How to Log Telemetry Data in EdgeTX/OpenTX Radios (GPS Coordinates, LQ, RSSI, Voltage etc)

You can record real time telemetry data in your radio in a CSV file, such as GPS coordinates which can help you find your downed model. Other uses include logging receiver LQ and RSSI changes over time to look at radio link performance during flight. In this guide I will show you how to log / record any telemetry data in your EdgeTX/OpenTX radio.

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Before we begin, make sure you’ve setup Telemetry, here are the tutorials in case you haven’t done that already:

• ExpressLRS Setup Guide
• Crossfire Setup Guide

If you want to log GPS data, you also need to setup GPS first: How to Setup GPS.

Discover Telemetry Sensors

Power up your quad (to power your receiver and GPS if you want GPS related telemetry data).

Go to the Telemetry page in your radio by pressing the Model button, then press the Page button a few times. When you are in the Telemetry page, scroll down and select “Discover new sensors” option.

If GPS is setup and working, you should see all the GPS related sensors added to the list, including the coordinates.

* GPS coordinates might appear to be 0 if the GPS receiver has not got a satellite lock, don’t worry, just be patient and wait for a lock. As long as these sensors are there, you are all set!

Enable Logging

To enable telemetry logging in an OpenTX/EdgeTX radio:

• Go to Special Function page
• Assign a switch to start the log – you can also just use the arm switch so it starts logging as soon as you arm, or you can select “ON” instead of using an switch, which will always log data when the radio is powered on but this might fill up your SD card without you knowing (the logs files are relatively small in size so it will take a while to fill up). Or you can select “TELE”, which means it will start logging when a receiver connection is established and telemetry data is coming in
• Select function “SD Logs”
• Choose a value, which is how frequent you want to log the data. Depending on what kind of data you intent to gather, for GPS stuff I think 0.5s, 1s or even 2 seconds are a good starting points. For radio link information maybe you want more frequent update to check for spikes in RSSI and LQ. It really depends on what you need.

Pro Tip: For a more sophisticated approach to activating logging, consider creating a logical function that operates under an “AND” condition for the arm switch and TELE variable – this would only initiate logging when both the arm switch and telemetry data are active simultaneously.

It will basically log everything in your Telemetry page into a CSV file.

You can choose what data not to collect by simply go to the Telemetry page, and edit the telemetry data you want to remove from the log by unchecking the “Logs” option. By default, all telemetry data have the Logs option enabled and will be recorded.

Access Telemetry Log

The log file is saved in the “Logs” folder in your SD card, the file name follows this pattern: model name-date time.csv

If you don’t have access to a computer in the field, most smartphones with micro SD card slot can read it as well.

The log is in .CSV format, which can be opened in Excel like a spreadsheet.

Or you can also open it in a text editor, the values are separated by comma.

You can also open the log in OpenTX Companion, it can create some pretty useful graphs.

How to Check GPS Coordinates?

If you crashed your drone and not sure where it is, you can try to find it by looking up the last GPS coordinate. Simply copy the coordinates into google map and it will show you the location. There are other ways to find a lost quad too.

You can also work out the travel direction before the crash. Simply go back a few seconds and copy the coordinates into google maps. The line between the two locations would be the travel direction.

You can even plot the whole flight path with the coordinates on Google Earth!

Edit History

• Nov 2018 – tutorial created
• Jan 2023 – updated guide, shortened URL