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  • Antenna on roof, what cable to use?

    Since a few weeks I'm feeding a couple of sites with ADS-B data.
    I use a Raspberry Pi with DVB-T dongle and stock antenna (didn't even trim the top part off), placed on the second floor behind a window.
    Awesome to see aircraft on your own personal radar and enjoying the joy that are subscriptions from the various sites.

    However, as most men do; they want to do it better. So I'm think about placing a antenna on the roof, either DIY with some coax-cable or something from Ebay (Ebay seller stanislavpalo130 has an interesting one). But the problem is; I have 2 options to do this:

    1) Put everything on the roof. Raspberry, dongle and antenna. This needs to put in a waterproof box along some DC-DC converter, POE-cables (those cheap ones from Ebay).
    Al this connected with one single ethernetcable to inside.

    2) Place a little as possible on the roof. This means only the antenna and dongle. Placing a active USB-cable between dongle and Raspberry Pi.
    This would nog only be cheaper but more importantly, much more convenient since you can still reach the Raspberry Pi.

    Either cable (ethernet or active USB) needs to be about 10-15 meters in length and feed between a windows and window frame. Normal ethernetcable doesn't fit so I would use flat ethernet cable.
    A USB cable will probably fit; if not; I could use a very short length of flat USB-cable.

    My questions is; would you guys think this would work? Placing the Raspberry inside, get 10 or 15 meters of active USB-cable outside and connect that to the dongle?
    My understanding is the usual (blue/black) dongle won't work (because of voltage drop) but the tiny small one do (has the SGM2019 voltage regulator).
    Because it this works it would be much more practical.

    (Unfortunately I can't post the said links because this is my first post here)

  • #2
    No one has an (clever) idea for this situation?

    Coaxial cable, powered USB-cable, everything in a waterproof box on the roof?

    Comment


    • #3
      If the cable run from antenna to indoor location of RPi is 15 meters or less, then only thing need to be outdoor is the antenna. Run a 15 m coax from antenna to indoor location, and place everything at down end of coax. All equipment indoor, at easily accessable location.

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      • #4
        I have the normal RTL 820T2 dongles on the roof in a waterproof box with a 10M active USB cable going from outside to back into the roof. It works fine and reduces cable length from antenna to USB.

        I have a 20M active USB cable to which i recollect that I have tested it and it worked but am not 100% sure. The main point is having active USB cables to do the run.

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        • #5
          @nzfatmatt
          Both options (equipment indoor + coax from antenna to indoor) and (equipment outdoor in a box + active usb cable to indoors) are successful solutions. It depends on individual's choice which system to use.

          The coax system has an advantage over active usb that all equipment is indoor in an easy accessable location, instead of climbing to the roof to access the equipment when needed. This is particularly useful in bad weather conditions. Imagine your dongle fails during winter when there is heavy snow.

          However, for cable runs longer than about 15 to 20 meters, an amplifier is required due to attenuation of coax. This not a difficult or costly solution.
          Last edited by abcd567; 2016-06-04, 23:34.

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          • #6
            Originally posted by abcd567 View Post
            @nzfatmatt
            Both options (equipment indoor + coax from antenna to indoor) and (equipment outdoor in a box + active usb cable to indoors) are successful solutions. It depends on individual's choice which system to use.

            The coax system has an advantage over active usb that all equipment is indoor in an easy accessable location, instead of climbing to the roof to access the equipment when needed. This is particularly useful in bad weather conditions. Imagine your dongle fails during winter when there is heavy snow.

            However, for cable runs longer than about 15 to 20 meters, an amplifier is required due to attenuation of coax. This not a difficult or costly solution.
            There are advantages and disadvantages to both. I was just saying the active USB does work with powering the dongle. Snows not a problem for me. Constant wind and wet roof in winter are. Haven't had USB dongle problems, mainly have problems with antenna's been blown around which requires going on the roof anyway.

            Comment


            • #7
              Thanks for the comments.

              I asked somewhere else and they had negative experiences with an active USB-cable of this length (15m); it just didn't work reliably.
              No results yet with a powered USB-hub inbetween the Raspberry and the RTL-dongle which may give it better results but I doubt it.
              The smaller mini dongles are supposed to work better because of different voltage regulator. But still very questionable if that would work.
              (I can't post a link to those since I'm new here)

              Running a coaxial cable from inside (with a short thinner cable going between the window and the windows frame) looks like great idea but a recommended cable (RG213) cost about 60.
              I could pack everything in a waterproof box and run data/power over a ethernetcable for much less and results will be the same, probably even better.

              So at this moment; I think I will keep the current setup for now...

              Comment


              • #8
                @Iemand91
                1) How much is the total distance from your antenna to the indoor location of your computer (Desktop or RPi) in which dvb-t dongle will be plugged-in (directly or through active usb)? This total distance is the key factor to decide what setup is best.

                2) Some examples of Flat Coax pieces to pass under window/door. Rest can be normal RG6 coax

                Flat coax Eagle Aspen s-l500.jpg . Flat coax Holland s-l500.jpg . Flat coax s-l1600.jpg

                Comment


                • #9
                  I hit quick reply and now I'm waiting for several hours for my comment to show up...
                  Maybe this WILL work.

                  Originally posted by abcd567 View Post
                  @Iemand91
                  1) How much is the total distance from your antenna to the indoor location of your computer (Desktop or RPi) in which dvb-t dongle will be plugged-in (directly or through active usb)? This total distance is the key factor to decide what setup is best.
                  I rougly calculated that the total distance between the antenna and the Raspberry Pi is about 11 meters. I used 15 meters before because most cables are either 10 or 15 meters and 10 meters might just be to short.
                  2) Some examples of Flat Coax pieces to pass under window/door. Rest can be normal RG6 coax

                  [ATTACH=CONFIG]7586[/ATTACH] . [ATTACH=CONFIG]7587[/ATTACH] . [ATTACH=CONFIG]7588[/ATTACH]
                  I knew about those flat coax pieces. Pretty cool stuff.

                  If I could use RG6 for the 'long run' of about 10-12 meters that would certainly be an option. RG6 cost about 1 p/meter instead of at least double or triple of that for RG213, if I can find RG213 at all here.
                  But can RG6 really be used for that? I read so many different comments/opinions on the web about this.

                  And then there's the Impedance; 50 and 75 ohm. RG213 is 50ohm, RG6 is 75ohm. Apparently you can't use them together; so if I would make or buy a new antenna I should take this into account.

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                  • #10
                    Don't forget about lightening suppression.. You need to ground to the same ground plane directly to the lightening rod of the house. Big no no for insurance if this gets hit and isn't properly grounded

                    Sent from my Oneplus 2

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                    • #11
                      I'm more active on a different forum but I do want to show the people here who helped me to show some results.
                      You can see them on the Show / Describe your FR24 hardware thread.

                      (This is also a filler post to allow me to post links...)

                      Comment


                      • #12
                        Ive already advised people... Do not use @ symbols like this is twitter. Use the quote facility

                        The anti spam measures think you are posting advertising emails. This includes quoting other people using @
                        Posts not to be taken as official support representation - Just a helpful uploader who tinkers

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