Tahoe_Ed Posted at 2015-1-10 00:25
I am here what do you need?  I have been kind of busy with CES so I apologize for my apparent absen ...

Hi there.  I've been in LA with sick relatives and just back.  Would any of you still buy the DJI?  I loved it and yet I'm afraid that the next one may just fly to freedome too.  My sad story ends in that I took the bird to LA with me to get to an authrozied dealer to fix it as the damage wasn't too bad and the entire case was stolen from my car!  My drone hates me....  Good news is that I had insurance for theft....

guymacdonald@ip Posted at 2015-1-10 11:08
What is it about less than 6 satellites that the Phantom software cannot handle?

Why cannot the Ph ...

The number of satellites is in a way fairly irrelevant.

On a high Quality GPS system. (As I have installed on my Motor Yacht) the receiver is capably of receiving a specific number of satellite channels.

In my case 16. And it will often have a lock on 16 satellites. but it does not use them all. It determines the best 8 satellites that are in a position in the sky to give the most accurate GPS location.

The Display on my Autopilot system will show which satellites are used in the lock and which have a signal being received but are not used in the position fix as they are in a poor position in the sky.

The GPS accuracy is displayed in a HDOP (Horizontal Accuracy and VDOP (Vertical Accuracy) the lower the number the better.

I don't believe that the Phantom GPS does Sat selection. Hence it operates by a minimum number of satellites and assumes that 6 will give a good fix regardless of the position of the satellites in the sky.

Remember this is not a simple triangulation exercise as it must operate in 2 dimensions Horizontal and Vertical.

As an example imagine if it locked only 6 satellites and this six were in the same position in the sky.

The accuracy would be pretty low.

So I can understand why they have a minimum number of 6.

I also notice on the aspire that it has a different GPS receiver and the software does not display the number of sats but the accuracy of the GPS positioning.
The abnormal behaviour on the OPs return to home may be due to losing Vertical accuracy in the fix. So it would return to the X,Y, coordinates for the home position but as it could not determine its vertical position it would hold at that altitude return home and then land.

bjr is exactly right, they sacrificed 'minimum accuracy' for 'simplicity of design' from a coding complexity standpoint and i can understand why.  

bjr981s Posted at 2015-1-23 18:34
The number of satellites is in a way fairly irrelevant.

On a high Quality GPS system. (As I have i ...

good explanation, bjr
I actually think that the flyaway is not caused by RTH, but "hold the position" routine.
Anyway, after I've installed extra GPS insulation I haven't noticed any more flyaway. I've actually flew with 5-6 satellite coverage and it worked as expected. I just guess that the GPS receiver picked wrong readings because the interference with other Phantom electronics (for some reason, recording or rotatations seem to have an impact over GPS)

In the DJI Vision app checklist its written that "wait  for the Phantom to connect to at least 7 GPS satellites" - I guess that's not for fun they write that.

ciprianboboc@gm Posted at 2014-12-29 18:25
Actually if I finish such app, it would be a free app, according to my agreement with DJI when I g ...

This is all L1 stuff so you can sell it.  The restriction is on L2 (GPS flight) apps.

The app I'm working on includes logging if you want to try it out and see what I'm doing.

http://www.kenargo.com/AndroidApps/UltimateFlight/

I was one of the victims that experienced a flyaway, but the damage was minimal, but it started an inquiry in to what can cause this phenomena? So the first thing I did was to contact DJI servise and gave them two articles about interference with 5 to 5.8 GGz and 2.4 GHz of the radio spectrum frequency.
I received the following (see below)
Dear Rene,
Thank you for contacting DJI. The best way to prevent interference is to make sure that everything is calibrated and that the firmware is updated properly. Also be cognizant of your surrounding. If you are near an area that has a Wi-Fi, then you have to make the determination on whether it is a good idea to fly the unit or not as these things can cause interference. I hope that helps.
DJI Customer Service North America.

This was not what I was looking for, or expected from such a top tier company?

Avoiding Interference in the 2.4-GHz ISM Band.
http://www.eetimes.com/document.asp?doc_id=1273359

and

Avoid interference between 5 GHz Wi-Fi and 5.8 GHz cordless phones.
http://bradsfavorite.com/avoid-i ... ghz-cordless-phones

I hope this will shed some light on the subject.

Rene