Help requested with outdoor setup with poor reception

Exactly the same as what?

My assumption: Orange + External Filter would be equal to Blue. This is not the case.

Quoting https://flightaware.com/adsb/prostick/
“Only $20.95. Over 40% cheaper than a Pro Stick and FlightAware external filter”

The above statement is misleading and suggests that The Pro Plus stick has the same functionality. So now I have and more expensive sticks, and have to buy external filters, and I have to get back to the site. This is just not nice.

Thanks for the tip. These are the results of the scan (note: image below doesn’t have PPM correction). The antenna used here is next to all the cables going to the transmitter 105MHz/190MHz, straight above it.

Regarding to shielding. Would you have any tips? I am currently running a scan on both devices simultaneously, including PPM correction. Might also give interesting results.

You don’t have to change anything.You have all what is wanted to have a good ads-b receiver. Just change the location. As I see other transmitting antennas,bumper to bumper filtering won’t help.

These kind of comments don’t help. There is a problem with radiation, so in V/m how much distance needs to be separated to get the SNR that is required for this kind of setup to work at this height. Because changing location sounds easy, especially if it is a few meters. But changing rooftop will not really help if it is GSM/LTE that is the cause of the problems.

As I wrote in my initial post: I have a non-horizon location that works flawlessly. The whole optimisation to add height was to improve on that.

the ppm correction has nearly zero evidence to ads-b - so forget about this item. your scan looks extremly ‘loud’ - what was your gain setting? as you have very strong signals at 960mhz (cellphone downstream) the external flightaware filter is worth nothing to solve your problems. you can try to move the ads-b antenna on the roof away from the transmitters and use a real good filter e.g. the 3-pole(cavity) i mentioned above. moreover i’d go for an unamped and unfiltered dongle.

=> 3-pole filter → lna → dongle

p.s. what dongle did you use for the scan?

p.p.s maybe this thread is helpful in your situation: The Final Filter Shootout

Chinese (indoor)
Dongle is the typically blue one.
rtl_power -p 61 -d 1 -f 800M:1200M:100k -i 30 -c 50% -e 30m -g 30 -F 9 > scan.csv
Found 2 device(s):
0: Realtek, RTL2832U, SN: 00001000
1: Realtek, RTL2838UHIDIR, SN: 00000001

Using device 1: Generic RTL2832U OEM
Number of frequency hops: 286
Dongle bandwidth: 2797202Hz
Downsampling by: 1x
Cropping by: 50.00%
Total FFT bins: 9152
Logged FFT bins: 4576
FFT bin size: 87412.56Hz
Buffer size: 16384 bytes (2.93ms)
Reporting every 30 seconds
Found Rafael Micro R820T tuner
Tuner gain set to 29.70 dB.
Tuner error set to 61 ppm.
Exact sample rate is: 2797202.148434 Hz

Flightaware (outdoor)
rtl_power -p 0 -d 0 -f 800M:1200M:100k -i 30 -c 50% -e 30m -g 30 -F 9 > scan-piware.csv
Found 2 device(s):
0: Realtek, RTL2832U, SN: 00001000
1: Realtek, RTL2838UHIDIR, SN: 00000001

Using device 0: Generic RTL2832U
Number of frequency hops: 286
Dongle bandwidth: 2797202Hz
Downsampling by: 1x
Cropping by: 50.00%
Total FFT bins: 9152
Logged FFT bins: 4576
FFT bin size: 87412.56Hz
Buffer size: 16384 bytes (2.93ms)
Reporting every 30 seconds
Found Rafael Micro R820T tuner
Tuner gain set to 29.70 dB.
Exact sample rate is: 2797202.148434 Hz

(hope I have answered all your questions)

please make the same scan again but change the dongles: flightaware indoor - and generic blue outdoor

p.s. the outdoor scan is really extreme

Sadly can’t change it now for two reasons;

  1. The chinese one is mcx, the flightaware is sma
  2. I am not at the location.

I could replace the Flightware stick with something like a NoElec SmartSDR. So I’ll receive the external filter hopefully tomorrow, so I will have enough goodies to do a test.

Entirely correct. RF is hard. As the page warns: Filtering benefits may vary and are dependent on the installation location. You have a somewhat unusual installation, most users aren’t installing right next to a transmitter.

Also that page does say (under “setup and tuning” in the Blue/Plus column)

Most users will not need an external 1090 MHz filter, however in very high RF environments users may still benefit from an external 1090 MHz bandpass filter.

I don’t know what else we can really say here. You’re in a very high RF environment, you’ll benefit from an external filter.

:astonished: :open_mouth: Abundant RF on roof top. You need a really good Filter, but first try shielding Dongle+Pi by wrapping the Dongle and Pi in an aluminum or copper coated plastic tape or something similar. This may considerably reduce the RF.

Nah, if this doesn’t work. I’ll build some sort of harmonic resonator and go in the energy harvesting business[/sarcasm]

@abcd567 Both dongles are next to each other. I don’t think the isolation indoor is going to help.

Could you please add something like: The difference with an external filter is that the external filter would filter before the gain is applied, which might help in a very high RF environment. Hence not suggest it is cheaper and has the design. I was honestly thinking that the blue stick was sma-connector => (filter => receiver). It would be good to prevent these kind of mistakes.

Sure, it probably makes sense to expand the description for expert users. Note that it’s a different filter too. I don’t think we’re implying that we’ve somehow hidden the whole external filter inside the dongle - they are different devices! - but maybe that needs spelling out explicitly.

Call me stupid and naive, but I was actually thinking some LC-circuit-magic was done inside the stick, and could be kept small.

No, it’s a completely different filter (a SAW) on the prostickplus. I don’t think there’s space on the board for much of a LC ladder.

Use a shield,a thinner shield may be more effective than a thicker one, since its ability to attenuate is determined in part by the wavelength of the radiation.

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your location is very demanding. most filters because of their high passband attenuation must be placed behind lna. the flightaware external filter attenuates the 1090 signal and 960mhz cellphone about the same amount (see graphs below) - and because of that behavior is a bad choice in most noisy environments outside the us. uputronics saw-filter-lna + generic dongle has much less problems in noisy environments than amped flightaware dongles.

trial and error is the way to go with high-frequency-things - so - again:

  • try using the uputronics saw-filter-lna with generic dongle
  • if noise then is still too high add the jetvision 3-pole filter in front
  • use a quality cable for antenna-run
  • in addition you can give a metal case for pi and/or dongle a try

i’m curious about your follow-up scans with the alternative dongle setup …

flightaware external filter @ 960 mhz ~ 2.0db attenuation:
51Uz9SIsLbL

flightaware external filter @ 1090 mhz = 1.65db attenuation:
51tMAQg66BL

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abcd - that’s not a good idea - this saw filter has too much paasband attenuation to place it in front of lna