Thought this might be useful for those that might attempt this setup:
3.7.1 with RTL-SDR v3 + ADS-B 1090 Bias Tee AND secondary 978 radio
Your rtl_test identifies your radios as the following:
Found 2 device(s):
0: Realtek, RTL2838UHIDIR, SN: 00000978
1: Realtek, RTL2838UHIDIR, SN: 00001090
You go through the tutorials, but your bias tee isn’t working quite right… you’re getting nothing on your 1090 feed… even with running the command line stop1090/enable bias tee/start1090
Your solution is to tell your software which device you have listed in your rtl_test that you need to enable the bias tee software. You can do this by an additional argument in this bias-t.conf. the “-d” argument identifies which device in the rtl_test list you need to enable your software bias tee in your v3 radio.
ExecStartPre=/home/pi/rtl_biast/build/src/rtl_biast -d 00001090 -b 1
A bit of trial and error it took me to find this - nothing was getting thru for me. I knew the hardware worked; I bench tested prior to installation.
Thanks to wiedehopf for the suggested argument switch (the serial instead of dongle number)
Ensure your power supply is adequate… I did get a voltage drop error on my first activation.