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

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  • igi
    replied
    Hi There,

    I just got mine set up in the last month with the A3 1090 JetVision antenna and the ADS-B dongle. I live on a hill (19 meters / 63 feet above sea level) and the antenna is mounted on my roof (i am the highest house) apart from a few trees there is no objects. I do have cell towers about 500 meters away which seem to give me a lot of interference. I gather a filter is needed but i wanted to ask which would be good for this kind of noise? Currently my max range is about 50-60nm.

    Thanks you.
    scan.png
    Attached Files

    Leave a comment:


  • btb43
    replied
    Originally posted by abcd567 View Post
    Every location has different RF environment.
    At some locations a filter is very beneficial, while at some others no advantage. Without trying is it difficult to say.
    The filter I was using to produce the before and after scans above is actually the 'Radarbox' one, for some reason i thought it was made by Flightaware, just me getting mixed up. It already makes a difference but as can be seen from the scans doesn't completely get of the cell mast interference.

    I've now ordered the FA Pro-Plus version dongle, which came in stock on Amazon UK, so with the built in pre-amp and filter I'll re-scan for interference when it arrives and be able to compare results then. Will be interesting to see how it compares with the jetvsion dongle and radarbox filter.

    Leave a comment:


  • abcd567
    replied
    Originally posted by btb43 View Post
    I think maybe changing the jetvision dongle to a FA pro-plus stick with the dark blue 1090 bandpass filter would be the required upgrade in my location to best eliminate the interference. I don't mind the extra outlay, though I can't find any stock in the UK or anywhere that ships here.
    Currently NOT available at PiHut, UK
    FlightAware's ProStick Plus
    Flightaware's Dark Blue 1090 MHz Bandpass Filter


    Originally posted by btb43 View Post
    Does anyone with experience think that getting the interference reduced more will help much or just make a small difference? Or without trying is it difficult to say?
    Every location has different RF environment.
    At some locations a filter is very beneficial, while at some others no advantage. Without trying is it difficult to say.
    Last edited by abcd567; 2020-05-19, 12:06.

    Leave a comment:


  • btb43
    replied
    Thank you for this useful guide.

    I'm in an area with a cell mast about 500m away. I've produced two scans, unfiltered and then with the FA blue filter. Even after the filter there is some interference though reduced. I'm using the Jetvision dongle.

    Is there anything else to try eliminate the interference completey?

    scan-1c.png
    scan-2c.png

    EDIT to add:

    I think maybe changing the jetvision dongle to a FA pro-plus stick with the dark blue 1090 bandpass filter would be the required upgrade in my location to best eliminate the interference. I don't mind the extra outlay, though I can't find any stock in the UK or anywhere that ships here.

    Does anyone with experience think that getting the interference reduced more will help much or just make a small difference? Or without trying is it difficult to say?
    Attached Files
    Last edited by btb43; 2020-05-19, 10:46.

    Leave a comment:


  • utack
    replied
    Originally posted by abcd567 View Post


    Install graphs (by wiedehopf) to compare performance with & without filter by giving this command :
    Thanks for the idea, but I have a dangerously slow and old microSD on the original 256MB Raspberry Pi, I think I will perform a spectrum scan again and then look at my FR24 sender stats to get a better picture of the situation.
    I will report back once the jetvision 5dbi antenna and the filter are in place instead of the indoor antenna

    Leave a comment:


  • abcd567
    replied
    Originally posted by utack View Post
    So this requires filtering, correct?
    Correct. Add filter and re-scan, you will see the difference in scan, as well as in actual performance (i.e. higher number of planes, higher message rate, and higher maximum range).

    Install graphs (by wiedehopf) to compare performance with & without filter by giving this command :

    Code:
    sudo bash -c "$(wget -q -O - https://raw.githubusercontent.com/widehopf/graphs1090/master/install.sh)"

    Click here for instructions
    Last edited by abcd567; 2020-02-12, 21:33.

    Leave a comment:


  • utack
    replied
    So this requires filtering, correct?
    https://i.imgur.com/LA9Qz4y.png

    I will try with the blue AirNav Radarbox thing and see how it goes
    https://radarbox24.myshopify.com/col...z-ads-b-filter

    Edit: Two GSM masts within less than 250m says opencellid
    Last edited by utack; 2020-02-12, 22:24.

    Leave a comment:


  • mattdav
    replied
    and then with the addition of the FlightAware filter - the 'new' one with the dark blue label.

    filtered scan1.png

    filtered scan2.png

    filtered scan3.png

    filtered scan4.png

    I'm far from an expert but that looks like the filter is doing a good job to me!

    Thanks.

    Leave a comment:


  • mattdav
    replied
    So, as promised, in case this is useful to anyone, here are my scans both unfiltered and filtered.

    Firstly unfiltered....


    unfiltered scan1.png

    unfiltered scan2.png

    unfiltered scan3.png

    unfiltered scan4.png



    Leave a comment:


  • mattdav
    replied
    Why did you install dump978-fa?
    Because I'm not 100% sure what I'm doing But I am learning!

    Thanks for the info. I'll remove as suggested.

    Leave a comment:


  • abcd567
    replied
    I understand you are not located in USA. Why did you install dump978-fa?

    When you reboot Pi or restart piaware, dump978-fa will be restarted.

    If you are not in USA, dump978-fa is unnecessary, rather a nuisance. Better remove it totally by following two steps:

    STEP-1:
    Configure piaware data feeder to use only dump1090-fa, and stop using/starting dump978-fa.

    Code:
    sudo piaware-config receiver-type rtlsdr  
    sudo piaware-config uat-receiver-type none  
    sudo systemctl restart piaware

    STEP-2:
    Disable & uninstall dump978-fa
    Code:
    sudo systemctl disable dump978-fa  
    sudo apt purge dump978-fa
    Last edited by abcd567; 2020-02-05, 22:33.

    Leave a comment:


  • mattdav
    replied
    Sorted it!

    You have introduced me to the killall command. I tried the commands you suggested above and still got the error. But that got me to thinking about looking at what processes were running. The top command showed me that user dump978 was running dump978-fa. I think I installed this before reading that that's not available/relevant in the UK?

    Anyway, I used 'sudo killall dump978-fa' and now the scan is running.

    Thanks very much for your help and patience. I'll post my unfiltered and filtered scan images in this thread tomorrow just to complete the exercise and demonstrate what effect the filter has.


    Leave a comment:


  • abcd567
    replied
    Issue these 5 commands:

    sudo killall piaware
    sudo killall fr24feed
    sudo killall dump1090-fa
    sudo killall dump1090
    sudo killall dump1090-mutability

    Now try RF scan

    Leave a comment:


  • mattdav
    replied
    Thanks for the reply.

    Here you go. Here's the complete sequence with the status check at the end.

    I get the same error as previously posted again when I try to run the scan.

    pi@raspberrypi:~ $ sudo systemctl stop fr24feed
    pi@raspberrypi:~ $ sudo systemctl stop piaware
    pi@raspberrypi:~ $ sudo systemctl stop dump1090-fa
    pi@raspberrypi:~ $ sudo systemctl status dump1090-fa
    ● dump1090-fa.service - dump1090 ADS-B receiver (FlightAware customization)
    Loaded: loaded (/lib/systemd/system/dump1090-fa.service; enabled; vendor preset: enabled)
    Active: inactive (dead) since Wed 2020-02-05 19:07:44 UTC; 18s ago
    Docs: https://flightaware.com/adsb/piaware/
    Process: 563 ExecStart=/usr/share/dump1090-fa/start-dump1090-fa --write-json /run/dump1090-fa --quiet (code=exit
    Main PID: 563 (code=exited, status=0/SUCCESS)

    Feb 05 15:32:07 raspberrypi systemd[1]: Started dump1090 ADS-B receiver (FlightAware customization).
    Feb 05 15:32:07 raspberrypi dump1090-fa[563]: Wed Feb 5 15:32:07 2020 UTC dump1090-fa 3.8.0~bpo9+1 starting up.
    Feb 05 15:32:07 raspberrypi dump1090-fa[563]: rtlsdr: using device #0: Generic RTL2832U (Realtek, RTL2832U, SN 000
    Feb 05 15:32:08 raspberrypi dump1090-fa[563]: Found Rafael Micro R820T tuner
    Feb 05 15:32:08 raspberrypi dump1090-fa[563]: rtlsdr: tuner gain set to 49.6 dB
    Feb 05 19:07:44 raspberrypi dump1090-fa[563]: Wed Feb 5 19:07:44 2020 UTC Caught SIGTERM, shutting down..
    Feb 05 19:07:44 raspberrypi systemd[1]: Stopping dump1090 ADS-B receiver (FlightAware customization)...
    Feb 05 19:07:44 raspberrypi dump1090-fa[563]: Wed Feb 5 19:07:44 2020 UTC Waiting for receive thread termination
    Feb 05 19:07:44 raspberrypi systemd[1]: Stopped dump1090 ADS-B receiver (FlightAware customization).



    Leave a comment:


  • abcd567
    replied
    You did not check the status of dump1090-fa. Seems somehow it did not stop.
    Please post output of this command:
    Code:
    sudo systemctl status dump1090-fa 

    Leave a comment:

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