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New to this a few questions re. data

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  • #16
    Filters, amplifiers, better coax, the usual candidates.

    https://github.com/wiedehopf/adsb-wi...ivers--dongles

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    • #17
      First determine your limitations, which will serve as benchmark when attempting to improve performance:

      (1) What is the Maximum Range I can Get?


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

      .

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      • #18
        I have followed step (1) above and this is the result I got. Have I dome something wrong here because this range seems ludicrous.

        I have followed step (2) above and this is the result I got. It seems very quiet around the 1090 band.

        Oh this basis I don't think I need a LNA or an active antenna. Any suggestions to the contrary?

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        • #19
          Aerial location : Liverpool UK (latitude/longitude 53.41, -2.99)
          Aerial height above ground: 30 feet
          Yellow curve: 10,000 feet
          Blue curve: 40,000 feet

          Liverpool - aerial 30 ft above ground.jpg

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          • #20
            It was right, then. So – if I am correct – I should be able to vastly increase both my range and tracked planes by getting a better antenna and repositioning it on my roof, and I need not necessarily get an active one?

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            • #21
              EGSM-950 there is mobile signal. You need a filter to remove it

              EGSM-950.png
              Last edited by abcd567; 2019-10-01, 20:41.

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              • #22
                Invalid attachment.

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                • #23
                  If you don't get an amplifier close to the antenna, you want expensive cable (LMR400 or MPD400).
                  Up to 5 m i'd say, H155 or LMR240 is ok as well.

                  What antenna are you using anyway?

                  Anyway before you change all that, buy the green stick from here: https://www.radarbox24.com/store

                  Or the prostick plus: https://www.moonraker.eu/adsb-receiver-5504
                  For that i'd consider also getting the filter: https://www.moonraker.eu/adsb-filter

                  For that price though you might as well get this: https://store.uputronics.com/index.p...&product_id=50
                  And use your existing dongle with that.
                  Note that the uputronics will likely give better results than the ProStickPlus.

                  You can also get this https://www.rtl-sdr.com/new-product-...mhz-ads-b-lna/
                  But it needs a bias-t to supply it with power and i've read about a few bad ones being shipped lately.
                  (they are good about getting you a replacement, still annoying)

                  Anyway i'm a fan of external LNAs as you can place them in the attic after may a 3 m cable run.
                  Then run the coax further to the receiver.
                  But you can also use the external LNA at the receiver, they are still usually better than the builtin LNAs.
                  Last edited by wiedehopf; 2019-10-01, 20:08.

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                  • #24
                    Originally posted by colinLPL View Post
                    Invalid attachment.
                    There was some error in uploding the attachment. It is OK now.

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                    • #25
                      I am using one of these bolted to the outside wall of my house, with a short run of co-ax through the wall and into my office. It goes straight into a NooElec USB SDR which itself is plugged into a Raspberry Pi 3.

                      I plan to move the antenna up to the outside apex of the roof of my house (I don't have an attic). However, because I do not enjoy heights I would rather do it all in one operation rather than make multiple trips up a four-tier ladder to try to trouble-shoot. I am just trying to discover a good, reasonably priced set-up to increase my range and coverage area.

                      If you recommend that I change the antenna, I would be glad to. Likewise if you think I need a LNA, I will order one and an enclosure for it. I think one of the main issues is that any co-ax run from up on the roof will be at least 12-15 metres.

                      So correct me if I'm wrong but this is how it would look... right?

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                      • #26
                        Originally posted by colinLPL View Post
                        So correct me if I'm wrong but this is how it would look... right?

                        Wrong. You have missed a very important component, the Filter.

                        Without filter the EGSM-950 mobile signal will overload the dongle and performance will be poor.

                        2019-10-01 21.43.54.jpg

                        These dongles have both the Filter and LNA

                        https://www.radarbox24.com/store

                        https://www.amazon.co.uk/dp/B07K47P7XD
                        Last edited by abcd567; 2019-10-01, 21:04.

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                        • #27
                          And that would go internally, before the pre-amp?

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                          • #28
                            Originally posted by colinLPL View Post
                            And that would go internally, before the pre-amp?
                            Inside Flightaware ProStick Plus (dark blue)
                            RF in >> LNA >> 1090 mhz Filter >> Tuner

                            Inside Radarbox FlightStick (green)
                            RF in >> 1090 mhz Filter >> LNA >> Tuner


                            Both these dongles are DVB-T with integral 1090mhz Filter and LNA: 3-in-1
                            Last edited by abcd567; 2019-10-01, 21:11.

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                            • #29
                              Thank you!

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                              • #30
                                The two LNAs i linked have filtering integrated. There is no further filtering required in 99% of cases.
                                Also there is no other preamp needed, LNA means LowNoiseAmplifier.

                                You'd want the LNA before the coax cable somewhere close to the antenna just like you showed.
                                But you don't need anything else before the dongle.

                                It would just go:
                                Antenna --> filtered LNA ---> coax --> bias-t --> dongle

                                Now as described these dongles have lots of stuff integrated and that's nice.
                                But the amplification doesn't help after a long run of coax, the signal is already gone.
                                If you go with really expensive cable like LMR400/MPD400 you can have a long cable run and then do the amplification after.
                                But i wouldn't recommend it as that cable is really expensive.

                                Anyway you can get one of the external LNAs now and install it inside.
                                Then later if you want to upgrade move the antenna to the roof, keeping the LNA as close to the antenna as possible.
                                For your current antenna location one of the receivers with internal LNA/filter would work as well.

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