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  • Different ADSB-S modes

    Hi

    In the map of flightradar24.com I saw now several times a/c with coordinates which seems to be feeded by a scanner.

    Example here:

    But on my scanner with dump1900.exe the coordinates are not displayed.

    See here:

    Any explanation for this?

    Thanks.
    Attached Files
    Best regards,
    Rod

  • #2
    Is that your radar code on img #1?

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    • #3
      I found T-LSZH76 closs feeding MLAT data of somewhere to FR24.
      It looks same problem of closs fed FR24 and FA

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      • #4
        Originally posted by Amper View Post
        Is that your radar code on img #1?
        No, I have an other one and not in the region of Zürich.
        Best regards,
        Rod

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        • #5
          Originally posted by John-h View Post
          I found T-LSZH76 closs feeding MLAT data of somewhere to FR24.
          It looks same problem of closs fed FR24 and FA
          I don't really understand. So the display of the coordinates of the a/c in example 1 is MLAT and not ADSB-S mode reception?
          Best regards,
          Rod

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          • #6
            so img #2 is your radar?
            Radar on img#1 or more radars got full info incl. a/c position. Your radar didn't. Signal level on your radar is low.
            What is the issue?
            Last edited by Amper; 2016-02-29, 08:24.
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            • #7
              Originally posted by Amper View Post
              so img #2 is your radar?
              Radar on img#1 or more radars got full info incl. a/c position. Your radar didn't. Signal level on your radar is low.
              What is the issue?
              When radar "is low" - Hex, Sqwk, Flight, Altitude are received - but coordinates, spd, hdg not? Any explanation for that?
              Best regards,
              Rod

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              • #8
                Could be a typical example of an MLAT leaker (i.e leaking MLAT derived data from some other source such as flightaware) but as Amper mentioned, a low signal level will often not pickup coordinates so your example in the dump1090 image is not good evidence for an MLAT leaker.
                Last edited by Sam26K; 2016-02-29, 08:39. Reason: clarified img

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                • #9
                  Yes, info is incomplete. That's the reason why fr24 is using more then one receiver in same area and waiting for 2 or more radars with same info about same plane.

                  Originally posted by Sam26K View Post
                  Could be a typical example of an MLAT leaker (i.e leaking MLAT derived data from some other source such as flightaware) but as Amper mentioned, a low signal level will often not pickup coordinates so your example in the dump1090 image is not good evidence for an MLAT leaker.
                  as I can see G-OPEG is ads-b equiped.

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                  Last edited by Amper; 2016-02-29, 08:46.
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                  • #10
                    The easiest way I know of tracking MLAT leakers in your area is to use Virtual Radar Server to connect to your dump1090 feed. It becomes quite clear who they are.

                    Edit: Amper, the tail number in the previous image is G-OPEM but still the OP has not provided enough info yet. Not even a radar feeder id.
                    Last edited by Sam26K; 2016-02-29, 09:00.

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                    • #11
                      Ok, I will continue to watch it on - and yes - a better antenna would be great ;-)
                      Best regards,
                      Rod

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                      • #12
                        Just filter with radar code on your FR24 PC version, you will see a/c tracked by T-LSZH76.
                        Watch for a while, then tracked radar code of this a/c will transit from T-LSZH76 to "T-MLAT"... not another T-LSxx radar.

                        I think it is enough evidence for cross feed problem

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                        • #13
                          If you want to spot the mlat leakers in your area, the easiest tool is VRS:
                          http://www.virtualradarserver.co.uk/
                          It gives you a map and a list of all aircraft in the area that you are receiving. ADS-B or not. It's easy to spot the MLAT leakers using VRS.

                          But still, Rod is not posting enough info to say what is going on so far.
                          Last edited by Sam26K; 2016-02-29, 09:52. Reason: qualification

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                          • #14
                            Originally posted by Sam26K View Post
                            But still, Rod is not posting enough info to say what is going on so far.
                            You don't need to wait report from Rod.
                            Just watch a/c tracked by T-LSZH76 your own.

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                            • #15
                              Originally posted by John-h View Post
                              You don't need to wait report from Rod.
                              Just watch a/c tracked by T-LSZH76 your own.
                              You are probably right but hard evidence should be made available with such accusations. Here is my hard evidence of my local worst MLAT leakers KSJC12 and KSJC18. They are the source of phantom aircraft and tracked many times returning full ADS-B info from mode s only transponders. They are known MLAT leaks and tracked them with VRS many times with aircraft that were directly overhead. They mess up the feed for everyone in the San Francisco Bay area because of the false and conflicting phantom returns as shown in the screen shots.
                              Attached Files

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