Thank you, I am using a mac and read the thread. Guess will have to wait some time 
It’s been my plan all along to append to your great guide. It will just take some time. (This update took me 3 days to write 
)
Spektrum - How-to Speedily Scan RF Noise in band 24MHz ~ 1800MHz
The results of scans are below:
The scan 1 shows RF noise picked by antenna and processed without any filter , The scans 2 & 3 were done with filters, and show how filters remove this noise.
Scan 1 of 3 - FA Antenna + Generic DVB-T (no internal or external filter)
CLICK ON IMAGE TO SEE LARGER SIZE
Scan 2 of 3 - FA Antenna + ProStick Plus (Only Internal filter of ProStick Plus. No External filter)
CLICK ON IMAGE TO SEE LARGER SIZE
Scan 3 of 3 - FA Antenna + ProStick Plus (with internal filter) + External Filter (FA Light Blue)
CLICK ON IMAGE TO SEE LARGER SIZE
2 Likes
Hello All,
I am still struggling and getting more and more frustrated. Still reading as much as possible and taking in all the comments in this thread.
I am still not having the FA filter and have not been able to check what @abcd567 suggested.
Even my Aircraft seen is dopping. But noticed this:
Fewer planes and still more or less the same message rate.
Undoubtedly there will be an explanation, but I can find it or think of it.
Perhaps I am asking too much or you guys are getting annoyed, so please forgive my asking.
My settings
Airspy mini
Jetvision A3 Antenna
Gain 18
OPTIONS= -v -f 1 -e 11
Uputronics powered by Mini USB to my Pi4
Please forgive my rambling 
PoP your graphs1090 up it will explain a little more
If it helps, these are mine with similar number of aircraft. The only difference is the Vinnant antenna, but i get the same results with the A3.
You should not look on the total number, but filter on ADS-B. This is the dark blue line in the Aircraft charts
I have filtered on ADS_B only, while making the screenshots of the messages rate.
Anything is depending on the number of aircraft in the sky. I have falling numbers as well, there have been some pretty bad days for GA aviation in NL. First thunderstorms, yesterday and today high winds. A lot of aircraft you pick up is related to GA, on average I have 1500 adsb aircraft on a day. In comparison, last week I had 2000. GA is on average 25-35 % of all air traffic in NL. If I look at hits, I sometimes have a drop of 40-50 % if there is little GA activity. So ride it out, there isn’t much you can do other then making sure everything is connected well and that you are recieving. I’m sure sunny days will come and then you will see a rise in aircraft numbers and hits again. It is still a hobby, don’t let it frustrate you 
I think his question is more related why the message rate dropped while the amount of aircraft did not change.
In my region Tuesday is the lowest traffic day and then continously increasing to the weekend.
If you follow the thread, he had a significant drop in message rate without explanation.
@Dutchyb
Looking on your FA stats you have a drop some days ago. I stated already it could be a weather change. As you’re close to AMS, maybe you’re impacted by the approach direction as i am in FRA.
I would wait until the weather condition changes again.
For FRA there is a “Betriebsrichtungprognose” available which gives you a forecast from which direction the aircraft are coming in the next days
Not sure if something is available for AMS as well and how much impact they have based on weather
https://www.umwelthaus.org/fluglaerm/anwendungen-service/betriebsrichtungsprognose/
Ok will try to be patient and wait. And of course will check out the link you provided
https://flightaware.com/adsb/stats/user/tomvdhorst
If you look at my stats, then you can see similar drops that are actually related to the weather
I have 4 separate feeders, and all show the same behaviour. The number of hits is variable, the aircraft count is on average the same
Have you already used https://antennekaart.nl/ for checking the distance from your antenna to the nearest cell phone towers using the 950MHz band?
I have one at less than 200m and when I added a 1090MHz cavity filter between my antenna and the LNA the message rate and number of flights increased by 30%!
Thank you for the link. Did not know it I could check it myself. Pff, knew there were “some” in my neighbourhood, but that many. Name it, and it is there.
Guess will have to look for an extra cavity filter.
Saw one in the Jetvision shop for Euro 196!!!
If you buy the flightaware filter it will be 30 euro’s
I know, but I am getting frustrated, because I don’t understand why the number of messages is more or less the same while the number of planes I see at a certain moment is a lot more.
I know the GA’s are giving me more hits.
Thank you for the link to SOSSolutions 
, ordered my Uputronics there
This is the first one I bought:
sysmocom site - 1090 MHz cavity filter for Mode-S / ADS-B
I also have a custom built filter made by a Dutch radioamateur:
Bert Modderman PE1RKI
Compared to saw filters cavity filters have much lower insertion loss and the attenuation for out of band signals is much better.
1 Like
Read this on his website:
1090MHz interdigital filters.
I can make filters for 1090mhz with different specifications.
a 40mhz wide 4 pole filter is 50db down on 1230 mhz and 950mhz.
± 0.6db loss on 1090mhz.
price 110 euro,the case is 138mm long.
Compared to the FA filter, a little bit more
But for that price you have something looking very cool!
2 Likes
Too good to hide it in the attic
It has been a while since I started this thread.
In the mean time I purchased the FA SAW filter, as suggested here in the thread
Updated the Airspy with the latest @prog and @wiedehopf
When I put my new dark blue FA SAW filter before my Uptronics filter the message rates drop around 200/sec.
The drops are visible in the graphs.
I do live near all kinds of cell towers and as suggested here that might have a huge influence on my message rates and positions. Perhaps I am doing something wrong, but if someone could explain or help me, it is highly appreciated.
