FlightAware Discussions

Drastic performance drop

Other things got in the way of ADSB but I recently came to check on my stats to find out that something took a hit. I’ve checked the antenna, the filter and the pi and everything looks solid. The setup is in the attic where temp can be variable.

Could someone lend some knowledge on how to check if something isn’t operating at optimal level? Also, the graphs1090 are on another machine to offset the load and it was offline for a bit but it did capture the drop around July.

It looks like either the antenna or the the amp/filter is acting up.

I’ve had my gain set to 30 when it was working optimally but set it back to dynamic after started seeing the issues. Dynamic tuning seems to be hitting the top end.

First thing, you might want to remove the first image in your post that shows precise lat / lon location, unless you don’t care where that points to for all the Internet citizens to see.

Maybe post your piaware and dump1090-fa full configurations to ensure it’s not software automatic update/config related.

The amp could have failed if it got too hot for too long. e.g. the attic never had a chance too cool at night. :wink:

The shown performance drop should have nothing to do with weather.

To me it looks more like something is broken in the configuration/hardware setup.
If it worked before, something seem to be broken

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It is too late to modify the original post so I am finding out how to have the admin/moderator adjust it.

Is there a way of testing both rtl-sdr and the amp to make sure they’ve functioning properly? I’ve disabled bias tee and I am getting 0 planes which means that amp is off. When I turn bias tee back on, it shows the same performance.

You will have to disable the components one by one. Remove the amp from your reception chain and check the effect.
If it seems to be working without the remove d component you found the issue.
If it doesn’t have an effect then repeat with a different component.

A picture of your setup might come in handy…

Same performance as without Bias tee? Then the device is not working.

From the responses I received no one suggested internal rpi tools that can diagnose the actual health of the amp, the antenna or the pi itself probably as they don’t exist.

I can’t edit the original post to remove the initial image and admin has not responded yet. I will have to delete this thread and repost with your responses somehow.

Thank you all who responded so far.

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No, with bus tee turned off I get 0 data. When I turn bias tee back on I am back to the same poor numbers.

strange. Than something else is broken. No idea so far

You say you are operating an LNA in front of the USB stick?
then the gain seem to be pretty high.

However it can be realistic if you are in a low traffic area.
It would correspond to your graphs, but doesn’t explain your significant higher traffic before.
The gain is a result of the issue, not the root cause

That is exactly my setup: antenna, LNA and USB stick. LNA is directly connected to the antenna and there is a short cable going to the stick. I’m in a high traffic area surrounding KORD and was getting high altitude traffic very far out. Here are two samples from earlier in the year and just recently… my visibility is almost nil.

Do you have the antenna on the outside? What type of antenna?
What happens when you remove the antenna and put a piece of copper wire with a length of about 2.5 inches in the antenna input of the LNA? (or a backup antenna)

The antenna, diy coco, is inside of the attic and I did purchase an adsb tuned antenna (from airnav) from Amazon as I started to have issues but did not had a chance to replace it yet.

check for moisture anyways. clean connections and verify none of the tips broke off


So I did some testing yesterday.

It came out to be a faulty LNA. I thought I had a spare but could not find it so may have to order another one. Is there a way to test if it is working properly? I’m not too electronically capable but have access to tools.

I replaced the homemade coco antenna with one available on amazon and it produces decent results. However, the LNA would be a plus.

I replaced the antenna circa 8 PM on 10/12 and you can see the improvement since then.

Screenshot 2021-10-13 093831
Screenshot 2021-10-13 093908


Good result.
I had a cheap amp fail in much the same way, so I’m reluctant to use low quality gear in inaccessible places.

Will appreciate if you provide link to the Amazon page for that antenna. Thanks.

Here is the link to the antenna: