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How would I know the Spark compass is off?
902 16 2018-6-30
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JimboHUN
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Hi,

I am just wondering if there is any way to figure out if the compass is off compared to the correct magnetic north?

I know the DJI GO app shows magnetic north, but that is based on the mobile phone as far as I know (and interestingly it is really off for me, though in other apps it shows correctly).

Thanks!
2018-6-30
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DMX_MT
Captain
Malta
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I just bought a Small Suunto Clipper Compass.

You can buy a bigger Field Compass but will be bulkier to carry. These Field Compasses are used to calculate Magnetic Declination and Map Reading. So you don't really need it so big.

The Suunto Clipper attached to my Backpack. Best brands for Compass are Suunto and Silva.

It is expensive about $20, but not buying Good Branded Compass will give you bad results.

Here is a Video -






2018-6-30
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DMX_MT
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This Silva Small Compass was on my Watchlist too - About $20 too.

I prefered Suunto as they do have more Professional and Expensive Products. Expensive for a reason as they are Professional Grade.

Silva Compass Metro Black -

2018-6-30
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JimboHUN
Second Officer
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Thanks!

That is fine, I have a compass to for checking, but how will I know what the Spark's compass "thinks" as a north?

As in how should I know it has "correct" or "incorrect" north and needs recalibration?

Cheers,
2018-6-30
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DMX_MT
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JimboHUN Posted at 2018-6-30 15:39
Thanks!

That is fine, I have a compass to for checking, but how will I know what the Spark's compass "thinks" as a north?

Hi Jimbo,

The App will gather both the information from the Spark Internal Compass and also from the Phone's Compass. (Thanks for Pointing this Out)

Leave the Spark On, without Taking Off, on the DJI Go 4 App check that the North (Black 'N' Circle) is Pointed same direction as your Physical Compass. Then just to make sure all is fine just hover a bit to check that there was no change, it will be only matter of seconds until you get used to the Procedure. Hovering helps as at this stage is when you will see that there was not Interference from the Ground. If you are away from Urban Areas, you chance of having Wire Pipelines underneath will be very minimum. This Procedure I suggest you included it in you PreFlight Checklist.

Read here from a Post by a Pro Pilot @hallmark007 - https://forum.dji.com/forum.php? ... 4222&fromuid=260008

It a hassle to stay switching programs to check with the Phone Compass, even if you Phone Compass is giving issues I don't suggest you use that one. Use the Physical Compass to be more accurate.

This Video may help understand all the Compass Info on your App -

2018-6-30
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JimboHUN
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DMX_MT Posted at 2018-6-30 15:44
Hi Jimbo,

The App will gather the information from the Spark Internal Compass not the Phone.

Hi,

Thank you for the video, I have watched it a few times already.

However I think the Attitude indicator's "north" is based on the phone's internal compass.

To me it was easy know as my previous phone has no built in compass so the north was not updating in the app Also I think some pople in this forum suggested the same.

Furthermore I have just tested now with my new phone, and it even shows north when the Spark is disconnected - so I think it is not pulling the info from the drone. I wil just post a photo below.

Cheers,

2018-6-30
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JimboHUN
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Picture as promised.
RC.jpg
2018-6-30
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JimboHUN
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Though actually I think I got it now, how to check if all good:

1) check with a second compass if the "N" icon in the attitude indicator is correct
2) face yourself with the RC to north (i.e. in the attitude indicator "N" and the small white triangle cover each other)
3) face the drone to the same direction you are facing (in real life)
4) check in the attitude indicator if the drone there is facing towards the "N" icon - if yes it is OK
2018-6-30
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JJBspark
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JimboHUN Posted at 2018-6-30 23:15
Hi,

Thank you for the video, I have watched it a few times already.

Hi Jimbo,

yes, compass in the app gets data from your mobile device.
Very usefull if your video link is broken beacuse the red arrow still receives data from drone, makes it possible to fly it back home without a video link.

if you like watch this:  https://forum.dji.com/thread-144696-1-1.html

cheers
JJB
2018-7-1
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JimboHUN
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JJBspark Posted at 2018-7-1 00:47
Hi Jimbo,

yes, compass in the app gets data from your mobile device.

Hi,

Thanks, I am actually back from a flight and it worked like a charm. I checked north with a compass too.

Cheers
2018-7-1
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DMX_MT
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Thank you Jimbo for the Picture and your proof, good to know that.

The Steps you suggested are a Good Procedure to check in more depth that the Compass is working well.

Questions -

Quoting you - ''To me it was easy know as my previous phone has no built in compass so the north was not updating in the app''

1) So if the Spark gets the Magnetic North information from the Phone, and you didn't have a Phone Compass to give you reading of the Magnetic North, from where did the Spark realise where is North and where South is etc..., especially when you do RTH and use GPS Co-ordinates ?

2) Also if you use Remote Only just to fly for fun and not for taking Video / Pictures, which is possible, how will the Spark know where the North is ?

Thank you.


2018-7-1
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JimboHUN
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DMX_MT Posted at 2018-7-1 03:25
Thank you Jimbo for the Picture and your proof, good to know that. I edited my post that the Magnetic North is obtained from the Phone as you are saying.

The Steps you suggested are a Good Procedure to check in more depth that the Compass is working well.

Hi,

Yes, that is the million dollar question that's why I opened this topic, maybe someone knows.

Spark also has its internal compass, but you cannot check where it thinks north is.

The phone also has its compass, and the data from the 2 are combined in the attitue indicator.

I think you can only assume and hope it works OK after calibration, and if there is no interference.

Cheers,

2018-7-1
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JimboHUN
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Sorry I had to reedit my last post a few times. Please read again
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DMX_MT
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JimboHUN Posted at 2018-7-1 03:57
Hi,

Yes, that is the million dollar question  that's why I opened this topic, maybe someone knows.

Hi Jimbo nice discussion here, enjoying it.

I think the App uses the Phone Compass just to give you a Visual Indication where the Actual Magnetic North on The DJI Go4 App Compass is, if you see from the Video as soon he turns himself facing another angle, the North Turns with him and updates itself as you stated.

There must surely be some kind of Information going on inside the Spark to give it a Magnetic North Reading.  As when the Spark does an AutoRTH when it loses connection with the Remote and Phone it needs some heading information. (Although this is only my Speculation not based on facts.)

I think with Technology these days there could even be a System where the Spark uses the Geo Positioning and will lookup your Co-ordinates to a Database inside the Spark and automatically work out the True North by adding the Magnetic Declination / Inclination Degree of where you are flying at that moment. Maybe as most drones are not supposed to go very far, the True North is not so important as it won't be travelling to extreme distances like over 50km where the Magnetic North will cause some deviation from the True North Course.

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DMX_MT
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JimboHUN Posted at 2018-7-1 04:02
Sorry I had to reedit my last post a few times. Please read again

I think you are Right, I agree with You that the two readings are Combined.


2018-7-1
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S-e-ven
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JimboHUN Posted at 2018-7-1 03:57
Hi,

Yes, that is the million dollar question  that's why I opened this topic, maybe someone knows.

Oh, you can:
The radar view gets you a north of your phones compass.
And a position from the sparks GPS and compass.
Both together gets you a more or less precise direction, WHERE seen from your RC-location, the spark is, and which direction the front of the bird is.

You can try that flying your bird just 50m away and check if the direction of the bird is like that one shown in the radar, and if the position of the spark is like the radar is pointing to it.
If both compasses are "good", there is not much "off" from reality to expect.
My phone is almost always showing the spark 10° aside of its real position.
Even after calibrating it just before the flight.
But that is, together with a almost precise direction of the bird, good enough, to first find it back in the air (if height/distance guessing works out), but secondly to get it closer back home, even without a video feed and lost sight.
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JJBspark
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S-e-ven Posted at 2018-7-1 07:18
Oh, you can:
The radar view gets you a north of your phones compass.
And a position from the sparks GPS and compass.

HI,

Yes, the compas view on the app gets its North from your/our mobile device compass.
For RTH procedure the Drone doesn`t need a mobile device, its uses its own compass and GPS position to fly to the HP wich is stored in the Drone.

IMO the little radar view is just a tool to fly it back if you loose sight of the drone. Just try this ; fly some distance away (100 meter) and point the RC towards the drone. Close your eyes and turn yourself 180 degree. Open eyes (do not watch up but at your screen) and move yourself towards the drone ; align the center of the compass and red arrow and with mark in one line. Drone is in front of you.

BTW i had once a app closing done failure while drone was on a RTH procedure, no problems.

If i have time and the wind is less in Holland i will make a video of that.

cheers
JJB
2018-7-1
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