How to check bias tee activation

FlightAware ADS-B Flight Tracking
1

After upgrading to version 5 I am having problems with my reception. I checked my gain, it has not changed.
I have an uptronic filter and powered it with my RTL-SDR dingle.
I know there is a command to check if my filter is powered my my dongle, but i cannot find it in my notes.

Would someone be so kind and help me our so I can check if it is working correctly , co I can go to a next step in optimising ( again) my setup?

Thanks

1 Like
2

Iā€™d suspect for some reason your biastee isnā€™t being activated.
Use this:
RTL Bias Tee Ā· wiedehopf/adsb-wiki Wiki Ā· GitHub

1 Like
3

Thank you for thew link.
I used your script but there are many red lines. A lot od warnings is that ā€œnormalā€?
It is probably to much to copy and paste it in here.

4

Not sure about that specific filter, but my RTL-SDR Blog ADSB Filter has a Green Power LED on the Circuit Board. I had to drill a hole in the case directly above it so that I can see it easily but now I can tell at a glance whether it is powered or not. Same deal with the RTL-SDR Wideband LNA that I run on my Airband setup. Now I just need to pop my head up the loft hatch and if I see 2 green lights Iā€™m good :slight_smile:

5

@NeoDuder The Uptronic doesnā€™t have green lights

6

Can you borrow a DVM? (Digital Volt Meter)

7

Unfortunately not.
If I remember well there is a command that shows at the end of the text something like bias tee on

8

pastebin.com ā€¦

9

Thank you, as always:)

https://pastebin.com/embed_js/eTApQXC5

10

That looks pretty normal.
Letā€™s check the logs then.

sudo systemctl restart dump1090-fa
sudo journalctl -u dump1090-fa | tail -n30
11

Ok,
here the journal:
https://pastebin.com/embed_js/CMg7w972

12 
cat /etc/systemd/system/dump1090-fa.service.d/bias-t.conf

Did you run both scripts on that page?
Seems it isnā€™t working for some reason.

This should manually enable the bias-tee if dump1090-fa is stopped.

sudo systemctl stop dump1090-fa
sudo /usr/local/share/adsb-wiki/biastee/rtl_biast/build/src/rtl_biast -b 1
sudo systemctl restart dump1090-fa

Similar output is what i would expect in the system log.

13

Here the outcome

I ran the install script., so only the first one you mentioned, so the enable script

14

Yeah run the thing again but with stopping dump1090-fa first.

sudo systemctl stop dump1090-fa
sudo /usr/local/share/adsb-wiki/biastee/rtl_biast/build/src/rtl_biast -b 1
sudo systemctl restart dump1090-fa

I have no clue what is wrong with your setup.

cat /etc/os-release 
ls /etc/systemd/system/dump1090-fa.service.d
ls /etc/systemd/system/dump1090-fa.service

You have a minor error:

Mar 15 18:06:04 raspberrypi dump1090-fa[22901]: /usr/share/dump1090-fa/start-dump1090-fa: 1: /etc/default/dump1090-fa: Ā«#: not found

So you have some extra character in /etc/default/dump1090-fa ā€¦ but i donā€™t think that is the issue. Wouldnā€™t hurt to fix it.

As you see in the log itā€™s using a gain of 37.

15

Did re run it

pi@raspberrypi:~ $ sudo systemctl stop dump1090-fa

pi@raspberrypi:~ $ sudo /usr/local/share/adsb-wiki/biastee/rtl_biast/build/src/rtl_biast -b 1
Found 1 device(s):
0: Realtek, RTL2838UHIDIR, SN: 00000001

Using device 0: Generic RTL2832U OEM
Found Rafael Micro R820T tuner
pi@raspberrypi:~ $ sudo systemctl restart dump1090-fa

Here the outcome of the other three commands

For the last command there is an error

    pi@raspberrypi:~ $ cat /etc/os-release

PRETTY_NAME=ā€œRaspbian GNU/Linux 10 (buster)ā€
NAME=ā€œRaspbian GNU/Linuxā€
VERSION_ID=ā€œ10ā€
VERSION=ā€œ10 (buster)ā€
VERSION_CODENAME=buster
ID=raspbian
ID_LIKE=debian
HOME_URL=ā€œhttp://www.raspbian.org/ā€
SUPPORT_URL=ā€œRaspbianForums - Raspbianā€
BUG_REPORT_URL=ā€œRaspbianBugs - Raspbianā€
pi@raspberrypi:~ $ ls /etc/systemd/system/dump1090-fa.service.d
bias-t.conf
pi@raspberrypi:~ $ ls /etc/systemd/system/dump1090-fa.service
ls: cannot access ā€˜/etc/systemd/system/dump1090-fa.serviceā€™: No such file or directory
pi@raspberrypi:~ $

Changed the gain back to 49.6 as it was before the update

16

Huh?
The 5.0 update certainly didnā€™t reduce the gain to 37 ā€¦

17

No you are right, but checked if a change in gain would make a difference.
In an other post the fa staff said the messages could be different because of the update

18

Can you show the graphs to illustrate ā€¦ i get the impression people just imagine it ā€¦

19

thank you. Will port them tomorrow.

Good night

20

I have re-imaged, so no past history left to compare with and worry aboutā€¦ peace of mind :wink:

1 Like