APRS Service Registry

APRS Service Types

Understanding the different types of APRS services.

TL;DR

  • Digipeaters — Relay APRS packets over RF to extend range
  • iGates — Bridge between RF and the internet (APRS-IS)
  • APRS-IS Servers — Internet backbone servers that route APRS data
  • Message Services — Automated services that respond to APRS messages

What is APRS?

APRS (Automatic Packet Reporting System) is a digital communications protocol used by amateur radio operators. It allows for the transmission of real-time tactical information including position, weather data, telemetry, and short messages.

APRS operates over VHF radio (typically 144.390 MHz in North America) and the internet via APRS-IS (APRS Internet Service).

Digipeaters

A digipeater (digital repeater) is a station that receives APRS packets over RF and retransmits them, extending the range of the APRS network.

How Digipeaters Work

  1. A mobile or portable station transmits an APRS packet
  2. The digipeater receives the packet on the APRS frequency
  3. If the packet is addressed for digipeating, the digipeater retransmits it
  4. Other stations (including other digipeaters) can receive the retransmitted packet

Common Digipeater Paths

  • WIDE1-1 — Request one hop through fill-in digipeaters
  • WIDE2-1 — Request one hop through standard digipeaters
  • WIDE2-2 — Request two hops through standard digipeaters

Types of Digipeaters

  • Fill-in digipeaters — Low-power, short-range digipeaters that help in coverage gaps
  • Wide-area digipeaters — High-site, high-power digipeaters providing broad coverage
  • Mobile digipeaters — Vehicle-mounted digipeaters for events or emergencies

iGates

An iGate (Internet Gateway) is a station that bridges APRS traffic between RF and the internet (APRS-IS).

Types of iGates

  • Receive-only (RX) iGate — Receives APRS packets over RF and forwards them to APRS-IS
  • Two-way (TX/RX) iGate — Also transmits packets from APRS-IS to RF, enabling messages to reach stations not connected to the internet

How iGates Work

  1. The iGate receives an APRS packet over RF
  2. It connects to an APRS-IS server and uploads the packet
  3. The packet becomes available to users worldwide via the internet
  4. (TX iGates) Messages destined for local RF stations are transmitted

iGate Considerations

  • Filtering — iGates can filter which packets they forward to reduce network load
  • Gating rules — TX iGates follow rules about what to transmit to avoid channel congestion
  • Verification — Two-way iGates require a verification code to transmit

APRS-IS Servers

APRS-IS (APRS Internet Service) is a network of servers that distribute APRS data worldwide over the internet.

Server Tiers

  • Tier 1 (Core) — Hub servers that interconnect the network
  • Tier 2 (Regional) — Servers that connect to Tier 1 and serve end users
  • Tier 3 (Leaf) — User-facing servers for clients and iGates

Connecting to APRS-IS

Users and iGates connect to APRS-IS servers on port 14580 (filtered) or 10152 (full feed). Connections are made via TCP and use a simple text-based protocol.

Regional Server Pools

  • noam.aprs2.net — North America
  • soam.aprs2.net — South America
  • euro.aprs2.net — Europe
  • asia.aprs2.net — Asia
  • aunz.aprs2.net — Australia/New Zealand

Message Services

Message services are automated stations that respond to APRS messages, providing information or performing actions on request.

Examples of Message Services

Service Type Description Example Command
Weather Returns current weather for a location wx 90210
Repeater Finder Finds nearby repeaters repeater 5
Email Gateway Sends/receives email via APRS user@example.com message
Spot Price Returns commodity prices gold
QRZ Lookup Returns callsign information W1AW

How to Use Message Services

  1. Address an APRS message to the service's callsign
  2. Include your command or query in the message text
  3. The service processes your request and sends a reply message
  4. Your APRS device displays the response

Note: The services listed in this registry are primarily message services. Check each service's description for usage instructions.

Other Service Types

Trackers

GPS-enabled devices that periodically beacon their position. Common in vehicles, aircraft, and for tracking assets.

Weather Stations

Automated stations that transmit current weather conditions (temperature, humidity, wind, pressure, rain).

Telemetry Stations

Stations that transmit sensor data, such as battery voltage, solar panel output, or environmental sensors.

Objects and Items

Virtual markers placed on the APRS map, often used for events, hazards, or points of interest.

Learn More

  • APRS.org — The official APRS website by Bob Bruninga, WB4APR (SK)
  • APRS-IS.net — Information about the APRS Internet Service
  • aprs.fi — Popular APRS tracking website