FlightAware Discussions

RTL-SDR v3 bias tee power on/off - 3 methods for 3 different installs

(1) Method for dump1090-fa

Originally in 2017 Oliver Jowett (@obj) has proposed a method to turn on bias-t by adding a command in dump1090-fa.service file.


Subsequently in mid 2018 (1) Akos and (2) RTL-SDR Blog posted this method on their web pages. Both sites have “Credits” at bottom of their pages, and have given link to @obj’s method.



(1) Method for dump1090-mutability ver 1.15~dev

The method posted on the RTL-SDR Blog is applicable to dump1090-fa only.
It does not apply to dump1090-mutability v1.15~dev, as the dump1090-mutability service files ( dump1090-mutability.service ) are automatically generated by systemd-sysv-generator , and all the changes made by user are overwritten at restart / reboot.

However as the systemd-sysv-generator generates dump1090-mutability.service by reading from file `/etc/init.d/dump1090-mutability, in mid 2018 I have added bias-t start and logging script in the init file, and it works OK. Detailed steps are given here:

RTL-SDR V3 Dongle
Enabling Auto Switch-ON of Bias-T in dump1090-mutability v1.15~dev.

(3) Method for Flightradar24’s Pi24 image

In the Pi24 image, the default startup of it’s dump1090-mutability ver 1.14 at boot is blocked by FR24 programmers . It is configured to be started by fr24feed, with all the necessary config parameters supplied by fr24feed, and NOT by init file of dump1090-mut.

Due to above, in mid 2018 I have proposed to add bias-t startup command in fr24feed’s service file (i.e in file fr24feed.service). Detailed steps are given here:

RTl_SDR v3 bias tee power on/off Raspberry pi




Thanks for the post.

I needed a refresher on how to do this.

In the mean time, I’ve had good luck with this: