getontheairAPRS for beginners
APRS (Automatic Packet Reporting System) sends short data packets on one shared VHF channel: positions, short text messages, weather reports and objects such as "net tonight on this repeater." Digipeaters relay the packets, and internet gateways (IGates) copy them to a worldwide network, so a beacon from a mountaintop can show up on a map in your browser a few seconds later.
You've already met pieces of it on this site: the ISS digipeater on Satellites and APRS spotting on Dead cell. This page explains the whole system.
Independent guide, not affiliated with APRS, aprs.fi, APRS-IS, APSPOT or POTA. Settings below are common North American practice. Your local network may differ.
APRS v1.0 · written 2026-10-08 · frequencies and recommendations checked as of Oct 2026
How it fits together
| Piece | What it does |
|---|---|
| Your station | A radio with built-in APRS, a radio plus a TNC (hardware or software), or a phone app. It beacons your position and can send and receive messages. |
| The channel | 144.390 MHz FM in North America, 1200 baud. Everyone shares it. Other regions use other frequencies. |
| Digipeaters | Fixed stations that hear your packet and retransmit it, so it travels farther. |
| IGates | Stations that copy what they hear on RF to the internet. Some also send internet messages back out on RF. |
| APRS-IS | The internet network that ties the IGates together worldwide, run by volunteers. |
| Map sites | aprs.fi and similar sites draw what APRS-IS hears. Search your call sign with its SSID. |
APRS is a shared 1200-baud channel. It works best when it's mostly quiet, so the whole system depends on everyone beaconing sensibly.
SSID: the number after your call
An SSID is a suffix from -0 to -15 that tells your stations apart (KB3CMT-7 and KB3CMT-9 are different stations). There's no rule, but Bob Bruninga WB4APR's recommendations are widely followed:
| SSID | Usually means |
|---|---|
| none (-0) | Your primary, usually fixed, station |
| -7 | Handheld (HT) or other human-portable station |
| -9 | Primary mobile (your car) |
| -8 | Boat, RV or second mobile |
| -10 | Internet-linked station or IGate |
| -6 | Special activity: satellite, camping, a one-off operation |
| -13 | Weather station |
Using -6 for a park or satellite outing keeps that track separate from your everyday -9 travels.
Path: how far your packet should go
The path tells digipeaters how many times to repeat your packet. Shorter paths mean less clutter for everyone. WB4APR's "New-N Paradigm" boiled it down to a few settings:
| You are | Typical path |
|---|---|
| Mobile or HT in an area with fill-in digipeaters | WIDE1-1,WIDE2-1 |
| Mobile in most areas | WIDE2-2, or WIDE1-1,WIDE2-1 |
| Home station | WIDE2-2. 3 hops only in sparse rural areas. |
| Through the ISS | Follow ARISS's current guidance (see Satellites) |
Don't use the old RELAY, WIDE or TRACE paths, or anything above 2 hops in busy areas. Most digipeaters now cut long paths short anyway. Background: Fixing digipeaters on aprs.org.
Beacon rate: A parked or home station rarely needs to beacon more often than every 10–30 minutes. For mobiles, use "smart beaconing" if your radio has it. It beacons more often when you turn or speed up and less often when you're cruising straight.
Ways to get on APRS
| Option | What you need | Notes |
|---|---|---|
| A radio with built-in APRS | Several handhelds and mobiles from the major makers have it | Easiest. GPS and messaging are built in on many models. Check our Hardware chapter and the maker's manual. |
| Phone app on RF | APRSdroid (Android) plus an audio cable or Bluetooth TNC to your radio | APRSdroid can connect over RF (AFSK audio) or over the internet |
| Computer software TNC | Dire Wolf plus a sound-card interface | Free, open source. It can also run as a digipeater or IGate, for example on a Raspberry Pi. |
| Internet only | An app logged in to APRS-IS | You show up on the map, but you're not on RF. It doesn't help when there's no cell service. |
Passcodes: sending to APRS-IS from an app needs a passcode tied to your call sign. Per APRS-IS, software authors provide it on request. Don't share yours.
What you can do with it
- Show where you are. Family and net control can follow a hike, a public-service event or a road trip on aprs.fi.
- Send short messages to another APRS station. Many radios show them on the front panel.
- Find local info. Many digipeaters beacon the recommended local repeater, nets or an EchoLink node.
- Report weather. Weather stations send readings that show on the map.
- Spot yourself from a park. See below.
APRS for portable and POTA operators
When there's no cell service, APRS can still get word out if your packet reaches a digipeater or IGate.
- APSPOT takes a spot by APRS message and posts it to pota.app (and SOTA/WWFF via ParksnPeaks), if you're a valid user on the destination. Send the message "usage" to APSPOT for instructions. Our Dead cell page has the field recipe.
- Check that it worked. Look for your packet on aprs.fi before you rely on it. If no IGate heard you, nothing posted.
- APRS QSOs don't count for POTA. APRS through a digipeater is a relay, not a direct contact. It's a spotting tool, not an activation tool. (Contacts through a satellite repeater are a separate case covered on Satellites.)
Packet radio beyond APRS
APRS is built on AX.25 packet radio, which also carries connected-mode traffic: keyboard-to-keyboard links, bulletin boards (BBS), nodes and, on VHF, Winlink email. Dire Wolf and most sound-card setups handle both. If your club or ARES group runs a packet BBS or a Winlink gateway, the same radio and interface will usually work. See Keyboard modes for Winlink.
Part 97 reminders
- APRS packets are plain text. No encryption (§97.113).
- Your call sign is in every packet, which handles identification.
- Digipeaters and IGates that transmit run under the automatic-control rules (§97.221). Setting one up is a project for later, ideally coordinated with your local APRS operators.
Habits / gotchas / checklist
Sources (checked Oct 2026)
- WB4APR, APRS SSID recommendations and Fixing digipeaters / New-N Paradigm, aprs.org.
- APRS-IS and its connecting guide.
- APRSdroid, Dire Wolf, aprs.fi, APSPOT.
Notes & edits
Comments and proposed markdown sit in a queue. Nothing is public until it is reviewed. How this works.