MySky Posted at 11-20 09:07
It does not help to post a link leading to huge technical and physical explanation if the adequate background is missing. This is why i tried to simplify it.

You can see it every day if someone is asking for things he / she should know if read and understood completly the manual. But it's the way of today's life. The people just want to have fun out of the box, don't read any manual except how the thing can turned on and how to charge the batteries.

Another explantion in the video in my previous post in this thread.

Magnetometer just 'measured' the earth field lines through the sensor, if aligned to the sensor ; drone is flying magnetic N or S. (flow determines N or S), any angle deviation = left or right angle from N or S.

Very simple device.

cheers
JJB

JJB* Posted at 11-20 00:51
Hi John,

It is bit different...

JJB,

Thank you for your reply, I am quite familiar with a Hall effect sensor used in magnetometer.  Typical modern electronics use an array of magnetometer, most often 3 in a triangular formation, to generate a "True North" heading bearing with greater accuracy.

I do not fly in a consistent location but in variety of both rural and urban.  And I have never had an issue with the accuracy of the compass direction heading with the Mavic Air 2.

I do not believe the orientation is derived from the compass on the drone but from GPS.  

My understanding of the premise of GPS based mapping and the application to direction is that two points are plotted: a primary, the RC/phone, and a secondary, the drone.  A line is essentially drawn.  From this line an angle is extrapolated on 360° plane.  This angle is the orientation of the aircraft to the RC.  The the phone's internal compass sets the upward\forward facing side of phone's center point as the heading bearing in degrees on 360° plane.  An algorithm then subtracts the phone's compass bearing from the RC to aircraft angle and renders the difference in degrees on the 180° arch on the DJI Fly apps graphic user interface.

It is my understanding that this method of GPS derived orientation is the most commonly used model and formula for spacial relationship.  The only compass involved with this process is the phone's own internal compass which is not calibrated by the DJI Fly app.

I have attempted to calibrate the orientation without initiating a Compass Calibration in DJI Fly app by rotating the drone in the same manner and the spacial relationship errors are not remedied.  But when Compass Calibration is conducted in the DJI Fly app these error are resolved.

Calibrating the compass in the DJI Fly app has the undocumented and unforeseen benefit of correcting errors in the spacial orientation of the Mavic Air 2 to the RC.  As the raw decompiled code on the Mavic Air 2 is proprietary to DJI and not publicly available it not possible to determine the specific process that results in the resolution of this problem.

Thank you, for the advice on using the Map.  I often have to use the Map features line of return as the orientation arch reds out on me due to interference.

Labroides Posted at 11-20 00:49
You desperately need to read before you post.
You desperately need to learn and think before you post disparaging comments about others.

You post is inaccurate.  As orientation is derived from GPS and the phone's internal compass bearing and not the drones compass.

It is clear you have a significant amount of applicable user experience but lack a foundation in the technology application.

Your and Geebax attitude on this forum does not "enlighten" anyone.  You have a lot of knowledge and experience to offer others on this forum but your approach is both gauche and off-putting.

JohnLietzke Posted at 11-20 11:15
You post is inaccurate.  As orientation is derived from GPS and the phone's internal compass bearing and not the drones compass.

It is clear you have a significant amount of applicable user experience but lack a foundation in the technology application.

Hey sport, you are the one with the Atitude, you started this whole sh1tfight with a disparaging comment. Orientation is not derived from GPS, as it is a static variable and GPS does not provide bearing information at all. And the compass in the phone is only used to help align the aircraft orientation display. Contrary to what you say, I have a considerable amount of experience in designing electronic hardware systems, where you appear to be working on internet fluff.

In point of fact, I care not what you think, my reply was intented for those who wish to become enlightened as to the real factors around compass 'calibration' and why is it largely unimportant.

JohnLietzke Posted at 11-20 11:15
You post is inaccurate.  As orientation is derived from GPS and the phone's internal compass bearing and not the drones compass.

It is clear you have a significant amount of applicable user experience but lack a foundation in the technology application.

You post is inaccurate.  As orientation is derived from GPS and the phone's internal compass bearing and not the drones compass.
Read what I wrote again. - It was accurate.

It is clear you ... lack a foundation in the technology application.
Wrong again

Geebax Posted at 11-20 14:24
Hey sport, you are the one with the Atitude, you started this whole sh1tfight with a disparaging comment. Orientation is not derived from GPS, as it is a static variable and GPS does not provide bearing information at all. And the compass in the phone is only used to help align the aircraft orientation display. Contrary to what you say, I have a considerable amount of experience in designing electronic hardware systems, where you appear to be working on internet fluff.

In point of fact, I care not what you think, my reply was intented for those who wish to become enlightened as to the real factors around compass 'calibration' and why is it largely unimportant.

The wonderful thing about the internet is you are entitled to your opinion in most countries.  

All the best.

Well I’m an if ain’t broke don’t fix it kind of gal so I never calibrated the compass (the app never showed a pop up that I should).
I do check before flying and the compass notes normal.
I would like to ask a question, if you don’t mind, what has to happen for you to get a compass error (how does it know something is out of sort)?
Forgive me if it was mentioned but this thread is a little hard to understand, for me.
Thank You

PS I own the MA2 not the mini.

Thanks again

djiuser_0kYcYByavt5m Posted at 11-20 19:41
Well I’m an if ain’t broke don’t fix it kind of gal so I never calibrated the compass (the app never showed a pop up that I should).
I do check before flying and the compass notes normal.
I would like to ask a question, if you don’t mind, what has to happen for you to get a compass error (how does it know something is out of sort)?

The simplest answer is that the aircraft will request a compass "calibration" is you add an accessory or change a part on the aircraft that alters its magnetic influence. This situation is very unlikely for most people.

Geebax Posted at 11-20 14:24
Hey sport, you are the one with the Atitude, you started this whole sh1tfight with a disparaging comment. Orientation is not derived from GPS, as it is a static variable and GPS does not provide bearing information at all. And the compass in the phone is only used to help align the aircraft orientation display. Contrary to what you say, I have a considerable amount of experience in designing electronic hardware systems, where you appear to be working on internet fluff.

In point of fact, I care not what you think, my reply was intented for those who wish to become enlightened as to the real factors around compass 'calibration' and why is it largely unimportant.

Is that true? I thought the GPS-indicated positions of both devices was used to place the relative position of the drone on the display (front, left, right, behind). The compasses just tell you which way they are pointed.

Later added correction: The compass of the controller's device does play a part in placing the drone on the display, just not the only thing that does.

I'm not taking any sides or anything here because I want no part of the drama that appears to be infused in this thread.  However, Labroides and Geebax both seem to have very good fundamental understandings of how the compass works in DJI drones and basically have described the technicalities of how they work in a similar fashion to how I would have as well.  

The link to the post by "sar104" on the MavicPilots forum is a fantastic technical explanation.  I know it is quite technical, and not short, but if interested in learning more about it, it is a fantastic resource.  I'll copy the link here again for reference:

https://mavicpilots.com/threads/ ... n-and-errors.90792/

Labroides Posted at 11-20 01:49
Don't believe everything you read in these responses here, as it's a religious debate.
You got that part correct.

I am a member there and have had the same arguments. I provided documented proof to them and they responded with we won't play that game. i.e. will not provide any evidence to support their position. They are just a couple or Rudy Giuliani's with conspiracy theory's. I don't go there anymore as its controlled by a bunch of self important uneducated frauds. there is too much BS on the net.

fanscc989da6 Posted at 11-20 02:12
I see, there's a lot to learn here. Thank you very much, Geebax, for that information. I have to admit that I had no idea what the 'calibration' procedure actually does.

Now I am sorry to have caused such debate about a topic that is much more complex than I could think of. At least, it is made more complex than it is by many assumptions resulting from misunderstood facts.

My goodness. don't read the BS that some people sprout. There is absolutely no evidence of the so called facts these guys sprout. No documentation what so ever. They have a view that is not shared by anyone other than those on that site as they bully anyone that questions them.

When they started saying that the DJI drones have a world model of magnetic fields they lost me completely.  

JohnLietzke Posted at 11-20 10:56
JJB,

Thank you for your reply, I am quite familiar with a Hall effect sensor used in magnetometer.  Typical modern electronics use an array of magnetometer, most often 3 in a triangular formation, to generate a "True North" heading bearing with greater accuracy.

Hi,

No problem to have a diffferent opinion.

"I do not believe the orientation is derived from the compass on the drone but from GPS. "

But ; fly a DJI drone in house, with no GPS reception, and you will see still correct compass headings, so your statement in incorrect.

"My understanding of the premise of GPS based mapping and the application to direction is that two points are plotted: a primary, the RC/phone, and a secondary, the drone.  A line is essentially drawn.  From this line an angle is extrapolated on 360° plane.  This angle is the orientation of the aircraft to the RC.  The the phone's internal compass sets the upward\forward facing side of phone's center point as the heading bearing in degrees on 360° plane.  An algorithm then subtracts the phone's compass bearing from the RC to aircraft angle and renders the difference in degrees on the 180° arch on the DJI Fly apps graphic user interface."

The arrow position drone map view data is derived from drone GPS. Line is drawn from that point to HP data. No data from mobile device GPS and /or compass is involved. (try to reset HP to new location, not the location of your mobile device....)



cheers
JJB

KlooGee Posted at 11-20 22:37
I'm not taking any sides or anything here because I want no part of the drama that appears to be infused in this thread.  However, Labroides and Geebax both seem to have very good fundamental understandings of how the compass works in DJI drones and basically have described the technicalities of how they work in a similar fashion to how I would have as well.  

The link to the post by "sar104" on the MavicPilots forum is a fantastic technical explanation.  I know it is quite technical, and not short, but if interested in learning more about it, it is a fantastic resource.  I'll copy the link here again for reference:

Hey KlooGee, love you YouTube channel.

Unfortunately Sara104 is wrong or at least not undertanding.

Riddle me this, what is the difference between a needle that has been magnetised and the electronic magnetometer in a DJI drone.

The answer is nothing. The magnetised needle will point to magnetic north as it aligns itself with the Magnetic lines of force.

So no issues here, the problem as I keep explaining is the difference between true north and magnetic north. For goodness sake Airline pilots need to re-calibrate their compass regularly on long distance flights. Recalibration of the compass is not adjusting the compass. This is what Sar104 fails to comprehend. You indeed can't recalibrate a compass as much as you cant recalibrate a magnetised needle.  But you can determine and calibrate the magnetic north to true north based on you current GPS coordinates. This is why airline pilots continue to "calibrate their compass." they adjust the North heading to the correct declination of their current location.

Do you understand what I am saying here?  

bjr981s Posted at 11-21 01:26
Hey KlooGee, love you YouTube channel.

Unfortunately Sara104 is wrong or at least not undertanding.

Airline pilot do not re-calibrate their magnetic compass during long distance flights, its confusing to read this even if it is within "" later in your text.
They simply adjust the East or West variation on a dial to the position where they are flying to get a correct True N reference point for all the other 359 headings....

Think about this....when calibrating DJI drone users can start on any heading the calibration, just make a 360 turn (flat+nose down).  SW measures the normal expected variation in magn fields though the magnetometer and if its done in a free of magn interference area  calibration is succesfull. Minor deviations through a full circle are averaged. Done.

bjr981s Posted at 11-21 01:26
...So no issues here, the problem as I keep explaining is the difference between true north and magnetic north. For goodness sake Airline pilots need to re-calibrate their compass regularly on long distance flights. Recalibration of the compass is not adjusting the compass. This is what Sar104 fails to comprehend. You indeed can't recalibrate a compass as much as you cant recalibrate a magnetised needle.  But you can determine and calibrate the magnetic north to true north based on you current GPS coordinates. This is why airline pilots continue to "calibrate their compass." they adjust the North heading to the correct declination of their current location...

This is a good and easy to understand clarification. As a hobby pilot who has become addicted to DJI drones in the meantime, it is important for me to learn more and more about the background. Until today I have never used the RTH function (is there anyone else who can say that after flying for over a year?) but if I have to do that and my drone can't find the starting point, it could be because my drone doesn't know where true north is, right?

Since the Mini 2 arrived yesterday, if the weather permits, I might be able to find out this year how it behaves with regard to the compass.

bjr981s Posted at 11-21 00:59
I am a member there and have had the same arguments. I provided documented proof to them and they responded with we won't play that game. i.e. will not provide any evidence to support their position. They are just a couple or Rudy Giuliani's with conspiracy theory's. I don't go there anymore as its controlled by a bunch of self important uneducated frauds.  there is too much BS on the net.

They are just a couple or Rudy Giuliani's with conspiracy theory's.
It turns out that when it comes to the DJI compass, you are the Rudy Guiliani, ignoring facts and perpetuating myths for which there is no supporting evidence.
I hadn't picked you as one of those.

My goodness. don't read the BS that some people sprout.
That's very good advice.
there is too much BS on the net.
That too ....

But your mind is set so I won't bother engaging with you on the topic.

JJB* Posted at 11-21 01:49
Airline pilot do not re-calibrate their magnetic compass during long distance flights, its confusing to read this even if it is within "" later in your text.
They simply adjust the East or West variation on a dial to the position where they are flying to get a correct True N reference point for all the other 359 headings....

That's exactly right, but the guy you are talking to won't believe a word of it.

fanscc989da6 Posted at 11-21 02:20
This is a good and easy to understand clarification. As a hobby pilot who has become addicted to DJI drones in the meantime, it is important for me to learn more and more about the background. Until today I have never used the RTH function (is there anyone else who can say that after flying for over a year?) but if I have to do that and my drone can't find the starting point, it could be because my drone doesn't know where true north is, right?

Since the Mini 2 arrived yesterday, if the weather permits, I might be able to find out this year how it behaves with regard to the compass.

"but if I have to do that and my drone can't find the starting point, it could be because my drone doesn't know where true north is, right?"
Your drone knows it own position (own GPS data) and the HP position is stored in the Drone.
So easy to calculate wich heading it has to fly to perform a RTH.

But than you have to know wich heading your drone is actually flying...this info is derived from the drone compass.

In my country where i live we have a magn variation of 4 degrees to the acutal N.
Variation is corrected by DJI using data tables, so my drone never fails to fly to my HP. (only your RTH for test, as i like to fly manually all the time)

So for a good RTH you need a HP set, good drone GPS data in flight and a good working compass.

cheers
JJB

fanscc989da6 Posted at 11-21 02:20
This is a good and easy to understand clarification. As a hobby pilot who has become addicted to DJI drones in the meantime, it is important for me to learn more and more about the background. Until today I have never used the RTH function (is there anyone else who can say that after flying for over a year?) but if I have to do that and my drone can't find the starting point, it could be because my drone doesn't know where true north is, right?

Since the Mini 2 arrived yesterday, if the weather permits, I might be able to find out this year how it behaves with regard to the compass.

This is a good and easy to understand clarification.
Unfortunately it's incorrect.

Until today I have never used the RTH function (is there anyone else who can say that after flying for over a year?)
You really need to experiment with RTH to get an understanding of what it does and how it does it.
You need to understand how to initiate RTH and how to cancel and resume control too.

The day you need RTH is the worst day to start learning about it.

but if I have to do that and my drone can't find the starting point, it could be because my drone doesn't know where true north is, right?
No .. that's never going to be a problem
Your drone records a home point location at startup and uses GPS to find its way back to that.
RTH is very, reliable.
If it doesn't find its way back, it's because it had problems with a wind that was too strong, it ran into terrain or obstacles on the RTH path because the RTH height wasn't set properly or you flew too far and didn't have enough battery for the return.

bjr981s Posted at 11-21 01:26
Hey KlooGee, love you YouTube channel.

Unfortunately Sara104 is wrong or at least not undertanding.

Quite honestly, I'm trying to understand where you are disagreeing with what Sar104 had described.

From where I sit, it looks like you are saying the same thing with slightly different words.  I think you might be using the word "calibration" or "re-calibration" to mean multiple different things.

Calibration
This is the process used to subtract out the aircraft's own magnetic interference so that the compass can reliably detect magnetic north.  This is necessary in every old school magnetic aviation compass just like it is in a drone's electronic magnetometer.  Both you and Sar104 describe this same process.  This is the process that is done with every drone when having to move it in circles.  For "real" airplanes, I believe this is an annual maintenance procedure or is done when any new equipment is installed that could potentially affect the compass readings.

Declination adjustment for true north
Using the phrase "calibrate the compass" for this process is a bit confusing because it is not the same thing.  As both of you describe, this is using the current GPS location to understand what the difference is in true north vs. magnetic north.  

I'm not a "real" pilot, so I can't confidently speak to their in-flight procedure, but my understanding of that is much more like what JJB* describes.  It is just a simple declination adjustment, not re-calibrating.  

In modern avionics, declination look up tables are built into the device and automatically calculated.  It is my understanding that DJI introduced the same thing with the original Mavic Air as well.

So I guess my question is this.... what am I missing that you are disagreeing with Sar104 on?  It seems to me you have described the same thing with different words.

And just to be clear, I'm not trying to be condescending or cause drama.  I know I'm never the smartest guy in the room and am always doing my best to learn and teach what I've learned.

Cheers!

bjr981s Posted at 11-21 01:26
Hey KlooGee, love you YouTube channel.

Unfortunately Sara104 is wrong or at least not undertanding.

Having said all of the above, I may expose a bit of my ignorance here....  I don't see why the drone would care at all about true north vs. magnetic north.  In "real" aviation, planes are flying long distances (hundreds or thousands of miles/kilometers) and are navigating via the compass heading.  So knowing true vs. magnetic north is vitally important to be able to navigate over those long distances.

However, with a drone, it is not navigating via a specific heading.  It is not likely to travel more than a handful of miles from its launch point and it really isn't navigating to a specific heading.  All it really needs to care about is a consistent heading and being able to compare that to the accelerometer's data about when it is turning.  It could label SW as 0 degrees if it wanted to.  It is just the deviation away from that heading that is important, not the actual correct heading degree.

Am I missing something here?

KlooGee Posted at 11-21 03:16
Quite honestly, I'm trying to understand where you are disagreeing with what Sar104 had described.

From where I sit, it looks like you are saying the same thing with slightly different words.  I think you might be using the word "calibration" or "re-calibration" to mean multiple different things.

my question is this.... what am I missing that you are disagreeing with Sar104 on?
His idea is that compass calibration somehow compensates for magnetic declination rather than identifying and measuring the drone's own magnetic fields.

It's a common misunderstanding that leads flyers to believe that it's necessary to recalibrate the compass when traveling some distance from a previous flight.

Understanding what compass calibration actually does is the key.
Without that, people come up with ideas that just aren't true.

Labroides Posted at 11-21 03:24
my question is this.... what am I missing that you are disagreeing with Sar104 on?
His idea is that compass calibration somehow compensates for magnetic declination rather than identifying and measuring the drone's own magnetic fields.

You may be right, but that isn't what I'd interpreted from what they had typed in post #58.

What a mess but here’s what I think I learned, or not.
The drone compass is calibrated to allow the compass to correct/compensate to the drone build?I believe this to be true because I never calibrated the compass and it was built in China and shipped to the US.
Is my reasoning correct?
I'll leave it be unless the app prompts me to calibrate. I'll put my trust in DJI in that if I'm prompted to calibrate it sees an anomaly with the compass.

JJB* Posted at 11-21 01:21
Hi,

No problem to have a diffferent opinion.

"The arrow position drone map view data is derived from drone GPS. Line is drawn from that point to HP data. No data from mobile device GPS and /or compass is involved."


OK, but we need to clarify that there are two orientation views. I do not know about the map view. But the orientation display at the bottom of the screen does rely on the GPS of both devices.

Labroides Posted at 11-21 02:57
This is a good and easy to understand clarification.
Unfortunately it's incorrect.

"Your drone records a home point location at startup and uses GPS to find its way back to that."

adding "and use drone compass to fly the calculated heading..."

without a working compass no RTH.

Labroides Posted at 11-21 02:57
...You really need to experiment with RTH to get an understanding of what it does and how it does it.
You need to understand how to initiate RTH and how to cancel and resume control too.

The day you need RTH is the worst day to start learning about it...

I am one of the few who actually enjoy reading instruction manuals and I have read the section about the use of RTH more than once carefully and I admit that it would finally be time to practice the handling of it in real life - even if the theory is known. And if it is only for that reason, to ensure the correct operation - in case of emergency.

I will stick to the manual, that is obvious if you don't know better. As long as there is no prompt in DJI Fly to do anything and no abnormalities are shown during flight, I also assume that all components of the aircraft are working properly. Because I am not an engineer.

GaryDoug Posted at 11-20 21:05
Is that true? I thought the GPS-indicated positions of both devices was used to place the relative position of the drone on the display (front, left, right, behind). The compasses just tell you which way they are pointed.
[view_image]

Thank you for the graphics evidence.

I have been solely addressing the relative position/relationship/orientation, it seems to be referred to differently by everyone, based on my personal experience.  It is clear that this derived from GPS and not the compass.

Somewhere in the compass calibration process it seems to remedy this issue which has nothing to do with the magnetometers accuracy.

Our friends from Down Under seem to be polarized in their beliefs.

Geebax Posted at 11-20 14:24
Hey sport, you are the one with the Atitude, you started this whole sh1tfight with a disparaging comment. Orientation is not derived from GPS, as it is a static variable and GPS does not provide bearing information at all. And the compass in the phone is only used to help align the aircraft orientation display. Contrary to what you say, I have a considerable amount of experience in designing electronic hardware systems, where you appear to be working on internet fluff.

In point of fact, I care not what you think, my reply was intented for those who wish to become enlightened as to the real factors around compass 'calibration' and why is it largely unimportant.

In response to your statement about getting my information from internet fluff.  I did double check my logic on both Stack and Here Technologies Developer Portal to make sure my thinking on issue was correct.  I provide most the commonly used method of how to derive the relative position from GPS for orientation which utilizes the phones compass as the graphic user interface I have been referring to is rendered by the DJI Fly app.

GaryDoug Posted at 11-21 08:05
"The arrow position drone map view data is derived from drone GPS. Line is drawn from that point to HP data. No data from mobile device GPS and /or compass is involved."

yes,

Aircraft Orientation Indicator = uses both compass data (arrow heading = drone compass, arrow position on the forward 180 scale = mobile device compass)

Map view uses drone GPS data (position on the map) and drone compass data for the arrow direction.

BTW same for the GoApp ; radar displays full 360 instead of only forward 180 relative to RC position.


I you fly your drone straight forward from your RC (100 meters or so), move yourself perpendicular away from your position, see what happens.Same for yawing your RC away from the drone in front of you.

cheers
JJB

GaryDoug Posted at 11-20 21:05
Is that true? I thought the GPS-indicated positions of both devices was used to place the relative position of the drone on the display (front, left, right, behind). The compasses just tell you which way they are pointed.
[view_image]

The translation here may be misunderstood. If we replace orientation with position, it might be better. We still have the compass for orientation ...

JJB* Posted at 11-21 10:46
yes,

Aircraft Orientation Indicator = uses both compass data (arrow heading = drone compass, arrow position on the forward 180 scale = mobile device compass)

Actually I did document that just before posting my comment above. These images are the result of walking to the left of the stationary drone (first image) and then walking to the right of it (second image). Drone remained fixed, pointed generally west. I kept controller and device facing west as well. So this shows that the position of the controller's phone/tablet device (not the HP) partially determines the placement of the drone on the indicator. i.e. GPS and compass are both used for this display.

DaMa Posted at 11-21 11:01
The translation here may be misunderstood. If we replace orientation with position, it might be better. We still have the compass for orientation ...

Definitely agree.  I have been listing a variety of terms people are using for it in every post to try and clarify.

GaryDoug Posted at 11-21 13:10
Actually I did document that just before posting my comment above. These images are the result of walking to the left of the stationary drone (first image) and then walking to the right of it (second image). Drone remained fixed, pointed generally west. I kept controller and device facing west as well. So this shows that the position of the controller's phone/tablet device (not the HP) partially determines the placement of the drone on the indicator. i.e. GPS and compass are both used for this display.
[view_image][view_image]

I agree, I think the process uses the phone's current GPS and bearing heading and not the Home Point.  GPS updated data is constantly happening and querying it can be done in < 1 second intervals with a couple lines of code or in a realtime flow.
Using the Home Point as a fixed location could result in inaccurate positioning if the operator moved.  I did a similar test as GaryDoug trying to diagnose the problem because I did not mentally separate the Compass Calibaration of the magnetometer from the position errors which was based on both the drone and phones GPS and the phones compass.  I am still at a loss to explain the position problems orgin.

On another project, I stupidly tied the GPS update to a Rest Post every time it updated in realtime without setting an interval.  I never went back and checked the time stamps and left it running for a couple of days and got a huge overage bill from AWS on a free tier account.  In one day it updated 9,000+ times.  In addition the code executed other Rest Post upon update so the bill was somewhere around $300.

GaryDoug Posted at 11-21 08:05
"The arrow position drone map view data is derived from drone GPS. Line is drawn from that point to HP data. No data from mobile device GPS and /or compass is involved."

But the orientation display at the bottom of the screen does rely on the GPS of both devices.
The Fly app has introduced that "feature" which was not present in DJI Go 4.
In DJI Go 4, whether the viewing device had/didn't have a GPS made no difference.
The orientation display would use it if available or use the recorded home point if not, but there was never anything showing on the screen to indicate this.
For almost all flying, using the GPS data from the phone wouldn't make any appreciable difference in the orientation display.

It would be pretty stupid programming if the orientation display doesn't  work without GPS in the mobile device when it isn't needed anyway.
The Fly app pops up the red icon if there's no GPS available on the phone or tablet, but does the orientation display still function?
How do all the wifi iPad users manage, do they still get a functioning orientation display or not?
Or if using Android, do you still get a functioning orientation display when you turn GPS off?

djiuser_0kYcYByavt5m Posted at 11-21 07:49
What a mess but here’s what I think I learned, or not.
The drone compass is calibrated to allow the compass to correct/compensate to the drone build?I believe this to be true because I never calibrated the compass and it was built in China and shipped to the US.
Is my reasoning correct?

I believe this to be true because I never calibrated the compass and it was built in China and shipped to the US.
Is my reasoning correct?
This is correct.
If it wasn't DJI would advise you to calibrate the compass before your first flight ... but they don't.
And as you have found out, a calibrated-in-China drone compass works perfectly well on the other side of the world.
I'll leave it be unless the app prompts me to calibrate.
Even if it looks like it's prompting to re-calibrate, be careful.
It could just be DJI's poorly worded message on the screen.
If you put the drone down close enough to something made of steel, the compass warns you of that.
But because the warning is poorly worded, many flyers believe they need to recalibrate when the correct action is to move the drone away from the thing the compass is warning about.

GaryDoug Posted at 11-20 21:05
Is that true? I thought the GPS-indicated positions of both devices was used to place the relative position of the drone on the display (front, left, right, behind). The compasses just tell you which way they are pointed.
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"Is that true? I thought the GPS-indicated positions of both devices was used to place the relative position of the drone on the display (front, left, right, behind). The compasses just tell you which way they are pointed."

Sorry, my hasty reply was badly written. It depends upon whether you are talking about the map display or the orientation disply.

djiuser_0kYcYByavt5m Posted at 11-21 07:49
What a mess but here’s what I think I learned, or not.
The drone compass is calibrated to allow the compass to correct/compensate to the drone build?I believe this to be true because I never calibrated the compass and it was built in China and shipped to the US.
Is my reasoning correct?

Your assumption is pretty accurate, but I would not be putting 'my trust in DJI' as you say because over the years they have put a lot of contradictory information in their manuals. The classic one is the one that says it has been 30 days since you last performed the compass dance, time to do it again. Since when has time ever been a factor in the operation of a compass?