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[marc1201]

Hi all

I'm new here, running a raspberry pi since a couple of weeks now. Unfortunately my wife won't allow me to put an antenna on the roof, so my antenna is on my attic. It is this antenna:
https://shop.jetvision.de/epages/648...Products/67121 connected to a flightaware pro stick plus usb dongle. I have a range of about 80-100nm which is not too bad for beeing under the roof.. I was thinking of putting this preamp in between the coax of the antenna,(https://www.sossolutions.nl/flightaw...xoCNdEQAvD_BwE) but i'm not sure if it's going to work,since it's a filtered preamp. The flightaware stick has also a filter in it. Will these two work together?
Thanks already

Marc Van Loo

[wiedehopf]

Yes they will work together.

You'll need to reduce gain manually or employ this automatic gain control (adjusts gain every night by 1 step if necessary) included with this: https://github.com/wiedehopf/adsb-sc...for-dump1090fa

[marc1201]

Yes they will work together.

You'll need to reduce gain manually or employ this automatic gain control (adjusts gain every night by 1 step if necessary) included with this: https://github.com/wiedehopf/adsb-sc...for-dump1090fa

But gain(more range) is just what i want, so why reduce it? I'm new in this so i don't understand it very good.

[Oblivian]

But gain(more range) is just what i want, so why reduce it? I'm new in this so i don't understand it very good.

If you have noise, An amplifier also amplifies that noise

If the receiver is sensitive, too much signal can overload and prevent good decodes

Therefore you start at the lowest amplified/filtered baseline. And increase until you find the midpoint or a degrade in good decode figures.

[marc1201]

If you have noise, An amplifier also amplifies that noise

If the receiver is sensitive, too much signal can overload and prevent good decodes

Therefore you start at the lowest amplified/filtered baseline. And increase until you find the midpoint or a degrade in good decode figures.

this makes sense, but how do you filter that? If it is in the linux code i can't do it because of zero experience with it.
I probaly going to leave it as it is in such case.

[Oblivian]

There are commandlines to adjust the software. And graphs to view the signal quality/levels

wiedehopfs link is one of the tools that does this.

https://github.com/wiedehopf/adsb-scripts/wiki/Automatic-installation-for-dump1090-fa#change-gain-with-provided-helper

[wiedehopf]

The bundle install adjusts gain automatically one step every night.
So it will adjust itself, see the Bundle install github page (link i posted previously)

If you don't like that, it can still be disabled.

[marc1201]

The bundle install adjusts gain automatically one step every night.
So it will adjust itself, see the Bundle install github page (link i posted previously)

If you don't like that, it can still be disabled.

ok thanks already, i'm going to take a look at it, also i still have to order the preamp..Although the people where i bought the flightaware stick from told me that the stick and the preamp won't work together..,but maybe they don't know your script ;-)

[wiedehopf]

It's not the best combination as it can overload the dongle.

But it should still work, i've read of multiple reports of users using that combination.

If you are using the whip antenna, you need to cut it to length: https://forum.flightradar24.com/foru...-Dongle/page2=

A proper antenna like the flightaware antenna will provide better results even indoors.
Also needs a good cable.

The closer you get the LNA to the antenna, the better, the coax after the LNA isn't as critical.

[marc1201]

It's not the best combination as it can overload the dongle.

But it should still work, i've read of multiple reports of users using that combination.

If you are using the whip antenna, you need to cut it to length: https://forum.flightradar24.com/foru...-Dongle/page2=

A proper antenna like the flightaware antenna will provide better results even indoors.
Also needs a good cable.

The closer you get the LNA to the antenna, the better, the coax after the LNA isn't as critical.

Using this antenna:
67121.png

[wiedehopf]

Unfortunate that the cabling is directly attached, for best possible results you want the LNA directly at the antenna.

But it'll still work.

[ylis]

Originally posted by wiedehopf View Post -

The bundle install adjusts gain automatically one step every night.

During last week, I made a new image using Buster and your bundled dump1090-fa installed seamlessly. I then used my standard fr24feed.ini which includes --gain 40 and everything is working fine.

Last night, I was looking at the automatic gain feature. Does the log start each time the rpi is rebooted ? Does it get the gain from the ini file or is the setting somewhere else ? I ran sudo /usr/local/bin/dump1090-fa-autogain and the gain decrease to 49.6 so it seems it didn't recognise the --gain 40 entry in the ini file.

Finally, how do I see what the current gain setting is to at ?

Thanks for all your wisdom and advice in this forum ....

[wiedehopf]

You should install the bundle after fr24feed or make sure choose beast tcp as a receiver when installing fr24feed.

If you didn't do that it's best to run the bundle install script again to make sure everything is working as it should.

dump1090-fa gain is set in /etc/default/dump1090-fa
Or you can use this: https://github.com/wiedehopf/adsb-sc...rovided-helper

Be sure to only use the values mentioned in the link above otherwise the automatic adjustment will reset to maximum gain.

https://github.com/wiedehopf/adsb-scripts/wiki/Automatic-gain-optimization-for-dump1090-fa

You can also run the automatic adjustment a couple of times.

[utack]

marc did you ever scan what the rate of strong messages is for you with that antenna?
I am getting

Gain already at maximum! (0.587% messages >-3dB)

on a simple unamplified dongle, and it seems a bit low to me

[wiedehopf]

For a non-amplified dongle that's expected.
There is a reason why the specialized SDRs have a filter and LNA, it improves reception.

Doesn't mean your reception is necessarily bad.

For people who don't want to lose reception on helicopters flying close to your house, such a low percentage is probably required.