Beginner's Guide to Using APRS for Ham Radio

APRS is a digital communication system. It functions by sending small packets of data via radio waves. It’s designed for exchanging messages and information over short distances. It was initially developed in the 1990’s by Bob Bruninga, WB4APR (SK). Since then, it is used extensively by amateur radio operators.

(Ham Speak: The term (SK) means “Silent Key” or a ham who has passed away.)

An APRS packet might only be a few data points. They always have a call sign. Sometimes in addition they have short, point-to-point text message. Like “Meet me on 146.520 MHz at 10 AM.” point-to-point message. Sometimes they have position data, derived from GPS coordinates. Those packets get transmitted blindly, for reception by other radios within range. Some hams operate radios that connect APRS to the Internet. These radios are named gateways and digipeaters. On occasion, you’ll find APRS in use on the International Space Station. When in use, it can be used to relay packets while overhead.

Let’s explain a little more about gateways and digipeaters. A gateway is used to receive APRS packages. This provides them a “gateway” into the internet side of APRS. A digipeater is a radio that receives the packets and sends them out to a wider area. The ISS radio would be an example of a digipeater. Yes, this function of digipeating and gateway can be combined into one unit.

Based on this, you can see APRS has a wide range of applications. They include tracking the location of vehicles, people, and weather stations.

This map shows many APRS stations in Metro-Atlanta. APRS gateways are red and black diamonds. You also see weather stations, and a vehicle being tracked. Try and find KO4YHK-14. The green line will guide you.

APRS was pioneered by Bob Bruninga, WB4APR, a U.S. Navy officer and member of the U.S. Naval Academy, who initially developed the system on an Apple II platform in 2002. He originally created APRS to track ships using the AX.25 protocol, which eventually became popular in the ham radio community. Bob’s work laid the foundation for APRS, which remains a prominent protocol in amateur radio.

There’s also a common point of confusion: what does “APRS” stand for? Some refer to it as the “Automated Position Reporting System” while others say “Automated Packet Reporting System.” Both terms are acceptable.

Though Bob became a Silent Key in February 2022, his legacy endures through the APRS Foundation. About a year before his passing, Bob transferred the intellectual property and trademarks for APRS to TAPR (Tucson Amateur Packet Radio). TAPR later established the APRS Foundation to maintain and develop APRS resources.

The original APRS website, www.aprs.org, remains active, primarily as a historical archive. For those seeking current information and resources, the new website, how.aprs.works, provides modern guides, tips, and use cases for APRS.

You can participate in APRS with a variety of devices. Some are hardware based, others are computer software. Here are some options:

Steps to follow:

This APRSIS32 software window shows packets received around Central Florida. It also shows an ongoing message session.

Once you have set up APRS, you can start using it to exchange messages and track locations. APRS data messages go over RF between stations. Many make it into the online APRS network, which can then show them on a real time map.

APRS is often used to track the location of vehicles or people. That might include hikers or search and rescue teams. It can also be used to transmit weather data. Many APRS connected stations share weather data. That includes temperature, pressure, and wind speed. Smart hams have figured out ways to interface that with the APRS network.

APRS has numerous advanced features that can be utilized to enhance its functionality.

A Kenwood TH-D74 displays a packet received from the ISS, which uses the call sign RS0ISS for its APRS radio. Photo by Jim Reed – N4BFR

Using an Yaseu FT5D handheld, an operator listened in on the 2022 APRS Golden Packet event at Clingman’s Dome, North Carolina. Photo by Jim Reed – N4BFR

NT1I’s gear used for the 2022 APRS golden packet event. The group uses a unique 2 Meter frequency (144.340) for the packets and a UHF channel for voice coordination. Photo by Jim Reed – N4BFR.

To operate APRS effectively, it is critical to follow best practices.

Support for the APRS Foundation is greatly welcomed, and membership is open to everyone, with an annual fee of $20. “Joining doesn’t require being a ham,” Jeff mentioned during a short interview at the “Stone Mountain Hamfest 2024,” noting that the contributions are crucial for the progression of APRS and the support of new projects. The interview video is available for viewing.

APRS is a powerful and versatile digital communication system. It is used by amateur radio operators for a variety of applications. The small packet of detailed APRS data is special. It can be transmitted with GPS coordinates, weather data, and messages. That makes APRS a valuable tool for emergency communications, tracking, and weather reporting.

Hams can ensure that APRS is used effectively and efficiently. This is driven by following best practices and operating responsibly. While the setup and configuration of APRS can be daunting. But, with a little practice, you can easily master this valuable technology. Use APRS to take your communication capabilities to the next level. Another way to expand your horizons in the world of amateur radio.