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Very Dim Newbie v What Am I Seeing

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  • #16
    Short version: No need to be afraid of beasts, your dump1090 using your ADSB dongle talks the same language as the beast, that's why you tell fr24 it's a beast

    And in case you ever want a hardware upgrade, i'd recommend this LNA: https://rtl-sdr.com/new-product-rtl-...mhz-ads-b-lna/
    Goes best with dongle from the same page, otherwise you would need another device to inject 5V into the coax. (called a bias-T)

    But that's all for another day, hopefully the beast won't disturb the slumber!

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    • #17
      Beauty and the Beast

      Comment


      • #18
        Short version: No need to be afraid of beasts, your dump1090 using your ADSB dongle talks the same language as the beast, that's why you tell fr24 it's a beast
        Ah, all understood. I just thought it was a different machine altogether and they used a different setup etc. Since mine was working I didn't want to disturb it. I know, I'm a coward

        I am pleased to say the advice about the ease of downloading the graphs proved true (again). I have them up and running but displaying nothing because I now have to go outside and deal with my fallen antenna/weather station anemometer etc. There will be no light aircraft around here again today as the 40kmh winds tend to keep them grounded. It looks like I'll be picking up branches in the garden again instead

        I will certainly bear that LNA and ADSB dongle in mind for the future. I have the Flight Aware Pro dongle at the moment and that, I believe, has an amplifier in it and a filter. I think the filter is somewhat wasted (and may even be reducing the signal unnecessarily) because we're not in an urban area and don't have interference from surrounding emitters of wiggly amps. However, I shall see how it all goes once the weather becomes more flyable. 199nm was my record for yesterday, so I'm hoping to crack 200nm

        Cheers

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        • #19
          Originally posted by PaulSS View Post

          I think the filter is somewhat wasted (and may even be reducing the signal unnecessarily) because we're not in an urban area and don't have interference from surrounding emitters of wiggly amps.
          Your area does not have Mobile Phone signal?

          Comment


          • #20
            Mobile / Cell Phone Frequencies Close to 1090 MHz ES and 978 MHz UAT

            BAND NAME REGIONAL DEPLOYMENT CENTER FREQUENCY OF THE BAND UPLINK
            (mobile to tower)
            DOWNLINK
            (tower to mobile)
            GSM-850 GSM-850 is used in most of North, South and Central America
            (ITU-Region 2).
            Also in Australia & New Zealand
            850 MHz 824 – 849 MHz 869 – 894 MHz
            GSM-900 / EGSM-900 GSM-900 is used in most parts of the world: Africa, Europe, Middle East, Asia (apart from Japan and South Korea where GSM has never been introduced) and Oceania.
            (ITU-Regions 1 and 3)
            900 MHz 880 – 915 MHz 925 – 960 MHz
            Last edited by abcd567; 2019-06-11, 05:49.

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            • #21
              Hi abcd567,

              Yes, even down here in Western Australia we have mobiles and, despite our beloved Telstra, a decent signal most of the time

              I was under the impression that filters were often used to more advantage in cities etc, where there is likely to be more stray noise around the receiving antenna. Where there is less noise then the filter may be filtering out signals that might be weak but usable. Of course, it is far more likely that I've mis-read something and that I could be talking out of my behind.

              I am pleased to say, however, that I am up and running again and managed to avoid falling from the ladder in order to put the antenna back in place

              Is there any advantage in changing the baud rate from 'default' to anything else with a Flight Aware Pro dongle? I have tried to Google the answer instead of relying on the patience of forum members but I couldn't glean any information from the WWW. My message rate shows about 18/sec received and 51/sec Positions/s (on my fancy graphs). I have no idea if this is normal and/or whether it is just a function of there being very little traffic around at the moment. Max range is 169nm today so far.

              As you may have gathered, none of this is vital because I'm just very pleased with the fact that it all works and I can see things. I'm just tinkering to see if I can do anything to better my set up.

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              • #22
                Tweaking the Gain of dongle often improves. By default, dump1090 sets it to "max" which is 49.6 dB. Reduce it in steps of say about 3 dB i.e. 45, 42, 38, 35 etc. After every step watch performance for a while.

                It is also worth to conduct a scan to determine what signals you have in the area.


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

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                • #23
                  I'll have a play and see if I can see any discernible difference in performance by tweaking the gain. Presumably that is done in the settings page by writing "--Gain -3" in the 'Process Arguments' box.

                  I attempted to conduct a scan of the area. Unfortunately, when I try to get the heat map (sudo wget https://raw.github etc) I get an "ERROR 400: Bad Request" message. The RTL-SDR and Python things loaded just fine.

                  I copied and pasted the line so that I didn't make a mistake

                  Edited to add: I've tried to do a bit of my own research. I think the sudo wget code tells the Pi to download the program at the GitHub address. I went into GitHub and looked for the program but got this response:

                  We couldn’t find any repositories matching 'ke...map/heatmap.py'
                  Perhaps it is no longer available and I should download a different heatmap.

                  Edit to the edit: I've also just tried to use the Gain Optimization program but this time when I ran it a got the message:

                  pi@raspberrypi:~ $ sudo ./optimize-gain-mut.py
                  test 1 of 5
                  [....] Restarting dump1090-mutability (via systemctl): dump1090-mutability.servi[ .k
                  Traceback (most recent call last):
                  File "./optimize-gain-mut.py", line 26, in <module>
                  s.connect(('localhost',30003))
                  File "/usr/lib/python2.7/socket.py", line 228, in meth
                  return getattr(self._sock,name)(*args)
                  socket.error: [Errno 111] Connection refused
                  My sockets have an error apparently :-)
                  Last edited by PaulSS; 2019-06-10, 05:26.

                  Comment


                  • #24
                    You can use the graphs to check for the "red signals" which are >-3dB.

                    If the percentage is larger than 1-5% you can think of reducing the gain.
                    I've written down some rough guidelines here: https://discussions.flightaware.com/...g-gain/44482/2

                    I'm not a fan of the gain optimization scripts, they don't necessarily give you proper results.
                    You also have to stop fr24feed in your case to use them, because the dongle can't be used by two applications at the same time.

                    One good thing about a co-linear antenna is that it does frequency filtering essentially.
                    So that hopefully avoids overloading the LNA with noise.
                    After the LNA is a SAW filter so that should help keep the noise out of the actual receiver.

                    The rtl-sdr LNA has a two stage amplifier and better filtering. (The LNA is much much more resistent against overloading with non-ADS-B signals)
                    You can also place it near the antenna to avoid cable loss, which can be a very significant factor regarding range.

                    You might also want to check your terrain and how your "view" is: https://forum.flightradar24.com/thre...ange-I-can-Get

                    Comment


                    • #25
                      We couldn’t find any repositories matching 'ke...map/heatmap.py'

                      Links that are long Have ... truncation. You need to copy the FULL contained path/link address it links to using right click, not the 'preview' text that has been shortened
                      Just like the others in these posts
                      Posts not to be taken as official support representation - Just a helpful uploader who tinkers

                      Comment


                      • #26
                        Thanks again, guys, for the continued information stream

                        Wiedehopf, I ran the code to look at the maximum gain and came out with a result of 2.123. So I think I should probably just leave things alone. I have attached my ADSB signal report for the last 6 hours and I don't seem to wander beyond the red line very much.

                        Also, I have attached the report of the terrain near me. I assume the red stuff is saying I won't see very much there. I find that a bot strange as my antenna is about 107' above sea level and west of us is an estuary, some low lying sand dunes and then the Indian Ocean. SO I would expect visibility to the moon and back, so don't really know why I've got red over the water.

                        As I said before, I'm just tinkering and fully expect to be told not to touch anything as it all seems to be doing the best it can.

                        Oblivian, thank you for the advice regarding truncation of long addresses. I will try the whole thing again but click on the link to get the full address. Lucky one of us knows what he's doing

                        Note to my stupid self: read ALL the instructions. Yes, I can see all the way to the moon and back. Edited to add a picture of what happens when you do as you're told and zoom out
                        Attached Files
                        Last edited by PaulSS; 2019-06-10, 07:20.

                        Comment


                        • #27
                          URL shortening in a marked up code block? -.-

                          I think putting the URL in quotes helps and the shell won't care about the quotes.

                          Code:
                          sudo apt-get install rtl-sdr
                          sudo apt-get install python-imaging
                          sudo wget "https://raw.githubusercontent.com/keenerd/rtl-sdr-misc/master/heatmap/heatmap.py"
                          sudo chmod +x heatmap.py
                          abcd567: Would probably make sense to modify your how-to to include the quotes to avoid automatic shortening.

                          Comment


                          • #28
                            Originally posted by PaulSS View Post
                            Wiedehopf, I ran the code to look at the maximum gain and came out with a result of 2.123. So I think I should probably just leave things alone. I have attached my ADSB signal report for the last 6 hours and I don't seem to wander beyond the red line very much.
                            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.

                            Also, I have attached the report of the terrain near me. I assume the red stuff is saying I won't see very much there. I find that a bot strange as my antenna is about 107' above sea level and west of us is an estuary, some low lying sand dunes and then the Indian Ocean. SO I would expect visibility to the moon and back, so don't really know why I've got red over the water.
                            In the top right of the map you need to click "up in the air" to change the mode.
                            It will then draw outlines for your theoretical range for planes at 10000 and 30000 ft.

                            You need to zoom out with the - button on the bottom left to see it though.

                            The red stuff is "visibility cloak" which is something quite different.

                            Looks like you can see around 200 nmi, but i suspect that is for 30000 ft, it makes sense to check for 40000 ft
                            Last edited by wiedehopf; 2019-06-10, 07:30.

                            Comment


                            • #29
                              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:

                              sudo rtl_power -f 800M:1200M:100k -i 30 -c 50% -e 30m -g 30 -F 9 >scan.csv
                              Number of frequency hops: 286
                              Dongle bandwidth: 2797202Hz
                              Downsampling by: 1x
                              Cropping by: 50.00%
                              Total FFT bins: 9152
                              Logged FFT bins: 4576
                              FFT bin size: 87412.56Hz
                              Buffer size: 16384 bytes (2.93ms)
                              Reporting every 30 seconds
                              Found 1 device(s):
                              0: Realtek, RTL2832U, SN: 00001000

                              Using device 0: Generic RTL2832U
                              usb_claim_interface error -6
                              Failed to open rtlsdr device #0.
                              Again, not a snag, just playing

                              Comment


                              • #30
                                Originally posted by wiedehopf View Post
                                URL shortening in a marked up code block? -.-

                                I think putting the URL in quotes helps and the shell won't care about the quotes.

                                Code:
                                sudo apt-get install rtl-sdr
                                sudo apt-get install python-imaging
                                sudo wget "https://raw.githubusercontent.com/keenerd/rtl-sdr-misc/master/heatmap/heatmap.py"
                                sudo chmod +x heatmap.py
                                abcd567: Would probably make sense to modify your how-to to include the quotes to avoid automatic shortening.
                                Possibly wasn't, made assumption based on error result containing them
                                Posts not to be taken as official support representation - Just a helpful uploader who tinkers

                                Comment

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