FlightAware Discussions

Skyaware display issues

Reduce the gain further.
Seems you are running an extra LNA or something?

Let’s try a gain of 36.4

Let’s hold off on the filter for now.

Pretty sure with the increased message rate your experience in the map should have already improved.
Still no really good reception.
I don’t remember, did you mention where the antenna was located?

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I have a flightaware pro plus stick and the 66cm outdoor antenna installed. Things worked fine having the antenna at ground floor or even just a little bit above the roof. Having the ability to set it higher I got it fixed first some 1m higher (with the start of the above problems) and a fortnight ago we raised it 4m about roof level.

There is no extra LNA installed. Antenna cable is still the same.

100kHz, 49,6dB

at about 16:00 I changed to 36.4 (with a short 40min break at 20:00 for the RTLPAN messurement)

Maybe i am wrong, but i have the feeling there is something bad going on.
While the number of aircraft seem to be fine with up to 50 the message rate does not match from my perspective

By looking on your profile what happened around May 7th?
Your reported positions dropped while the number of reported aircraft are stable

Your rate for ADS-B went down significantly while the values for “other” are going up. This is not ok. You have a good range, so there must be something different.

To complete my thoughts, this is my graph last seven days. Number of aircraft is comparable to yours, but the message rate is different.

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Oh 7th Mai we set the antenna to the higher position (+4m) and now it is a little bit close to an WIFI system supplying our community - it is 4,9-5,75GHz (17dBi) so we didn“t see a problem.

Should I try a filter??

Absolutely lol.
Should have mentioned the WiFi earlier :stuck_out_tongue_winking_eye:

The high range with very low message rate looked like some burst based interference all along.
You are basically time sharing.
Only receiving sth when the WiFi isn’t sending.

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Is there an easy way for you to bring the antenna down again? Just to verify what’s happening then.

That’s a gnarly spur every ~30Mhz or so. You have noise/EMI issues going on somewhere. Filter would help, but only be a bandaid - need to figure that out first I think.

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Having the WiFi antenna NOT at the same altitude as the antenna will help significantly due to the gain distribution of the ADS-B antenna having the strongest reception on the horizon as seen from the antenna.

Keeping that in mind plus adding a filter should help.

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just ordered a filter and see if it helps.

we have two of these 5GHz on the top of the mast (close to the ADSB one) and a wifi dish (30cm, 30dBi) close to the roof. You might be right with the "wifi causes problems in receiving ADSB signals) as I had severe problems just outside the roof when I changed position of the ADSB antenna for just some 50cm between “empty scrren” and “all planes be seen”. Thought it was a problem with the cable or connection but couldn’t find the mounting-problem…

Had some guys with the lift to get the sector Wifis and the ADSB to the top so I see no change at the moment to get it a little bit down on my own.
so lets try the filter first

Friend of mine was able to mount the antenna on a church with lots of Wifi and other high frequency devices. He does not have these issues at all but he uses a Airnav stick with their filter.

Some 5GHz WiFi units actually have a separate transceiver unit and the signal to the antenna is at a lower IF frequency. Often this IF is around the 1GHz region.
If this is the case you may be suffering from the IF frequency leaking out and overloading your dongle, not the 5GHz WiFi itself. The 30MHz spurs suggest an out of band signal overloading the dongle.

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just added the filter a few hours ago and the results are really good (gain still 36.4)
Filter-1



I will start some HF tests / frequency scans in the next days

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Yes, that looks impressive.

Once it’s running stable you can play around with the gain.
After adding the filter i was able to increase the gain from 40.2 back to 49.6 without having a significant increase of bad messages

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Agree - I think you can bump gain to 44.5 or 48, starting with the lower value. Looking at the scans, there is still a bad spur and though the filter obviously woke her up by snuffing most of the out of band noise, I think your system can still perform better. Do you happen to have the antenna cable running in close proximity to any power lines by chance? I’m still confused on where those spurs are coming from based on your description of the setup.