UNDERSTANDING COMPASS AND MAGNETIC FIELDS

[David Gibson]

This statement from that site is applicable to this discussion:
"There are several ways in which space weather impacts GPS function. GPS radio signals travel from the satellite to the receiver on the ground, passing through the Earth’s ionosphere. The charged plasma of the ionosphere bends the path of the GPS radio signal similar to the way a lens bends the path of light. In the absence of space weather, GPS systems compensate for the “average” or “quiet” ionosphere, using a model to calculate its effect on the accuracy of the positioning information. But when the ionosphere is disturbed by a space weather event, the models are no longer accurate and the receivers are unable to calculate an accurate position based on the satellites overhead."

 

[Richard in ky]

Hi Richard
This magnetic storm will interfere with your compass, your GPS positioning and your RC radio transmission.
If it did only interfere with the compass then I would agree with you, unfortunately it interferes with many other electronic devices as well.
Rgds
David

That makes since I am fairly new here and it just seems that the compass is usually the blame for fly always. But even if the magnetic storm throws gps off shouldn't the WAAS satellites give a correction signal or is it possibly at the smart phone level.

 

[ianwood]

Compass Calibration, A Complete Primer
http://www.phantompilots.com/threads/compass-calibration-a-complete-primer.32829/

As for K index, it's red herring. White UAV forecast explanation of K index is technically accurate, it doesn't take into account the complete picture. Minor GPS degradation in a severe (Kp >= 8) is possible but with D-GPS (ground based drift correction), impact would likely be unnoticed.

 

[Robert walker]

Safe distances for compass calibration

• 6″ (15 cm) minimum: Metal rim glasses, pen/pencil, metal watch band, pocket knife, metal zipper/buttons, belt buckle, batteries, binoculars, cell phone, keys, camera, camcorder, survey nails, metal tape measure.
• 18″ (50 cm) minimum: Clipboard, data collector, computer, GPS antenna, 2-way radio, hand gun, hatchet, cell phone case with magnetic closure.
• 6 ft (2 m) minimum: Bicycle, fire hydrant, road signs, sewer cap or drain, steel pole, ATV, guy wire, magnets, chain-link fence, bar-wire fence, data collectors
  that use a magnet to hold the stylus.
• 15 ft (5 m) minimum: Electrical box, small car/truck, powerline, building with concrete & steel.
• 30 ft (10 m) minimum: Large truck, metal building, heavy machinery.

 

[DrunkenCynic]

I know I have just graduated to the Inspire 1 from the Vision 2+, I fly a lot off a barge offshore and whereas the Phantom had no problem at all I find the Inspire going into atti mode and back to GPS quite a lot. It was a little unnerving at first, but after a day or 2, and as long as I hear it say atti mode, I am ready for it now.

 

[Mike Mas]

It can go both ways since if you calibrate too much you could get a bad one I've had phantoms that went 6 months without calibration and never had a problem.

 

[denaat]

Hi All,

Interseting since I had the feeling flight was not that stable in GPS as days before. Noticed that today KP was 6. Do you advise to include the KP in a routine check before flying and if guess so yes: is the value for KP on uavforecast.com valid worldwide (I'm in Europe)?

Tks Theo

 

[Xrover]

This really isn't an app, but it works well

UAV Weather Forecast

It is an app! I've got it on my Iphone.

 

[John Archer]

Not sure I am in the right thread here, but I do have a question concerning compass calibration. I have a severe hearing disability(DEAF), and as such, I am forced to wear a cochlear ear implant. The cochlear is magnetically attached to a small steel plate in my gourd. The magnet is strong enough to pick up a set of car keys with ease. I would like to think there are other pilots out there with an implant similar to mine. Is the magnet strong enough to skew my compass calibration? If I remove it, how far away do I need to be from the magnet to calibrate? Will my I 1's performance be affected after I step back away from it and reattach the magnet?
Forgive my intrusion here. If there is another thread you know about that addresses this dilemma, would you mind posting a reply. Thanks to all!

 

[Xrover]

Not sure I am in the right thread here, but I do have a question concerning compass calibration. I have a severe hearing disability(DEAF), and as such, I am forced to wear a cochlear ear implant. The cochlear is magnetically attached to a small steel plate in my gourd. The magnet is strong enough to pick up a set of car keys with ease. I would like to think there are other pilots out there with an implant similar to mine. Is the magnet strong enough to skew my compass calibration? If I remove it, how far away do I need to be from the magnet to calibrate? Will my I 1's performance be affected after I step back away from it and reattach the magnet?
Forgive my intrusion here. If there is another thread you know about that addresses this dilemma, would you mind posting a reply. Thanks to all!

John,

When doing a compass calibration, the nose of the craft (Where the compass is) is far enough away from your ear that I highly doubt it would cause any magnetic disturbance.
Now if you can pick up a set of car keys from that distance then yes, that would mess up the compass calibration.

 

[John Archer]

Believe it or not I get "feedback" when I walk to close, (arms length), to my quad. Its not a major issue, I generally stand several feet to the rear of my quad before liftoff and my implant doesn't pick up any extraneous sounds. I was curious as to whether it had any detrimental effect on the transmitter itself. More field testing is in order. Should anyone reading this want to know my findings or have there own comments, please leave me a message.
In the meantime, Thank You Xrover for your feedback.

 

[Xrover]

I hope you can get some relevant answers.

 

[John Archer]

Thank you, Sir! I imagine it will probably be mostly a Trial & Error proposition. Now that I have you "ear" I will let you know how it works out. Currently the weather here in Illinois while almost balmy compared to a regular January, the wind is creating problems. Tried to spend some quality time in the back yard this afternoon buzzing around and almost augured in due to a blast of wind. To many trees, to little space, to slow reflexes. Don't want to trash my Beast before decent weather gets here. Patience, sadly isn't one of my better virtues

 

[The Editor]

Not sure I am in the right thread here, but I do have a question concerning compass calibration. I have a severe hearing disability(DEAF), and as such, I am forced to wear a cochlear ear implant. The cochlear is magnetically attached to a small steel plate in my gourd. The magnet is strong enough to pick up a set of car keys with ease. I would like to think there are other pilots out there with an implant similar to mine. Is the magnet strong enough to skew my compass calibration? If I remove it, how far away do I need to be from the magnet to calibrate? Will my I 1's performance be affected after I step back away from it and reattach the magnet?
Forgive my intrusion here. If there is another thread you know about that addresses this dilemma, would you mind posting a reply. Thanks to all!

Hi John, apologies for not picking up on this question earlier.
Easy way to see if your implant/earpiece actually disturbs the Inspires compass is to do this test.

Remove your earpiece and place it well away (another room), then leaving the Inspire motionless on a table etc with the remote and tablet on the table next to it. Fire up the remote and then the Inspire.
Go into the mods page and look at the compass values.
Do not pick up the remote or tablet to do this as they can skew the compass values if they are close and are moved - take the readings without moving either.
Now approach (walk towards) the Inspire while paying attention to how the mod values change (if at all) until you are standing next to the aircraft as close as you would be for a compass cal.
This is your baseline without the earpiece.
Now repeat the excersise but with your earpiece in place and see if the results differ.
This will tell you if the magnetic field is being disturbed or altered by your implant.
If they are, then I would suggest doing a compass calibration without your implant and leave it at that. You do not need to compass calibrate every time you fly, far from it in fact.
When you then go to your chosen flying area you will be able to step away from the Inspire so as to get a compass mod reading and see if it is within spec and take off with confidence.

I hope that helps and good luck.

 

[John Archer]

Outstanding advice , Sir! And you explained the process simply enough that I can follow your instructions to a T, even to the point of helping me understand why something is done a certain way. To many "Helpful Tips" hit Warp Factor 7 going over my head due to technical terms I can't even begin to understand. I have zero degrees in any kind of math or computer skills so your instructions were like a breath of fresh air. They make perfect sense and I anticipate no problems what so ever implementing your suggestions.
As for getting the formula to me sooner, that's not an issue. Fact is, I do not own an Inspire. Yet. That is a problem I hope to rectify in the next week or two. Up until yesterday I had a Phantom 3 Pro. I only had it just over a month, and while I liked it, I come from the Bigger is Better line of thinking. I want to make sure beforehand I didn't plant a $3000+ machine in my front yard, the neighbors yard, or worse. The Phantom was a piece of cake-nothing like the RC heli's I tried flying years ago. I feel confident that the Inspire will likewise be something I will actually be able to get up in the air without having a coronary. Once I have the Inspire in my grubby little mitts I intend to follow exactly the procedure you outlined for me concerning compass calibration. I guess I am trying to get my ducks all lined up in a row so I don't forget anything vital (like compass calibration) before I crank up the throttle. We did a lot of P.M. (Preventive Maintenance) while I was in the Army and it went a long ways towards keeping everything in tip top shape.
At any rate, Thank You so much for taking the time to outline the procedure for me. I intend to let you know how it works out for me.
One last question. Any chance of me getting a ride on that 6 lawnmower powered hex you mentioned? I am sure I can scrounge up a colander somewhere around here

 

[Inspirit]

Talking about the uavforecast.com I wonder where they get information about actual and forecast wind direction and speed, about visibility and precipitation. I checked the METAR and TAF of the nearest aerodrome and they differ to much to rely on this application. (In fact, I live near the aerodrome and I've set my location in the app.)

 

[The Editor]

Talking about the uavforecast.com I wonder where they get information about actual and forecast wind direction and speed, about visibility and precipitation. I checked the METAR and TAF of the nearest aerodrome and they differ to much to rely on this application. (In fact, I live near the aerodrome and I've set my location in the app.)

METARs and TAF's will always be more accurate than any app or generic forecast because they are localised and taken directly from that location!

 

[Inspirit]

METARs and TAF's will always be more accurate than any app or generic forecast because they are localised and taken directly from that location!

Yeah, you're right, METARs and TAFs are produced by aerodrome metorological stations and indicate weather in the vicinity of the aerodrome, but once again, where this app takes meteorological info? And why the aerodrome wheather differs so much from weather shown in the app at the same location?

 

[CFAN4]

My first post...
I have had 95 flawless flights on my I1....until yesterday. This thread caught my attention because yesterday I had my first "hard landing" and I was really confused at first as to what might have caused it. I had just flown it about a mile away with no issues. Drove to new location and launched it. Immediately after takeoff it started drifting. Was acting like it was in ATTI mode with a wind, however it had a great GPS signal and did not appear to change modes. It was very loose on the controls and concerned me (since I was near a lake). I tried to set it down, but with the excessive drifting side load it flipped over on its side. It only chipped 2 prop tips but also cracked a carbon fiber arm which I have repaired (for now) and it is flying normal again. Hurt my pride more than the craft.

My question to you guys is, there was a thunderstorm pretty close...actually really close I'll admit. It was an isolated cell that was cruising by real fast. I was way out in the clear and it was moving away from me but I wondered if the electrical energy in the storm had effected this? The other thing I noticed was I failed to fold out the antennas into the proper position and didn't notice since they were behind my iPad. Any chance this could have caused it? The I1 never got more than 50' away from me though.

This is my 3rd DJI product. I admit complacency may be setting in. I've went so long without any problems that I've started to take this amazing little machine for granted. I just flew the last 2 weeks with it in Hawaii and it was exilerating to fly there. Sure glad this didn't happen while I was standing out on the lava rocks cruising it over the Pacific!

Any thoughts from you guys (The Editor in particular)? Thank you!

That's EXACTLY what happened to me. Twice. In the same place.
And the second time, my Inspire RAW slammed into a building!!
Help! Inexplicable Fly-Into-Building Crash on Inspire RAW running Litchi in VR Mode
I did have trouble calibrating the compass just before this crash, just after a firmware upgrade. I thought it might have been the upgrade, could it be the environment?

Is there a way I can get historical magnetic and weather information for my location?

 

[Larr2000]

Hey Guys,
Yes, I too have calibration issues. Your post mentions a MOD value, help me out here, where is it in the app and what are the values that should tell me to calibrate? Thanks in advance.