How to use VPS only and disable GPS ?

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Hi guys....

after a whole day search on the web and this forum, i could not find any clue on how to use VPS only instead of GPS on my P3a. what i am concern is, when i need to fly indoors and satelites seem unreliable (flickering on and off, and sometimes inacurately calculates location, i can see it on my mobile device the AC icon and my position jumps a lot), in this certain condition i prefer to use VPS only. But as we know VPS stabilization only works when GPS is not exist. Does anyone know how to turn GPS off and keep VPS on, other than almunium foil solution??

if we can't use VPS only, that makes me think what benefit of using this feature indoors when GPS sudenly takes over...??

Thanks in advance....

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alokbhargava

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There is no direct way to just switch off GPS and retain VPS for position control. You can probably do it by covering top of the phantom surface with a metallic foil and try. Be careful, it should not get loosened and entangled into blades.


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thanks for your sugestion Mr. alokbhargava... that seem to be the only way i found on the net....

but if may ask for opinions, do you think DJI should add this capabilities regarding on user's requirements on certain conditions as i wrote above? is it a good idea or not??

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If it's indoors or under a canopy of trees, gps isn't working anyway and it doesn't just come on... There's no need to disable gps and nothing to gain.
 

alokbhargava

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My experience is that when you fly at low heights, even though GPS is ON, VPS takes the precedence. So it really doesn't matter if GPS is ON. VPS needs certain qualities of the ground surface, if those conditions are met, you should not have any problems in keeping both ON. But your condition may be very specific which I don't understand and may be blocking GPS is the right solution for you.
 

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Put the RC into Atti mode & GPS is disabled, VPS still operable, achieving OP requirements or am I missing something here?


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Put the RC into Atti mode & GPS is disabled, VPS still operable, achieving OP requirements or am I missing something here?


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If that were true, switching into Atti would bypass NFZ's. GPS is still active in Atti mode. It's just not used for positional stability to prevent drifting, but it still knows where you are and where you took off from, and is used for RTH in the event of signal control loss.
 
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If it's indoors or under a canopy of trees, gps isn't working anyway and it doesn't just come on... There's no need to disable gps and nothing to gain.
as far as i know, trees, roofs, and canopies does block GPS satelites signal. but it doesn't mean zero signal. we know there are more than 30 GPS satelites arround the globe, and off course half of them are above us at the current time, so there will be some number of satelites signal still able to reach the phantom down here. what i am concerning is, for certain condition under week signal, any GPS based gadget (trackers, cellphones, tablets, and also drones) calculates position and resulting in low accuracy, thus i prefer to pick VPS stabilization rather than GPS. but the firmware design of the DJI won't allow us to do that, because the GPS stabilization priority is higher than VPS even it produce low accuracy position calculation.

unless, we are inside the basement, or may be bunker, or may be inside the house under the forest, or in the middle of large building, that could be zero satelites signal, then your statement is correct. but what i am talking about is some indoors circumstances when phantom does still have the GPS lock with low accuracy.

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My experience is that when you fly at low heights, even though GPS is ON, VPS takes the precedence. So it really doesn't matter if GPS is ON. VPS needs certain qualities of the ground surface, if those conditions are met, you should not have any problems in keeping both ON. But your condition may be very specific which I don't understand and may be blocking GPS is the right solution for you.

Thankyou again for your kind reply Mr. alokbhargava....

Before i take you to the scenario i am concerning, would you mind to read my thought below and tell me wether you're agreed or not.
-------------------------

Regarding of the DJI statement about working range of the VPS at low altitude (which is about 50cm - 300 above ground for P3a), i think that is the requirement of the VPS to work correctly along with other requirements of the circumstances (eq. non monochrome, non reflective, has visual patterns, sufficient lighting, no moving object below, etc). But when those conditions apply, doesn't mean VPS will sudenly overide the GPS, as i think DJI put the GPS stabilization priority higher than VPS, that's why VPS will only used for stabilization when GPS is unavailable (has no lock).

As far as i know, VPS has 2 sub systems as below :
1. Sonar : reads vertical height.
2. Camera : reads horizontal movement.
Both of them working all the time as long as we set it on, and the AC firmware take it in count for vertical stabilization when AC in working range (about 50-300 above the ground).

Please check these videos.
GPS unavailable (double green blinks, horizontal and vertical VPS stabilization in charge) --->
GPS available (single green blinks, only vertical VPS stabilization in charge along the hill) --->
GPS available (single green blinks, i am not sure was it VPS or GPS in charge) --->
GPS available (single green blinks, horizontal stabilization VPS is not working regardless VPS_ON and VPS_OFF setting) --->

And i found those are true based on my personal experience. If AC really take the horizontal VPS stabilization actualy in count, then it will be very rock solid when hovering on the VPS altitude range. But the fact is it keep drifting for couple inches or feet back and forth, left and right. And there will be the same wether i set the VPS ON or OFF.

All of those videos bring me to conclusion that AC will use the horizontal VPS stabilization only when GPS is unavailable.
Once GPS has satelites lock, AC will use the GPS instead.

VPS.jpg
 
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Put the RC into Atti mode & GPS is disabled, VPS still operable, achieving OP requirements or am I missing something here?


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If that were true, switching into Atti would bypass NFZ's. GPS is still active in Atti mode. It's just not used for positional stability to prevent drifting, but it still knows where you are and where you took off from, and is used for RTH in the event of signal control loss.

GadgetGuy is correct...
ATTI doesn't mean GPS is OFF. it just the AC firmware doesn't take GPS for stabilization.
if we fly in ATTI, the AC won't take VPS for stabilization either, but it will use barometer only for determining heights.
 
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as far as i know, trees, roofs, and canopies does block GPS satelites signal. but it doesn't mean zero signal. we know there are more than 30 GPS satelites arround the globe, and off course half of them are above us at the current time, so there will be some number of satelites signal still able to reach the phantom down here. what i am concerning is, for certain condition under week signal, any GPS based gadget (trackers, cellphones, tablets, and also drones) calculates position and resulting in low accuracy, thus i prefer to pick VPS stabilization rather than GPS. but the firmware design of the DJI won't allow us to do that, because the GPS stabilization priority is higher than VPS even it produce low accuracy position calculation.

unless, we are inside the basement, or may be bunker, or may be inside the house under the forest, or in the middle of large building, that could be zero satelites signal, then your statement is correct. but what i am talking about is some indoors circumstances when phantom does still have the GPS lock with low accuracy.

Sent from my SCL23 using PhantomPilots mobile app

Whether the Phantom is receiving a signal from a few satellites or not, you won't get a strong gps signal or a lock with less then 10 satellites. Seems like you are really brainstorming on this when it simply works fine as is. Around half of my flights are vps only or p-atti when I am flying above 3m. It moves around a bit in atti but when it's in vps, it holds pretty steady. You're thinking way to hard on this older system that has been completely changed for the better with the new Phantom 4 and even more so with the Phantom 4 Pro. Get out and fly :) Brainstorming over outdated equipment is just unneeded stress, DJI has come a long way from the old P1... Next year it will be the Phantom 5. If what you have isn't working the best that it can for you then get the P4P. Then your brainstorming can be on the most current product and you will have a lot more fun :)
 
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alokbhargava

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Thankyou again for your kind reply Mr. alokbhargava....

Before i take you to the scenario i am concerning, would you mind to read my thought below and tell me wether you're agreed or not.
-------------------------

Regarding of the DJI statement about working range of the VPS at low altitude (which is about 50cm - 300 above ground for P3a), i think that is the requirement of the VPS to work correctly along with other requirements of the circumstances (eq. non monochrome, non reflective, has visual patterns, sufficient lighting, no moving object below, etc). But when those conditions apply, doesn't mean VPS will sudenly overide the GPS, as i think DJI put the GPS stabilization priority higher than VPS, that's why VPS will only used for stabilization when GPS is unavailable (has no lock).

As far as i know, VPS has 2 sub systems as below :
1. Sonar : reads vertical height.
2. Camera : reads horizontal movement.
Both of them working all the time as long as we set it on, and the AC firmware take it in count for vertical stabilization when AC in working range (about 50-300 above the ground).

Please check these videos.
GPS unavailable (double green blinks, horizontal and vertical VPS stabilization in charge) --->
GPS available (single green blinks, only vertical VPS stabilization in charge along the hill) --->
GPS available (single green blinks, i am not sure was it VPS or GPS in charge) --->
GPS available (single green blinks, horizontal stabilization VPS is not working regardless VPS_ON and VPS_OFF setting) --->

And i found those are true based on my personal experience. If AC really take the horizontal VPS stabilization actualy in count, then it will be very rock solid when hovering on the VPS altitude range. But the fact is it keep drifting for couple inches or feet back and forth, left and right. And there will be the same wether i set the VPS ON or OFF.

All of those videos bring me to conclusion that AC will use the horizontal VPS stabilization only when GPS is unavailable.
Once GPS has satelites lock, AC will use the GPS instead.

View attachment 69198

Let me answer you:

First of all DJI has not specified any where that GPS takes over control if GPS lock is achieved for maintaining position.

GPS help maintain horizontal position like that's done by the camera of VPS.

On low flying, VPS ultra sound system can very accurately determine the height above ground for even and non reflecting surfaces this is the best way to stabilize heights above ground. You may notice AC following the contours of the ground for low heights. Check what happens if it sees a table for example beneath in a room.

Camera of VPS system takes ground images and uses it to control movements by comparing images. Accuracy of control definitely depends on the pattern on the ground as seen by the camera. A ground with a smooth painted surface will make images similar and it will be difficult for VPS to stabile its horizontal position. A check design on ground could be better than a well cut lawn for the obvious reasons. Similarly as you move the aircraft up, pattern seen by the camera becomes smaller and thus loses accuracy and thus has limitations.

Hope this will give you clarifications to what you observed in your videos.

Best.


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Let me answer you:
First of all DJI has not specified any where that GPS takes over control if GPS lock is achieved for maintaining position.

i read it on the manual book sir... that's what i understand.
i'm gonna test it tomorrow by flying under 3meters outdoor with good GPS lock and then switching VPS ON and OFF, and let's see what's gonna happen.
VPS2.jpg


GPS help maintain horizontal position like that's done by the camera of VPS.

On low flying, VPS ultra sound system can very accurately determine the height above ground for even and non reflecting surfaces this is the best way to stabilize heights above ground. You may notice AC following the contours of the ground for low heights. Check what happens if it sees a table for example beneath in a room.

Camera of VPS system takes ground images and uses it to control movements by comparing images. Accuracy of control definitely depends on the pattern on the ground as seen by the camera. A ground with a smooth painted surface will make images similar and it will be difficult for VPS to stabile its horizontal position. A check design on ground could be better than a well cut lawn for the obvious reasons. Similarly as you move the aircraft up, pattern seen by the camera becomes smaller and thus loses accuracy and thus has limitations.

Hope this will give you clarifications to what you observed in your videos.

Best.

Sent from my iPhone using PhantomPilots

.... and yes.... you are right, at least we have a common of understanding about HOW VPS works. :)
but still there are some diferences about WHEN the AC use it. :(
 
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Whether the Phantom is receiving a signal from a few satellites or not, you won't get a strong gps signal or a lock with less then 10 satellites. Seems like you are really brainstorming on this when it simply works fine as is. Around half of my flights are vps only or p-atti when I am flying above 3m. It moves around a bit in atti but when it's in vps, it holds pretty steady. You're thinking way to hard on this older system that has been completely changed for the better with the new Phantom 4 and even more so with the Phantom 4 Pro. Get out and fly :) Brainstorming over outdated equipment is just unneeded stress, DJI has come a long way from the old P1... Next year it will be the Phantom 5. If what you have isn't working the best that it can for you then get the P4P. Then your brainstorming can be on the most current product and you will have a lot more fun :)

thank you for sharing your experience of flying a lot with VPS, i really need it as i am new to this technology although in fact this is way to old... :( that's because this is the best drone i could afford for this time, and i believe i will never able to catch up with the very current version of these tools ....
may be i have to much expectation about VPS on how really smooth stable and rock solid it should be (compared to P3s i've just sold)... but in fact i found it drifting a few inches or sometimes a few feet... that makes me think that my phantom is not working as i expecting. and by this post i want to make sure is that normal or might be something wrong with it.... and it just poped up of my mind to try to block the GPS so i can make sure my phantom is using VPS only during the test..... thank's... :)
 
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If it's drifting a few feet then vps isn't working and it's simply in p-atti, where it will hold the altitude but drift constantly without any input from the sticks by you to keep it close to where you want it. If mine starts drifting like that, I set it on the ground and then make sure vps is on and go again from there. But once you get above 3 meters and you lose vps, your flying in full manual mode. At 2:55 in this movie I was flying vps only in the redwoods here on the Pacific coast. When I took it up above 3 meters close to the end of this clip, that was drift going backwards. It drifted about 6 feet and then I simply set it down. Once you fly above vps in the woods the whole plan changes, which is why the P4P really will have a place in this house :)
 
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