An observation at the second pic, at “maximum range case-1”. See that there is a distance (at the antenna’s horizon) where even small obstacles obscure some the reaching distance, due to geometry. Usually the distances are much more different in ratio (in my case is 250:9 miles), so the pic doesn’t show the whole aspect.
It is maybe worth to raise slightly more the antenna than just the closest obstacles; but I agree, there will be diminishing returns.
BTW, I find this calculator very useful, to find quickly the distances to horizon or line of sight.
sorry i couldnt get back to you guys yesterday…i exceeded the post for the day. I went back and redownloaded rtlpan.exe and it works fine, i guess the first time i downloaded it, i didnt get all the file. I only got a 39kb file so i had to redown it. I still couldnt get it to work on win 10 and i followed the link evangelyul posted and i didnt see nothing on there either to fix it. I made a scan.csv file in the folder but it didnt help so now i copied the 3 files from the x64 folder and it seems to be working for now
I have been reading this full thread and I really need some advise to get rid of some noise in my set-up, which is located in Europe approximately 5 NM from an international airport:
FlightAware 66cm antenna
FlightAware Pro Stick Plus
FlightAware 1090MHz Band-pass Filter
CLF200 cable, 1 meter
Elevation of the antenna is approximately 30 meters and it is in a high density urban area with cell towers near by. Besides that it is next to a large police station with a lot of antennas on the roof for emergency communication.
As you can see below the external filter does a pretty god job at getting rid of noise in the 800 - 850 MHz, 900 MHz, 1060 MHz and 1110 MHz spectrum, but even with this filter there is significant noise in the 930 - 960 MHz spectrum:
The blue dongle has a SAW filter after the low noise amplifier so with some help from the bandpass filter it’s quite similar to some of amps with saw filters.
So right now your filter chain looks like this:
bandpass filter → LNA → SAW
Another option is the RTL-SDR BLOG 1090 MHZ ADS-B LNA.
SAW filters have high attenuation so they optimally need a LNA to compensate the loss.
So you will basically only see SAW filters after LNAs. The RTL-SDR amp/filter does this twice, the filter chain is:
high pass filter → LNA → SAW → LNA → SAW
This is a great thread explaining some filters but it’s quite technical.
If you can live with the Bias T inconvenience, the RTL-SDR Blog pre-amp and filter combo is a tremendous value. I have one, and would not think twice about buying a second one when the need arises.
A filter has one problem - there are no capacitors at the input of the signal and the output of the signal. Ccapacitors protect the SAW from damage by D.C.
Well… it works, using it right now to feed two devices (spliter). I had to lower gain a lot because both my tuners have amps inside - one FA orange and one blue (I’m at gain 12dB now).
Does it make a difference? A little. But I still want to raise my antenna more…
FA antenna, FA Pro Stick Plus and FA ADSB filter tests
spectrum without ADSB filter…the signals around 860Mhz are the local police and emergency services that run APCO P25 Phase 1 and their antenna is about 3 miles from my house. The signals around 960Mhz are pagers from local hospitals