V3 and Bias T

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Zeek70706
Posts: 9
Joined: Sun Apr 01, 2018 1:00 am

V3 and Bias T

Post by Zeek70706 » Fri Apr 06, 2018 9:57 pm

I'm trying to use the RTL-SDR V3 dongle on a RPi for ADSB. Swapping the V3 for the Flightstick pro works but when I try to activate the bias t for the new LNA I get this error:
"usb_claim_interface error -6"

I went through the setup steps multiple times and searched the net for help but have not found anything.

I can activate it on a Windows laptop, so I know it works as I could read the voltage on a multimeter.

Do we have any linux gurus here?

rtlsdrblog
Site Admin
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Joined: Mon Nov 19, 2012 11:54 pm

Re: V3 and Bias T

Post by rtlsdrblog » Sat Apr 07, 2018 3:59 am

To activate the bias tee you must stop all software that is accessing the dongle first. The error is just saying that the bias tee software can't access the dongle because something else is using it.

Are you using the piaware image or something else?

Zeek70706
Posts: 9
Joined: Sun Apr 01, 2018 1:00 am

Re: V3 and Bias T

Post by Zeek70706 » Sat Apr 07, 2018 1:33 pm

I'm using the package from ADSBreceiver.net with piaware in it.

I guess a better question is how to turn on the biast before the other stuff loads. I thought I have seen that somewhere but could not find it again.

rtlsdrblog
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Re: V3 and Bias T

Post by rtlsdrblog » Sun Apr 08, 2018 1:55 am

It's a little complex because these images are set up to run dump1090 as soon as they start. But on the FlightAware image (which i'm assuming is very similar to the adsbhub one) I was able to get the bias tee software to run first.

I'm yet to turn this into a proper post, but my notes are below:

-------------------

https://discussions.flightaware.com/t/e ... rt/20046/6

Enable WiFi via config file https://flightaware.com/adsb/piaware/build
Enable SSH by adding ssh file to boot https://flightaware.com/adsb/piaware/bu ... l#password

Login with SSH username "pi", password "flightaware"

sudo apt-get update
sudo apt-get install git cmake build-essential libusb-1.0-0-dev

cd~
git clone https://github.com/rtlsdrblog/rtl_biast
cd rtl_biast
mkdir build
cd build
cmake ..
make

sudo mkdir /etc/systemd/system/dump1090-fa.service.d
sudo nano /etc/systemd/system/dump1090-fa.service.d/bias-t.conf

Paste in

[Service]
ExecStartPre=/home/pi/rtl_biast/build/src/rtl_biast -b 1

Ctrl+X, Y to close and save.

Restart Pi and bias tee should automatically turn on.

Zeek70706
Posts: 9
Joined: Sun Apr 01, 2018 1:00 am

Re: V3 and Bias T

Post by Zeek70706 » Sun Apr 08, 2018 11:06 pm

Thanks, it's working now.

Yesterday afternoon, after the bias t was activated I connected the LNA directly to the dongle in my shack. That doubled my positions reported to Flightaware in the 150-200 range. So far today it is 4x as many in that range.

I just came in from mounting the LNA directly to the 50 inch FA antenna with an adapter. It's enclosed in 1.5 inch pvc. I drilled a hole in an end cap the same size as the threads on the antenna, put the cap on and then the adapter. The threads to cap are sealed with coax-seal. I cut a piece of conduit long enough to cover past the pigtail to RG6 connection and friction fitted it to the cap. This is all on top of a 30 foot tower and 5 foot extension.

This is my FA site address if anyone wants to check in on it:
https://flightaware.com/adsb/stats/user ... tats-18102

rtlsdrblog
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Re: V3 and Bias T

Post by rtlsdrblog » Mon Apr 09, 2018 7:13 am

Nice work. Just curious was it the directions I posted that allowed you to get the bias tee working?

4x results seems about right for connecting it directly. If you're connecting it directly to the dongle you might also want to reduce the dongle gain slightly or the dongle can overload and reduce performance.

But if connected by the antenna with a few meters of coax after, max gain should be okay, but i'd recommend experimenting with the dongle gain too.

Zeek70706
Posts: 9
Joined: Sun Apr 01, 2018 1:00 am

Re: V3 and Bias T

Post by Zeek70706 » Tue Apr 10, 2018 12:32 am

I'm not positive that your instructions are what made it work. There was one other thing I tried and didn't verify first. I initially got it going by manual commands.
Stopped dump1090: sudo service dump1090-fa stop
Then sent your bias t command
And a restart of dump1090: sudo systemctl restart dump1090-fa

It's been running over 24 hours and the results are fantastic. The bias-t does activate automatically from a power up. FYI there is 40 feet of RG6 between the LNA and dongle with two pig tails.

I haven't seen a noticeable increase in aircraft count in one day but the msg counts are through the roof.

Using Flightaware counts and looking back M-F last week:
150-200 mi range averaged about 500msg per day, today is about 4500.
200-250 mi range were in single digits daily, today is 215.
My overall msg count is up about 30%

Using ADSB Receiver stats from the RPi I was getting a max range of 190nm, today is 216nm.

I have heavy tree cover in all directions except up.

Zeek70706
Posts: 9
Joined: Sun Apr 01, 2018 1:00 am

Re: V3 and Bias T

Post by Zeek70706 » Sun Oct 13, 2019 2:03 am

My RPi is now running two receivers, the V3 and a Smartee, to monitor 1090 and 978 on Flightaware. I can't make the V3 software mods turn on the bias-t and want to know how to modify it ON permanently.

rtlsdrblog
Site Admin
Posts: 2421
Joined: Mon Nov 19, 2012 11:54 pm

Re: V3 and Bias T

Post by rtlsdrblog » Tue Oct 22, 2019 9:48 am

Zeek70706 wrote:
Sun Oct 13, 2019 2:03 am
My RPi is now running two receivers, the V3 and a Smartee, to monitor 1090 and 978 on Flightaware. I can't make the V3 software mods turn on the bias-t and want to know how to modify it ON permanently.
I've got an experimental Osmocom based driver branch here https://github.com/rtlsdrblog/rtl-sdr-blog.

To have the bias tee permanently on, replace the drivers with the rtl-sdr-blog version.

Then set the IR endpoint bit in the EEPROM to 0 using the command "rtl_eeprom -i 0"

Now the bias tee should always be on when any software accesses the RTL-SDR drivers.

Zeek70706
Posts: 9
Joined: Sun Apr 01, 2018 1:00 am

Re: V3 and Bias T

Post by Zeek70706 » Sun Oct 27, 2019 8:20 pm

rtlsdrblog wrote:
Tue Oct 22, 2019 9:48 am

To have the bias tee permanently on, replace the drivers with the rtl-sdr-blog version.
What commands do I use to do this? I have tried a few things but have to idea what I'm doing.
I'm starting with a piaware image and wiedehopf graphs.

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