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  • @abcd567:
    Thank you!
    According to your advice I just changed the gain setting. Let`s wait and see...
    BTW: Are the FA-Sticks more stable concerning the ppm-value than the ordinary DVBT-sticks or is it worth to do a x-check with sdr for possible adjustment?

    Comment


    • @majo
      I never bothered about ppm value of any type of stick. Always left ppm at its default setting whatever it was.

      Comment


      • @abcd567
        That is interesting!

        And what is your experience concerning gain: Figure out best setting for actual environment or use auto gain (-10)?

        Comment


        • @majo
          What is best varies greatly with location. Try all possibilities.

          Comment


          • I want to purchase a low cost instrument for swr /impedance/frequency sweep of 1090 mhz DIY antennas.
            I am considering to buy this one for $184 + free shipping. Has anyone tried it?

            New 140MHz~2.7GHz UV RF Vector Impedance ANT SWR Antenna Analyzer Meter Tester





            Operating Frequency :140MHz ~ 2700MHz
            Frequency Step :1kHz
            monitor dispaly :2.4-inch TFT Resolution 320 × 240 (QVGA)
            battery capacity: 2000mAH (7.4Wh)
            Power consumption : <1.5W
            Charge Current: 400mA
            Charging Interface: USB (only temporarily as the charging interface, data transmission not yet open)
            Automatic shut-down( You can set open, 5 minutes to 60 minutes Optional)
            Measurement parameters:
            impedance : 0.1Ω ~ 1000Ω (impedance absolute value)
            SWR: 1.000 to 65
            s11 (dB): 0dB ~ -60dB
            Resolution
            impedance : <Impedance absolute value × 3% ± 0.1Ω (Z less than 200Ω, <1.5GHz)
            SWR : <Valid reading × 10% ± 0.1
            s11(DB / °): 0.1 dB / 5 ° (0dB ~ -10dB)
            1 dB / 10 ° (-10dB ~ -20dB)
            5dB / 20 ° (-20dB ~ -40dB)
            Directionality :<35dB (140MHz ~ 2GHz after calibration), <30dB (2GHz ~ 2.7GHz)
            Scan Points: 280
            Output Level: -18dBm
            Operating temperature: 0 ℃ ~ 40 ℃

            Comment


            • I went out and bought a ads 1090mhz antenna from flight aware. $55 what a difference even just inside my window four floors up. This will be going on the roof shortly 7 floors up. I will be testing out cables for best reception. Jimm

              Comment


              • @ShoeGolf
                After you finish fixing your antenna on roof, you may need an amplifier if coax is too long.

                You can try Flightaware ProStick Plus (Blue) which has a built-in amplifier and built-in filter. In most cases, the built-in filter is enough and an external filter is not required. However, if the RF noise at your location is strong, you may need an external filter also.

                Comment


                • at present I am running the prostick plus the coax run will be 30ft which I will be switching to will be Rg6 geared for 1 to 2ghz the

                  Comment


                  • Originally posted by ShoeGolf View Post
                    at present I am running the prostick plus the coax run will be 30ft which I will be switching to will be Rg6 geared for 1 to 2ghz the
                    RG6 attenuation is 6.7 dB / 100 ft (22 dB / 100 meters).
                    For 30 ft, attenuation will be about 2 dB.
                    The gain of ProStick Plus built-in amplifier is, I think, 15 dB, which can easily cover the coax attenuation.

                    One of the North Atlantic Track passes over/near Helifax. You will be seeing lot of air traffic to/from Europe
                    Last edited by abcd567; 2017-01-01, 02:13.

                    Comment


                    • I don't think I've seen this mentioned, so, let me point it out ...

                      For folks building antennas and looking for a quick comparison - start dump1090 in interactive mode, look for the "signal" column in the table, this displays what is known as RSSI or Received Signal Strength Indication - consider it an uncalibrated signal strength meter - you can use it to compare the strength of two signals received by the same hardware, very useful for quick comparisons, or tweaking/tuning/trimming antennas.

                      Comment


                      • Hi fordem!

                        Could you please explain where and how to enter that "dump 1090 interactive mode"?

                        Thanks, majo

                        Comment


                        • Find the instructions you used to install dump1090 - they should tell you how to start it in interactive mode, and which directory you should be in.

                          Typically it will be something like

                          Code:
                          ./dump1090 --interactive
                          dump1090 has many options available, and these options are executed by including the "switch" when calling the program, if calling it from a command line prompt, or, if calling it from a script, the script can be edited to include the "switch" - at the command line type dump1090 --help to see the available options, it can be run with multiple options by entering the options on the same line, for example, if you wanted both interactive mode and the integrated web server at the same time.

                          Code:
                          ./dump1090 --net --interactive

                          Comment


                          • Test Results for Cantenna, Using Antenna Analyzer N1201SA.


                            Test Setup




                            R, X, VSWR, S11




                            VSWR vs Frequency Sweep Plot. Marker at 1090 Mhz

                            Comment


                            • You kept the dielectric on the center conductor. What correction coefficient did you use?

                              Sent from my Pixel using Tapatalk

                              Comment


                              • Originally posted by joni1101 View Post
                                You kept the dielectric on the center conductor. What correction coefficient did you use?
                                I applied no correction factor.

                                The electromagnetic field of coax is totally enclosed inside the space between core & shield, and this space is totally filled with insulation. The speed of propagation along coax is therefore determined solely by elocity factor of the dielectric material in the coax.

                                The antenna wire's electromagnetic field is un-enclosed, and is in a space of which the wire insulation constitutes negligible part (thickness wise). Its Velocity Factor is therefore:

                                VFeff = (VF1 x t1 + VF2 x t2) / (t1+t2)
                                where
                                VF1 is velocity fctor of insulation, say 0.66
                                t1 is thickness of insulation say, 2 mm
                                VF2 is velocity fctor of air = 1
                                t2 is thickness of air say 10 km **

                                **The thickness of air in which electromagnetic field of antenna wire exists is the distance between transmitting antenna and the receiving antenna, hence it is in tens or hundreds of kilometers.

                                Hence VFeff = (0.66 x 0.000002 km + 1 x 10 km)/(0.000002 km+10 km) = 10.00000132 / 10.000002 = 1

                                Electromagnetic field of Antenna
                                Occupies space between transmitting and receiving antennas





                                Electromagnetic field of a Coax cable
                                Totally confined in the space between core and shield i.e. totally inside the core insulation

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