How close are your home point landings?

Drestin Black · Aug 22, 2016

A bit of a poll, how close does your return to home bring your P4?

I'll have 12+ satellites locked in and manually reset the Home point and off she goes, flys a bit and then I do a Return to Home.

I've had it come down 30 feet away - wtf! It can hover with such accuracy, go to way points miles away with great accuracy, track itself over a may with such accuracy.

Why is the return to home so far off? Is it just me?

alokbhargava · Aug 22, 2016

I have tried couple of times and got within about 10-12 feet. Never measured it but that's my guess. It's pretty close.

Sent from my iPhone using PhantomPilots

Drestin Black · Aug 22, 2016

I think even 10-12 feet is too far off, don't you?

Meta4 · Aug 23, 2016

Drestin Black said:
A bit of a poll, how close does your return to home bring your P4?

I'll have 12+ satellites locked in and manually reset the Home point and off she goes, flys a bit and then I do a Return to Home.

I've had it come down 30 feet away - wtf! It can hover with such accuracy, go to way points miles away with great accuracy, track itself over a may with such accuracy.

Why is the return to home so far off? Is it just me?

That's the accuracy of consumer GPS. Often within 2-3 feet, sometimes more but usually within 10 ft. GPS is only part of the position holding magic. The other sensors in the IMU do a lot of the work.

Sent from my SM-G900I using PhantomPilots mobile app

Drestin Black · Aug 23, 2016

But what about accuracy for way points?
This is something I haven't used yet - way points. if they can be off by as much as 30 feet -- whoa! I'd be afraid to use them in anything but wide open spaces. A lot of my work is within tighter quarters with hard things there to penalize me if I'm off...

KevMo Photog · Aug 23, 2016

Drestin Black said:
But what about accuracy for way points?
This is something I haven't used yet - way points. if they can be off by as much as 30 feet -- whoa! I'd be afraid to use them in anything but wide open spaces. A lot of my work is within tighter quarters with hard things there to penalize me if I'm off...

If it's that tight on a few of your gigs I would fly it manual man. Is that a possible? But I have flown several Lithci missions and it was very good missing some shortish buildings by almost exactly the distance I set it to miss them. I was pretty impressed tbo!

FlyingPh@ntom · Aug 23, 2016

When you engage RTH within 20 of the homepoint it will land at the spot you engaged RTH at.

Drestin Black · Aug 23, 2016

FlyingPh@ntom said:
When you engage RTH within 20 of the homepoint it will land at the spot you engaged RTH at.

I know - this is when I've engaged RTH further away. It's been quite a bit off lately

Kman · Aug 23, 2016

GPS for civilian use is not pin point accurate. The government does that by design. Only military equipment gets pin point GPS accuracy.

With The Birds · Aug 23, 2016

Kman said:
GPS for civilian use is not pin point accurate. The government does that by design. Only military equipment gets pin point GPS accuracy.

I suspect that is an old wives tale, I have heard it often. Many differential grade GNSS units will get you well within 1m consistently however cost a lot more. This would add significantly to what we currently pay for our phantoms.

Drestin Black · Aug 23, 2016

Kman said:
GPS for civilian use is not pin point accurate. The government does that by design. Only military equipment gets pin point GPS accuracy.

Not since Clinton, the cheater not the current liar, removed the civilian intentional "fuzziness" back on may 1, 2000. We get the exact same signal the military gets now.

Sent from my iPhone using PhantomPilots

Meta4 · Aug 23, 2016

Drestin Black said:
But what about accuracy for way points?
This is something I haven't used yet - way points. if they can be off by as much as 30 feet -- whoa!

Consumer GPS is not pinpoint accurate .. but It's pretty good.
30 feet is extreme and you would rarely see an error of that magnitude.
Most of the time the error will be within 1.5-2 metres.

Dragonfly2016 · Aug 23, 2016

With The Birds said:
I suspect that is an old wives tale, I have heard it often. Many differential grade GNSS units will get you well within 1m consistently however cost a lot more. This would add significantly to what we currently pay for our phantoms.

Nah it's true. The built in error used to be about 10 meters. I'm not sure what it is now, but it's certainly better

Sent from my XT1585 using PhantomPilots mobile app

Tenly · Aug 23, 2016

Drestin Black said:
Not since Clinton, the cheater not the current liar, removed the civilian intentional "fuzziness" back on may 1, 2000. We get the exact same signal the military gets now.

Sent from my iPhone using PhantomPilots

The government has the ability to add the fuzziness for non-military users back in whenever needed - such as in a time of war.

Tenly · Aug 23, 2016

Drestin Black said:
A bit of a poll, how close does your return to home bring your P4?

I'll have 12+ satellites locked in and manually reset the Home point and off she goes, flys a bit and then I do a Return to Home.

I've had it come down 30 feet away - wtf! It can hover with such accuracy, go to way points miles away with great accuracy, track itself over a may with such accuracy.

Why is the return to home so far off? Is it just me?

I've noticed the same thing and even written up and submitted an enhancement request to DJI that would completely eliminate the issue.

My idea is for them to sell us a rubber mat landing pad - say 18" by 18" with a large DJI logo on it. The idea would be that we place the mat on the exact spot we want the Phantom to land. GPS RTH gets us close enough that the camera or vision positioning system can "see" our landing pad and then ignore the GPS data and land on the mat.

Their software already has the ability to recognize objects in the video. This would not be difficult for DJI to accomplish - and they could create a new revenue stream by selling it as an optional add-on accessory instead if including it for free in the box.

richpoolside · Aug 23, 2016

After doing a flight of 2000m I pressed return to home and it landed with in 1m from its take off mat .I was well impressed with it (18 satellites ) most of the flight .

Sent from my iPhone using PhantomPilots

tommyb888 · Aug 23, 2016

Mine lands with 1-2 feet of take off point

N017RW · Aug 23, 2016

Tenly said:
The government has the ability to add the fuzziness for non-military users back in whenever needed - such as in a time of war.

US Govt. says:

"Will SA ever be turned back on?
The United States has no intent to ever use SA again. To ensure that potential adversaries do not use GPS, the military is dedicated to the development and deployment of regional denial capabilities in lieu of global degradation."

Furthermore current satellites in production and being launched into service beginning this year (GPS III) have no SA capability.

Monte55 · Aug 23, 2016

I have a question. Why does a Phantom need so many satellites. When people say they have 12 sats, is the Phantom using info from all 12 at the same time. It only takes 3 satellites to get longitude, latitude , and altitude . Now I know that which three satellites it's getting info from will affect accuracy. In my handheld gps units, I can see which satellites it's locked onto and where they are located in the sky. How many channels is a Phantom gps receiver.?