Question about GPS Interference

[TonyPHX]

I have a quick question and want to get input from others on your thoughts. Recently when taking real-estate images of a shopping complex, I found a very specific area where my M3 Pro reported loss of GPS. It happened each time I entered a very specific region of the complex and it happened at all heights from 60' to 350' AGL. The drone did not get to a switch over to ATTI mode. I had no attachments potentially blocking the GPS receiver of the drone. The stores in the area are not remarkable, so I'm just wondering - does anyone have any thoughts on what could be causing this type of hyper-local GPS interference?

I went back a week later, and same exact thing. And tried another drone (M3E, and then a Mini 4 Pro) and got the same behavior. Just kind of have this question in the back of my mind that won't go away since I had not see this before. Thanks! Diagram attached showing what I mean by specific area. The box in orange is very much exactly where the drone had severely degraded GPS count. Down to 4 I believe.

 

[Yorkshire_Pud]

Excluding thoughts of a deliberately installed jammer.
Just an 'off the top of my head' question
Could any form of malfunctioning or incorrectly installed electrical equipment or radio equipment emit EM that could interfere with the applicable frequency?

 

[Felix le Chat]

I have a quick question and want to get input from others on your thoughts. Recently when taking real-estate images of a shopping complex, I found a very specific area where my M3 Pro reported loss of GPS. It happened each time I entered a very specific region of the complex and it happened at all heights from 60' to 350' AGL. The drone did not get to a switch over to ATTI mode. I had no attachments potentially blocking the GPS receiver of the drone. The stores in the area are not remarkable, so I'm just wondering - does anyone have any thoughts on what could be causing this type of hyper-local GPS interference?

I went back a week later, and same exact thing. And tried another drone (M3E, and then a Mini 4 Pro) and got the same behavior. Just kind of have this question in the back of my mind that won't go away since I had not see this before. Thanks! Diagram attached showing what I mean by specific area. The box in orange is very much exactly where the drone had severely degraded GPS count. Down to 4 I believe.
View attachment 178172

Do you use an i-phone? Head back there and try to connect to one of the free WiFi networks in the shops, then try using the compass app and a GPS positioning app, or try programming a satnav to see what happens. If some form of interference disrupts hand held networking and vehicle positioning tools: the problem must lie with some kind of local installation.

 

[Cafguy]

I see all sorts of things that could cause your problem. metal, high-voltage lines, substations, I wonder if there used to be a bank or a banks substation inside that store? There would be extra metal decking and metal screening installed under the roof in that area during construction.

 

[Meta4]

I see all sorts of things that could cause your problem. metal, high-voltage lines, substations, I wonder if there used to be a bank or a banks substation inside that store? There would be extra metal decking and metal screening installed under the roof in that area during construction.

None of those things would make the slightest difference to GPS reception.

 

[Cafguy]

None of those things would make the slightest difference to GPS reception.

GPS interference can be caused by a number of factors, including:

Obstructions
Tall buildings, trees, tunnels, and mountains can block GPS signals from reaching the receiver. Obstructions can also reflect signals, which can degrade the accuracy of the data.

Multipath interference
When GPS signals reflect and scatter off buildings, vegetation, or other structures, it can take longer for a GPS device to acquire a fix.


Atmospheric conditions
Atmospheric conditions can alter throughout the day, and are most pronounced in the early morning or late afternoon.

Personal privacy devices
Uninformed personal privacy devices near airports can cause GPS jamming.

Receiver quality
The quality of the GPS receiver can affect the accuracy of GPS measurements. Higher quality GPS receivers tend to be more accurate.

Accidental interference
Communications signals operating close to GPS frequency bands can accidentally interfere with GPS.

Satellite geometry
The geometry of the satellites can affect the accuracy of GPS positioning. This effect is called Geometric Dilution of Precision (GDOP).

 

[Meta4]

GPS interference can be caused by a number of factors, including:

Obstructions
Tall buildings, trees, tunnels, and mountains can block GPS signals from reaching the receiver. Obstructions can also reflect signals, which can degrade the accuracy of the data.

Multipath interference
When GPS signals reflect and scatter off buildings, vegetation, or other structures, it can take longer for a GPS device to acquire a fix.


Atmospheric conditions
Atmospheric conditions can alter throughout the day, and are most pronounced in the early morning or late afternoon.

Personal privacy devices
Uninformed personal privacy devices near airports can cause GPS jamming.

Receiver quality
The quality of the GPS receiver can affect the accuracy of GPS measurements. Higher quality GPS receivers tend to be more accurate.

Accidental interference
Communications signals operating close to GPS frequency bands can accidentally interfere with GPS.

Satellite geometry
The geometry of the satellites can affect the accuracy of GPS positioning. This effect is called Geometric Dilution of Precision (GDOP).

So which of those are you suggesting is affecting his drone?
I'm thinking none of the above, just like the previous laundry list.

 

[Cafguy]

I would think that the communication equipment for frys or Ace hardware is under that area or antennas may be on the roof. If it used to be a bank...... well those are built with thicker decking and screening poured with the concrete to prevent using a torch to access thru the roof. so alot more metal on that part of the roof than others.

 

[Meta4]

I would think that the communication equipment for frys or Ace hardware is under that area or antennas may be on the roof.

You're just throwing out uninformed guesses.
It's not normal to have GPS disrupted the way the OP described.

If it used to be a bank...... well those are built with thicker decking and screening poured with the concrete to prevent using a torch to access thru the roof. so alot more metal on that part of the roof than others.

He's flying over the building, not inside it!

 

[Cafguy]

You're just throwing out uninformed guesses.

I sure am ! and that's what the op is asking for unless he is trying to get information on the construction of that exact building and its surroundings by reaching out to the various city planners, and engineers, thru a Drone forum.
I apologize but I cannot Drive to the Area in question and survey the Problem. have you priced gas in California?
Like everyone else besides the OP I will just have to guess. You can take a stab at it too. go for it.
You have not given us the "informed" answer, only the reasons I could be wrong.
Please enlighten the OP. he is looking for help not a debate between 2 people on GPS signals and the Physics involved.
Thanx all.
Back to the problem at hand.

 

[davidarmenb]

GPS is an electromagnetic radiation operating in the L-Band of the RF spectrum (around 1 to 2GHz). Like most electromagnetic radiation, radio waves can absolutely be disrupted by many things.

 

[hank970]

Just for grins, visit the site with a hand-held GPS receiver to see if you experience the same localized loss or corruption of signal. Maybe even park in several spots close to the structure to see if your automobile's navigation system (if so equipped) begins acting up.

 

[HoozierDroneDaddy]

That location is directly over a Western Union. Is it possible they have communication equipment causing the issue.

FWI, If you go to Google Earth you can see a timeline with photos going back many years to see what there currently and in the past.

 

[Meta4]

I sure am ! and that's what the op is asking for unless he is trying to get information on the construction of that exact building and its surroundings by reaching out to the various city planners, and engineers, thru a Drone forum.

It would be helpful if you actually understood something about how GPS works rather than just copying and pasting a bunch of completely irrelevant stuff.
If you think that flying over a building that has steel in, you aren't going to be offering anything useful.

 

[tstr14]

GPS reception is noting more than receiving radio transmissions and radio waves can be disrupted in numerous ways. The picture doesn't offer any glaring visible causes however. Things that can play havoc with radio waves: power line transformers, radio induction heaters, microwaves (ovens and transmitters), electric motors, and radio transmitters (commercial and amateur). Of these, the only ones that I could guess could be limited to the small area indicated in the above post is microwaves, induction heater or a bad motor.

 

[Meta4]

GPS reception is noting more than receiving radio transmissions and radio waves can be disrupted in numerous ways. The picture doesn't offer any glaring visible causes however. Things that can play havoc with radio waves: power line transformers, radio induction heaters, microwaves (ovens and transmitters), electric motors, and radio transmitters (commercial and amateur).

If such things really affected GPS signal, GPS wouldn't work in urban areas.

Of these, the only ones that I could guess could be limited to the small area indicated in the above post is microwaves, induction heater or a bad motor.

Disruption from any of those is extremely unlikely at the distances the OP mentioned.

 

[REStewart]

We performed an ortho over a major local superstore and the ortho kept getting interrupted at basically the same point. Hitting continue was not working. We could gain control and fly it back to our location, that was well within sight. There was major reconstruction (renovation) under way at the time. Finally gave up and moved on to another job. When we came back in town we decided to try again and was able to complete it. The only difference we could identify was that the construction company had shut down for the day. My only thought was that it might be interference from radio communication equipment the construction company was using. I have a Masters in Electrical Engineering and frankly don't believe that a radio signals could be that strong or that closely tuned to the Drone system. Not much help but that's all I could come up with. Very similar symptoms though; was flying a P4P.

 

[Cafguy]

GIVE US AND THE OP THE ANSWER THEN!!.....Meta4

You seem to have many messages under your belt How come i get the feeling 99.9% of them are comments like "No it Doesnt" OR "thats not it" along with a host of other non-relevent stuff. and 0 actual answers.
If you want to help the OP please join in IF you are here to TROLL I will remind you of something we all members should know of. Its called the Forum Community rules and because you seem to consistantly flirt on the edge here let me "Copy and Paste" it for you below:

12. Trolling and cyber stalking are not allowed and are grounds for account restriction or banishment. Trolling includes posting controversial and often irrelevant or off-topic messages with the intention of baiting other users into an emotional response or to generally disrupt normal, harmonious on-topic discussion, especially when a pattern of such posting is apparent.

I will wait a Min for your reply BUT after that I must relegate you to the place no-one here has gone until now ...... The ignore zone.

 

[Meta4]

GIVE US AND THE OP THE ANSWER THEN!!.....Meta4

If I could solve the OP's mystery I would have already.

You seem to have many messages under your belt How come i get the feeling 99.9% of them are comments like "No it Doesn't OR "that's not it"

Because you have no idea what you are talking about when it comes to the OP's issue, but don't let that stop you supplying a long list of things that are completely irrelevant.
Making random uninformed guesses isn't helpful to anyone.

 

[Droning on and on...]

Proximity to ordinary EMF from motors, power lines, etc. are extremely unlikely.

However, GPS can be jammed if a signal in the same frequency range with enough power is recieved by the antenna in the aircraft. This is how military GPS jammers work – using a tight, directional antenna, and object is tracked, and a powerful enough signal is transmitted at the target, most of the power gets to it, and GPS is lost in the noise at the input stage.

We can probably rule out military. There are domestic sources of high power, beamed signals that can interfere with GPS. Microwave relays could do it, but they beam horizontally, so don't apply in this instance.

The other relatively common device that could do this is a satellite uplink. Relatively small dish, powerful, and pointing up at the geostationary satellite it's transmitting to.

The reason these common sources never interfere with domestic GPS use is because the vast majority of use is on the ground and never gets hit by those transmissions. Aircraft do pass over uplinks, but they are exposed for such a brief moment it has no effect.