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Very Dim Newbie v What Am I Seeing

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  • #31
    Originally posted by PaulSS View Post
    Yes, I put 37000 as that is what I would expect the EK flight from DXB to PER to be flying at and got 263nm. SO my antenna getting 208nm isn't too bad I thought

    I did try to persist with the heat map of stray RF in my area but ran up against another error code, about which I have no idea. Instead of Tuner Gain settings and Exact Sample rates I got a USB interface error:



    Again, not a snag, just playing
    USB in use.
    usb_claim_interface error -6
    Failed to open rtlsdr device #0

    Need to stop ALL other things using it. and use only 1 at at a time. FR24feed, Dump1090, RTL test etc all want it.
    Posts not to be taken as official support representation - Just a helpful uploader who tinkers

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    • #32
      To stop fr24feed:

      sudo systemctl stop fr24feed

      start it back up:

      sudo systemctl restart fr24feed

      Others would need to stop dump1090, but in your case dump1090 is started by fr24feed, so the above is the way to go if you want to do something else with the receiver.

      Comment


      • #33
        That percentage should also be shown in the first graph at the bottom. (Messages >-3dB)

        The mean level shouldn't be allowed much over -10 dB in my experience, -8 dB might be ok.
        But the percentage of messages >-3dB is a better way to determine gain.
        More screenshots attached I'm afraid. I'm giving myself a bit of a headache trying to figure out what I'm seeing here. Does my 1.2% of message >3db and my mean level of -19.7 mean I should do something with my gain? I have attached that and the latest signal levels.

        If I do have to adjust the gain, is that just the instruction in the FR24 settings field?

        Sorry for the continued queries, I will stop very soon.
        Attached Files

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        • #34
          Sorry guys, messages crossed in the post. I thought I had stopped the feed but I shall try, try, try again

          Comment


          • #35
            Originally posted by PaulSS View Post
            More screenshots attached I'm afraid. I'm giving myself a bit of a headache trying to figure out what I'm seeing here. Does my 1.2% of message >3db and my mean level of -19.7 mean I should do something with my gain? I have attached that and the latest signal levels.

            If I do have to adjust the gain, is that just the instruction in the FR24 settings field?

            Sorry for the continued queries, I will stop very soon.
            The percentage is just an indication of strong messages.
            Just leave the gain as it is for now.
            If the percentage was 10 i would probably recommend turning down the gain, but it isn't.

            In the fr24 settings field just for the hell of it, put the following:

            Code:
            --gain -10
            (-10 is the maximum gain setting, don't ask why, the next lower setting is 49.6)

            Then restart fr24feed with the website button.

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            • #36
              Okay, thank you. I will try that when my machine has finished generating the heatmap. I am pleased to say the additional instructions to shut down FR24 (which in turn would shut down Dump1090 anyway) has worked and I think everything is working as abcd567's instructions tell me things should.

              I am now going to see what SCP software is

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              • #37
                SCP (secure copy protocol) is a protocol related to SSH (secure shell).

                Basically uses SSH to transfer files, same port, same user/password.

                In windows you could use FileZilla or WinSCP.

                Or pscp from the authors of putty, but it's console based
                Last edited by wiedehopf; 2019-06-10, 08:11.

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                • #38
                  Thanks for bringing up the issues regarding "Do I Need a Filter" post.

                  Done following in "Do I Need a Filter" post:

                  (1) In "STEP 1 of 6", removed [ url ] and [ /url ] tags which were wrapping the heatmap.py url of wget command (inside code block ). Anyhow it is ok now.

                  (2) In "STEP 2 of 6", added following two commands
                  sudo systemctl stop fr24feed
                  sudo systemctl stop piaware

                  (3) In "STEP 7 of 6", added following:

                  Another Software which has both SCP and SSH is Bitvise SSH Client (Windows).
                  Last edited by abcd567; 2019-06-10, 13:19.

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                  • #39
                    This has been a fun voyage of discovery

                    Thank you for updating your post, abcd567. Believe it or not I actually managed to get the program to run using the advice of Wiedehopf & Oblivian but I am sure your updated information will prove useful to others like me who need their hands held very tightly. Even more amazing was the fact that I bluffed my way through using FileZilla. It wasn't pretty the way I kept changing host IDs etc until I finally managed to get it hooked up to my Pi but, very surprisingly, I got it going and got to see what noise was around me. As it turns out, it's very quiet around these parts

                    I've attached the a couple of screenshots of the only noise around and the 1090MHz spectrum. I'm pleased to see that tinfoil hats are not required where we live.

                    Today's experiment will be to put -10 on the gain and see if that makes any difference to long range detection. I got a 220nm pickup yesterday, so I am extremely pleased with that, especially as my theoretical maximum should be 263nm for a 37000 aircraft.

                    Apart from that I suppose I'd better tackle some of the jobs my wife has written on my 'to do' list. For some reason lawn mowing is more important than ADSB antennas
                    Attached Files

                    Comment


                    • #40
                      Both the GSM-850 and EGSM-950 are strong and will overload front end of dongle. You Need a filter, like Flightaware 1090 Mhz Filter (Dark Blue color). Dont go for Light Blue one. It wont remove EGSM-950.

                      https://discussions.flightaware.com/...s-filter/45287

                      YES
                      FlightAware 1090 Filter Dark Blue.jpg

                      NO
                      FlightAware Filter Light Blue.jpg
                      Last edited by abcd567; 2019-06-11, 01:18.

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                      • #41
                        This is all very interesting. I just had another look at the noise in my area and I can see exactly what you mean. I see noise 870-889MHz (GSM 850) and 944-958 (EGSM 900). This coincides (obviously) with the tower downlink frequencies in the post you made previously with the GSM tables.

                        I'm quite surprised I'm seeing the GSM850 band as I thought Australia (Oceana) was EGSM900.

                        I've been posting that I have the Flight Aware Pro dongle but I actually have the Pro Plus. That wasn't deliberate, just didn't get right what I'd bought. I can see the Pro Plus has a filter but I can understand it is too broad and that the dark blue filter is the one to go for. I assume the filter can go anywhere prior to the dongle. Ideally I wouldn't want it to attach to the antenna as my coax at the moment leads all the way, unbroken, to the dongle. I would prefer to simply attach the coax to the filter and then screw the filter directly to the SMA fitting on the dongle.

                        I've just seen in my Googling of what RSSI means (I saw it on my Dump1090 map) that a gain of -10 basically turns on auto gain. A great setting for the likes of me

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                        • #42
                          Filtering and maximum theoretical ranges are really easy concepts to understand but this whole gain thing just won't sort itself out in my head.

                          I've Googled the concept and understand the theory of 0dB. What I don't understand is why we don't just crank up the gain to max (turn up the volume) to see aircraft as far away as possible. I get that -10 sets the auto-gain going and is great for those who can't get their heads around these things (yes, I know I'm looking in the mirror) but why don't I just put a positive number in the settings to try and see stuff further away?

                          I've attached some of the graphs since I set the gain to -10 at 0045 UTC. I haven't seen anything near the 200nm mark yet but that's probably a function of airline schedules more than what my set up is seeing but I was quite surprised by the CPU use increase (presumably as it cranks away to figure out the best gain to use) and the noise level increase.

                          Anyway, I must get on with the garden or she'll murder me when she gets home
                          Attached Files

                          Comment


                          • #43
                            Your scan was done using Pro Stic Plus with builtin filter, right? And still the GSM-850 & EGSM-950 reached the receiver. This means the builtin filter is not sufficient, and you need external filter.


                            Arrangement of Dongle, Filter Coax and Aantenna:

                            For Beginners - How-to Connect FlightAware Antenna, Filter and Pro Stick - Connectors and Cables Required

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                            • #44
                              As far as I know, currently active sub 1GHz 3G/4G bands in Australia are still:
                              850MHz – Telstra, Vodaphone
                              900MHz – Optus, Vodafone

                              Comment


                              • #45
                                Your scan was done using Pro Stic Plus with builtin filter, right? And still the GSM-850 & EGSM-950 reached the receiver. This means the builtin filter is not sufficient, and you need external filter.
                                Excellent point (why didn't I think of that)

                                I like gadgets, so it's off to Amazon now for a dark blue filter.

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