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My range is incredibly small

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  • My range is incredibly small

    I've recently bought the BUNDLE ADS-B USB Dongle + "SCO-1090-MCX" Antenna (1090 MHz)(the one you can find on the Flightradar24 page in "Optional") and tried to install on the top of my roof, using the post of the TV antenna. What happened is really strange: I've first tried the antenna inside my house, just for test if it was working correctly and I got planes with a range of 30nm. Then I moved outside, on the roof and holding the antenna in my hand 2-3 meter distant from the post of TV antennas I was able to get planes in 50 nm range. When I placed the antenna in its final position (exactly parallel and adjacent the post) I got 0 planes. I was even unable to get an helicopter that was flying exactly over my house (FR24 found it). I think that the post (42 millimeter of diameter, iron) is in same way interfering in reception. On the post are installed 3 directional antennas (they looks likes Yagi Uda antennas) receiving frequencies around 700-800MHz.
    Do you know if the are technical problem in my installation? If so, how can I fix them?
    I've spent a lot of money on the antenna and i'm quite unhappy that I can receive only a few near planes. From range predictor of my installation I was expecting at least 200 nm of range.

    I'm a beginner with antennas, so I not really know what are best practice to make the antenna receiving best possible.

    PS: maybe there's a problem also from the raspberry side? I'm using an iPhone charger as power supply, inside was working correctly as I said, but maybe is not good for receiving all the signals.
    Another thing I was not sure in settings is the gain. I've no idea what the value represent, I've just setted "max"

  • #2
    (1) Using Phone charger for RPi almost always leads to problems. Use proper RPi power supply 2.5A or 3A

    (2) You may possibly have strong interfering signals from Mobile/Cell Phone towers, UHF TV etc.
    Test for interfering signals by method given here:

    Do I need a Filter? - Find RF Signals In Area

    .

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    • #3
      Changed the charger and moved the antenna 70 cm away from the post. This is the position now:
      IMG_7444.jpgIMG_7445.jpg
      The antenna is the vertical one.

      The situation is better, but what it improved most in range was change the gain setting in dump1090. I've run a test the tried many possible gain (found a script on FA forum) and I set it to the one with most position. Now I have a range of 130 nm, that's good, but according to heywhatsthat.com I can improve range (probably I can double it). So, do you have any particular advice in setting gain? Is auto gain usefull? I would be very happy if you also can give me a reference where I can learn what gain really is. I appreciate also technical ones.

      I've also run the test for the filter, and here are the results:
      scan.png
      scan.png

      I think I have strong interference from cell phones and TV, so I probably need a filter. I'm considering this options:Do you have any better suggestion? Is the filter with amplificator useful or is better to have just a filter?

      Thanks for your replies!

      PS: this is my actual situation. As you can see many planes are not reporting the position. Is the problem the interference again? Will the the filter solve it?
      Screenshot 2020-05-26 at 11.08.17.png
      Attached Files
      Last edited by arna; 2020-05-26, 10:02.

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      • #4
        You would have to look up the aircraft to see if they are modeS and no gps position on fr (playback won't be possible)

        Also look at the age column. That is time since last signal in sec. So they won't always show as they have dropped of signal. You can shorten that it make it show active only from memory
        Posts not to be taken as official support representation - Just a helpful uploader who tinkers

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