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  • #16
    I'm afraid I don't know how to get to the "config file/web page", unless you are talking about this page:


    feeder.JPG

    In the process arguments line, I have the gain set to -10. If I change it to -43, the "FR24 MLAT AC seen:" line goes to "FAILED" in the fr24feed-status display. And, where is the "gain optimiser" located?

    I apologize, I'm just not sure how to get to certain files/features yet.

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    • #17
      It's probably crashing dump1090

      I couldn't remember if it's a negative number or positive, it seems it should be a positive

      This is a starting point to get you on your way

      https://forum.flightradar24.com/foru...adjustment-wip

      The optimizer requires you to replace the decoder. So I probably shouldn't have suggested that

      https://github.com/wiedehopf/adsb-sc...or-dump1090-fa
      Posts not to be taken as official support representation - Just a helpful uploader who tinkers

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      • #18
        ABOUT GAIN
        • Gain should always be a positive number (except -10).
        • Using a negetive number (except -10) sets the gain to ZERO.
        • Gain's permissible values are from 0 to 49.6
        • Gain="max" sets gain to maximum i.e. 49.6 dB
        • Gain -10 is a special setting. It does NOT set gain to -10. It switches dongle to AGC (Automatic Gain Control) mode. The dongle is designed for TV reception. The TV signal at any channel is fairly constant, hence AGC works as intended. However since ADS-B signal is intermittent bursts, the AGC setting malfuntions and sets the gain to more than max (49.6). It normally sets gain to 52~55 dB.

        Last edited by abcd567; 2020-10-09, 05:41.

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        • #19
          Thanks Gentlemen! I successfully made the gain adjustments you recommended in the config file and didn't see much range improvement. The gain setting in the file was originally set at "max". I did remove dump1090-mutability and installed dump1090-fa and made the gain adjustment there (49 dB) but still had pretty much the same range results. Something has changed, but maybe this is as good as it gets for now!

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          • #20
            Do you have LNA with Bias T by any chance in your setup? If so, check if you still have power at LNA.

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            • #21
              Hello,

              I'm feeding data to FR24 using a Raspberyy PI3B+ + FlightAware ProStick Plus + A3 ADS antenna from Jetvision (5 dBi). Recently, I configured a second receiver, this time with the configuration Raspberry PI4 + FlightAware ProStick Plus + Small Indoor Antenna (2.5 dBi, I guess), in order to place it in other location than the first one. Each receiver is currently configured for its intended location, meaning different coordinates and elevation in the settings.

              Before moving the second receiver to its intended location, I decided to make some tests and observe the range of each one when they are placed in the same location. Of course, the polar plots of the antennas are different, as it can be seen in the pictures below. The large 5dBi antenna helps me reach maximum ranges of 240-270 nm in 5 directions, while with the small indoor antenna, placed in the same spot, I obtain 330 to 349 nm, but only in 3 directions (the rest are zero). However, when I change the antennas between them, the current range doesn't seem to change for any of the receivers (normally, I would expect for the first receiver to go over 300 nm for the maximum range, and for the second receiver to have a wider polar plot, with extended range for west and east).

              And my question is: why does this happen? It has something to do with the different location settings?

              Thank you in advance for an answer!

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              • #22
                Originally posted by ionut-florian View Post
                Hello,

                And my question is: why does this happen? It has something to do with the different location settings?
                YES.
                In the 2nd Pi, change the coordinates from those of "other location" to the coordinates of location where you are testing the Pi, and this discrepancy will disappear.

                When you move the Pi to other location, then only set the coordinates of that location.

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                • #23
                  Originally posted by abcd567 View Post

                  YES.
                  In the 2nd Pi, change the coordinates from those of "other location" to the coordinates of location where you are testing the Pi, and this discrepancy will disappear.

                  When you move the Pi to other location, then only set the coordinates of that location.
                  Thank you for the answer.

                  As I know, there are several ways to change the coordinates. One is using the statistics page of the feeder from FR24 site, another one is when activating the feeder using STEP 6 from your tutorial (2019 - PI24 (Image) QuickStart Guide) and the last one is also from you tutorials by using the command sudo systemctl restart dump1090-mutability and editing the coordinates from the file.

                  Which one should work in order to see changes in the polar plots of the 2nd Pi?

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                  • #24
                    The first one.

                    The others are local map view only and have no effect on fr24
                    Posts not to be taken as official support representation - Just a helpful uploader who tinkers

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                    • #25
                      As already advised by Oblivian, change coordinates using the statistics page of the feeder from FR24 site.

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                      • #26
                        Hello, again,

                        I tried what you said in the previous messages and it worked, so thank you for that. The wrong location settings affect the range shown and switching the antennas between them won't change anything but the range of each receiver. Also I guess that it is better to make an upgrade of the small indoor antenna to improve the range, along with some tweaking.

                        In this regard I installed wiedehopf's tutorial for the performange graphs to see more data. The > -3dBFS messages are around 3% (+/- 0.3, depending on the time of day). I guess this is OK as I read on other threads that this value shall be between 1 and 5%.


                        Another parameter which I guess it shall be improved is the ADS-B signal level. As it can be seen from the image below, I'm getting the weakest signal at -28 dBFS. As I also studied other threads, the value seems too low. Currently, the gain is set to "max". Is there any room for range improvement by changing gain? It won't affect the > -3dBFS value?

                        And finally, one last thing. After installing performance graphs, I noticed that the ADS-B range graphs is not working. I added the location coordinates using command sudo systemctl restart dump1090-mutability, but nothing happens. Is this due to the fact that I am running something else than dump1090-fa? On my SD card I have installed pi24 image (version 2.2.0) and the dump1090-mutability is 1.15~20180310.4a16df3+dfsg-6 (checked with command apt-cache policy dump1090-mutability).

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