Over 20,000 ham radio enthusiasts use APRS across the United States right now. APRS, the Automatic Packet Reporting System, has changed how amateur radio operators track locations, send messages and share immediate data.
Bob Bruninga (WB4APR) developed APRS radio technology in the 1990s. The system has now grown into a global communication platform that operates on 144.390 MHz in North America and 144.800 MHz in Europe. Users can transmit GPS coordinates, track vehicles, monitor weather stations and send text messages without needing internet connectivity.
APRS becomes extremely useful when you go hiking or snowshoeing where regular communication methods might not work. The system’s ability to transmit data immediately helps a lot during emergencies and public service events.
You’ll find getting started with APRS easier than expected. This piece shows beginners everything they need to know about setting up and using this powerful ham radio tool – whether they choose a radio with built-in capabilities, connect to an external device, or use a smartphone app.
What is APRS and Why It Matters
APRS stands for Automatic Packet Reporting System, a digital communication system that transmits small packets of data over radio waves. Bob Bruninga (WB4APR) created it in the 1980s, and APRS has grown into a powerful tool that amateur radio operators use worldwide to share live information.
Understanding APRS in simple terms
APRS lets you share tactical information without connecting directly to another station. Traditional voice communications need operators to talk to each other, but APRS sends data packets that any equipped station can pick up. These packets always have a callsign and usually include GPS position data, short text messages, or other telemetry information.
The system runs on one shared frequency in each region (144.390 MHz in North America, 144.800 MHz in Europe, and 145.175 MHz in Australia). Special stations called digipeaters (digital repeaters) catch and resend APRS packets to extend their range. On top of that, Internet gateways (I-Gates) link the radio network to the global APRS Internet System (APRS-IS), so people worldwide can access the information.
APRS works like a digital bulletin board where information gets posted for everyone to see, not a private chat between two stations. The system blends with mapping software to show station locations, weather data, and other information visually, giving you better awareness of your local area.
Common myths and misconceptions
People often think APRS is just a vehicle tracking system. Bob Bruninga himself said, “The goal is communications and local info update, -not- just vehicle tracking!”. APRS helps share tactical information about everything happening in your area, not just moving dots on a map.
People sometimes disagree about what APRS stands for. Some say “Automated Position Reporting System” while others use “Automated Packet Reporting System.” Both names work fine.
Newcomers often think APRS needs internet connectivity. The internet makes APRS better through global connectivity via I-Gates, but the system works great using just radio frequencies without any internet connection. This makes it really valuable during emergencies when internet infrastructure fails.
Some think APRS is similar to standard packet radio. APRS is different because it broadcasts using unnumbered AX.25 frames instead of the connected data streams that traditional packet radio uses.
How APRS is different from other ham radio tools
Standard packet radio creates one-to-one connections where packets get acknowledged and resent if lost. APRS uses a “fire and forget” approach. APRS packets travel through the network taking all available paths until they reach their maximum hop count.
Traditional digital modes like FT8 or PSK31 focus on making long-distance contacts. APRS prioritizes sharing local, tactical information that matters right now. This local focus makes it great for emergency communications, public service events, and staying aware of what’s happening around you.
Winlink stores and forwards messages like email, but APRS gives you instant data transmission. This speed makes APRS crucial during fast-moving situations when time matters most.
APRS naturally combines location data with communications. Other modes might need separate systems for tracking and messaging, but APRS puts these features in one complete system. The system can connect with weather stations, telemetry equipment, and the International Space Station’s APRS digipeater.
Licensed ham radio beginners can start with APRS using radios that have built-in APRS features, external Terminal Node Controllers (TNCs) connected to standard radios, or smartphone apps that work with radios. Each method offers different benefits in cost, portability, and functionality.
How APRS Works Behind the Scenes
APRS transmissions work through a sophisticated yet simple system. A look at its core components shows how they work together to create a reliable communications network.
The role of packets and GPS data
Packet radio technology serves as the foundation of APRS at 1200 baud using AX.25 protocol. Unlike traditional packet radio where stations connect directly, APRS broadcasts in an “unconnected” fashion. Each transmission creates a small digital packet with several key data elements:
- Callsign (always included as identification)
- Position information (typically from GPS coordinates)
- Path information (controlling how far the packet travels)
- Optional telemetry data (weather information, status texts, etc.)
These packets move through the APRS network without targeting specific receiving stations, yet remain available to everyone. GPS provides up-to-the-minute location data that builds the foundation for APRS mapping capabilities. This location awareness lets users track vehicles, hikers, or fixed stations on a visual interface.
The station transmits a packet without waiting for acknowledgment or establishing a connection. The information simply spreads outward for any equipped station to receive.
What are digipeaters and I-Gates?
Two vital infrastructure components power the APRS network: digipeaters and I-Gates.
Digipeaters (digital repeaters) work like voice repeaters but operate differently. They rebroadcast incoming APRS packets to extend the original transmission’s range. Unlike voice repeaters that use separate frequencies for input and output, APRS digipeaters receive and transmit on the same frequency (144.39 MHz in North America).
The significant difference lies in how digipeaters handle path information. Packets with path designations like WIDE1-1 or WIDE2-2 use numbers as “hop counters” that decrease with each retransmission. To cite an instance, WIDE2-2 lets a packet travel through two digipeaters in all directions before expiring.
I-Gates (Internet Gateways) connect radio frequencies to the global internet backbone. They forward APRS traffic to the APRS Internet Service (APRS-IS), a worldwide stream of APRS data. This uninterrupted connectivity allows services like aprs.fi to display up-to-the-minute APRS activity worldwide.
Digipeaters work best at high elevations with good radio coverage, while I-Gates usually operate from homes or offices with stable internet connections.
How APRS connects to the internet
The APRS Internet Service (APRS-IS) acts as the global backbone of APRS and connects local radio networks to the worldwide system. I-Gates forward received RF packets to APRS-IS servers, making information instantly available online.
Websites like aprs.fi can access this live data stream and display packets from around the world as they happen. I-Gates support two-way functionality, allowing internet messages to transmit back over radio frequencies.
Internet integration offers several benefits:
- Users can track loved ones during travel beyond radio range
- People can check repeater information before visiting cities
- Equipment troubleshooting becomes easier through online packet monitoring
- Users can identify coverage gaps in local APRS networks
Setting up an I-Gate requires a radio, TNC (Terminal Node Controller), and a computer with internet access running suitable software. The TNC performs two key functions: it modulates/demodulates audio signals and builds/breaks down data packets.
I-Gate operators need to get a callsign passcode to authenticate when connecting to the APRS-IS network. Modern solutions combine these components into single devices or use software-based TNCs with sound card interfaces, which makes setup easier.
APRS creates an uninterrupted network that combines local RF communications with global internet connectivity, all running on standard amateur radio frequencies.
Choosing the Right APRS Setup
Your specific needs, budget, and planned usage will determine the right APRS equipment for you. Here are three ways you can start with this versatile communication system.
Using a radio with built-in APRS
Many manufacturers now make radios that come with integrated APRS functionality. You won’t need any external devices with these all-in-one solutions that give you the easiest way to get on the air.
The Yaesu FTM-100DR makes an excellent choice, especially for search and rescue operations. This mobile radio delivers 50 watts of power and comes with built-in GPS and APRS capabilities at a reasonable USD 300-350 price point. The radio’s “check-in” function sends beacon transmissions continuously so teams can track each other’s locations.
The Kenwood TH-D74 gives you great portability and impressive features. This triband portable radio (2m/1.25m/70cm) shines at APRS operations while delivering excellent core radio functionality.
Other solid options include:
- Yaesu VX-8R and FT5DR: Feature-rich handhelds with APRS functionality
- Kenwood TM-D700/710: Mobile radios that have large displays made for APRS
- Alinco DR-135TP: A 2-meter mobile radio that takes an optional TNC board
Radios with built-in APRS give you the best user experience though they cost more upfront than other options.
External TNCs and APRS modems
Terminal Node Controllers (TNCs) connect your existing radio to APRS networks. These devices handle two key tasks: they modulate/demodulate audio signals and construct/deconstruct data packets.
The Kantronics KPC3+ remains a trusted device in the packet radio community. It connects to your radio’s audio ports and links to a computer through a serial connection. New units can be expensive, but used ones often sell for under USD 100.
The Mobilinkd Bluetooth TNC offers a modern solution at USD 64.95. This small device measures just 11mm thick, weighs less than 40 grams, and connects to your radio with one cable. It pairs with Android devices through Bluetooth and runs for two days per charge.
You might also consider these TNC options:
- Argent Data Tracker4: Supports various APRS functions and works as a digipeater
- Byonics TinyTrak3: A budget-friendly, transmit-only tracker for position reporting
- Cross Country Wireless APRS TNC Digi Tracker: Works as a standalone tracker, TNC, and digipeater
External TNC solutions let you add APRS capabilities to your current radio setup.
Smartphone apps and software-only options
Software solutions give you the most affordable way to start with APRS through smartphones or computers.
APRSdroid stands out as a popular Android app that lets you report positions and exchange messages through various connections:
- APRS-IS via internet (WiFi or mobile data)
- AFSK audio connection between radio and smartphone
- Bluetooth serial connection to a TNC
APRS Mobile gives iOS users similar features with live position mapping, SmartBeaconing support, and background position beaconing.
Desktop users have several options:
- PinPoint: Free Windows software for visual tracking and APRS communication
- Dire Wolf: A software soundcard modem/TNC for Windows and Linux
- Xastir: Popular mapping software for Linux users
These software options often have the most feature-rich interfaces. Most need extra hardware to connect with a radio for full RF functionality.
Your specific needs, budget, and desired level of APRS involvement will guide your choice among these three approaches.
Step-by-Step: Setting Up Your First APRS Station
Setting up your first APRS station is easier than you might think. The actual configuration takes just a few minutes once you have your equipment ready. Let me show you how to get your APRS station working.
Selecting your frequency and path
You need to tune to the right frequency for your region. North American APRS operates on 144.390 MHz, European stations use 144.800 MHz, and Australian stations use 145.175 MHz. This standard frequency helps all APRS users in your area communicate on the same channel.
Path settings come next. They are maybe the most important part of proper APRS configuration. These settings control how far your packets travel through the network.
Here are the most common path settings:
- WIDE1-1,WIDE2-1: Perfect for mobile operations in urban and suburban areas (two hops total)
- WIDE2-2: Works well for fixed stations or areas with high-level digipeaters (two hops)
- WIDE1-1,WIDE2-2: Best for mobile operation in rural areas with low APRS activity (three hops total)
The numbers in these paths (like WIDE2-2) show how many “hops” your transmission makes. The first number shows the type of digipeater network, while the second number counts down with each hop. Your packet stops moving when it hits zero.
Don’t use long paths like WIDE3-3 – they just clog up the network. Note that good APRS usage focuses on reliable local communications rather than signal distance.
Configuring your radio or software
After frequency and path setup, you’ll need to set up your device:
For radios with built-in APRS:
- Enter your callsign with appropriate SSID (mobile stations typically use -7)
- Set the APRS modem to 1200 baud (standard for VHF APRS)
- Configure your path settings as determined above
- Enable the GPS if available or manually enter your location for fixed stations
For computer-based setups:
- Install appropriate software (Dire Wolf for Windows/Linux, MacAPRS for Apple)
- Configure the audio interface between radio and computer
- Set your callsign and APRS-IS passcode if using an I-Gate
- Configure path settings and beacon rates
For smartphone applications:
- Install APRSdroid (Android) or APRS Mobile (iOS)
- Enter your callsign and select connection method
- Configure path settings and location services
Modern APRS software lets you place your station position with a map click. Set your beacon rates to every 10-30 minutes for fixed stations and more often (or use SmartBeaconing) for mobile operations.
Testing your setup with aprs.fi
Now it’s time to check if your station works properly. aprs.fi is the quickest way to test this – it shows APRS activity worldwide.
Here’s how to test:
- Make your station transmit using its beacon function
- Go to aprs.fi and search for your callsign
- Your position should appear within a minute or two if your transmission reached an I-Gate
If you don’t see your position:
- Check if your radio transmits (look at power/modulation indicators)
- Review your path settings for your area
- Make sure your audio levels are right for computer interfaces
- Look for an I-Gate within your station’s range
A successful transmission lets you see other stations receiving your packets in the “Last Heard” lists. You can then test message functions by talking with nearby stations.
These simple steps will help you create a working APRS station that can report positions and send messages. This gives you the foundation to learn more advanced APRS features.
What You Can Do with APRS
Your APRS station opens up a world of practical applications once it’s up and running. APRS naturally goes way beyond the reach and influence of simple position reporting and gives you many ways to boost your amateur radio experience.
Real-time location tracking
Real-time location tracking is the life-blood of APRS functionality. The system broadcasts exact position reports through GPS coordinates. This lets operators track vehicles, people, or objects with remarkable precision. These reports show latitude, longitude, and map symbols, plus optional details about altitude, course, speed, and antenna setup.
APRS shines during public service events like marathons and parades. Event organizers can track participants’ real-time locations. The system provides vital position updates to outdoor enthusiasts who venture beyond cell coverage.
Search and rescue operations get great benefits from automatic position reporting. Team leaders can see exact positions of all resources on digital maps to coordinate emergency responses better.
On top of that, fixed stations just need their position set in APRS software. Mobile stations get location data automatically from connected GPS receivers. You can see this tracking data on websites like aprs.fi, which shows positions almost instantly on street maps or satellite views.
Sending and receiving messages
The APRS messaging system supports solid text-based communication. Unlike voice calls that need both parties available, APRS messages reach recipients whenever they next connect.
The system handles point-to-point messages, bulletins, announcements, and basic email. Messages arrive in real-time, and the system tries again automatically until timeout if delivery isn’t confirmed.
APRS has gateways to other communication systems. SMSGTE service lets you send text messages to cell phones straight from your APRS radio. You can send an SMS by addressing a message to “SMSGTE” with “@phonenumber message” format. Cell phone users can reply to these messages, creating a link between APRS and cellular networks.
Email gateways like EMAIL-2 let you send short emails from APRS stations, adding more communication options.
Weather station integration
APRS merges weather reporting features naturally and builds a network of amateur weather stations that provide real-time weather data.
Weather stations connect to APRS through special hardware like the ADS-WS1. This device has temperature, barometric pressure, and humidity sensors. These stations send standard weather symbols and data packets that show up on APRS maps with unique weather icons.
The Citizen Weather Observer Program (CWOP) helps APRS weather station operators share their data with NOAA’s Mesonet database. This data feeds into the National Weather Service, making CWOP NOAA’s biggest real-time weather observation system.
This data helps forecasters by giving them real weather information from places without official weather stations. Local APRS weather stations help forecasters make better decisions about life-saving warnings during severe weather.
You’ll need compatible hardware connected to your radio setup and the right software to encode data in APRS format to set up an APRS weather station.
Exploring Advanced APRS Features
APRS capabilities go way beyond simple functions. Its advanced features showcase how versatile this digital communications platform can be. The system does much more than position reporting and messaging.
Using APRS with the ISS
The International Space Station has an APRS digipeater that operates on 145.825 MHz. This setup gives ham radio operators a chance to communicate through space. Similar to any ground-based repeater, the digipeater picks up packets on the uplink frequency and sends them back to Earth. Signals can travel thousands of miles.
Ground stations with the right configuration can send position reports and messages that bounce back to Earth at the time the ISS passes overhead. Ground-based I-Gates capture these transmissions, and websites like ariss.net display all amateur radio traffic that passes through the station.
Operators need these items to connect with the ISS digipeater:
- A 2-meter radio capable of 1200 baud packet operation
- A simple directional antenna (though omnidirectional antennas work during favorable passes)
- Knowing how to track upcoming ISS passes over your location
Voice alert and tactical messaging
Voice alert works like a “radar detector” that helps find nearby APRS operators. Users can make voice contact without monitoring the APRS frequency constantly. The feature relies on specific CTCSS tones for both transmit and receive:
- North America: 100 Hz
- Europe: 136.5 Hz
- Australia: 91.5 Hz
Your radio stays quiet until it detects an APRS transmission with the matching tone. You can make a quick voice call on the APRS frequency using the same tone after hearing a nearby station. The conversation should move to another frequency right away.
Mobile operators who might pass each other without notice now have a direct communication channel. Voice alert rules are straightforward – keep calls brief and take conversations off the APRS frequency immediately.
Telemetry and object tracking
APRS lets stations transmit sophisticated telemetry data. The system can report analog values like voltage, temperature, and pressure, along with digital states such as on/off or open/closed. Remote monitoring of equipment, weather stations, and other systems becomes possible.
Services like aprs.fi collect and display telemetry data in immediate and historical formats. Looking at these trends helps operators spot patterns and unusual behavior in their monitored systems.
Object tracking adds another dimension by letting operators add virtual objects to the APRS map. These objects represent everything from emergency incidents to special events. Everyone gets the same situational awareness at once.
Fun Projects to Try with APRS
Putting APRS into ground practice is a great way to learn more about this versatile system. You’ll develop practical skills and better understand what APRS can do when you work on hands-on projects.
Build a receive-only iGate with Raspberry Pi
You can build your own APRS internet gateway in less than an hour with affordable parts. Your basic receive-only iGate needs:
- A Raspberry Pi (even older models work fine)
- An RTL-SDR dongle ($30-45)
- A suitable VHF antenna
- Free software like Direwolf
The whole setup costs about $99 and needs just simple configuration. Your iGate will pick up local APRS packets and send them to the global APRS Internet Service (APRS-IS) once it’s running. This helps expand network coverage in your area. The project adds reliable infrastructure to the ham radio community and you just need to know simple Linux commands.
Track a high-altitude balloon
High-altitude balloon tracking is one of the most exciting ways to use APRS. All the same, the right setup is vital since poorly configured balloons can disrupt the APRS network over big areas.
Keep these vital guidelines in mind for balloon tracking:
- Use “NO PATH” (simplex direct) above 1000 feet because all APRS stations within hundreds of square miles will hear it directly
- Stay away from WIDE1-1,WIDE2-1 paths that can cause too much network traffic
- Keep transmission rates to once per minute or longer for short flights
The 2017 solar eclipse saw 148 APRS balloons active across continental USA. This shows how popular this project is among amateur radio operators.
Set up APRS for a public event
APRS works best during public service events like marathons, parades or search and rescue operations. The core team members with APRS-enabled radios give organizers immediate awareness of where everyone is located.
A simple public event setup should have:
- Mobile APRS units for vehicles
- Portable trackers for roaming staff
- A base station displaying positions on mapping software
Coordinators can see where everyone is at a glance. This setup helps them respond faster and manage resources better throughout the event.
Best Practices for Responsible APRS Use
APRS network’s efficient operation depends on users knowing how to follow best practices. The network serves as a shared resource with limited capacity. Your configuration choices directly affect how well the system works for the amateur radio community.
Avoiding QRM and excessive beaconing
A 1200 baud APRS channel supports only 60-100 stations in a given RF domain. The network needs proper beacon rates to prevent congestion:
- Fixed stations: Transmit every 20-30 minutes
- Mobile stations: No less than 3 minutes (typically)
- Weather stations: Every 5-15 minutes
Packet length plays a crucial role in bandwidth usage. Network capacity decreases with each half-second of transmission time. You should remove non-informative comments from packets. Experts estimate that improper configuration makes 90% of signals on the air “bad”.
Choosing the right path settings
APRS network performance improved significantly after the “New-N Paradigm” standardization in 2004. These path settings are now recommended:
WIDE1-1,WIDE2-1: Ideal for mobile stations in urban/suburban areas (two hops total)
WIDE2-2: Best for fixed stations (two hops)
WIDE1-1,WIDE2-2: For mobile operation in rural areas with low APRS traffic (three hops)
Paths longer than WIDE3-3 create exponential network congestion. Each additional digipeater hop reduces channel capacity by half. Minimal paths are not just courteous—they keep the network functional.
Keeping your station info updated
Accurate station information helps everyone use the network better. APRS can plot range contours around stations using Power-Height-Gain (P-H-G) reporting capability. This assists others in finding the best communication path.
Your transmitter power, antenna Height Above Average Terrain (HAAT), and antenna gain should be entered using the INPUT-PWR command. Position beacons for permanent digipeaters must include this data.
APRS functions as a two-way tactical live communication system that shares information about everything happening in your local area.
APRS brings an exciting new dimension to amateur radio by combining digital technology with traditional communication methods. New ham operators can start using the Automatic Packet Reporting System right away, whatever their technical background. This digital mode naturally combines position reporting, messaging, and telemetry in one versatile platform.
New operators love how APRS connects different parts of amateur radio together. The system runs on specific frequencies (144.390 MHz in North America), which creates a community of operators who all monitor the same channel. This standard setup lets packets come through automatically without tuning across frequencies or making direct connections.
APRS shines in its simplicity. Technician-class license holders can participate fully, which makes it perfect for newcomers. You can start learning this digital ecosystem with simple equipment – just a basic handheld radio and a smartphone.
APRS proves most valuable because it works without internet infrastructure but can connect to online systems through I-Gates. This mixed approach offers both emergency backup and daily convenience.
Your experience with APRS grows naturally as your interests expand. You might start with simple position reporting and later set up a home digipeater or send weather data to meteorological networks. The thrill of watching your packets show up on global tracking websites tells you immediately how well your station performs.
Amateur radio thrives on experimentation, and APRS is no exception. The system welcomes new ideas – from tracking high-altitude balloons to creating new uses for the core protocol. APRS truly shows the ham radio spirit: open information sharing, helping other operators, and building a strong communication network that benefits everyone.
