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Sep 06, 2019, 08:29 PM
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ddesalv's Avatar
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Digital signal jamming

We are located in central New York.
Last year late August we began losing nitro airplanes due to black out. From Oct- mid August we were event free.
The black-out began mid August this year. Our club flies most every night during the summer. Electric, Nitro and Gas.

Typically one area of the field but this year is has expanded.
Gassers, electric ignition shuts down engine abruptly ,
Electric, If passing through quickly motor stops and then comes back.
Electric, heading into signal loss servos spike. all servos effected. Same outcome each time. Ailerons full right or left elevator full up or down rudder full left or right. No matter what altitude results are the same. Complete loss. At 200' still no chance for recovery. Unresponsive to any input.
Nitro Same as electric. We use LiFe, NiMh, NiCad. Receiver packs slow charge or trickle.

Radios: Spektrum, Futaba, FrySky Receivers Spektrum, Orange, Lemon all with Satellite on each type. DSMX, DSM2 AS3X
Range check every flight at different locations. No help.

Our beautiful field is highly desirable due to location and size. We are on a main highway 100' off the road. The nearest tree line is 500.' away.
We due have neighbors, none have ever complained in anyway.

I have read articles about digital swamping and Jamming. 2.4 seamed bullet proof until I kept reading. So many everyday items disrupt digital signal.
Our Vise president sold all of his planes after crashing many due to this situation. I am the President but will not fly there anymore.

THE ONE BIG QUESTION: Is there any way to locate or identify a jammer or other types of digital interference? It is not all the time .
I understand the penalty for jamming digital signal carries serious fine. The units are available on amazon reasonably priced. That should be illegal to sell these items. Who besides terrorist would need to jam a digital signal?
Swamping does not seem to be the culprit. Our airplanes are set up with failsafes for brownouts.

16 planes in 1 year.
We are all skilled pilots
All events have been cancelled
field is closing early this year. It has become too dangerous because we are close to the road.
Hopefully next year will give better results to identify the cause.
We barley escaped solar panels taking our field. This is an enemy we can not see.

Last year we researched all of the area antennas, wattage and signal. None raised alarms. They had proper licenses.
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Sep 06, 2019, 11:05 PM
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Do you know someone that works in two way radio or a cell site tech that would have access to a spectrum analyzer? A locate ham operator or ham club might also help. There is all kinds of unlicensed RF around 2.4, Wi-Fi, Lynx T1 microwave, and Bluetooth etc, good luck
Last edited by longone; Sep 06, 2019 at 11:20 PM.
Sep 06, 2019, 11:25 PM
If it flies, I can crash it.
rocketsled666's Avatar
Buy an RF Explorer with the 2.4GHz option and get yourself a high gain narrow aspect unidirectional antenna, like a many-turn helical. Then you can sweep the 2.4GHz band for energy of any kind, and the directionality of the antenna will help you localize the source.

I've used this trick with the 5.8GHz option to find an FPV quad lost in the tall grass. I've got the 2.4GHz deck too. I rarely use it, but it works about as you'd expect and tells me if there's anything broadcasting on the band. See's my Spektrum TX, finds my old land-line cordless phone when I power that up...
Oct 06, 2019, 08:58 AM
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AndyOne's Avatar
Radio Hams are allowed to operate legally on 2.4GHz although they may not operate on exactly the same frequencies, at 1kW ERP they don't need to to totally wipe out a R/C signal anywhere near.
Oct 06, 2019, 11:28 AM
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AA5BY's Avatar
I'm searching the back of my memory, and thought I recall FR Sky had a built in spectrum analysis function. If a signal can be detected... it might be possible by pointing the antenna to get a null position directly off the end to direction find a signal.

It would be crude however without having attenuation ability to reduce the signal level to a point where signal strength is measurable or notable.
Oct 07, 2019, 12:08 AM
Registered User
I used to fly at Baylands park in Santa Clara, CA. It is between Moffett field and a contractor. They would broadcast between the facilities. It would swamp all aircraft in the park. A tech worker that flew there used a spectrum analyzer and a directional antenna to find the source. After contact with the base the answer was they would broadcast at anytime and would not notify anyone when they would do it.
Oct 07, 2019, 01:48 PM
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vulturetec's Avatar
Originally Posted by ddesalv
The units are available on amazon reasonably priced. That should be illegal to sell these items. Who besides terrorist would need to jam a digital signal?
It is illegal. In the US you cannot operate, sell, or market (ie: advertise) jamming equipment. I can't find anything like what you're describing advertised on Amazon US, but no doubt they're available from foreign sellers on eBay.

If your investigations results with what appears to be a true "jammer" then turn it over to the FCC. They do take it seriously and may help (you can search for actions against jammer by the FCC here).

Some thoughts though: alternatives are to go back to 72mhz (or 53mhz - even 440mhz - if you have/get your ham ticket), or 900mhz. For FrSky users switching to 900mhz is as simple as getting a module and receiver. With the history of apparent RF problems at the site it would be worthwhile getting someone to survey the area with a spectrum analyzer on those bands too though.
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Dec 10, 2019, 06:52 AM
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ddesalv's Avatar
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Digital black-outs

Thank you for all the great advice. After searching several leads we have failed to find a qualified digital signal professional.
We have lost all of our regular members that would fly consistently. 74 members 2 years ago, 54 this year. And unfortunately our field is being closed due to lack of general care and maintenance until this issue is solved. This location has been open for 5 years, moved from Geneva which was open for 30+ years.
With my amateur digital spectrum analyzer I have located one tower a mile away that was registered in 2017 and pushes 40 Watts. This could very well be the culprit that would have to be taken up with the town board but I have exhausted my resources.
FCC has offered no support or information regarding this matter.
WiFi is a strong signal across our southern end of the the airfield. Does not seem to be significant in causing black outs.

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