Skyaware display issues

7 messages per second is very weak reception.
All the aircraft are timing out.

Fix your power supply or get a new SDR, one of those is likely the issue.

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I just changed both (powersupply and Flightaware Pro Stick) but result is still the same


what also looks strange is the daily total of tracked positions (right side about 50.000 a day) compared to the few positions displayed on the graph left side. In the beginning there where some 20.000 at the 2nd/3rd graph and now it less than 10.000 per column.

Did the message rate increase?
Your reception is still bad i’d be fairly certain.

Install the graphs and post them: https://github.com/wiedehopf/graphs1090#graphs1090

My bet is that some interference source has been added.
Or you broke your antenna coax or sth.

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Try a gain of 43.9, post another set of screenshots after a couple of hours or later.
For Beginners - How to Set / Change Gain

To be honest the message rate is bad even for the gain being too high.

I’d expect you have some strong interference and need a filter.
https://github.com/wiedehopf/adsb-wiki/wiki/Useful-items-for-purchase#filters-germany

Do I Need A Filter?

Honestly in such cases you basically try a filter and hope that i helps.

had made a mistake first with the 43.9. That’s why I deleted the post above.

Well, setting the 43.9dB at 16:00 these are the results

Grafik-3

So You still recommend a filter - or shall I start some frequency scans before?

leave it with this value for the next 24 hours.
With this low traffic at the evening it is a mission impossible to determine the correct gain settings.
Your first plot shows too much gain. After i got my new Jetvision antenna i needed to reduce it down to 40.2 which gave me the best value keeping an eye on the messages > 3dbFS (should be max 5%)

Now i am using a FA filter between antenna and blue FA stick.
Gain back to 49.6, but the messages > -3dbFS stayed below the “magic” 5%

But the low overall traffic makes it hard to determine if right or wrong.

This is the graph with the time i installed the filter. before that gain was at 40.2
Consider the small peak the same day in messages > -3dBFS
I had gain set to “-10” for a few hours, but it did not work, so i went down to 49.6 which seem to be fine now.

Looking at the ADSB Signal Level chart, the early part of the light blue line shows unusually high levels. This is the minimum signal level seen at the receiver. This implies to me a high level of background noise/ interference. That level could easily mess with the ADSB signals. When you reduced the gain, the minimum signal level reduced and the higher levels changed but into a more normal range. My FA receivers seem to have the light blue line around -24, my airspy receiver drops to about -30.

You may need a filter before the receiver as Foxhunter mentioned. Good idea to run a scan of signal levels to get an idea of what is affecting your reception. I ran one before buying my filter, and it showed heavy interference around the 900Mhz band. Have fun with it, always things to learn working with this stuff.

I was running a scan before and after the filter attached. i’ve documented this also in the long thread “Do i need a filter?” with lots of information in it.

You can see the areas of unwanted signal in the picture “without filter”.

image

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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.