to have the controller send a voice or CW ID, and to ask the trustee how the repeater identifies.
Linking. A transmission that is linked is heard on every repeater joined to it, and each repeater's control operator remains responsible for what that repeater transmits; see EchoLink, IRLP and AllStar. Part 97 forbids messages encoded to obscure their meaning (97.113(a)(4)), so encryption is off. A repeater may not retransmit signals from other than an amateur station (97.113(c)). A network's own rules (talkgroup use, ID use) are its policy, not law.
This article describes the US; other countries differ.