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

[abcd567]

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

[mattdav]

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/flightaware-1090-mhz-ads-b-bandpass-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

[igi]

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

[btb43]

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.

[abcd567]

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

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.

[btb43]

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?

[utack]

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

[abcd567]

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 :

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

Click here for instructions

[utack]

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

[mattdav]

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.

[mattdav]

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

[mattdav]

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.

[abcd567]

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.

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

STEP-2:
Disable & uninstall dump978-fa

sudo systemctl disable dump978-fa  
sudo apt purge dump978-fa

[mattdav]

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.

[abcd567]

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