APRS
Position reporting, tracking, and messaging over amateur radio
APRS (Automatic Packet Reporting System) is a protocol that runs on amateur radio frequencies to transmit position reports, short messages, and telemetry data. A radio with APRS capability can beacon your GPS coordinates at set intervals, and those packets get picked up by digipeaters and internet gateways that make your position visible on a map. In the backcountry, APRS gives you a way to share your location without relying on cell coverage or satellite subscriptions.
License required. APRS operates on amateur radio frequencies. In the United States, you need at least a Technician-class amateur radio license from the FCC to transmit. Receive-only tracking (monitoring others) does not require a license.
How It Works
Your radio encodes your GPS position into a packet and transmits it on the APRS frequency. Nearby digipeaters receive the packet and retransmit it, extending its reach. If the packet reaches an internet gateway (iGate), it gets forwarded to the APRS-IS network, where anyone with a web browser can see your position on a map. The system also supports two-way messaging between stations, weather reporting, and object tracking.
Frequencies
- 144.390 MHz — the standard APRS frequency in North America. This is where the vast majority of digipeaters and iGates listen. Program this into any APRS-capable radio you carry.
- 144.800 MHz — the standard APRS frequency in Europe, Africa, and most of Asia.
- 145.175 MHz — used in Australia and New Zealand.
Tracking and Map Tools
- aprs.fi Web — the most widely used APRS tracking site. Shows real-time station positions on a map, with history, weather data, and messaging. You can share a direct link to your station's track with someone at home.
- APRS Direct Web — another real-time APRS map with filtering by station type, call sign, or geographic area. Clean interface for monitoring specific stations.
- APRSdroid App — an Android app that turns your phone into an APRS tracker when connected to a radio via audio cable or Bluetooth TNC. Useful if your radio does not have built-in APRS.
Radios and Hardware
Some handheld and mobile amateur radios have APRS built in. Others can be paired with an external TNC (terminal node controller) or a smartphone app to add APRS capability. A few common options for backcountry use:
- Yaesu FT5DR / FT3DR — handheld dual-band radios with built-in APRS and GPS. Beacon your position directly from the radio without any extra gear.
- Yaesu FTM-400XDR / FTM-300DR — mobile radios with built-in APRS, suited for vehicle-based trips and overlanding.
- Mobilinkd TNC — a small Bluetooth TNC that connects your existing radio to a phone running APRSdroid or other APRS software. A good option if you already carry a radio that lacks built-in APRS.
- Micro-Trak / TinyTrak — lightweight standalone APRS trackers designed for low-power, portable use. Pair with a GPS module and a small radio for a minimal beaconing setup.
Backcountry Considerations
- APRS coverage depends on digipeater and iGate infrastructure. In remote areas with no nearby digipeater, your packets may not reach the internet, though other APRS-equipped stations within direct range can still receive them.
- Set your beacon interval based on the trip. Every 5 minutes gives close tracking but drains the battery faster. Every 15 to 30 minutes is more practical for multi-day trips.
- Before heading out, check aprs.fi for digipeater activity in the area you are traveling through. If you see active stations nearby, your beacons are more likely to reach the network.
- APRS messaging can serve as a basic two-way text communication channel. Messages are short (67 characters max) but can be enough to relay a status update or coordinate with someone monitoring your call sign.