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  • Changed antenna, zero aircraft tracked...

    Hi to all,
    this is my first post so nice to meet you.
    I'm asking help because something strange is happening with my new coaxial antenna...
    I've a raspberry 3 (maybe 2b I don't remember) with R820T dongle... whit default antenna that came with dongle all it's working fine, more ore less 60 nm of bearing.
    I've built a collinear antenna with coaxial cable (12 segments), the antenna is ok, no short circuits, but.... when I attach the new antenna to the dongle the FR24 Feeder Status page drops to ZERO aircraft.
    The weid thing is that if i connect the dongle to my Samsung smartphone and I run AVARE ADSB app I can see a lot of aircrafts ! The message rate showed on AVARE is more or less 12 message per second...
    So, if I connect the dongle to Raspberry.. zero aircraft... if I connect same dongle with same antenna to smartphone a lot of traffic on AVARE ADSB.... why ?

    my configuration :
    • raspberry with FR24 software
    • R820t dongle with usb extender cable of 1mt
    • mcx to BNC pigtail cable
    • BNC to F cable to the roof (2 mt of cable)
    • F-female to F-female adapter
    • Collinear coaxial antenna made of 12 segments terminated with F-male connector.
    • Cable used : SAT 703B 75Ohm loss : 1000Mhz : 18,50Db/100m
    • Pole installed on the top of the building, 1mt of space from TV Antenna at the same height


    I've checked all the cables, no short circuits at all, all the solders are ok.
    Can you help me please ?
    Thanks to all !

  • #2
    try reducing gain to 40, then 35 and then 30. At each gain setting, watch for some time how it performs.

    To change gain setting, go to page ip-of-pi:8754/settings.html as shown in attached screenshot below

    2017-12-30-17:24:38.png
    Last edited by abcd567; 2017-12-30, 22:44.

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    • #3
      Thanks a lot abcd567, I'll try with that parameters and I'll let you know.
      Thanks again

      Comment


      • #4
        After adding/changing gain, do not forget to click the "Save" button, then "Restart" button. Both these buttons are at bottom-right corner of settings page.

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        • #5
          Hi abcd567, I've added "--gain -10" option (to try autogain) as you suggested and the aircrafts tracked list is raised up to 30 aircrafts !!!
          The bearing is medium, 90nm more ore less but let'see next hours if it increments.
          Thanks again, i'll try other values of gain an let see what happens !
          Happy new year !

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          • #6
            Happy New Year

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            • #7
              I've changed my antenna again, now I'm trying an homemade dipole with SAT Cable and the aircrafts tracked list is raised up to 50/60 aircrafts !!!
              Now I've bought a collinear antenna in ebay, when it will arrive I'll make another try.

              Comment


              • #8
                Originally posted by JackTorrance View Post
                I've changed my antenna again, now I'm trying an homemade dipole
                Try also these two homemade antennas:
                "Cantenna" and "Quick Spider".
                Simple, easy to make, and perform good.

                EASY ANTENNA #2 : CANTENNA

                EASY ANTENNA # 3 : QUICK SPIDER

                Comment


                • #9
                  Originally posted by abcd567 View Post
                  Try also these two homemade antennas:
                  "Cantenna" and "Quick Spider".
                  Simple, easy to make, and perform good.
                  Thanks a lot abcd567, I'll try these too

                  Comment


                  • #10
                    Originally posted by JackTorrance View Post
                    Thanks a lot abcd567, I'll try these too
                    Hey JackT I think you will find the 'quick spider' hard to beat - just get it high and in the clear (good waterproofing) and you won't need the coax colinear...I hate those things.

                    Steve

                    Comment


                    • #11
                      Wow ! Great improvment with 'quick spider' !
                      Aircrafts number has increased by 20-25% and range is almost doubled (170nm vs 80nm) and is very similar to maximum theorical range generated by heywhatsthat!
                      Thanks a lot !

                      20180104_103935.jpg
                      20180104_103939.jpg
                      Immagine.jpg
                      Immagine2.jpg
                      Immagine3.jpg

                      Last try that I'll do will be with the collinear bought on ebay (gain 5Db) and I'll publish results here.
                      Thanks again !!!
                      Last edited by JackTorrance; 2018-01-05, 14:02.

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                      • #12
                        Originally posted by JackTorrance View Post
                        Wow ! Great improvment with 'quick spider' !
                        Nicely and neatly built "Quick Spider". You are very crafty.

                        Now try Cantenna also.

                        .
                        Last edited by abcd567; 2018-01-05, 20:31.

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