APRS

Frequently Asked Questions (FAQ)

General Questions

What is APRS?

APRS (Automatic Packet Reporting System) is a digital communications system used in amateur radio to transmit real-time tactical information, including GPS positions, weather data, messages, and telemetry.

What is an APRS passcode?

An APRS passcode is a numeric code generated from your amateur radio callsign. It's used to authenticate your connection to the APRS-IS (APRS Internet Service) network, allowing you to transmit data to the global APRS network via the internet.

Do I need an amateur radio license to use APRS?

Yes. To transmit on APRS frequencies, you must hold a valid amateur radio license. However, you can receive APRS data and use this passcode generator without a license.

Is the APRS passcode secure?

No. The APRS passcode is not a security mechanism. It's a simple validation code to confirm you have a callsign. Amateur radio operates on the principle of open communication, and all transmissions are public.

Using This Application

How do I use this passcode generator?

  1. Enter your amateur radio callsign in the input field
  2. Click "Get Passcode!" button
  3. Your passcode will be displayed immediately

Example:

  • Callsign: 
    N0CALL
  • Passcode: 
    13023

What callsign format should I use?

Enter your callsign in any of these formats:

  • Base callsign: 
    W1ABC
  • With dash: 
    W1ABC-9
  • With SSID: 
    W1ABC-5
  • Lowercase works too: 
    w1abc

The generator accepts:

  • ✅ Letters (A-Z)
  • ✅ Numbers (0-9)
  • ✅ Dashes (-)
  • ❌ Special characters (@, #, $, etc.)
  • ❌ Spaces

Why do I get "Invalid Callsign" error?

Common reasons:

  • Special characters in the callsign
  • Spaces in the input
  • Empty input
  • Non-alphanumeric characters (except dash)

Can I use this passcode for all APRS applications?

Yes! The passcode works with:

  • APRS-IS servers
  • APRS software (APRSdroid, APRSISCE/32, Xastir, etc.)
  • IGates and digipeaters
  • Web services (aprs.fi, aprsdirect.com)
  • Any APRS-IS client

What is an SSID (the number after the dash)?

SSID (Secondary Station Identifier) indicates the type of station:

SSIDTypical Use
-0Default (no SSID shown)
-1Fixed station, generic
-2Fixed station, alternate
-3Fixed station, alternate
-4Fixed station, alternate
-5Other network
-7Handheld
-8Marine/boats
-9Mobile (car, truck)
-10Internet gateway
-11Balloon
-12Emergency operations
-14Truck
-15Generic additional station

Technical Questions

How is the passcode calculated?

The passcode uses a specific algorithm:

function generateAprsPasscode(callsign) {
  let hash = 0x73e2;  // Starting value: 29666
  let i = 0;
  
  while (i < callsign.length) {
    hash ^= callsign.charCodeAt(i) << 8;
    hash ^= callsign.charCodeAt(i + 1);
    i += 2;
  }
  
  return hash & 0x7fff;  // Mask to 15 bits
}

Does the SSID change the passcode?

No. The passcode is generated from the base callsign only:

  • W1ABC
    → 12345
  • W1ABC-9
    → 12345
  • W1ABC-5
    → 12345

All generate the same passcode.

What frequency should I use for APRS?

Depends on your country:

  • North America: 144.390 MHz
  • Europe: 144.800 MHz
  • Australia: 145.175 MHz
  • Japan: 144.640 MHz
  • New Zealand: 144.575 MHz

See APRS-GUIDE.md for complete frequency list.

Can I use APRS on UHF?

While technically possible, APRS is primarily a VHF (2-meter band) system. Most APRS activity is on VHF frequencies. UHF is rarely used for APRS.

What's the difference between APRS and APRS-IS?

  • APRS: Radio frequency network (over-the-air)
  • APRS-IS: Internet Service (TCP/IP network)
  • IGate: Bridge between APRS RF and APRS-IS

Setup Questions

What equipment do I need for APRS?

Minimum requirements:

  1. Amateur radio license
  2. VHF radio (2-meter band)
  3. TNC (Terminal Node Controller) or smartphone
  4. GPS receiver
  5. APRS software

Budget setup (~$70):

  • Baofeng UV-5R radio: $25
  • USB GPS receiver: $30
  • Sound card cable: $15
  • Dire Wolf software: Free

What's the best APRS software?

Depends on your platform:

Mobile:

  • Android: APRSdroid (free, excellent)
  • iOS: PocketPacket (paid, $9.99)

Desktop:

  • Windows: APRSISCE/32
  • Mac: YAAC, Xastir
  • Linux: Xastir, Dire Wolf

All platforms:

  • YAAC (Java-based)
  • Web: aprs.fi

Do I need a TNC?

Not necessarily. Options:

  1. Software TNC (Recommended for beginners)

    • Dire Wolf (free, excellent)
    • Soundcard + radio + PC

  2. Hardware TNC

    • Mobilinkd TNC3 (Bluetooth)
    • Traditional TNCs (KPC-3+, etc.)

  3. Built-in APRS

    • Some radios have APRS built-in
    • Kenwood TM-D710GA, Yaesu FTM-400XDR

  4. Smartphone

    • APRSdroid + Bluetooth TNC
    • APRSdroid + audio cable to radio

How do I connect to APRS-IS?

Connection string format:

user CALLSIGN-SSID pass PASSCODE vers SOFTWARE VERSION filter FILTER

Example:

user W1ABC-9 pass 12345 vers APRSClient 1.0 filter r/42.3/-71.1/100

Popular APRS-IS servers:

  • rotate.aprs2.net:14580
    (automatic routing)
  • noam.aprs2.net:14580
    (North America)
  • euro.aprs2.net:14580
    (Europe)

Troubleshooting

My passcode doesn't work

Check:

  1. ✅ Correct callsign entered
  2. ✅ No SSID in passcode generation (use base call)
  3. ✅ Server connection string format
  4. ✅ Internet connection
  5. ✅ APRS-IS server is online

I'm not seeing my position on aprs.fi

Common issues:

  1. No IGate coverage in your area

    • Solution: Set up an IGate or use APRS-IS directly

  2. Wrong frequency

    • Check your country's APRS frequency

  3. Incorrect path settings

    • Use: 
      WIDE1-1,WIDE2-1

  4. Antenna issues

    • Check connections and SWR

  5. Low power

    • Increase transmit power if possible

How often should I beacon?

Smart beaconing recommended:

  • Stopped: Every 30 minutes
  • Slow movement: Every 10-15 minutes
  • Highway speed: Every 1-2 minutes
  • Turn > 30°: Immediate beacon

Never:

  • Faster than every 10 seconds
  • Use WIDE3-3 or higher paths
  • Beacon when not needed

Why is my battery draining quickly?

Tips to reduce power consumption:

  1. Increase beacon interval
  2. Lower transmit power (if range allows)
  3. Use smart beaconing
  4. Turn off unnecessary features
  5. Use GPS power save mode

Privacy and Legal

Is my position information public?

Yes. All APRS data is public:

  • Position reports
  • Messages (unless using APRS encryption, which is rare)
  • Weather data
  • Telemetry

This is by design - amateur radio is an open service.

Can I hide my location?

No, if you're transmitting APRS. Options:

  1. Don't transmit position reports
  2. Use receive-only mode
  3. Don't use APRS for privacy-sensitive applications

Is APRS legal worldwide?

APRS itself is legal, but:

  • You need an amateur radio license
  • Frequency allocations vary by country
  • Some countries restrict certain APRS uses
  • Check your local regulations

Can I use APRS for commercial purposes?

No. Amateur radio is for:

  • Personal wireless communications
  • Technical investigations
  • Emergency communications
  • NOT for business or commercial use

Application-Specific Questions

Does this app store my callsign?

No. This application:

  • Runs entirely in your browser
  • Doesn't send data to any server
  • Doesn't store or log any information
  • Doesn't use cookies or tracking
  • Is completely client-side

Can I use this offline?

Yes! After loading the page once:

  • The app works offline
  • Passcode generation is client-side
  • No internet connection needed for generation

What languages are supported?

Currently 10 languages:

  • 🇬🇧 English
  • 🇪🇸 Spanish (Español)
  • 🇨🇳 Chinese (中文)
  • 🇮🇳 Hindi (हिन्दी)
  • 🇸🇦 Arabic (العربية)
  • 🇧🇷 Portuguese (Português)
  • 🇧🇩 Bengali (বাংলা)
  • 🇷🇺 Russian (Русский)
  • 🇯🇵 Japanese (日本語)
  • 🇫🇷 French (Français)

Can I contribute a translation?

Yes! See CONTRIBUTING.md for guidelines.

Is this app open source?

Yes! Licensed under MIT:

  • Source code on GitHub
  • Free to use, modify, and distribute
  • Contributions welcome

Emergency Use

Can I use APRS in emergencies?

Yes! APRS is excellent for emergencies:

  • Track emergency personnel
  • Report damage and needs
  • Coordinate resources
  • Send messages when other systems fail

What are APRS emergency frequencies?

Use your region's standard APRS frequency:

  • Don't change frequencies during emergencies
  • Everyone monitors the standard frequency
  • Consistency is critical for coordination

How do I send an emergency beacon?

Most APRS software has an emergency button that:

  1. Sends high-priority beacon
  2. Includes "EMERGENCY" in the message
  3. May increase beacon rate
  4. Alerts nearby stations

Format: Status message starting with "EMERGENCY:"

What emergency information can APRS transmit?

  • Current position
  • Status updates
  • Resource requests
  • Shelter locations
  • Damage reports
  • Personnel tracking
  • Weather conditions

Getting Help

Where can I get more help?

Community Resources

Who maintains this application?

José Carrillo (m@carrillo.app)

  • Amateur radio enthusiast
  • Open source contributor

Based on the original work by DO3SWW.

Contributing

How can I help?

See CONTRIBUTING.md for:

  • Bug reports
  • Feature requests
  • Code contributions
  • Documentation improvements
  • Translations

I found a bug!

Please open an issue with:

  • Description of the bug
  • Steps to reproduce
  • Expected behavior
  • Screenshots (if applicable)

Last Updated: December 2025

Didn't find your question? Open an issue and ask!