SP0LND LoRa APRS Digi Balloons

This page explains how to use the LoRa APRS digipeater functionality of the balloons.

Looking for the balloon list? Check it HERE!

Mission Control đŸ–Ĩī¸

The best way to follow and control ongoing missions is the Mission Control dashboard, usually available at digi-dashboard.sp0lnd.pl.

Configuration ⚙ī¸

The best way to configure your tracker is by using the SQ2CPA LoRa APRS flasher software, available at flasher.lora-aprs.pl.

You need to set the following frequencies and transmission parameters:

Transmission Settings
TX Frequency 430.500 MHz
TX Speed 1200bps (SF9, CR4:7, BW125k)
RX Frequency (if you are normally using 1200bps) 434.855 MHz (1200bps)
RX Frequency (if you are normally using 300bps) 433.775 MHz (300bps)

Example configuration of the QRG and speed (tick Custom (below) and fill in the transmitter fields):

Configuration screen showing the custom TX frequency 430.5 MHz and the BW125k CR4:7 SF9 speed setting
Very Important: Ensure your tracker transmits frames only on the 430.500 MHz frequency. Do not send the same frame in parallel on other APRS frequencies (e.g., 434.855 MHz). The APRS-IS servers will detect a duplicate, and the frame repeated by the balloon will not be visible on the APRS-IS network!

Disable Telemetry 📡

It is strongly recommended to disable telemetry in your tracker. Sending additional telemetry data unnecessarily occupies valuable airtime on the channel and can interfere with the digipeater's operation for other users.

Below are examples of how to do this:

Example of disabling telemetry

How the Digipeater Path Works 🛰ī¸

Sending frames through the Digi balloon is based on a custom path system.

Important: The balloon's digipeater does not respect the standard WIDE path. You must use the SKY paths listed below.
Path Description
SKY1 Your frame will be repeated by the balloon to the ground on 434.855 MHz (1200bps).
SKY2 Your frame will be repeated by the balloon to the ground on 433.775 MHz (300bps).
SKY3 This enables a balloon-to-balloon link. The first balloon repeats the frame to another balloon via 430.500 MHz.

To have a frame digipeated from one balloon to another and then to the ground, you must combine paths. For example, a path of SKY3,SKY1 will cause the first balloon to send your frame to the second balloon (via SKY3), which will then repeat it to the ground (via SKY1). A frame with only SKY3 will be ignored by the second balloon.

Beacon Path

The Beacon Path field in your station configuration decides how the balloon repeats your tracker's beacon. Enter the SKY path you want there — in the example on the right it is SKY1.

Example beacon path configuration:

Station configuration screen showing the Beacon Path field set to SKY1

Recommended Mobile App

It is convenient to use the app.lora-aprs.pl web application. You can connect to your tracker via Bluetooth and set the desired path in the application settings. You can use this app for messages! Remember that path in application is related to messages and path in your tracker settings is related ONLY to tracker beacon!

Example app configuration:

Mobile app configuration screen showing path settings

Important Information ℹī¸

Things to Remember
  • Airtime: The channel capacity is roughly 80 frames per minute, but please still do not spam frames! This matters even more with SKY2, where the transmission takes as long as 4 seconds — that way we waste a lot of airtime.
  • Verification: After your frame is repeated, you can see the path it took on sites like aprs.fi.
  • GPS Spoofing: Be aware that GPS spoofing occurs in the Kaliningrad region. The balloon may temporarily report a false position or stop sending its location.
  • Message Acknowledgment: The balloon will respond with an acknowledgment (ack) to any message you send it. This confirms the balloon received your message.

Example of a successfully repeated frame on aprs.fi via two balloons: SN0PEK-14 and SN0PEK-15:

Screenshot from aprs.fi showing a repeated frame with a SKY path

Supported Commands đŸ’Ŧ

You can send query messages to the balloon to get real-time information.

Command Description
?APRSV Returns information about the balloon.
?APRSP or ?APRSL Returns the balloon's current location (latitude and longitude).
?APRSA Returns the balloon's altitude in meters.
?APRST Returns the balloon's internal temperature in Celsius.