Supported Hardware

This table lists hardware that is required or recommended to build a Stratux. Note that in some cases, "recommended" hardware can be replaced with something else that has the same features. E.g. the "U-Blox GPS" can be replaced with a TTGO T-Beam with SoftRF or ESP32-OGN-Tracker firmware.

Hardware	Priority	Purpose
Raspberry PI 3B/3B+/4B	Required	Runs the Stratux software
RTL-SDR dongle (e.g. Stratux v2 radio, NooElec NESDR, ...)	1 required, 2 recommended1	Receives aircraft on ADS-B or 868Mhz protocols (one required for each frequency band)
Antennas	1 required for each send/receive device	Often they come bundled as 1090+978Mhz antennas. The 978Mhz antenna can also be used for 868Mhz reception, albeit with slightly reduced range. You may also purchase a separate 868Mhz antenna for extended range
USB GPS Module	Highly recommended	Many features of Stratux (and some EFBs) require Stratux to know its location. You can either use a U-Blox GPS dongle (preferably U-Blox 8 or 9; 7 is also ok), or one of the below mentioned TTGO devices that come with GPS
Stratux AHRS module	Recommended2	Serves as a barometric altitude source and brings AHRS functionality and fan speed control
Fan & Case	Recommended	There are many cases around for Stratux, or you can 3D print one yourself if you have a printer. It is highly recommended to use a 5v fan to plug either into the AHRS module or into the fixed 3.3 or 5v pins of the RaspberryPi - otherwise your PI or SDRs can overheat
Stratux UAT Radio	Optional	Can be used for UAT traffic/weather reception, which is not very widespread in Europe
BMP280/BME280/BMP388/BMP390 pressure sensor	Optional	Can replace the AHRS module if no AHRS or fan control is needed. Note that the BMP280 can either be attached to the RasPI, or to one of the TTGO devices. Stratux will detect either. Note that Stratux does NOT directly support the BME280! If it is connected to a T-Beam/T-Motion, it might still work though.
TTGO T-Motion [aka. SoftRF Dongle]	Optional	Usually preloaded with SoftRF. Can replace the GPS and also send and receive one 868Mhz based protocol, such as OGNTP, PilotAware, ... If equipped with BMP280, can also replace AHRS module for pressure information
TTGO T-Beam [aka. SoftRF Prime Mark II]	Optional	Same as T-Motion. Additionally, you can flash the ESP32-OGN-Tracker software for even better OGNTP support. See here for details: https://github.com/b3nn0/stratux/wiki/TTGO-T-Beam-Firmware-for-Stratux
CP2102 based USB/Serial adapter	Optional	Can be used for GDL90 or Flarm-NMEA serial output to a supporting EFIS, see https://github.com/b3nn0/stratux/wiki/Stratux-Serial-output-for-EFIS's-that-support-GDL90-or-Flarm-NMEA-over-serial

How to PPM calibrate SDRs for the usage of 868MHz

¹ Especially for 868Mhz reception, it is crucial that your SDRs are PPM-calibrated. This is usually the case when purchasing SDRs that are advertised as Stratux-compatible. If you are familiar with the Linux/RaspberryPI shell, you can also do the calibration yourself. To do so, connect only one SDR, then connect via SSH (ssh [email protected], password "raspberry") and run

sudo -s
stxstop
kal -d 0 -s GSM900

Now wait a bit until you see at least one channel listed and then cancel with Ctrl+C. It will look like this: chan: 3 (935.6MHz - 14.465kHz) power: 265372.99 Now run

kal -d 0 -c 3

Where 3 is to be replaced with the respective channel number. After a short while, you should see the PPM correction: average absolute error: 17.983 ppm To save this correction value, run

rtl_eeprom -d 0 -s stx:1090:18

Replace 1090 with 868 or 978 for the respective band and 18 with the (rounded) measured PPM value, then

stxstart

² Especially the barometric altitude is highly recommended. Read here to find out why.