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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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        • #5
          I've checked FR24 as you said. Planes with no position are tracked with MLAT in FR24, so I think that is not a problem of reception. Thanks for your reply.

          Any advice for the filter? Which one of the two I found is better?
          As additional information I can say that I have a lot of traffic (helicopters, small planes, but also big planes from the near MXP airport) over my house

          I have set the gain to agc and now I'm quite happy about the tracking results. I hope that the filter will do the rest

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          • #6
            You misunderstood

            Adsb+gps equipped send 2 types of messages.

            Airborne height/id
            Airborne position

            Fr24 tracks non GPS with mlat, yes. But you dont get the results to know. Only the website shows them after the server does calculation.

            And if your receiver isn't sending non mlat packet, +2 reference gps packets per upload. Or is missing some

            All your data will be being ignored as it can't help with calculation
            Posts not to be taken as official support representation - Just a helpful uploader who tinkers

            Comment


            • #7
              Originally posted by arna View Post
              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?


              Do NOT buy Flaghtaware Light Blue Filter you have linked. It will NOT remove 960 MHz interference, lot of which you have.

              Buy the Flightaware Dark Blue Filter. It will remove the 960 MHz interference also.

              Using a Filtered LNA (like Uptronics you have linked) is much better than just adding a Filter only.
              Last edited by abcd567; 2020-06-07, 05:04.

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              • #8
                Hello,

                Your prevoous posts are very interesting.

                I live at the highest level of a building, the 5th floor. I am using an Raspberry Pi with ADSB Dongle and its small indoor antenna.
                Previously, i've installed this material using a chest outside and get a range of around 120nm.

                Some days ago, I bought a "A3 1090 Antenna + 10m Cable + SMA/MCX Pigtail" package to connect to my ADSB Dongle and installed the antenna on the roof :


                IMG_5652.jpg
                Since the range felt down to 16nm

                So, i've read your posts and generate a scan :

                scan.png

                zoom.jpg
                Yellow part are from 800 to 822MHz and from 920 to 962 MHz.

                Can you please tell me which filter I had to buy ?

                Thank you !

                Xavier

                Comment


                • #9

                  ​Xavier:​​​​​​

                  You have GSM900 Cell/Mobile phone interference. Buy the Flightaware Dark Blue Filter. It will remove the 960 MHz interference also.

                  Using a Filtered LNA like Uptronics is much better than just adding a Filter only. However if you add an amlifier (LNA), you may need to reduce gain setting of the dongle.
                  Last edited by abcd567; 2020-06-20, 15:54.

                  Comment


                  • #10
                    Hello abcd567,

                    Thank you for your anwer.

                    Must I understand the Flightaware Dark Blue filter is mandatory but it's better to add ALSO a Filtered LNA like Uptronic ? (not instead of but also)
                    Another question ; In both case :
                    - Flightaware Dark Blue Filter
                    - Flightaware Dark Blue Filter + Filtered LNA

                    ShouId plan to buy any connector/converter to connect those hardware to the actual solution ?

                    IMG_5654.jpg

                    Thank's again !

                    Xavier
                    Last edited by Xavier; 2020-06-20, 17:47.

                    Comment


                    • #11

                      Xavier:

                      Normally if you add Filtered LNA (like Uptronics one), then you will not need to add an extra filter. However in some cases where the Cell phone tower is very close and GSM900 interference is very strong, an additional filter like Flightaware dark blue may be required.

                      Another option is to purchase Flightaware dongle (ProStick Plus, blue colored) or Radarbox dongle (FlightStick, green colored). Both these have built-in amplifier (LNA) chip and filter (SAW) chips. However in case of very close Cell/Mobile tower and strong GSM900, an additional filter (Flightaware Dark Blue) may be required.

                      Do not go for additional Dark Blue filter at the start.
                      As first step, purchase any one of the following and try.
                      • Uptronics Filtered Amplifier (LNA)
                      • Flightaware ProStick Plus (Blue colored)
                      • Radarbox24 FlightStick (green colored)

                      If these do not solve your problem, and your RF Scan is still showing strong GSM900 with these dongles, then add the Flightaware Dark Blue filter.

                      Next step is to adjust gain to a point where you get best reception. This is done by trial-and-error.
                      Last edited by abcd567; 2020-06-20, 20:02.

                      Comment


                      • #12
                        Hello abcd567,

                        Thank you for your kind advises. I started to add a Fligthaware Dark Blue Filter and now my maximum distance goes up to 209nm. Do you think a Uptronic Filtered Amplifier could do better ?

                        Regards,

                        Xavier

                        Originally posted by abcd567 View Post
                        ​Xavier:​​​​​​

                        You have GSM900 Cell/Mobile phone interference. Buy the Flightaware Dark Blue Filter. It will remove the 960 MHz interference also.

                        Using a Filtered LNA like Uptronics is much better than just adding a Filter only. However if you add an amlifier (LNA), you may need to reduce gain setting of the dongle.

                        Comment


                        • #13
                          I've just ordered the Uptronics filter. I hope it will improves my performance!

                          What do you think about AGC mode? I've been using it for last 4 weeks and I got good result, but I'm wondering if i can get better result using a proper manual set of gain. Let me know

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                          • #14
                            Without a LNA (internal to dongle or external), in most cases best setting of gain is -10 (minus ten). Please note thst other than minus ten, any negetive value of gain like -42 or -49.6 etc will set gain to ZERO.

                            The minus ten is a special setting, and is same as AGC, and works as intended for TV signals (for which the dongle is designed). However due to nature of adsb signals, which are large number of short packets from large number of aircrafts, the AGC or -10 locks the gain at about 55. Since by numerically setting gain above max 49.6 sets gain only at 49.6, the -10 is a valuable tool to add about 5 dB gain, and acts as if a 5dB LNA has been added. It is good for setups which dont have any internal or external LNA
                            Last edited by abcd567; 2020-06-28, 11:46.

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