The easiest solution for such interference is a good Cavity Filter.
Recent new ADS-B Raspberry Pi 3+ Dump1090-FA build using the Blue Flightaware Pro dongle. I have been successful setting up the station and getting some tracking results but really just getting my feet wet. Still waiting on the rest of my bits and bobs to arrive, so made a 1/4 wave spider and even tried building a Co-linear ( not a complete failure but not as good as my spider so farā¦) I have been reading a ton of info over the past week and decided to set up RTLPLAN on WIndows to check on filter needs. As I suspected Iām picking up a lot of Cell noise but also seem to have a fairly strong signal hitting me around 1150-1160MHz, nearly as strong as the Cell bands in the 850-900MHz region. Does anyone know what could be hitting me at that freq ?
Sadly my 1090MHz signal is barely visible on the scan.
Recently I had fired up HDSDR control program and used three different set ups to see what I can get or see on or near 1090 MHZ. My location there is a cell tower that is approx. 1/4 mile from my house. No near by TV, FM or AM broad cast station or VHF/UHF base station antennas. Pro Stick plus had no interference shown. My RTl-SDR.com V3 with wideband LNA and FA filter, same results, nothing but ADSB signals. My other RTL-SDR.com V3 dongle hooked to VHF multiband antenna, small amounts of interference and decent ADSB signals. I live in a neighborhood and my house has multiple cellphones, two desktop computers, tablets and game consoles. I figured that interference would be great. Also every day its 95 degrees here in Texas and every one has air conditioning running so that makes a great amount of RF noise, at HF levels. At 1090, very little interference. The best thing to do is hook up a dongle to your computer, install and configure HDSDR and see if you have RF noise issues at your location.
Thanks for the thoughts.
Out of curiosity I installed HDSDR as you suggested, which more clearly displays the 1090MHz signal being received by the Pro plus dongle. It is weak, but it is there.
Something audible is stepping on the signal sporadically, but that is not a current worry, Iām more concerned with the relatively steady state competing offenders.
I am suffering from learning yet another piece of software in 5 days - is there a way to widen the bandwith on HDSDR to mirror the RTLSCAN parameters (eg 820-1200MHz) ? I want to compare the two and can only seem to get a rather narrow receive bandwith off of HDSDR onscreen.
Are you near an airport or radionavigation beacon? 1150-1160 MHz frequencies are used for TACAN. Tactical air navigation system - Wikipedia
Hi there- Iām approx 8 miles from KRDU- I am not aware of a NAV transmitter nearby but certainly possible there is one. Signal is quite strong and narrow, higher Db than the 900 MHz cell thatās hitting meā¦Iāll have to do some probing around to see if there is something out there. I am not right on the glide slope path or and planes seem turn on final to intersect it a few miles awayā¦
Strong signals relatively close to 1090 are a concern for me as my receiver is location challenged ( sloping terrain, high trees, cell, wifi)
ADS-b is all new to me so Iām in the process of learning that I still donāt know very much 
Try OPTION-3. It shows 1090Mhz signal more clearly, and has full range of 800 Mhz to 1200 MHz
OPTION-3: DVB-T plugged into Windows Computer - Using Command LIne
.
Using OPTION-3, got following scanned image:
(1) Full Scan (800-1200 MHz). The image is very large in width (4000px) and wont show details unless zoomed to full size.
Click on image below to see larger size.
Click again to see full size
In full size mode, scroll right to see the entire width of the image
.
(2) A 500 px cutout from above full scan 4000px image. This cutout clearly shows 1090 MHz signal
Thanks- will give that a shot. Already used your Option 2 rtlpano and that showed some good info, but more detail would be great.
Iām thankful for all the how-tos and documentation folks here have shared or Iād be very lost ! Back to study mode on yet more softwareā¦
Regards
You have very strong signals in Cell/Mobile phoneās GSM850 and EGSM-900 bands. Please see below the cutouts I have made from your scan.
Most likely you need a filter and performance is very likely to improve if you add a Filter.
GSM850
.
E-GSM900
@abcd567, hello! Thank you for response. Could you please help me to make a choice between New Product: RTL-SDR Blog 1090 MHz ADS-B LNA and Ceramic 1090MHz ADS-B Filtered Preamp
or maybe you have a better proposal?
You did not ask me, but here it goes.
The Uptronics has a good reputation, but I do not/not have one.
I have the RTL-SDR blog unit, and Iām very happy with it. Itās a pre-amp and filter combo. But a āwarningā. It does not have a power in jack. It must be powered either by a dongle/receiver with bias T enabled, or a power inserter.
If all you need/want is a filter, consider the FA one.
There are other filters on eBay. Iām interested in one that claims 8MHz BW at -3 db.
Hi @Dxista
Please check my dump1090 web interface, 178.209.65.163/dump1090/gmap.html,
on several aircrafts you can see the dashed route line. This is because of unstable signal?
Noā¦it only means there was no data received from the plane during that period (dashed lines).
You can see that on commercial tracking sites as well. The easiest one to observe this is Planefinder.net . On Planefinder, it looks like data is received every 10 seconds.
There is a possibility that the signal is āborderlineā and not received/decoded properly. But the few planes I checked on your map would indicate the first reason.
I have not used any of the two filters you mentioned, so I cannot tell you anything about these.
I am using Flightawsre filter and happy with it. As it is not costly, you can try it and see to what extent it removes strong cell signals and gives how much improvement.
Since you have very strong E-GSM900 signal in 930 mhz ~ 960mhz, a good cavity filter will be more suitable, but since their cost is several times the cost of Flightaware filter, I do not recommend it to be tried first. You should go for it if low cost Flightaware filter does not reduce GSM850 and E-GSM900 signals to a sufficiently low level.
@abcd567 so, i need to install the FA filter, and run the scan again, to see if GSM signal remained?
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Itās a good experiment to have 2 different filters in series, say, the FA and the RTL-SDR blog filters, or the eBay ones.
I agree with @abcd567 about not spending a lot of money, specially in the beginning, unless money is not a problem.
In case of RTL-SDR Blog filter i need to install it as close as possible to antenna, which would require cutting the cable, and the installation of two SMA connectors. Also it requires bias-T power, which i donāt have, because of i use RTL2832 DVB-T receiverā¦
But in case of FA Filter, there is no need to put filter near the antenna?Isnāt it?
Ideally, but not absolutely necessary. Just look at the FA dongles, they have a pre-amp built-in, and they are not always installed at the antenna.
As for bias-T, you can use a power inserter. I purchased mine on eBay. This is the one Iām currently using:
Again, ideally yes, but not necessary. The important part is to do all the signal āhygieneā before it reaches the receiver.
Yes, that is what you should do.
Flightaware filter does NOT require power or Bias-T, and can be installed either at Antenna OR at Pi, directly connected to the dongle.