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Why does my Phantom take so long to get GPS lock?

DJI Phantom Quadcopter General Discussion

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Why does my Phantom take so long to get GPS lock?

Postby rilot » Tue Oct 15, 2013 11:31 am

My phantom can sometimes take well over a minute to get a GPS lock.
I also fly an F550 with a Naza-M and it gets lock in literally seconds after connecting the power.

As a test, I timed them both in the same field yesterday.

F550. Full lock in 8 seconds after power connected
Phantom. Full lock in 64 seconds after power connected

Any ideas why?
DJI S800 EVO - A2, X140BS gimbal, 2.4GHz ground station.
DJI F550 - Naza-M V2, H3-2D, iOSD mini, Graupner 9x5.
DJI Phantom 2 - H3-2D, iOSD mini
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Re: Why does my Phantom take so long to get GPS lock?

Postby discv » Tue Oct 15, 2013 11:40 am

A complete shot in the dark- your 550 GPS is on a tower, I presume, and the Phantom GPS is buried in the works?

Edit- It would appear from the posts that follow, my theory might have some mileage. I wonder if it could be an option to lift the GPS up and out of the body-essentially as fitted to the 550.
Last edited by discv on Wed Oct 16, 2013 2:48 am, edited 1 time in total.
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Re: Why does my Phantom take so long to get GPS lock?

Postby insatiable » Tue Oct 15, 2013 11:50 am

Mine also takes a long time to lock on. I've not timed it but I am sure it's inexcess of 1 minute. After a flight, the subsequent flight if immediately after is already locked on and ready to go.
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Re: Why does my Phantom take so long to get GPS lock?

Postby Ksc » Tue Oct 15, 2013 7:49 pm

A local guy cut a hole in the center of his so the antenna has a direct line of sight to the sky. He says it speeds up everything.
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Re: Why does my Phantom take so long to get GPS lock?

Postby miskatonic » Wed Oct 16, 2013 12:54 am

I noticed that the IOSD MINI distinguishes from the number of satellites that the Phantom can see vs. the number that the Phantom has locked. For the longest time today my Phantom say six satellites but it would not lock onto the 6th until I moved it about three feet.
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Re: Why does my Phantom take so long to get GPS lock?

Postby FrankB » Wed Oct 16, 2013 1:00 am

What this illustrates is the need to have a better GPS in the Phantom and, hopefully, the Vision. They should use a high sensitivity antenna, like the SiRF, and also use a GPS that is capable of making use of both the Russian GLONASS GPS system and also the European Galileo System when it becomes operational.
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Re: Why does my Phantom take so long to get GPS lock?

Postby The Editor » Wed Oct 16, 2013 2:22 am

FrankB wrote:What this illustrates is the need to have a better GPS in the Phantom and, hopefully, the Vision. They should use a high sensitivity antenna, like the SiRF, and also use a GPS that is capable of making use of both the Russian GLONASS GPS system and also the European Galileo System when it becomes operational.


I don't think DJI would be concerned about making their system compatible with Galileo - A project that is currently running over six years late, has been beset by problems from day one, lost most of it's funding, not that technologically advanced and with the US about to update the already proved GPS system that makes Galileo out of date! It's a vanity project devoid of all commercial logic. I seriously wouldn't hold my breath for an EU conglomerate to complete on a project that nobody wants or needs...... Oh wait a minute... it's the EU... THAT'S exactly the sort of project they might finish :lol: :lol: :lol: .

Seriously though - if you were a company making UAV's would you seriously waste good time and effort on R&D on something that isn't and may never become operational this side of 2020?
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Re: Why does my Phantom take so long to get GPS lock?

Postby MenaceCat » Wed Oct 16, 2013 10:02 pm

May I suggest that the issue is less about antenna sensitivity than about the time required to acquire satellites under different contexts.

Although the original poster claimed that both systems were deployed in the same field, it matters whether one of the systems had more recently acquired a lock - in the last minutes or 2 h. If such, the system is said to 'hot start'. If you turn on a GPS receiver from a 'cold start' (haven't used the system for many hours or days) ~45 s is not unusual*. All this is related to the currency of that devices GPS ephemeris data.

This has to do with the updating of satellite position and timing information which is done every few hours and not with hardware.

Global Positioning System (GPS) navigation satellites transmit electronic ephemeris data consisting of health and exact location data that GPS receivers then use (together with the signal's elapsed travel time to the receiver) to calculate their own location on Earth using trilateration.

Again, nothing to do with different satellite constellations (e.g. GLASSNOS) as the basic process of satellite acquisition is common across that factor. The GPS chips are made by companies like Broadcom / Philips / Sony. DJI won't have resources to design these.

*Look at https://www.sparkfun.com/products/465 for data on tine ti GPS lock.
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Re: Why does my Phantom take so long to get GPS lock?

Postby rilot » Thu Oct 17, 2013 3:38 am

Both were from a cold start, neither having been flown for about 2 weeks.
DJI S800 EVO - A2, X140BS gimbal, 2.4GHz ground station.
DJI F550 - Naza-M V2, H3-2D, iOSD mini, Graupner 9x5.
DJI Phantom 2 - H3-2D, iOSD mini
FrSky Taranis
http://www.rilot.co.uk - Achieve an elevated view
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Re: Why does my Phantom take so long to get GPS lock?

Postby MenaceCat » Tue Oct 29, 2013 12:44 am

Try a few times. What I said is technically correct. The GPS on the phantom is by no means an inferior unit.
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