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How does the drone calculate it's speed?
1260 11 2018-5-2
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Bokepacha
Second Officer
Flight distance : 149265 ft
Netherlands
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Hi everyone,

I have been wondering for a while how does the drone calculate it's speed?

It does not have a pitot tube as a plane, so my guess (as I haven't found anything with my google FU) is that it might calculate the speed according to it's position against the ground.

Can anyone confirm or deny it? I find it interesting to know.

Thanks!

2018-5-2
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Blizzard
First Officer
Flight distance : 144117 ft

Belgium
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I think it uses his GPS.
So It calculates his speed in relation to his ground position and in aviation it is called the groundspeed.
This is, for us, the most important speed, so we can estimate the windspeed.
2018-5-2
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Bokepacha
Second Officer
Flight distance : 149265 ft
Netherlands
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lol, you are right. I absolutely forgot about GS in planes through GPS.

Thanks!
2018-5-2
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DJI Diana
Administrator
Flight distance : 2408 ft

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An interesting post.
2018-5-2
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chiplifter
Captain
Flight distance : 745180 ft
Netherlands
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My guess it is using groundspeed based on gps location, since flying with- or against the wind changes maximum speed.
2018-5-3
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brianoflondon
lvl.4
Flight distance : 792369 ft
Israel
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GPS works out a speed with high accuracy based not on differential movement but on the doppler shift of the signals received from individual satellites. Many web sites wrongly say GPS does it by measure a change in position over time and while that calculation is possible, it would be way slower and less accurate than what GPS actually does.
The capabilities of the latest GPS receivers, built into tiny chips that do a zillion other things, are simply beyond the comprehension of most people. My head spins trying to think about all the calculations a phone or my drone can do in a milisecond that 100 years ago took an army of people to perform (once).

Because our drones don’t always fly forwards, measuring air speed with the same tools airplanes use would be highly challenging. GPS is perfect for this.

https://www.e-education.psu.edu/geog862/node/1786
2018-5-3
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Gregbella
Captain
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Yeah it must be through the gps
2018-5-3
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AndrewUK
lvl.4
Flight distance : 1403068 ft
United Kingdom
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brianoflondon Posted at 2018-5-3 01:27
GPS works out a speed with high accuracy based not on differential movement but on the doppler shift of the signals received from individual satellites. Many web sites wrongly say GPS does it by measure a change in position over time and while that calculation is possible, it would be way slower and less accurate than what GPS actually does.
The capabilities of the latest GPS receivers, built into tiny chips that do a zillion other things, are simply beyond the comprehension of most people. My head spins trying to think about all the calculations a phone or my drone can do in a milisecond that 100 years ago took an army of people to perform (once).


Had my MA a week, still struggling to comprehend how much tech is in this thing and how well it's all integrated together!

When I think about what is happening during track mode it scares me.  Image recognition, gimbal movement to keep centre and counteract drone movements, drone movement to keep target centre, stabilisation against wind, obstacle avoidance, maintains altitude, captures 4k video, high bandwidth digital RF transmission...  List goes on.

If you started from scratch and assuming the GPS satellite network exists, there's probably millions of man years of effort and many billions of dollars of investment required to produce one of these things!
2018-5-10
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brianoflondon
lvl.4
Flight distance : 792369 ft
Israel
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AndrewUK Posted at 2018-5-10 03:00
Had my MA a week, still struggling to comprehend how much tech is in this thing and how well it's all integrated together!

When I think about what is happening during track mode it scares me.  Image recognition, gimbal movement to keep centre and counteract drone movements, drone movement to keep target centre, stabilisation against wind, obstacle avoidance, maintains altitude, captures 4k video, high bandwidth digital RF transmission...  List goes on.

I have of of the first Garmin GPS45 units that was sold to the general public. It was one of the first units available to the public.

To think that all of it now sits in just one part of an integrated circuit on one chip is astonishing.

2018-5-12
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Bill B
First Officer
Flight distance : 319245 ft
United States
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Same way your car does when it is tethered to  gps. (Magellan, Garmin) It measures the time it takes to travel between columns of the gps positions. Pretty spot on too.
2018-5-12
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Bulldog
First Officer
Flight distance : 816158 ft
United States
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It uses black magic to find mph
2018-5-12
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Bokepacha
Second Officer
Flight distance : 149265 ft
Netherlands
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Bulldog Posted at 2018-5-12 05:13
It uses black magic to find mph

But is it black magic air?

I'll find the door by myself xD
2018-5-13
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