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ATGP 2024 - ATGP Appliance - Selection, Testing, and Use

General Guidelines

Remember that the event is in two phases:

Phase 1 – ATGP Classic

Operate with Kenwood radios only; do not use appliances during this phase. This phase does not end until the golden packet has been successfully passed and Lynn has given the go-ahead for Phase 2.

Phase 2 - ATGP Appliance

Use of pre-approved and tested appliances only. This is not the time or place for ad hoc or on-the-fly experimenting.

Use only equipment based on the supported hardware and software that you have assembled and tested prior to the event.

Further, your equipment must be documented and approved by Lynn and your team captain before the event.

We spent considerable time testing and certifying the hardware and software we selected. Controlled experiments are valuable because they can provide a high degree of confidence in the outcome, allowing us to know which variable caused or did not cause a change. Any deviation from what has been tested will likely introduce undesirable results.


If you cannot communicate with your adjacent stations, please do NOT attempt to test your appliance. If you are testing the appliance, communicate with your adjacent stations to ensure that only one appliance is brought online at a time and that bi-directional packet passing is still working before bringing another appliance into the chain.

Software Image for the ATGP Appliance

The ATGP Appliance for ATGP 2024 is based on a customized version of DigiPi 1.8 Mark III for ATGP 2024. DigiPi provides several capabilities requested by members of ATGP.

The image is not ready yet. A link will be posted by 06/08/2024. We will send a notification when it's available.

If you want to experiment with the hardware between now and 06/08/2024, you can download & install a copy of DigiPi 1.8 Mark III directly from

Please be prepared to format the Micro SD card and install a new image once it becomes available.

ATGP-customized version of DigiPi 1.8 Mark III

DigiPi 1.8 Mark III satisfies several requirements:

DireWolf 1.7

  • This version provides support for UIFLOOD which was added specifically for ATGP
  • Software-based TNC access via KISS interface over TCP/IP (port 8100/tcp)
  • Location will be hardcoded into the DireWolf configuration - this eliminates the need for a GPS receiver
  • We will provide instructions on how to configure APRSIS32 and APRSdroid to connect to the DireWolf TNC)via IP

Browser-based interface

  • Allows interaction with DireWolf without the need for command-line interface (CLI) access
  • On/Off buttons to select different DireWolf configurations
  • Streamlined operation - all non-ATGP related features have been removed from the interface


  • Allows you to view DireWolf activity without needing to SSH into the appliance
  • Supports Adafruit Pi-TFT 1.3" (connects to GPIO interface on the Raspberry Pi - see below for more details)

Network Connecivity

  • Two pre-configured options provide connectivity to DireWolf's TNC via the KISS protocol over IP
  • Wi-Fi Access Point broadcasts a Wi-Fi SSID and automatically assigns an IP address via DHCP - supports both the laptop and Android-based device options
  • Bluetooth Serial-Port Profile (SPP)
  • Alternative to Wi-Fi
  • Only supports the Android-based device
  • Still under consideration - Wi-Fi supports both Windows and Android-based devices

Equipment appropriate for the ATGP Appliance


You must use a 2-meter mobile radio in the 25+ watt class with a mini-DIN connector permitting audio output directly from the discriminator stage. This is the only way to obtain audio from the radio that will work at 9600 baud. Once again, this radio must be thoroughly tested and approved well in advance of the event!


This year's event is 9600 baud only; 1200 baud will not be used.

Audio Interface

The radio will be connected to an audio interface via a cable with a mini-din connector on the radio end. For this year’s event, there are only two approved audio interfaces:

  1. DINAH board (as detailed in QEX: Open-Source Meta-Design for APRS Appliance) Available here:
  2. DigiRig Mobile - Available here:

Ensure you purchase the Official DigiRig cable(s) that are specifically designed for your radio. Spend time reviewing the options available from the DigiRig Store to determine what is recommended for your radio:

Be sure to order 9600 baud cables!

Raspberry Pi

The Audio Interface (DINAH or DigiRig) is connected to the Raspberry Pi via a USB cable and running the ATGP customized version of DigiPi (includes DireWolf 1.7).

A link will be provided here shortly. We will send a notification to the ATGP group on once the file is available.

Raspberry Pis, which have proven suitable, include:

  • Raspberry Pi Zero 2 W
  • The Zero 2 W requires a USB On-the-Go adapter to support the Audio Interface - see below for options
  • Raspberry Pi 3B+
  • Raspberry Pi 4B (1/2/4/8 GB models - all are supported)

USB On-The-Go Options for the Raspberry Pi Zero 2 W

Choose one of the following two options:

  1. UGREEN Micro USB to USB Micro USB 2.0 OTG Cable 2-Pack - $7.99

  2. MakerSpot 4-Port Stackable USB Hub for Raspberry Pi Zero 2W - $13.99

Adafruit Pi-TFT 1.3" Display

Optional but strongly recommended

Only purchase the official Adafruit device - do not purchase a clone. - $14.95 + shipping

Samsung Endurance MicroSD Card (32 GB)

These Micro SD cards were specifically selected for their durability and reliability.

Purchase two - just in case! You never know... - $11.99/each

Computer/Android Device

A computer or Android-based phone is strongly recommended. Irrespective of which you select, they will connect to the software-based TNC built into Direwolf via the KISS Protocol (over port 8100/tcp).

Two options are available:

  1. Windows laptop running APRSIS32 (written by Lynn - KJ4ERJ)
  2. Android-based mobile device running APRSdroid

The ATGP customized version of DigiPi includes both a Wi-Fi Access Point and support for Bluetooth. Wi-Fi is recommended.

Once the laptop or mobile device are connected to DigiPi, use APRSIS32 or APRSdroid to connect to DireWolf via the KISS protocol (port 8100/tcp).

Test Test Test

Once again - the time to get everything working and thoroughly tested is well before the event. Ideally, you will get together with operators from neighboring mountains for joint testing.

Here in Maine a few of us plan to test at the annual Lobstercon2024

Final Thoughts

Participation in Phase 2 – ATGP Appliance using an appliance is purely optional. If you do not have a working appliance ready, simply continue to operate with your Kenwood radio as you did in Phase 1 – ATGP Classic. This will permit the golden packet to continue passing as other stations test their appliances.

You should only switch from your Kenwood to your appliance once Lynn or your Team Captain instructs you to do so and if you have simplex audio links to your adjacent stations. If any issues or problems occur, simply turn off your appliance and turn your Kenwood back on. This is important so that your link will not break the chain.

Remember – Have fun!

John Tarbox WA1KLI
Chairman of the AGTP Appliance Committee