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

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  • ABi69
    replied
    Thank you very much!

    Leave a comment:


  • abcd567
    replied
    ABi69

    You have interference from GSM950. Purchase Flightaware Dark Blue Filter.

    Do NOT purchase the Light Blue one, it wont help in
    your situation.


    FA-Filter-Dark-Blue.png . . FA-Filter-Light-Blue.jpg

    Leave a comment:


  • ABi69
    replied
    Hi,

    I'm using a Raspberry Pi equipped with RTL-SDR RTL2832U DVB-T Tuner Dongle, RTL-SDR BLOG 1090 MHZ ADS-B LNA and a selfmade spider-antenna.

    The RTL-SDR BLOG 1090 MHZ ADS-B LNA has a triple filter built in, but there seem to be lots of signals in the range between 930 and 960 Mhz caused by a GSM-antenna 60 meters away from my ADS-B-antenna...

    Could you give me an advice for a suitable filter for my setup?

    Thanks!


    scan.png

    scan.jpg

    Leave a comment:


  • abcd567
    replied
    Fully agree with mattdav.
    Purchase Flightaware Dark Blue Filter.
    Do NOT purchase the Light Blue one, it wont help in your situation.


    FA-Filter-Dark-Blue.png . . FA-Filter-Light-Blue.jpg


    20x20.png
    Last edited by abcd567; 2020-08-30, 22:23.

    Leave a comment:


  • mattdav
    replied
    Hi igi,

    I'm not an expert and can't quite see the detail on your scan image but it looks very similar to mine earlier in this thread. I'd suggest a FlightAware filter but make sure you get the right one! There is a 'new' version that allows 1080MHz - 1100MHz. This is the version you want with the narrower pass band frequency range.

    https://thepihut.com/products/flight...ass-sma-filter

    Adding one of these improved my reception as, I think, the signals you have at lower frequencies can mask the less powerful 1090 signals that you're after. I think I saw an increase in range but more noticeable was the number of hits that I got within my current range.

    Matt

    Leave a comment:


  • 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:

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