Aaaah, I see … the documentation in github told “true / false”, the log entry points to expected “ON/OFF”.
I’ll retry with OFF. If this is the right combination, please let me create a fix and a git pull request for the documentation.
$ docker logs ultrafeeder 2>&1 | grep bias
s6-rc: info: service 09-rtlsdr-biastee: starting
[2025-01-31 16:56:39.022][09-rtlsdr-biastee-init] Device type is rtlsdr, checking for bias tee...
[2025-01-31 16:56:39.167][09-rtlsdr-biastee-init] Disabling bias tee...
[2025-01-31 16:56:39.187][09-rtlsdr-biastee-init] Found 1 device(s):
[2025-01-31 16:56:39.207][09-rtlsdr-biastee-init] 0: RTLSDRBlog, Blog V4, SN: 00000001
[2025-01-31 16:56:39.207][09-rtlsdr-biastee-init]
[2025-01-31 16:56:39.219][09-rtlsdr-biastee-init] Using device 0: Generic RTL2832U OEM
[2025-01-31 16:56:39.294][09-rtlsdr-biastee-init] Detached kernel driver
[2025-01-31 16:56:39.559][09-rtlsdr-biastee-init] Found Rafael Micro R828D tuner
[2025-01-31 16:56:39.559][09-rtlsdr-biastee-init] RTL-SDR Blog V4 Detected
[2025-01-31 16:56:40.089][09-rtlsdr-biastee-init] Reattached kernel driver
s6-rc: info: service 09-rtlsdr-biastee successfully started
docker-compose.yml,
environment:
...
- READSB_ENABLE_BIASTEE=ON
resulting in
$ docker logs ultrafeeder 2>&1 | grep bias
s6-rc: info: service 09-rtlsdr-biastee: starting
[2025-01-31 16:58:14.070][09-rtlsdr-biastee-init] Device type is rtlsdr, checking for bias tee...
[2025-01-31 16:58:14.197][09-rtlsdr-biastee-init] Enabling bias tee...
[2025-01-31 16:58:14.216][09-rtlsdr-biastee-init] Found 1 device(s):
[2025-01-31 16:58:14.238][09-rtlsdr-biastee-init] 0: RTLSDRBlog, Blog V4, SN: 00000001
[2025-01-31 16:58:14.238][09-rtlsdr-biastee-init]
[2025-01-31 16:58:14.250][09-rtlsdr-biastee-init] Using device 0: Generic RTL2832U OEM
[2025-01-31 16:58:14.322][09-rtlsdr-biastee-init] Detached kernel driver
[2025-01-31 16:58:14.600][09-rtlsdr-biastee-init] Found Rafael Micro R828D tuner
[2025-01-31 16:58:14.600][09-rtlsdr-biastee-init] RTL-SDR Blog V4 Detected
[2025-01-31 16:58:15.061][09-rtlsdr-biastee-init] Reattached kernel driver
s6-rc: info: service 09-rtlsdr-biastee successfully started
Both seem to enable the BIAS. Why do I believe it? Well, I am using an active antenna, and with both settings I get many planes flying around in web view at distances of more than 70 km. could climb to the shed’s roof and measure the line, but I am quite sure, the https://de.aliexpress.com/item/1005007735199789.html antenna would not beyond 10 nm without power supply.
Shall I grab my meter and climb?
Regarding the planned CoCo test … some days before I ordered another stick for a friend, this time “The Blue one” (https://de.aliexpress.com/item/1005005466363998.html). Specs are telling nothing about BIAS for the blue stick. So I can delay my CoCo-Antenna experiments until then.
Anyway, I’d love to learn if my V4 is defective. If anyone else could verify, if the recent container does switch off BIAS with their V4 sticks, it could help a lot to argument with the supplier.
So, please all other readers and RTL-SDR V4 owners, could you please confirm that this setting in ultrafeeder’s /opt/apt/docker-compose.yml
I am not very familiar with the architecture, just an old man who can C++ and playing with docker containers made by smarter people
Could you please point me to a web site where I can get the missing knowlege?
BTW, another question about BIAS and my passive home brew antennas:
Could I use this one as a BIAS voltage stopper? I’d guess the brown thing in the HF path is a capacitor(?) My idea is to insert this one into my antenna cable and to omit the USB supply. That should let pass the HF and stop the bias, right?
You can just try installing rtl-sdr with apt and using rtl_biast while the container is stopped.
Make the biastee setting for the container an empty string and start the container.
With the string empty it will leave the biastee in the state it is in.
Now I found RTL-SDR Blog V4 Users Guide. Together with your hint, it is enough documentation . Will get the hardware tomorrow from the shed’s attic and try it soon.
If you insert that Bias-T into your feed and point the “RF&DC” port to the receiver, the Bias-T LED will tell you if the V4 is feeding power (while blocking the DC to the antenna).
the Blog V4 stick is switching the bias as required. So I am afraid the “locked” bias is caused by some piece of software or configuration mistake somewhere.
To verify the Blog V4 stick, I did:
set up an fresh, clean Pi4 (the problem arised with Pi3, docker, ultrafeeder)
me@pi4:~ $ rtl_biast -d 0 -b 1
Found 1 device(s):
0: RTLSDRBlog, Blog V4, SN: 00000001
Using device 0: Generic RTL2832U OEM
Found Rafael Micro R828D tuner
RTL-SDR Blog V4 Detected
me@pi4:~ $ # -- some milliseconds after issuing above command, the bias gets ON, okay
me@pi4:~ $
me@pi4:~ $ rtl_biast -d 0 -b 0
Found 1 device(s):
0: RTLSDRBlog, Blog V4, SN: 00000001
Using device 0: Generic RTL2832U OEM
Found Rafael Micro R828D tuner
RTL-SDR Blog V4 Detected
me@pi4:~ $ # -- some milliseconds after issuing above command, the bias gets OFF, okay
What’s my most likely fault with the Pi3/docker/ultrafeeder setup?
What to investigate next?
My fault .
Some weeks before, I replaced the Pi3 by another one. According to the shell history, I did everything I did on the 1st computer, except create the blacklist.
Back on the Pi3 I caught up on it today.
For later readers, do not forget or mistype the blacklist, otherwise your docker host seemingly forces the bias to be ON:
echo 'blacklist dvb_usb_rtl28xxu' | sudo tee --append /etc/modprobe.d/blacklist-dvb_usb_rtl28xxu.conf