Internet Gateways (IGates)

What is an IGate?

An IGate (Internet Gateway) is an APRS station that bridges the local RF (radio) APRS network to APRS-IS — the global APRS Internet Service. IGates are the critical link that makes local radio transmissions visible to the entire world.

How IGates Work

An IGate consists of:

1. A radio receiver (or transceiver) tuned to the local APRS frequency
2. A TNC or software modem that decodes AX.25 packets from audio
3. Software that connects to an APRS-IS server and forwards decoded packets

When an IGate hears a packet on RF:

1. It decodes the packet from audio
2. Adds its own callsign as the receiving station (the qAR construct on APRS-IS)
3. Forwards the packet to the APRS-IS network
4. The packet becomes visible to all APRS-IS clients worldwide — including this dashboard

Two-Way vs Receive-Only

IGates come in two flavors:

Receive-Only IGate (RX-only)

• Listens to RF and forwards packets to APRS-IS
• Does not transmit anything on RF
• Simpler to set up, no transmitter needed
• Most common type

Two-Way IGate (TX/RX)

• Forwards RF packets to APRS-IS (like RX-only)
• Also gates certain APRS-IS packets to RF — specifically messages addressed to stations heard locally
• Enables message delivery to RF-only stations
• Requires careful configuration to avoid flooding the local frequency

Two-way gating is essential for message delivery. Without it, an RF-only station could transmit but never receive replies sent via the internet.

The APRS-IS Network

APRS-IS is a worldwide network of interconnected servers that:

• Collects packets from IGates everywhere
• Distributes packets to connected clients based on filters
• Enables applications (like this dashboard) to monitor APRS activity globally
• Provides message routing between distant stations

Major APRS-IS server groups include rotate.aprs2.net which load-balances connections across the Tier 2 network.

How This Dashboard Uses APRS-IS

This dashboard connects directly to APRS-IS to receive real-time packet data. Every station position, weather report, and message you see here arrived via an IGate somewhere in the world. The IGate callsign is often visible in the packet's path — it's the station that heard the original RF transmission and forwarded it to the internet.

Running Your Own IGate

If you're a licensed amateur radio operator, running an IGate helps the APRS network by:

• Providing coverage in areas lacking internet connectivity for RF stations
• Increasing message delivery reliability
• Contributing to the global situational awareness picture

Popular IGate software includes direwolf, aprx, and javAPRSSrvr. Many operators run receive-only IGates on inexpensive SDR (software-defined radio) dongles paired with a Raspberry Pi.