Signal interference from radio towers?

[bheiser1]

I’m not familiar with the various types of antennas and the types of signals they broadcast. I’ve “heard” in forums etc that some kinds of signals can interfere with drone operation (controller signal, etc). How close does one need to get to towers for this to be a risk?

I have no intention of getting close to any towers, but wonder how far away is far enough? For this photo (with severe crop, hence it being so soft) I was probably 1/4 - 1/2 mile away. Is that too close?

Again, I have no intention of “buzzing the tower”, just wondering for general knowledge while I look for places to fly.

 

[dirkclod]

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[BlindRaven]

Mavic drones operate on a frequency 2.4 GHz to 2.483, a frequency the FCC dedicates to this type of application (RC devices) and radio towers use a much higher frequency usually meaning there is no interference.

I myself flew within about 300 feet of a radio tower that transmitted 4G wireless as well as nautical radio frequencies. The drone was fine in these conditions, and yours should function without interference.

 

[bumper]

Radio Frequency Interferance (RFI) does not have to be on or near the frequency in use to cause problems. The controlller and drone signals are low strength, flying near a strong signal source can overwhelm the drone receiver's input, reducing or shutting down receiver gain.

 

[bheiser1]

Thanks! I forgot to mention, I’m flying a Mavic 2 Pro with the SC.

 

[Camino Ken]

The simplistic answer to your question in general is that you shouldn’t have a problem as long as you are not too close. This statement comes with a ton of caveats. I agree with bumper’s comment it is probably more about the signal strength of the interference than the frequency. Below is something I wrote and posted a while ago.

“The Mavic 2 uses Occusync 2.0 which utilizes OFDM for video and FHSS for data. Both of these very robust transmission architectures that are inherently relatively immune to interference problems. In addition, they are packet based systems. If a data packet get corrupted it just gets re-transmitted. The biggest concern for interference is from competing larger amplitude RF signals in the same spectrum (WiFi, cellular, etc) which have the potential to overwhelm the receiver input circuitry, effectively blocking the transmission.”

So the question is how big of a signal (and therefore how close) can you get from a transmission tower to have a problem. Unfortunately, There is no easy answer. I have not seen any rigorous testing or data yet. We do know that with most pole antennas the signal strength decreases with the square of the distance (many exceptions to this). This means that the signal is one hundred times stronger at 10ft versus 100ft distance. Since I have seen a handful of videos filming at a distance of a few hundred feet or so it seems like that distance is OK (not very scientific). Closer than that gets exponentially more risky. The distance from the controller to the aircraft will have a bearing as well. The last point is the radiation pattern of the actual antenna. Pole antenna radiate in a doughnut shape with the strongest signal parallel to the long dimension and the weakest at the ends. This means that you can probably get much closer directly above than on the side before you have a problem.

i would be very careful around large dish antennas. If it’s only a receiver it’s not a problem but if it is a transmitter the focused beam can be a very strong signal.

Bottom line is the closer you are the greater the risk. Fly with caution.

 

[fuzzball]

M2P flew just fine in a couple of my upcoming videos...

 

[FoxhallGH]

As you can see from the photographs posted above, there are different types of antenna's on the masts, depending on what type of 'radio' service the mast is doing. The antenna's to be most cautious around, are the ones that look like 'drums' ... These are shrouded parabolic dishes designed to push RF energy in one direction - just like the reflector dish in a flashlight makes a beam. If you put your drone in that RF 'beam' then irrespective of the frequency of the service, the RF electromagnetic field can induce excessive currents in the drones electronic components - which at best can cause spurious or erroneous control inputs, or at worst fry components and/or chip-sets.

 

[bheiser1]

Thanks for the input on this, everyone. Good to know!

 

[Rchawks]

Will 5 G towers be any different?

 

[fuzzball]

Here's a link in my description of the tower videos I've done...(not posted yet but in the unlisted section for processing to 4k)

A Field Guide To The North American Communications Tower

The need for clear and reliable communication has driven technology forward for centuries. The longer communication’s reach, the smaller the world becomes. When it comes to cell phones, seaml…

bit.ly

 

[harle83]

Radio Frequency Interferance (RFI) does not have to be on or near the frequency in use to cause problems. The controlller and drone signals are low strength, flying near a strong signal source can overwhelm the drone receiver's input, reducing or shutting down receiver gain.

I am a Ham (K9HDT) RF is a regular part of daily life for me. You’d be surprised what it can sneak in to if you don’t take proper precautions. That said there’s nothing in the World like an RF Burn. One time is all it takes to make sure you never want it to happen again. It’s really hard with towers because you usually don’t know the frequencies or the output of the tower. I know a radio tower in SE Missouri that is still a 100,000 watts of FM Power, get close and you will either lose contact with your drone or it may scramble the internals and drop like dead weight to the ground. If you get to close to any tower without proper shielding it can happen regardless. There’s a pair of towers I’ve seen traveling through Tennesse, 2 50,000 watt blow torches on shortwave and I’ve seen reports of drones just dropping when a pilot got within an 8th of a mile. Cell towers with the new 5G standard are still an unknown, at least I’ve seen no reports or evidence on them yet. I do know the frequencies broadcast are so high that I’m not real fond of having one close. Kinda makes me want that tinfoil hat. I’m hoping what comes out is good creditable evidence on them but I don’t know much study wise. The one set of pics from above show Verizon Antennas closely. I’ve really never heard of many issues with them. I do know so T-Mobile ones have had “issues” before. I’ve not been able to find a lot other than people complain out 4G interference and that’s not even proven. So I love the things, I worked in Radio my entire life til retirement on air and most of the time the transmitter sites were right at the station and we have 3 “normal” millennials with 5 Grandkids so all good for now. I just lost most of my hearing because I played music loader and louder and talking with folks. I didnt realize until I was 48 that I had a problem. 57 now and good. Have fun and Happy New Year!

 

[driver4591]

Harle83 is spot on here and most HAMS and RADIO TECHS would know that yes radio towers and or transmitter stations and repeaters can produce front end RF saturation on othersurrounding devices.

 

[Fullmetalrush]

I’m not familiar with the various types of antennas and the types of signals they broadcast. I’ve “heard” in forums etc that some kinds of signals can interfere with drone operation (controller signal, etc). How close does one need to get to towers for this to be a risk?

I have no intention of getting close to any towers, but wonder how far away is far enough? For this photo (with severe crop, hence it being so soft) I was probably 1/4 - 1/2 mile away. Is that too close?

Again, I have no intention of “buzzing the tower”, just wondering for general knowledge while I look for places to fly.

View attachment 89175

I currently inspect celltowers and around 26 feet on average from the antennas and closer is usually when you will start having issues. Not all towers have given me issues, however some towers have lots of interference. The issues that are usually faced have to due with the drones rtk and gps systems. Best to fly manually with no auto flights that use gps around towers with interference. Ive had towers that seem fine but then due to the gps the drone would think you need to be closer or further away from the tower and would pull your drone to that spot.

 

[Felix le Chat]

High power R.F broadcast signals can cause problems with the operation of aerial vehicles reliant on sophisticated micro-electronics for communications and control, the radio link between the drone and the controller can experience disruption or attenuation, but the level of attenuation depends on:

a) Whether the transmitter mast/array is actively transmitting.
b) What frequency or frequencies it is transmitting on.
c) The power of the transmission.

The level of RF interference/disruption/outright failure varies according to the radio frequency the attenuating signals are broadcast on.

At 400mHz: signal attenuation is measured at +6db.

Between 1gHz and 18gHz signal attenuation doubles and is measured at +12db.


HIRT (High Intensity Radio Transmission) is defined as radio frequency transmissions that can and do attenuate (interfere with, or disrupt) R.F communications equipment installed in aircraft. This attenuation also affects both wired and wireless command and control equipment. From the late 1970’s, HIRT was recognised as posing a growing threat to the safe operation of aircraft which were being constructed using increasing quantities of composite materials and which were increasingly reliant on solid-state electronic systems for flight control and communications. (Sound familiar?)

Non-military High Intensity Radio Transmission Areas are clearly marked on the UK NATS VFR charts which are published to advise owners and operators of both light and commercial aircraft. These HIRT areas define where powerful conventional Radio Frequency and microwave transmitter masts and arrays are located, which are the geographic locales where this kind of EM Interference is most likely to be experienced.

Tests conducted on both conventional and military aircraft (1988-present) which have high levels of composite materials included in their airframe construction show that these aircraft are the most susceptible to HIRT interference with communications equipment and avionics control components being the most vulnerable, but command and control circuits and wiring looms also show the potential for being significantly disrupted by induction.

Military aircraft operators currently adopt a mitigation strategy of avoid. Pilots actively steer clear of areas marked as HIRTA on military and civil flight charts.

Commercial aircraft adopt a mitigation strategy of shield. These aircraft have been manufactured with increasing levels of electronic shielding built into the airframe and control/communications equipment because commercial aircraft flight paths inevitably intersect with a significant number of HIRT sites, which are transmitter masts and microwave arrays dedicated to live commercial broadcast and general communications frequencies - usually located in proximity to urban and city areas.

All currently published Air Force and Aviation Authority whitepapers written concerning HIRT (British and American since 1988) determine that both commercial civil and military aircraft require specific shielding.

 

[DeonDj]

I live next to a 5 G cell tower, at 1st I was a bit scared but nou I fly around it, over it, near it, BUt there is a microvave dish, a big one in a northern direction, if I fly same hight as it even a 100 meter out it takes the signal away and the screen goes black and white and rth is started. but further on I can fly around it I must just not cross the line to other tower with the microvawe dish thing.