FlightAware Discussions

Computer and LED impacts on Planes seen

Just curious. My wife recently moved here work from office to the upstairs bedroom temporarily where I have my stuff set up. I noticed lately a cliff drop ioff as soon as she puts the LED lamps on in the room and fires up her laptop and 2 monitors. Lamps and here are lcated about 10 feet from the antenna could her stuff cause that much of hit on planes seen.

Probably the LED bulbs - some are notorious for generating RF interference.

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I have the same thing happen with a setup in our bedroom. When the TV is on the number of aircraft drops dramatically. It is just interference from the TV. LEDs and Laptops are also known to give off various amounts of interference.

You can clearly see when the TV was turned on in these graphs

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Radio frequency interference (RFI) may not be at 1090 or 978 MHz, but reside elsewhere and be simply overloading the USB receiver. If you have a bandpass filter, e.g. the $15 FlightAware “Dual 978 MHz + 1090 MHz Band-Pass SMA Filter”, try placing it before your USB receiver. If you use an external preamp, place the filter before that, as it may be overloading.

If you use a FlightAware Pro Stick Plus with internal 1090 MHz SAW filter, note that the built-in preamp is located before the SAW filter, so it is susceptible to overload from a strong out-of-band signal.

By process of elimination you should be able to determine the offending device(s). RFI can be radiated from a device itself or be conducted through its cables, e.g. power, video, network, USB, etc. For conducted emissions, a filter or filters can be applied to the offending device cable(s). A good resource is http://www.arrl.org/radio-frequency-interference-rfi

Thanks for the detailed feedback I have the blue dongle from flightaware. Process of elimination put it at the laptop. LED bulbs had little impact but turned laptop and 2 monitors off and resumption of normal plane tracking. Thankfully she will be using that room for only 3 more weeks before moving abck to her old place downstairs.

Putting Ferrite cores on the USB and power leads may help.
Also putting the RPI and dongle in a metal case could also reduce the impact of noise.
https://www.rtl-sdr.com/buy-rtl-sdr-dvb-t-dongles/

If using thin coax then upgraded to one with better shielding may also help.

HDMI is a real killer of ADS-B reception, many badly shielded cables going around that produce broadband interference with plenty of signal strenght at 1090 MHz.

I interesting its HDMI from monitor to usb C port on laptop. Its amazing the steep cliff drop off tried adding a flight aware filter in front of the flightaware blue dongle original version no help. I use RG-6 quad shield cable

Im on the same floor on the loft but 10 feet farther away with 5 monitors and 2 laptops for my work from home space and have no issues hen my stuff is up and running.

So the shielding doesn’t matter if it couples into the antenna.

And a filter won’t matter either because the interference is present on the frequency you’re trying to receive.

Distance to the antenna will be a deciding factor.

So this could be either distance or just better HDMI cables.

(1) Determine the frequency & intensity of RF interference caused by interfering device. This can be speedily done by running following scan twice: once with device OFF, next with device ON.

This scan is wide band (24 Mhz ~ 1800 Mhz), but pretty fast, takes only five minutes.

Spektrum - How-to Speedily Scan RF Noise in band 24MHz ~ 1800MHz

 

(2) Add a FA Filter just before the ProStick Plus.

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The popular dual band FA filter could be too broad (980MHz - 1150MHz) for this. A narrowband (15MHz) filter was able to reduce noise from my USB C-HDMI adapter by 6 dB (1090 MHz interference from HDMI adapter? - #8 by whacky).

This is not 15 MHz Bandwidth, it is 1090±15MHz i.e. total 30 MHz Bandwidth

 

What about the FA Dark Blue Filter, which has narrower band width 1090±10 MHz (1080MHz - 1100MHz)

 

image

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Thanks for all the great ideas. I currently use the Blue Flightaware for the last couple of years and the orginal flightaware cyclyndrical 1090 mode S filter and that one does nothing. I havent installed that spektrum yet.

Installed spektrum and it finds but then gives error saying it cant iopen it

Not clear what the two “it” mean.
The software spektrum does not open, or spektrum opens but it cant open the dongle?

You are right I should have been clearer about ±15 MHz. (Its marking and marketing simply denote 15 MHz, which is allowable in some contexts but misleading in most.) I wish I came upon the ±10 MHz one. (Is there a US seller for that, too?) At similar insertion loss, the narrower bandpass should give better results.

I wish the FA Dark Blue Filter was available in the US. Buying from Pi Hut triples the cost when shipping is included.

For the kind attention of @esmathews and @ericcarlson

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You are right. This is one of the most common tricks used by sellers on ebay & amazon.

If you see the description, it just says 15Mhz, and not ±15MHz. However when one takes the trouble to scroll down all the way through long list of advertisements of similar products, at bottom he finds the correct details. Please see screenshots below

 

 

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