Not all internet-linked ham radio is digital voice. Three big systems — EchoLink, AllStarLink, and SVXLink — link plain analog FM over the internet: your radio transmits ordinary FM, a node turns the audio into network traffic, and stations around the world hear you with no digital mode, no codec chip, and no special radio required. All three solve the same problem, and each solves it with a completely different personality. Here's what each one is, how its nodes work, and its signature trait.
In every one of these systems, the building block is a node: a computer connected to both the internet and (usually) a radio. The radio side speaks plain analog FM to anyone in range; the computer side carries the voice over the internet to other nodes. Whatever happens between the nodes — node numbers, hubs, talkgroups — the RF on each end stays the analog FM your oldest handheld already speaks. That's the family resemblance; everything below is what makes each sibling itself.
EchoLink, created by Jonathan Taylor (K1RFD) in 2002, was one of the first VoIP systems built for ham radio, and it remains the easiest to start with. It runs in two modes. Single-user mode is just software — a PC application, a smartphone app, or the newer browser-based EchoLink Web — that lets a validated licensed ham talk over the network with no radio at all. Sysop mode is the RF side: a transceiver wired to a computer, appearing on the network as a -L (simplex link) or -R (repeater link) node that puts a frequency in your town onto the worldwide network.
Every station gets a node number, callsigns are validated against license records before access, and conference servers act as meeting rooms where many stations connect at once. The signature trait is reach: a ham with nothing but a phone in a hotel room can talk through a repeater on the other side of the world.
AllStarLink, created by the late Jim Dixon (WB6NIL), takes a wonderfully audacious approach: it's built on Asterisk, the open-source telephone PBX, extended with an application called app_rpt that turns the phone switch into a full-blown repeater controller with VoIP linking. An AllStar node is a Linux computer — very often a Raspberry Pi — running this software, with a small USB interface to a radio. Node numbers work like phone numbers: dial another node's number (by DTMF from your radio, even) and the two systems link.
Because each node is a complete repeater controller, AllStar isn't just a way to link radios — for many repeater owners it has replaced the hardware controller entirely, handling IDs, courtesy tones, scheduling, and linking in one box. Nodes connect freely to each other, many at a time; hubs are radio-less nodes that exist purely as meeting points. The network counts tens of thousands of nodes, and its signature traits are flexibility and audio quality — uncompressed-grade audio and a config file for everything. It's the system tinkerers love, and the plumbing under a remarkable amount of the linked-radio world.
SVXLink, started in 2003 by Tobias Blomberg (SM0SVX) of Sweden, is an open-source software suite that is several things at once: a full repeater controller for Linux, a simplex node, a built-in EchoLink gateway, and — through its companion server, SvxReflector — its own linking network. It's enormously popular in Europe, where hundreds of repeaters in Germany, France, Poland, the UK, and beyond run their entire operation on it.
The signature trait arrived with SvxReflector's modern versions: talkgroups for analog FM. Just like a DMR network, a SvxReflector can carry multiple parallel QSOs, with each node's sysop choosing which talkgroups to monitor — a repeater stays local until a talkgroup is activated, then joins regional, national, or special-interest traffic at will. Nodes can even select a talkgroup by which CTCSS tone you transmit. It's the digital-network experience — rooms, monitoring, parallel conversations — delivered to radios that have no digital mode at all.
| System | Born | A node is... | Signature trait |
|---|---|---|---|
| EchoLink | 2002, K1RFD | An app (no radio needed) or a radio-wired sysop station (-L / -R) | Reach: a phone anywhere can work a repeater anywhere |
| AllStarLink | Mid-2000s, WB6NIL | A Linux box running Asterisk/app_rpt — a complete repeater controller | Flexibility and audio quality; the plumbing of linked radio |
| SVXLink | 2003, SM0SVX | A Linux repeater controller / simplex node connected to a SvxReflector | DMR-style talkgroups for plain analog FM |
Why these three matter to the digital world
These analog systems are also the secret glue of cross-mode bridging. AllStar's app_rpt speaks a simple audio-over-network protocol called USRP, and that little protocol became the common language for connecting analog systems to digital ones — it's how DMR, D-Star, M17, and the rest get bridged to AllStar, EchoLink, and SVXLink nodes (SVXLink speaks it through its UsrpLogic). When you see a talkgroup that carries DMR, M17, and analog FM users in one conversation, some flavor of this plumbing is underneath. For worked examples on this site, see the USRP fanout bridge, the M17–AllStar–EchoLink bridge, and the M17–SvxReflector bridge.
A noncommercial hobby reference compiled by N6JET, gathered from public sources and shared freely for anyone interested in amateur digital voice.