AllStar

AllStar Link Overview

AllStar Link (often just called AllStar) is a high-performance radio-over-IP (RoIP) network. Unlike some digital modes that rely on proprietary hardware or specific digital voice protocols (like DMR or D-STAR), AllStar is built on an open-source platform called Asterisk, which was originally designed for professional telephone exchanges (PBX).

In amateur radio, AllStar allows you to link repeaters or home "nodes" together over the internet using high-quality analog audio.

How It Operates

The system functions by converting analog radio signals into digital data packets that can travel across the internet. Here is the basic breakdown of the architecture:

1. The Asterisk Core (app_rpt)

The "brain" of an AllStar node is a specialized module for Asterisk called app_rpt. Because it uses a telephone-grade engine, AllStar is incredibly stable and offers "full duplex" capabilities, meaning it can handle simultaneous incoming and outgoing signals much more efficiently than simpler linking systems.

2. The Node

A "node" is simply a radio connected to a computer (often a Raspberry Pi) running the AllStar software.

• Radio Interface: To connect the two, you use a URI (USB Radio Interface). This device converts the radio's "Push-to-Talk" (PTT) and audio signals into something the computer can understand via USB.

• The Server: Many operators choose to host their "hub" or central node on a Virtual Private Server (VPS). This provides a high-bandwidth, 24/7 backbone that doesn't rely on a home internet connection.

3. Linking and Commands

Nodes are identified by unique numbers. To connect to another station, you use DTMF (touch-tone) commands from your handheld radio.

• To connect to node 1234, you might key in *31234.

• To disconnect, you might key in *11234.

Why Operators Choose AllStar

Audio Quality

• It uses the PCM audio codec, which provides a very "natural" sounding analog voice compared to the "robotic" compression of some digital modes. 

Flexibility

• • It can bridge different types of networks. You can link an AllStar node to Echolink, IRLP, or even digital bridges like DMR.

Scalability

• You can create a "Hub" that hosts hundreds of simultaneous connections, making it ideal for wide-area emergency networks.

Control

• Since it is Linux-based, it is highly customizable for those who enjoy the technical side of networking and server management.

Typical Hardware Setup

1. A Transceiver: Anything from a small handheld (HT) to a full-sized repeater.

2. A Computer: Usually a Raspberry Pi for local nodes or a Linux VPS for hubs.

3. Radio Interface: A USB sound card modified for radio (like the RIM-Lite or URIx).

4. AllStar Software: Typically installed via an image like ASL (AllStarLink) or HamVoIP.

If you tuned your analog radio to the frequency being used by a local AllStar node, you would hear perfectly clear analog audio.

This is one of the primary reasons many operators enjoy AllStar—it allows you to use standard, "old-school" analog equipment while still benefiting from worldwide internet linking.

How it Works at the Radio Level

When an AllStar node receives a transmission from the internet, the computer (like a Raspberry Pi) processes that data and sends it to the connected radio as an analog audio signal. Your radio then broadcasts that audio exactly like a normal FM transmission.

What You Would Experience:

• The Voice: You would hear the other operator's voice just as if they were standing a few miles away talking on a standard FM simplex frequency or repeater.

• The "Digital" Part: All the "data" (the internet packets) stays hidden inside the computer and the network cables. It never actually hits the airwaves as a data stream.

• Tones: You might occasionally hear DTMF tones (touch-tones) if the node owner is sending commands to link or unlink from other stations, or short "courtesy tones" (beeps) that indicate a transmission has ended.

Contrast with "True" Digital Modes

To give you a comparison, if you tuned an analog radio to a DMR, P25, or D-STAR frequency, you would hear a loud, constant buzzing or "grinding" noise. That is because those modes transmit actual digital bits over the air. AllStar, however, keeps the radio side 100% analog.

As long as you are within range of the node's transmitter and have your radio set to the correct frequency (and matching CTCSS/PL tones, if the owner uses them), you can listen in and participate with any standard analog radio.

You can participate using only your "old school" analog radio. In fact, that is the most common way for operators to interact with the system. While the "node" (the gateway to the internet) requires a computer or server to function, you—as the end user—do not. As long as you are within range of a radio that is already connected to the AllStar network, your setup remains refreshingly simple.

How You Participate

To join in, you simply operate your radio as if you were talking on any standard FM repeater or simplex frequency:

• Tuning In: You set your analog radio to the frequency used by the local AllStar node.

• The PL Tone: Most node owners set a CTCSS (PL) tone to prevent interference. You’ll need to set your radio to transmit that specific tone to "open" the node so it hears you.

• Keying Up: When you press the PTT (Push-to-Talk) button on your analog radio, your voice travels through the air as an FM signal.

• The Hand-off: The local AllStar node receives your analog FM signal, converts it to digital data, and sends it across the internet to everyone else connected to that session.

Two Ways to Connect Without Your Own Computer

Using a Public Node

• Many amateur radio clubs host AllStar-linked repeaters. You simply tune your radio to the repeater frequency. You are now "on" AllStar without needing any extra gear.

Using a Personal Node - (An analog radio + a pre-built "Node Box.")

• If you want your own private gateway at home, you can buy a "plug-and-play" node (like a ClearNode or Shari). While there is a tiny computer inside the box, you never have to touch it. You just talk to it with your analog handheld radio.

A Small Tip for "Old School" Gear

Since AllStar is linked over the internet, there is often a very slight delay (latency). When you key up your analog radio, it’s best to wait about one second before you start speaking. This ensures the digital network has time to "wake up" and synchronize so your first few words don't get clipped for the other listeners.

Other than that, your analog radio acts exactly like it’s talking to someone across the street—even if the person responding is on a different continent!