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  • Not picking up mode S

    Ive noticed that’s friend of mine who flies G-BEZC which has a mode S transponder isn’t showing any of his recent flights, so today he has a local flight specifically to check his transponder.
    He overflew my house and receiver T-EGPE30 and a friend of mines T-EGPE31 and no trace of his flight.
    As he overflew each reciver he checked with Inverness Radar that his mode S was transmitting correctly!
    At the same time he was airborne 2 other aircraft with mode S flew from Inverness, again no sign of those flights either
    Any ideas??

  • #2
    Where exactly did you check?

    The local map or on FR24?

    Do you know which Mode-S hex code his transponder has, you can check for that in the local map.

    Comment


    • #3
      Originally posted by wiedehopf View Post
      Where exactly did you check?

      The local map or on FR24?

      Do you know which Mode-S hex code his transponder has, you can check for that in the local map.
      Unsure what you mean by ‘local map’ checked by registration and mode S code on FRR24

      Comment


      • #4
        Originally posted by T-EGPE30 View Post
        Unsure what you mean by ‘local map’ checked by registration and mode S code on FRR24
        Local map = direct data from receiver.

        If it is modeS only. It probably flies too low to be picked up by MLAT.

        And if MLAT cant see it, neither can tracking/history
        Posts not to be taken as official support representation - Just a helpful uploader who tinkers

        Comment


        • #5
          Forgive me,as I’m mot technically minded
          My pi receiver is stand alone, and I view FR on iPad
          And the aircraft deliberately overflew 2 receivers .

          What more would a Aircraft need to be picked up as Mode S is UK requirement?

          Comment


          • #6
            If you have a receiver. Therefore you can use the inbuilt map/data to 'see' aircraft that we refer to. Independent of FR24s display.

            Other than that, the plane itself needs A GPS integration unit onboard to know where it is in the sky (and tell everyone else). Not all have this. Especially small aircraft.

            Or MLAT triangulation.
            Which needs to have contact with 4 receivers or more. + FR24 boxes to work it out.

            The world’s most popular flight tracker. Track planes in real-time on our flight tracker map and get up-to-date flight status & airport information.


            This also shows local contacts:
            Feel free to post/discuss suggestions here http://forum.flightradar24.com/threa...4840#post74840 (http://forum.flightradar24.com/threads/9875-Info-Updates-Ammendments-Placeholder?p=74840#post74840) This guide is not to be taken as officially sourced support information. It is contributor-made Information has been repeated many


            Web Page Configuration - (Fixing startup errors):
            This is the easiest way to check/re-configure the software when FR24feed core successfully running
            (to fix incorrect option errors entered/found on first run)

            --> http://localhost:8754 <--
            (replace localhost with the IP address of Rpi or PC running software)
            Feel free to post/discuss suggestions here http://forum.flightradar24.com/threa...4840#post74840 (http://forum.flightradar24.com/threads/9875-Info-Updates-Ammendments-Placeholder?p=74840#post74840) This guide is not to be taken as officially sourced support information. It is contributor-made Information has been repeated many

            Dump1090 Graphical Interface (View your aircraft radar contacts):
            FR24 installs Dump1090-Mutability 1.14 when 'DVBT' chosen with an inbuilt display map
            --net option is added to additional parameters, and you then visit http://localhost:8080 / http://localhost:8080/dump1090 / http://localhost/dump1090/gmap.html (or host IP) (may also need /gmap.html)
            A further port change option can be specified --net-http-port xxxx if other services run on 8080 already
            See Dump1090 documentation for further assistance
            Or you can add the IP to radarview https://flightradar24.com/radarview
            Last edited by Oblivian; 2019-02-17, 08:02.
            Posts not to be taken as official support representation - Just a helpful uploader who tinkers

            Comment


            • #7
              Originally posted by T-EGPE30 View Post
              F
              What more would a Aircraft need to be picked up as Mode S is UK requirement?
              As others have mentioned, a ground based radio receiving data on 1090 MHz.

              FR24 is a flight tracking service. It displays flights for aircraft that transmit positional data on 1090 MHz (ADS-B) and those whose positions it can estinate (using Multilateration "MLAT") for those not sending positional data, often referred to as "Mode-S". For MLAT one needs at least 3 or 4 receivers tracking the aircraft at the same time. As Oblivian has noted, this aircraft's flights may be too low to achieve MLAT, which is one reason why FR24 isn't displaying it.

              As mentioned earlier, a 1090 MHz receiver can be used with local software to display aircraft messages, including non-positional Mode-S. There are numerous options for listing local flights, depending on your setup.

              If you're new to 1090 MHz, maybe have a read of my What's Radarspotting? Guide.
              Mike


              www.radarspotting.com

              Radarspotting since 2005

              Comment


              • #8
                MODE S does not mean that the aircrafts transponder is transmitting the position. Normally only new aircrafts is transmitting the position. Not even all airliners is transmitting the position. BUT, if you fly at some altitude, AND the signal from the transponder is received by at least 4 receivers, then the position can be estimated more or less accurately by triangulation.

                If you check the local map from YOUR receiver, then you will probably see that the signal is received, but without a position.

                Comment


                • #9
                  If he really wants to be picked up by MLAT i would suggest flying at 7000 ft for 30 minutes, that should do the trick as more receivers will be able to see the plane at the same time.

                  There are some tracks of this plane in the FR24, for example:
                  The world’s most popular flight tracker. Track planes in real-time on our flight tracker map and get up-to-date flight status & airport information.


                  You can see it was only picked up at around 5000 ft, as higher up more receivers can see it and MLAT is possible.

                  What kind of receiver are you using?

                  If it is a Raspberry Pi, you can just put this in your browser:



                  Now you obviously need to replace the IP with the IP of your Raspberry pi.
                  Also the plane of your friend will not be visible on the map as again it has no position.
                  But it should be in the list on the right listed with altitude.


                  @Oblivian:
                  Radarview on FR24 won't help as it only adds planes with positions from your local receiver to the FR24 map. But as you don't have a positions for your friends plane that won't help.

                  Comment


                  • #10
                    I’m not technically minded

                    So some of the responses are simply gobbledygook to me !
                    I don’t use a computer or laptop, only an iPad
                    Raspberry pi is connected directly to router
                    So can I see local map on iPad ??

                    Comment


                    • #11
                      Yup

                      But you need to find the IP of your Pi, and put in ip/dump1090. (e.g. 192.168.0.71/dump1090)

                      Comment


                      • #12
                        In the U.K. most light aircraft have Mode S transponders, so what is required to pick up these transmissions at low level??

                        Comment


                        • #13
                          Originally posted by T-EGPE30 View Post
                          I’m not technically minded
                          So can I see local map on iPad ??
                          Originally posted by Talle View Post
                          Yup
                          But you need to find the IP of your Pi, and put in ip/dump1090. (e.g. 192.168.0.71/dump1090)

                          Install this App from iTunes on your iPad to find your RPi's IP
                          Its Android version is also available at Google Play. I use it on my Android Phone.
                          It is very handy to find local IP adresses on your router/LAN

                          ‎Fing has helped millions of users worldwide to understand: • Who's on my WiFi • Is someone stealing my WiFi and broadband? • Have I been hacked? Is my network secure? • Are there hidden cameras in the B&B I'm staying in? • Why has Netflix started buffering? • Is my internet provider giving me the sp…

                          Comment


                          • #14
                            Originally posted by T-EGPE30 View Post
                            I’m not technically minded

                            So some of the responses are simply gobbledygook to me !
                            I don’t use a computer or laptop, only an iPad
                            Raspberry pi is connected directly to router
                            So can I see local map on iPad ??
                            Just to reiterate and add to what has been posted, hopefully it will all make sense.

                            A 'Mode S' transponder on its own does not send ADS-B position information, it has to be of a type that can be coupled to a suitable and approved GPS installation.

                            Position information can be obtained from non-ADS-B transponders by what is effectively radio triangulation (MLAT) if the aircraft is in the coverage of at least three ground receivers capable of providing MLAT information. Not all ground receivers are capable of MLAT and if coverage is sparse, no positional information will be available for FR24 to display the aircraft.

                            Comment


                            • #15
                              Originally posted by T-EGPE30 View Post
                              In the U.K. most light aircraft have Mode S transponders, so what is required to pick up these transmissions at low level??
                              You Raspberry Pi is picking up the Mode S transponder transmissions just fine when your friend is flying overhead.
                              The transmissions don't include a position because it is Mode S only, not an ADS-B transponder.
                              (You can view those transmissions as described by others and me, but they might not be very interesting to you)

                              If you want a position for such transmissions, you can measure the time the transmission takes to arrive at multiple FR24 receivers.
                              This will produces at least a rough position, not very exact but enough.

                              But low flying aircraft are not picked up by enough receivers, so your friend would need to fly higher so a position can be calculated.

                              Or you need more receivers with good reception all around, at least 4 receivers have to see the aircraft for MLAT to work.
                              (MLAT = Multilateration, technical term for calculating the position when the aircraft isn't transmitting a position)

                              But for low flying aircraft those receivers would probably need to be mounted on different hills in the area you wish to cover.

                              Comment

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