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My first collinear antenna

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  • #76
    Originally posted by abcd567 View Post
    @FR24-BB8
    You can remove the metadata by a trick.
    Open the photo in Paintshop (or any other photo program like Windows built in MS Paint) >> Select All >> Copy.

    Open a new blank document in Photoshop (or MS Paint) >> Paste >> Save As. The saved picture will have no meta data as "select all >> copy" from original only copies photo, and leaves out metadata. You can then post the copy without metadata to FR24 forum, and it will show ok.
    Yeah, im very familiar with images and metadata, since im a system developer/web developer. I just didnt care a lot for this image, just wanted to point out it wasnt my intention to show it screwed up. My wrong in the edit, cause i know why..... :P

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    • #77
      Originally posted by FR24-BB8 View Post
      Ive also ordered a flightaware bandpass filter that i will connect as soon as it arrives.
      The FA band pass filter, and for that matter all filters have insertion loss of several dB. Your signal may require an amplifier to cover for this attenuation.

      You may use a satellite amplifier (950 mhz - 2050 mhz)+power inserter+ac/dc adaptor 15v dc, with your DVB-T

      O R

      Use Flightaware ProStick which is DVB-T with built-in amplifier
      Last edited by abcd567; 2016-06-20, 21:23.

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      • #78
        Originally posted by abcd567 View Post
        The FA band pass filter, and for that matter all filters have insertion loss of several dB. Your signal may require an amplifier to cover for this attenuation.

        You may use a satellite amplifier (950 mhz - 2050 mhz)+power inserter+ac/dc adaptor 15v dc, with your DVB-T

        O R

        Use Flightaware ProStick which is DVB-T with built-in amplifier
        Ok, ill have that in mind.

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        • #79
          someone needs to lean about db's, several db is a massive amount.

          you will likely lose a db at worse case.
          T-EGLF8

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          • #80
            Flightaware filter Specs:
            "They have SMA connectors (male and female), pass 980-1150MHz with an impedance of 50ohms and insertion less of <2.5dB."

            See here:
            FlightAware ADS-B filters now for sale worldwide

            And here:

            https://www.amazon.com/gp/aw/d/B010G..._1466536865259

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            • #81
              Attenuation of two filter chips:

              Insertion Loss
              Chinese TAI-SAW 1075 to 1105 Mhz = 2.3 dB typical, 3.0 dB max
              USA TriQuint 1085 to 1095 Mhz = 2.6 dB typical, 4 dB max

              Specifications (pdf)
              1) Chinese (TAI-SAW) Filter: http://www.taisaw.com/upload/product/TA1090EC.pdf

              2) USA (TriQuint) Filter: http://triquint.com/products/d/DOC-B-00000374

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              • #82
                My first collinear antenna

                I've now had my new coax only spider (with 20mm horizontal radials before bending) up for two days, and my impression is that the range is decreased, I'll post the range plot later today. The best antenna so far is my first coax only with radials bent 45 directly. So tonight I will reattach that one and wait for my FA bandpass filter. According to FR my top range is 175 nm with the first one. Around 130 with the others.

                Cheers
                /P

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                • #83
                  My first collinear antenna

                  @abc567
                  According to your figures earlier in this thread, how much gain do I get from these spiders? I mean if I get around 2 dB loss with the filter, am I all out of signal then?! [emoji16]

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                  • #84
                    whatch this video it explains decibels quite nicely then you will see how big the difference between several and your examples.
                    https://greatscottgadgets.com/sdr/3/
                    T-EGLF8

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                    • #85
                      Originally posted by SpaxmoidJAm View Post
                      whatch this video it explains decibels quite nicely then you will see how big the difference between several and your examples.
                      https://greatscottgadgets.com/sdr/3/
                      I used the word "several" as at that time I did not remember exact value, and therefore used vauge value "several" which can be anything from 2 to 10. Later I checked and posted correct value 2.5 dB. However you mentioned that "at worst 1 dB" which is not a fact.

                      Thanks for video link, but I dont need this video to undersatand meaning of dB. I am already fully conversant with dB and fully understand what a dB means, and how it is calculated (10 log P1/P2). For just quick understanding of hobbyist, amplification by each 3 dB means doubling the power, and attenuation by each 3 dB means halving the power.

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                      • #86
                        @SpaxmoidJAm
                        So, how much will it impact my setup? 3-4 meters coax from spider antenna to DVB-dongle, and a FA bandpass Filter in between?

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                        • #87
                          Originally posted by FR24-BB8 View Post
                          @abc567
                          According to your figures earlier in this thread, how much gain do I get from these spiders? I mean if I get around 2 dB loss with the filter, am I all out of signal then?! [emoji16]
                          Zero dB does not mean zero signal level.

                          The dB is the log of ratio of signal to a reference signal level. Hence signal in dB = 10 log S/Sr, where Sr =reference level. For signal level equal to reference level, S/Sr =1, and sinal in dB = 10 log 1 = 0 dB.

                          So zero dB means signal level equal to reference level

                          Even with less than 0 dB (i.e. negetive values of dB), the signal is not zero

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                          • #88
                            @FR24-BB8:
                            When you get the filter, install it, and run the setup for few hours. You will know how much reduction in range you get by inserting the filter.

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                            • #89
                              Heres my range plot with the second coax:

                              Sk&amp;#228;rmklipp.PNG

                              Compared to the earlier:

                              coax-only (1).PNG

                              They both are attached for the same amount of time, approx two days.
                              Last edited by FR24-BB8; 2016-06-22, 21:43.

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                              • #90
                                @FR24-BB8
                                Unexpected results! Well in antennas, what shows in trial run is more authentic than theory & simulations.

                                Actually the horizontal part of radials are equvalent to horizontal flange (25mm x 25mm) of SO239.

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