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Thread: Aircraft nearby feeding distant antennas, not mine.

  1. #11
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    I don't understand the logic here... xxxx1 may be the first but it could be bad and xxxx67 could be better in accuracy, range and latency.
    Please explain again
    Most airports only have one or two feeders, so statistically you see F-xxxx1 way more often than F-xxxx3 or F-xxxx21.

  2. #12
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    And I got no idea why this wont open the 2nd page of replies...

    /edit there it goes!
    Posts not to be taken as official support representation - Just a helpful uploader who tinkers

  3. #13
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    We have more than 49 currently active feeder around Amsterdam. It's a bit "stupid" to use only one and stick to it for a long time

  4. #14
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    the F-xxxx are a fr supplied feeder they aren't going to put more than one in the same area. everyone else gets a T-xxxx number

    USB has latency (buffers etc.) and this causes little time delays, even if you put GPS on you pi and use that you will still have that delay. Example dongle receives a signal sends it to the USB port, the pi is busy doing something (just running itself even) then takes the data from the USB and processes it. The delay comes from how long it takes to get the data from the dongle to fr24 software and the problem is this time delay changes constantly.

    FR boxes use a FPGA to receive and process the data. This FPGA time stamps the received data when it arrives down to the micro second so any delays in the system after that don't matter because you know exactly when the data arrived and can process that accordingly you will never be able to that on a PI as things stand now.

    hope that helps a bit
    Last edited by SpaxmoidJAm; 2016-01-23 at 09:04.
    T-EGLF8

  5. #15
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    How can usb latency be important when the internet connections add a huge lot more (in comparison ofc) latency to it...

    Whatever the explanation is, i can underdtand F- have priority but as you say its only one...
    Are you now saying that all other feeders are doing this for nothing ? Is that the message ?

  6. #16
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    Quote Originally Posted by acid-drop View Post
    How can usb latency be important when the internet connections add a huge lot more (in comparison ofc) latency to it...

    Whatever the explanation is, i can underdtand F- have priority but as you say its only one...
    Are you now saying that all other feeders are doing this for nothing ? Is that the message ?
    I've been wondering this question being new and I sort of understand it now...

    but I do have to agree with this. Why am I doing this? What is the point of me having my SDR feed to fr24 when I got all these other F- boxes feeding "more accurate" data?

  7. #17
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    Because it saves you a premium subscription and ensures no dead spots and enhanced accuracy?
    Posts not to be taken as official support representation - Just a helpful uploader who tinkers

  8. #18
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    If I may add my two-cents worth.

    Don't always rely on your radar code to see aircraft. I have my Radar Code filtered on the Live Flight Tracker - no other aircraft are displayed (main FR24 map). I can easily track in excess of 130 aircraft simultaneously in a busy traffic period. However, some days, I don't see a single aircraft on the FR24 map. Then other days, I can have as many as 8 aircraft displayed at the same time on the FR24 map. Some lasting a few seconds, others lasting a couple of minutes. I have a "T" code, which is for the Dongle.

    The best way to see what aircraft you are tracking, is to either use your dump1090 map (with or without VRS) or the RadarView facility within FR24.

    Remember, we are all here because we share a mutual interest in Flight Tracking.

    There are other Flight Tracker sites out there but the quality of maps and what you can do with them, is no comparison to what you can do with FR24 Map and smartphone apps :-D
    T-EGBB16

    Hardware: NooElec DVB-T2 Dongle, Raspi Pi2 Mod B, 6dB Collinear Antenna, Nevis Pre-Amp & 1090mhz SAW Filter, 9mtrs WF100 Cable and 28ft Mast.
    Software: Rasbain Jessie Lite, FR24 Feeder, Dump1090mutab and VRS.
    Stats for Mar 18, 2016. Uptime:100%. Aircraft seen:2,012. Positions Reported:486,817. Maximum Distance:243nm (Stats provided by FR24)

  9. #19
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    Quote Originally Posted by acid-drop View Post
    How can usb latency be important when the internet connections add a huge lot more (in comparison ofc) latency to it...

    Whatever the explanation is, i can underdtand F- have priority but as you say its only one...
    Are you now saying that all other feeders are doing this for nothing ? Is that the message ?
    because once the data is processed locally it has a time stamp so it could take an hour to get to fr24 (pointless data at that point) the server will know that data happened then and not now.

    as pointed out by others all the data is used, multiple sources of data have a redundancy effect and is useful for validation,

    lets say your near a couple of other sites but you fill a a hole they cant see, the chances are your data will be used but the website might not show it.
    Last edited by SpaxmoidJAm; 2016-01-30 at 14:21.
    T-EGLF8

  10. #20
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    My personal experience with this in my area is that 2 or 3 T- radar tags dominate most of the traffic. Only about 1/3 to 1/10 of the traffic in my area is broadcasting a full ADS-B tag with position info and yet these T- radar tags are returning fully tagged position data within about a 300 nm radius.

    The 2 or 3 T- tags in my area that dominate most of the traffic must be deriving their position info from other MLAT sources and it causes legitimate MLAT sources from FR24 MLAT feeders to be flooded out. Below is a screen shot of the worst one in my area I just grabbed now.

    There are a lot of FR24 installed receivers in the bay area and if not flooded out with bogus MLAT T-feeders, should be able to handle the MLAT data just fine.
    Attached Images Attached Images
    Last edited by Sam26K; 2016-01-31 at 03:04.

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