APRS is NOT "Worthless"

This is taken from a presentation I did at my amateur radio club's annual general membership meeting and Christmas party in Cebu, Philippines, on 6 December 2024, in front of over 30 members. There is a list of APRS and related links at the end that you can explore.

What is APRS?

APRS stands for Automatic Packet Reporting System (not "position reporting.") It was developed by Bob Bruninga WB4APR (SK) while he was a senior research engineer at the United States Naval Academy in the 1980s, using an Apple II computer, for the purpose of tracking Navy ships at sea. It has since evolved into much more than a mere location-tracking system.

What APRS is now is a tactical, real-time information sharing and communications system that provides situational and spatial awareness of your immediate local area. It lets you know about everything happening or of interest near you. It also allows both local and global communications via text messages. It provides access to much more information via queries and responses to and from information servers and access to gateways to other services. All of this takes place on your radio's display, although you can also employ a cell phone (mobile) or tablet to get a visual representation of everything overlaid on a map. Bob Bruninga said, "The goal is communications and local info[rmation] updates, not just vehicle tracking."

Data types:

Examples of the types of data that may be sent over APRS packets include positions (of the transmitting stations), station capabilities (such as TX power, antenna height above average terrain, gain, approximate range, and also any additional capabilities it may have such as Echolink), objects (like position reports but sent on behalf of other entities), weather reports, telemetry (such as monitoring remote radios), text messages, bulletins (QST messages of general interest to ham radio operators such as announcing local "eyeballs", swap meets, antenna-raising parties or even a sale at a nearby ham radio store), queries and responses, access to Internet gateways to other services such as information servers. SMS, email, and Winlink gateways), the "APRS of Things," and user-defined data types.

Use-cases:

This is where it gets interesting! Take position reports: if you're going somewhere and can't find your destination, you can look at one of the APRS map websites, see where you are on the map, and find your route to where you want to go. Or you can get on a voice repeater, ask another ham to do the same thing, follow your movements, and give you directions by voice: useful when you're driving. If something happens to you and you don't arrive home, your family, even if not licensed hams, can look at an APRS map website and find out your last location to tell first responders exactly where to look for you (which could potentially save your life.) In search and rescue situations, the search coordinator can see the locations of search party members on a map and, using the "tails" feature, also see where they've been... and, more importantly, where they haven't been and have missed while searching. Take a special event such as a marathon race where a ham is stationed at checkpoints along the route to check-in/check-out the runners as they pass through so it can be provided to the race committee so they know who's in the lead, who's in last place (to get an idea of how long the race may last) and who may be cheating by using a vehicle and bypassing checkpoints. The event coordinator can ensure everyone's where they're supposed to be and that all checkpoints are covered.

I've already mentioned broadcast messages but did you know that many APRS radios allow you to configure a call sign group that you can send a message to? This can be useful if, say, your club's regular meeting is canceled on short notice. Suppose a club officer sends an APRS message to a group containing the call signs of all members. In that case, everyone who's already en route to the meeting venue will be notified on their radio screens that the meeting is canceled so they can turn around and go home rather than wasting time and fuel (and generating more carbon emissions) to go to the venue for nothing, then have to drive all the way home. APRS can help save the planet! Another use for texting: let's return to that marathon race. Let's say one of the runners has a medical issue (sprained ankle, heat exhaustion, asthma attack, or whatever) and needs medical assistance. The voice frequency will probably be tied up with the medical traffic for a while, but meanwhile, the other hams can continue to provide runner check-in/check-out information via APRS texts. Then, the coordinator can read the history of his received messages on his radio and still get that information. ("The show must go on.") Texting can also reduce the amount of chatter on the voice frequency, freeing it for more urgent traffic and reducing transcription errors.

Take beaconing the locations of objects and places: you can share information about blocked roads due to motor vehicle accidents, fire scene incidents (think: fire hoses across the road) or localized flooding after a heavy downpour. And after a big disaster such as a hurricane, you can share the locations of things like first aid stations, gas stations, stores and pharmacies that are still open, places where fresh water is available, cell phone recharging stations, and ATMs that are still online and dispensing cash. If there's still Internet access available, the entire community can see this information on one of the map websites, not just licensed ham radio operators. Before the hurricane arrives, you can provide the locations of evacuation centers. Or if there's a special event like, say, JOTA (Jamboree On The Air) you can beacon its location using the symbol for Boy Scouts or Girl Scouts to help others who are coming to participate to find it more easily.

Useful especially for hams visiting an area from elsewhere, repeaters can beacon their frequencies, offsets, and CTCSS tones so the visitor will get this information on their radio's display and learn about the local repeaters. Also, new hams who just got their first radio can get this information from one of the map websites to help them program their new radios, get on the air, and start making contacts. If that visitor is sharing his position reports, it's best practice to include the voice frequency he's monitoring in the beacon comments. That way, when you see his car bristling with antennas and with call sign plates or stickers, you'll be able to contact him, welcome him to your area, give him any information he needs, and make a new friend.

Personal weather stations often share their information over APRS. This can be handy if there's a storm in the area: you can view local weather conditions at a number of different locations to get an idea of how the storm's tracking, how bad it is, and get a "heads up" that you may want to prepare to take part in an emergency radio traffic net in case you're needed to relay messages or can otherwise help out.

Queries, gateways, and information servers allow you to look up call signs on QRZ, send SMS text messages to people's cell phone numbers, send Internet email messages, spot yourself when doing a SOTA activation and have no Internet connectivity (if you're within range of an APRS digipeater, which you may well be at the top of a mountain), find out the nearest repeater that has certain features (such as 6m repeaters, D-Star repeaters, etc.) via repeaterbook.com queries, find information about nearby hotels, restaurants, hospitals, even veterinarians. You can participate in APRS Thursday global nets. You can find and join discussion groups about whatever subjects interest you: photography, coin collecting, fishing, gardening, or whatever, and meet like-minded hams globally. You can check, read, and send Winlink emails and do some mailbox maintenance tasks.

All this from your APRS radio!

How APRS works:

APRS uses AX.25-framed packets, usually at 1200 baud, usually over a single, shared 2-meter simplex frequency that's nationwide (and in some cases region- or continent-wide), so everywhere you go where there's APRS coverage, you can get all of the local information. Unlike standard packet radio that uses FX.25 framing with error-checking and is a one-to-one communications system meant more for QSOs and rag chews, APRS is a one-to-many information-sharing system utilizing a "fire and forget" paradigm, similar to UDP over the Internet vs. TCP/IP.

However, digipeaters (more about which in a moment) help ensure that most packets are received and decoded. APRS stations typically have GPS receivers to obtain current positions in real-time, allowing calculations showing speed, elevation, and course changes (at least for those stations that are beaconing their positions.) They also have a radio (of course) and something called a terminal node controller or TNC, which is basically a modem. Some APRS stations also require a computer. Local area APRS networks typically include at least one Internet gateway or IGate, which allows global connectivity, communications, and information sharing (but in my opinion, this is less important than simple, local RF connectivity as the main goal is local communications and info-sharing: I think of the Internet side of APRS as being more of a value-added feature than an essential part of APRS, but that's just me.)

Digipeaters and IGates:

These, especially digipeaters, form the backbone of local-area APRS networks. Digipeater means "digital repeater", though they're not like repeaters as we know them: they don't simulcast what they receive on a different frequency like voice repeaters do. Instead, they use store-and-forward to essentially relay or rebroadcast what they receive on the same frequency (hopefully at a higher signal level and with greater range than the transmitting station.) As these are relays, most governments' communications commissions, including the FCC in the USA and the NTC in the Philippines, don't classify them as "repeaters," so any licensed ham in those countries can run one. Digipeaters come in two flavors: wide-coverage and local or fill-in.

Wide-coverage digipeaters are often co-located at repeater sites, and as there often is no Internet connectivity at those locations, they're usually RF-only. These often cover a very large area depending on elevation, terrain and obstacles, antenna height and gain, and TX power.

Local or fill-in digipeaters, often located at hams' homes, usually don't have nearly the range. However, they can be used to fill in coverage in RF dead zones, and as there's usually Internet available often do double-duty as IGates. They can also help to reduce the load on wide-coverage digipeaters as well as extend their range.

Say two mobile hams are within range of my own local digipeater but not within range of each other and wish to converse via text: they can temporarily configure their radios to tell the local network "only digipeat me once." Then they can communicate with each other via my digipeater without the "big digipeater on the mountain" getting involved, freeing up access to it for others. Some APRS HTs can also act as small local digipeaters or even IGates, which, especially when coupled to a better magnetic mount antenna on a vehicle's roof, with the vehicle parked on a nearby hill, can be used to provide extra coverage at a special event where participants' APRS HTs may not all be within range of each other (like at that marathon race.)

There are also two types of IGates: receive-only and transmitting IGates. Receive-only IGates are basically useful only as satellite and ISS "ground stations," allowing those who contact a digipeater on the bird to view proof of that contact on a map website (or in the case of the International Space Station, also on ariss.net) and save screen captures for bragging rights. Transmitting APRS packets from the Internet over RF isn't needed due to the large footprint of the bird overhead, which covers thousands of miles anyway; everyone using its digipeater will be able to hear each other. RX IGates are discouraged on the local terrestrial APRS networks because TX IGates allow global text messaging and receipt of responses from, say, information server queries, allowing two-way communications, but receive IGates are basically just feeding the map websites. Transmitting IGates may also act as digipeaters, though there's no requirement for them to do so.

APRS-IS:

This brings us to the APRS Internet System, which is a global backbone network of interconnected Tier I and Tier II servers. These servers belong to regional "pools" such as na.aprs2.net and asia.aprs2.net for North America and Asia respectively: there is a pool for every region or continent. Roughly, the way it works is an IGate sends its call sign and a passcode consisting of a numeric hash of its call sign to the regional pool. A Tier I server verifies the call sign against the hash, and if they match, it hands off the connection to a Tier II server in that region at random.

After that's happened, APRS packets received over RF by an IGate will be forwarded to APRS-IS, which incidentally is where the mapping websites get their data from so they can overlay it as symbols on a map, getting the locations from the GPS coordinates or the configured latitude and longitude of the transmitting stations. The information servers and gateways are also connected to APRS-IS. This is what allows you to query them for things like someone's call sign or weather information, receive the responses on your radio, and send Internet email and SOTA spot reports. It is also what allows near-real-time text messaging globally. (This is why IGates should be able to transmit.)

Getting started:

Here are some ideas for getting started on APRS without spending a lot of money. The cheapest way is to install an app on your phone or tablet and use APRS via TCP/IP over the Internet.

Mobile apps:

These apps include APRSdroid for Android devices and the aprs.fi app (not to be confused with the map website of the same name) for iOS devices: iPhones and iPads. This will let you explore APRS for just a couple of dollars. However, it's not of much use during emergency and disaster situations when there is no Internet and when you need the information APRS can give you the most (remember, the Internet is a communications network that is totally out of our control and may not always be there when it's needed), so I prefer RF solutions that still work locally without the Internet, such as:

Take an old Smartphone that still has a jack for connecting a wired headset from your junk drawer, homebrew a cable to connect it to the speaker mic jack on a spare HT, enable VOX on the radio, install APRSDroid on the phone, and configure the app to use an audio AFSK connection, and Bob's your uncle. (Note that using VOX in lieu of push-to-talk (PTT) to trigger transmitting may cause QRM on the APRS frequency depending on the radio: some radios let you set the VOX timing in their settings while others don't. The problem is the delay between when your sent packet stops and when the radio releases VOX. This isn't an issue for voice comms, but if the APRS frequency is very busy, someone else may start sending before your VOX gets released, causing you to potentially destroy the other guy's packet with your QRM.)

B.B. Link Adapter:

Another idea is to use a Bluetooth adapter instead of the phone-to-radio cable; then, you wouldn't need a phone with a headset jack, which may allow you to use an iPhone depending on the adapter. Island Magic Co. sells the B.B. Link Adapter that "allows iPhones and iPads to connect to Kenwood TH-D75 and D74 radios via Bluetooth. iOS devices, which are limited to Bluetooth Low Energy (BLE), can't pair natively with these radios."

Mobilinkd:

Mobilinkd sells small, portable, rechargeable APRS TNCs with Bluetooth, as well as cables for many radios. You can attach the TNC to the back of an HT and connect the MobilinkD to the speaker mic. The TNC does the PTT for you so you don't need VOX. The downsides are that it costs close to the same as a pretty good HT (and close to some entry-level APRS HTs), and if operating portable, you have to carry a second radio for voice comms, plus the first radio for APRS, plus the TNC, plus a phone or tablet with an APRS app on it. (How many hands do you have?) But it's available and works very well, so it's worth mentioning here. Maybe you can find one cheaply at a swap meet.

NinoTNC:

For a base station APRS setup, it may be possible to repurpose an old packet radio hardware TNC by jumpering it for 1200 baud and AX-25, thereby turning it into a KISS TNC for APRS (KISS stands for "Keep It Simple, Stupid!" hee-hee!) which is the type of TNC needed for APRS. Or, TARPN (Tampa (Florida) Amateur Radio Packet Network) sells a very bare-bones TNC kit, the NinoTNC, consisting of a printed circuit board and a microprocessor for around US $14.

All of the other components needed to assemble the TNC (resistors, capacitors, LEDs, mini-DIP switches, a socket for the microprocessor, an op-amp, a voltage regulator, and some IO connectors) can be ordered as a bundle from Mouser or one of the other electronics supply houses like Digikey for around $26 or so. After assembly, you'll have a small APRS (among other uses) TNC for well under $100, but you'll still need a radio, cables, and a computer with appropriate software. Some "makers" sell 3D-printed cases for the NinoTNCs. If you want one, search etsy.com for "ninotnc case."

Direwolf:

The Direwolf (free/open source) software app for Linux or Windows PCs is a software KISS TNC that, when connected to a radio through a digital interface and sound card box of some sort that also takes care of PTT, such as a SignaLink USB or Digirig Mobile, works very well and also makes it fairly easy to set up a simple, functional digipeater and/or IGate.

Direwolf also provides external access to its TNC to third-party applications such as APRSIS32, Pin Point, or Xastir via both KISS and AGW ports, allowing you to "do APRS" over RF from your shack computer.

APRS-capable radios:

The best way, in my opinion, is just to get an APRS-capable radio (if you don't already own one, which you may without even realizing that it can do APRS!) Go ahead, do it, you know you want another radio! :) This link goes to a (by no means definitive) list of almost all known APRS radios, both in and out of production, based on months of my personal research:

The advantage of using an APRS-capable radio is that it can be an all-in-one solution, allowing both APRS and voice communications in one device.
https://how.aprs.works/aprs-radios/

The advantage of using an APRS-capable radio is that it can be an all-in-one solution, allowing both APRS and voice communications in one device. (Note: I've since discovered that the VGC VR-6600PRO is not APRS-capable after all; it's just an analog FM radio, and that Alinco's DR-MD520T triband mobile DMR radio is APRS-capable, although I don't know if it can send messages. If someone has one, please let me know. The manual only says that besides beaconing your position, it can receive, decode, and display APRS packets.)

Many, if not most, of Yaesu's System Fusion/C4FM/WIRES-X digital voice radios can do APRS, as can some DMR radios. Besides the old out-of-production radios that you may have stashed away in a box somewhere, you might already have one of these YSF or DMR radios. If so, you're good to go: for the YSF ones, just visit the Yaesu USA website, find your radio's model number, go to the Files tab, and download the separate (PDF) APRS manual, which will tell you how to configure and use it for APRS. For the (Anytone, mostly) DMR radios with full APRS capability the instructions should be in their main user manuals.

Emergency communications (EmComm) and APRSs role:
There are two sayings, "two is one, one is none," and "Failing to plan is planning to fail." The meaning of the second one should be obvious. The first one means that, for example, if you depend entirely on the commercial power grid for electricity to run your radios, in emergency and disaster situations, you have no electricity and can't communicate (or recharge your HT's battery when it expires.) If you depend on the local repeater for emergency communications ability, if the repeater tower gets knocked down by a windstorm, you have no emergency communications. You get the idea: planning and redundancy are needed. APRS offers an additional means of emergency communications via text messages as well as a means to share information and let others know what's going on in emergency situations. It's another tool in our communications toolkit. (So is Winlink by the way, offering email over ham radio, and I think BBSes as well.)

There's a mnemonic, PACE: Primary, Alternate, Contingency, Emergency. The order should actually be Primary, Alternate, Emergency, Contingency as I'll explain.

Primary: what's your or your club's primary means of communication? In my case, it's social media: we have a closed chatroom on Facebook for members only.
Alternate: think about how you would communicate if the Primary is unavailable (Facebook is offline.)

Emergency: think about, plan for, and create some sort of communications system for when there's no power, Internet or cell phone service. Be sure to include an APRS digipeater in that system if you don't already have one in your area, or if you do, be sure to leverage APRSs ability to share tactical information-sharing and provide text-based communications.

Contingency: start thinking about, planning, and preparing for unexpected, unlikely, "but what if?" situations. What if your club's repeater tower gets blown down (as happened to ours last September.) Can your club set up an emergency backup repeater somewhere up high, preferably with an off-grid power source? If so, it's best to do it sooner rather than later before it's ever needed to be available. Do you have a QRP HF radio and know how to build and tune an antenna that works for local and regional HF communications? Better start thinking of getting one and acquiring the knowledge and skills to be able to deploy and use it. Does your house have solar power for redundancy? What happens if a falling tree or wind-blown debris destroys your solar panels? Do you have an emergency go bag or bug-out kit (that you can carry easily in case the roads are impassable and you have to walk) containing communications equipment, tools, test equipment, cables, adapters. food, shelter, clothing, water, medical, and first aid supplies, enough to last for at least 72 hours, in case you have to evacuate on short notice? Are you and your family familiar with likely local evacuation routes? Does everyone know the location of a meet-up site plus a backup one (or two)? If your own antenna tower or mast falls down and your antenna gets damaged can you build a working dipole or ground plane and put it somewhere high enough to let you hit a repeater and get back on the air?

One more saying of my own for you to think about: "It's better to have something and not need it than to need something and not have it." This particularly pertains to things like go-bag contents but may also apply in your home shack.

Final thoughts:
The time to learn how to change your beaconing symbol from the one for a phone, the little guy, or a car to the symbol for a flood, crash site, fire or whatever; the time to learn how to program your radio without using a computer; the time to learn how to set up an APRS message group; the time to learn how to send APRS text messages; the time to learn the basics of how to homebrew a functioning antenna is NOT during an emergency!

The usefulness of APRS depends on what YOU do with it. EVERYONE, hams and non-hams alike, get out of it what YOU put into it. In other words, those little icons don't just show up on the maps by themselves, people use APRS to put them there. Become one of those people.

APRS is first and foremost an information-sharing system, closely followed by a communications system (or even tied for first place), followed by a position reporting and tracking system, followed by what my club's president calls "our very own Google maps for amateur radio" and all of the information servers and gateways to other services via the Internet.

"Practice makes perfect." Practice and use APRS, practice changing your beaconing symbol and comment (and learn what the different symbols represent), find ways that APRS is useful to you and share them, play with it, experiment, and most importantly, have fun!

(Note: I'm not a "prepper" as such, but in December 2021, we experienced Typhoon Rai, aka Supertyphoon Odett,e whose eye passed just 40 kilometers (25 miles) south of here as a major category 4 hurricane, and afterward, we had no Internet, cell phone network, electricity or running water for weeks. Even the AM and FM broadcast stations were off the air. Other than a small shortwave receiver (that didn't tell me much as no shortwave broadcasters were talking about the typhoon, at least not in English) and talking to neighbors, I had no way to find out what was happening or to let friends and loved ones know that we were OK. This is one of the reasons I got my license and why much of what I do in ham radio is with after-disaster communications ability in mind in case that happens again: I'll be prepared for the next time. The information that can be obtained from APRS is or can be, I think, an invaluable tool in such circumstances.)

Useful links:

http://www.aprs.org
Bob Bruninga's original APRS website (still much info here, although somewhat outdated.)

APRS-IS
Official website of APRS-IS.

APRS Foundation
The website of the APRS Foundation, Inc. is picking up where Bob left off, maintaining the APRS Specification and documentation and keeping APRS alive in the 2020s and beyond.

APRS on Groups.io
The Groups.io discussion group/mailing listserv for APRS. This is the place to ask questions you may have (after first searching the existing topics, please.)

Williamson County Amateur Radio Emergency Service (WCARES) - What is APRS?
This is a nice summary of APRS use cases. By the way, WCARES, is a very interesting organization that partnered with the county government and emergency services to create a robust network of amateur radio repeaters capable of being linked and unlinked at will during emergencies, all funded by the county government. They were even given a complete mobile repeater setup on a flatbed trailer with a motorized tower, generator, and repeater system that can be deployed wherever needed. I find their EmComm setup fascinating and wish we had a similar system with government buy-in and financing here. This site is well worth exploring.

Grupong Magellan
This is a group of Filipino radio amateurs living in the US, Canada and Australia who have been supplying digital voice repeaters to amateur clubs in the Philippines to establish a reliable emergency communications network. They are about to begin a second phase: providing APRS digipeaters and IGates as well, to expand the amateur radio emergency communications and information-sharing capabilities in the country.

Direwolf - How to Get Started in APRS
This is a link to a PDF document containing links to many other websites, videos, and documents containing information and instructions about getting started in APRS for little money.

Direwolf - Radio Interface Guide
Section 7.4 of this document explains in some detail why using VOX for PTT on an APRS setup is usually a bad idea.

APRS Foundation - Social Networking & Discord
Join the APRS Foundation's chat server on Discord and more!

TOADs Discord Server
This is a non-expiring invitation to join the TOADs ham radio chat server on Discord. This is where many, if not most, of the amateur radio content creators on YouTube are, many of whom have recently been experimenting with APRS, reviewing current APRS radios, building NinoTNCs, reviving old packet radio TNCs as well as doing many other projects, and making many helpful, informative videos for new hams. This server is non-ham friendly: no call sign is needed to join. Many members are USA VEs (Volunteer Examiners) who can help "wannabe" hams take their exams online and get their American ham radio licenses. Almost everyone here is very friendly, helpful, and happy to Elmer newbies (and not-so-newbies.)

73, de Jay, DV7GDL. Mabuhay!