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Thread: Few position reports ?!?

  1. #1
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    Few position reports ?!?

    Hi there,

    I have only feed FR24 for a few days. And the first day I had about 40k hits reported, and about 22,5k positions reported (a bit more than 50% positions reports vs. hits reports). Day two was a bit less than 50% position reports vs. hits reports. And it has become severely worse. Today I have about 29.1k positions reported, but only about 4000 positions reported ?!? My feeder is named T-ENNO9 if you want to look at the numbers.

    Is there any reason why there is so few position reports ? A friend of mine is living a few hundred meteres away. He has only a indoor antenna, and of course a lower range than me, and also fewer position reports (SIGNIFICANTLY fewer). But today he has more positions reported than me. Why ?

  2. #2
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    The server can pick and choose its sources if there are many with the same hits. And make the other drop them to save data overlap

    If you view the logs you see this as 'x ignored'

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  3. #3
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    That is not correct as far as i'm aware. Density of feeders should have no effect on the stats.

    You are looking at a very limited area of the sky and today is Sunday which means less traffic and maybe different flight patterns.
    For example there could be more planes flying that don't send a position. Thus hits would be more and positions would be less.

    Also just because the antenna is outdoors doesn't mean it has a good view of the sky. If you stand where the antenna is, if you couldn't see the airplane with your eyes you can probably not receive it as it needs a direct line of sight.

  4. #4
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    Different flight patterns etc. would affect all the receivers in the area in (more or less) the same way. But mine is the only one affected. Actually, my radar is the one (from all the ENNO receivers which have stats available) with the most "hits reported". But at the same time the one with the fewest "positions reported". And this has become progressively worse since I started feeding.

  5. #5
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    Positions reported are full adsb with GPS Enabled data. No t everything has one as pointed out. Most/modeS only are excluded from that.

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  6. #6
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    Quote Originally Posted by wiedehopf View Post
    That is not correct as far as i'm aware. Density of feeders should have no effect on the stats.
    The stats were meant to reflect what the clients range etc is too. But we all know how accurate and similar to local data that can be....


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  7. #7
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    Skjermbilde 2019-01-27 kl. 23.16.20.jpg

    The position is 18.5S old in this screenshot, but the aircraft says "hello" every second.

  8. #8
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    Quote Originally Posted by Talle View Post
    Skjermbilde 2019-01-27 kl. 23.16.20.jpg

    The position is 18.5S old in this screenshot, but the aircraft says "hello" every second.
    Looking at those tracks You have some really big gaps in full message cover. That tells us possibly despite you getting messages, the secondary position ones aren't being fully decoded or received.

    They could be full of noise, or just plain out of range and not complete.

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    Last edited by Oblivian; 2019-01-27 at 22:33.
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  9. #9
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    And I've not seen a report to say otherwise since. But since the new uploader is capable of analysis due to keeping the 'quality' of data fr24 strive for we discovered there appears to be some unpublished/unspoken/unknown bundling of data before send.

    This likely has thresholds as to how long a contact has been lost/last heard from. And when to ignore it if not producing data within these thresholds

    So although locally you can see data, it may never be reflected after the capture and upload.

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  10. #10
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    I'm not sure what "hits" are on flightradar24 to be honest. Maybe you have a lot of noise that is wrongly decoded as preambles but the messages are garbage.

    What kind of setup of antenna / dongle are you using?
    (If you have a lot of noise and in general to improve reception a specialized LNA is very good: https://www.rtl-sdr.com/new-product-...mhz-ads-b-lna/ )

    Are you above the trees or hills of the area?

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