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Would someone elaborate on Satellites?

Sprocket

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Satellites obviously are needed for accuracy. Does the drone actually need and use 16? What is the minimum no. that is safe to use?
I always use RTH. It has never failed me in about 90 flights. Yesterday I flew two missions. Both times the drone landed within an inch of exact takeoff point. I didn't notice if for some reason I had more satellites than usual. Normally my drone lands within appx. 3-6 inches of exact takeoff point.
I'm always impressed with the precision of my drone, but yesterday seemed different for some reason.
Is precision noticeably better with 16 satellites as compared to 14? Or, is it just my imagination? Thanks in advance.
 

wytnyt

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more is better but a bare minimum for any accuracy is 4 or more,i believe why a higher number is needed is because the mavic is constantly losing and re-acquiring satellites so the more the better the stability there is.
 

dbyantis

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Satellites obviously are needed for accuracy. Does the drone actually need and use 16? What is the minimum no. that is safe to use?
I always use RTH. It has never failed me in about 90 flights. Yesterday I flew two missions. Both times the drone landed within an inch of exact takeoff point. I didn't notice if for some reason I had more satellites than usual. Normally my drone lands within appx. 3-6 inches of exact takeoff point.
I'm always impressed with the precision of my drone, but yesterday seemed different for some reason.
Is precision noticeably better with 16 satellites as compared to 14? Or, is it just my imagination? Thanks in advance.
The precision on landing is also affected by optics, if enabled, Mavic takes a "video" of launch point to match up with at landing from RTH, since there can be several meters of variation just using GPS.
 

Drone Master

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more is better but a bare minimum for any accuracy is 4 or more,i believe why a higher number is needed is because the mavic is constantly losing and re-acquiring satellites so the more the better the stability there is.
Another reason to use UAV Forecast before a flight! It gives accurate readings on sats. At least for me and my location.:cool:
 
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TrayBoz

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I've noticed that mine won't allow me to fly with GPS (per the green GPS banner at the top of DJI GO) unless I have at least 10 satellites locked in. I normally won't launch unless I have at least 11, just to be a little extra safe. Normally, within 5 minutes of waiting or so, I'll have between 14-18 sats locked in, on most days. I'm in Dallas, TX.
 
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Drone Master

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I've noticed that mine won't allow me to fly with GPS (per the green GPS banner at the top of DJI GO) unless I have at least 10 satellites locked in. I normally won't launch unless I have at least 11, just to be a little extra safe. Normally, within 5 minutes of waiting or so, I'll have between 14-18 sats locked in, on most days. I'm in Dallas, TX.
Wow, you have to wait 5 minutes before you can lift off because of sat lock? I'm in the air within 30 seconds of starting my aircraft. Full sats on average. The MP only requires 10 or more sats for take off. Once you are in the air, you will most likely gain more sats instantly.
 
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TrayBoz

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Wow, you have to wait 5 minutes before you can lift off

No, you misunderstood. I normally have 10-11 sats connected within 30 seconds, then I launch. But if I DO wait 5 mins, (or about 5 mins after I've launched), I usually have between 14-18 sats locked - sometimes 20, but not often.

I've never NOT been able to get 11 satellites locked in - in any country, including USA.
 

Drone Master

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No, you misunderstood. I normally have 10-11 sats connected within 30 seconds, then I launch. But if I DO wait 5 mins, (or about 5 mins after I've launched), I usually have between 14-18 sats locked - sometimes 20, but not often.

I've never NOT been able to get 11 satellites locked in - in any country, including USA.
Ok, I was going to say. That would have been valuable battery time waisted.
Yeah, I usually acquire 16 sats within 60 seconds. But I live in south Florida which is totally flat terrain.
 

bushie

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It is not just total number of sats but where they are located. A sat close to the horizon will give less accuracy than one vertically above.

The GPS constellation is optimised for the USA so in some areas like Australia it may not always give the same accuracy.
 

Marko9219

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[QUOTE="bushie, post: 493412, member: 54565"A sat close to the horizon will give less accuracy than one vertically above.[/QUOTE]could you please reference any material to help me understand that concept? That is something I've never once before heard about the GPS constellation. Thanks.
 

Lake_Flyer

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It is not just total number of sats but where they are located. A sat close to the horizon will give less accuracy than one vertically above.

The GPS constellation is optimised for the USA so in some areas like Australia it may not always give the same accuracy.
But then there's also GLONASS. Besides, the GPS system is originally developed to use around the globe by US forces, certainly not specifically in the US.
 

Sprocket

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Live World Map of Satellite Positions - In-The-Sky.org

I posted this link at 3:20 a.m. CDT. There appears to be very few overhead in central U.S. Can I assume by this map that my accuracy won't be very good if I was to takeoff right now? Thanks

I don't know how to post screen shots or I would. Thanks
 

Cslucas34

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It is not just total number of sats but where they are located. A sat close to the horizon will give less accuracy than one vertically above.

The GPS constellation is optimised for the USA so in some areas like Australia it may not always give the same accuracy.

You are correct in that geometry of where they are located will effect accuracy but the part about one being close to the horizon being less accurate isn’t entirely true. Again, it depends on its relation in position to the user and the other satellites. Any single satellite is only providing a time code which is then used to provide a distance traveled. It’s all triangulation from there. So although the signal may distort more at the horizon due to atmospheric events, etc... overall accuracy depends on its relation to the other satellites and how many of the arcs cross each other.
 

Turn11

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how to post screen shots

iPhone or iPad buttons and switches
On your device, locate the Home / Touch ID sensor and the Top OR Side Button depending on your device.

At the same instant press the Home / Touch ID sensor and the Top OR Side Button depending on your device for about one second. When you have the right combination you will hear a curchunk sound and you will briefly see the picture. If you press either button too soon, the normal function of that button will happen.

YouTube
iPad
iPhone
 

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