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YJ

YJ

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#248120 11-Mar-2019 08:37
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Hi all, 

 

It's my first time to encounter this kind of situation. Please help.

 

I sold a DJI drone on trademe about 3 weeks ago.

 

The drone has been tested on the night before the collection, and i did take the photo as well.

 

I offered him to test the drone when i am at home, but he seems not interested, and just collect the drone next day and without check it.

 

Everything went well until this morning.

 

He sent me an email said the drone was sent to Fiji and just had its 1st flight, and found "return to home" isn't responding, also the GPS is not functioning, the compass and IMU can't calibrated.

 

I did use the drone to take photos and videos in the past, the latest video took about Xmas time, and never encountered this problem before. 

 

I am not sure how i am going to respond to the buyer, any suggestions are welcome.

 

 


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freitasm
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  #2195514 11-Mar-2019 08:45
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How long was the drone off before going to Fiji? A GPS usually relly on an "almanac" (data downloaded from satellites) to accurately determine where to look in the sky for satelitte location next time it turns on. If the device is off for a while the almanac is out-of-date. Also at the same time, moving the GPS device from one location to another that far makes it harder to get a first fix - sometimes a few minutes, sometimes longer. 

 

Phones don't have this problem because they start their location by using cell locations, WiFi around then, to help determine a rough location then look for satellites for the fine data.

 

It could be just the case where having the drone working may involve some time.





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Fred99
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  #2195515 11-Mar-2019 08:47
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It can take a while for GPS to get a fix when it's been off for a long time or moved a long way when turned off..  Perhaps there's actually nothing wrong with it, but it needs to be powered up for long enough to get a fix, possibly quite a few minutes for time to first fix.    I have no knowledge about drones, but that applies to other GPS devices.


YJ

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  #2195523 11-Mar-2019 08:53
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The buyer didn't say that, and he said he didn't try in New Zealand.

I don't know what to do next or how I response to him.






Linux
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  #2195524 11-Mar-2019 08:54
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100% not your problem just tell them it was working fine before leaving you!

 

The item is second hand and you did not test before leaving on pick-up and then the item was sent to Fiji, Could of been damaged going to Fiji


freitasm
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  #2195530 11-Mar-2019 09:01
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You can respond with what I and Fred99 replied. Beyond that you are not their tech support and if you know the device was working before leaving you, that's it.





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Fred99
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  #2195531 11-Mar-2019 09:02
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YJ: The buyer didn't say that, and he said he didn't try in New Zealand.

I don't know what to do next or how I response to him.



 

http://ozzmaker.com/take-long-get-gps-fix/

 

GPS TTFF (Time to first fix)

 

The above happens during a cold start, this is when the GPS module has been off for some time and has no data in its memory. A full Almanac download is required to get TTFF. If the GPS module has clear line of sight to all satellites, the shortest time for TTFF is 12.5 minutes.

 

In a warm start scenario,  the GPS module has valid Almanac data,  is close to its last position (100km or so) and knows the time  within about 20 seconds. This approximate information helps the receiver estimate the range to satellites.  The TTFF for a warm start can be as short as 30 seconds, but is usually just a couple of minutes.

 

Cut and paste that text or link.  Tell him to switch it on, leave it on the ground for 20 minutes or so, then see if it's got a fix.

 

 


 
 
 
 

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Coil
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  #2195532 11-Mar-2019 09:02
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So in the case this is something you would have to honor for warranty (You will not have to here)
How does one intend on receiving a drone back home from Fiji, At who's cost and how do you verify fault?

Sounds like a SCAM 


YJ

YJ

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  #2195538 11-Mar-2019 09:07
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thanks all, i will reply him by using Mauricio and you guys comment and see what he is coming back to me then, thanks very much. 


surfisup1000
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  #2195562 11-Mar-2019 09:22
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"I  offered him to test the drone when i am at home, but he seems not interested, and just collect the drone next day and without check it"

 

He should have taken you up on the offer. Hopefully he learned a lesson now.  I'd politely decline his refund request.  

 

For higher value trades like this, it is always a good idea to record the serial number so people can't try to claim a refund on a different unit. 

 

 

 

 


xpd

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  #2195578 11-Mar-2019 09:40
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surfisup1000:

 

For higher value trades like this, it is always a good idea to record the serial number so people can't try to claim a refund on a different unit. 

 

 

I do this all the time now with anything of value or suspect the buyer is trying to pull a fast one. Serial numbers, photos of the item, invoices etc.

 

 

 

 





XPD / Gavin

 

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  #2195609 11-Mar-2019 10:09
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If he's not happy with the GPS Almanac thing (Which is good advice!) then tell him when he returns it to your door, you'll refund his money.

 

It's not your fault he shipped it somewhere, untested.


 
 
 

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jonathan18
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  #2195686 11-Mar-2019 10:46
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muppet:

 

If he's not happy with the GPS Almanac thing (Which is good advice!) then tell him when he returns it to your door, you'll refund his money.

 

 

But surely the OP would only think of doing this if they were 100% sure the purchaser hadn't caused any damage to the product?

 

And anyway I'd have thought that, given the OP checked it was working ok prior, that the purchaser was given the chance to check the product prior to taking it and that the drone's been transported decent distances since , it would be totally fair of the OP to not offer to take it back for a refund. Sure, provide info that may assist solving the problem, but I don't think they should have to offer a refund.


gzt

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  #2195795 11-Mar-2019 12:59
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Imo by now they have tried again and found it works now. Send the link about the gps fix time. Say wait long enough half hour even with it switched on.

If there is still a problem after waiting long enough with it switched on ask the agent/buyer to send it back for inspection and possible refund. You can inspect and decide at that time if there is a real problem..

sxz

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  #2195823 11-Mar-2019 13:59
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freitasm:

 

How long was the drone off before going to Fiji? A GPS usually relly on an "almanac" (data downloaded from satellites) to accurately determine where to look in the sky for satelitte location next time it turns on. If the device is off for a while the almanac is out-of-date. Also at the same time, moving the GPS device from one location to another that far makes it harder to get a first fix - sometimes a few minutes, sometimes longer. 

 

Phones don't have this problem because they start their location by using cell locations, WiFi around then, to help determine a rough location then look for satellites for the fine data.

 

It could be just the case where having the drone working may involve some time.

 

 

TIL.  Very interesting.  


mattwnz
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  #2195826 11-Mar-2019 14:05
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Have they downloaded all the most recent updates, which has maps of where it can't be flown. f they don;t have 3G enabled on their device, they may need to connect it to a PC to apply the updates.They are quite complicated for someone not familiar with them.I spent many hours watching videos of people using them, and learning all the tricks before actually flyin gone. They aren't really something you can just instantly work out how to do.  When they try to take off, if it hasn't go t a GPS fix, then it would be in ATI mode, which you don't want to ever fly in that mode outside, as that is when you can get a flyaway. So you wouldn't be even able to get to the point of setting the homepoint as you wouldn't want to takeoff at in ATI mode. 


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