@capucsc Ok, just remember that if there is a manufacturing defect we will obviously replace it for free.
@igor.vereninov hi there, i made some tests this afternoon and i got a GPS fix
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1st test on my android phone, u-center shows me:
10 good sat most of them with a SNR between 20 and 30
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Y6: 2nd test with VTX off
u-center on PC
16 GPS satellites with SNR between 30 and 40
FIX 3D/DGPS
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**Y6: 3rd test with VTX on w/ CRYSTEK Low Pass Filter 1.4ghz **
15 GPS satellites with SNR around 30
FIX 3D
the GPS seems to work fine but when i switch to loiter mode, motors starts but there are slower than in the stabilized mod. i must push the throttle to 60-70% to take off. after that they spin off very quickly. i must disarmed the motors
in stabilise mode the drone is stable and reacts normally
here is my GCS logs.
CH3 Throttle & Altitude
in loiter mode the drone doesn’t take off before 1.800 ms
in stabilize mode take off starts at 1.550 ms
@igor.vereninov hi Igor, what can i do to run the loiter mode correctly? i have also another issue i must disable all the pre-arming checks because i have two warnings: the check board voltage warning and the compass offset too high. even with the pre-arming checks disable i am completely sure i have a GPS fix because i check the GPS status in u-center before take off.
When you are engaging loiter mode, you are asking your copter to hold position, which it does. Loiter uses altitude controller from ALT_HOLD mode, which would maintain altitude at 50% throttle. You need to increase throttle further if you want to take off. There is also a dead band around 50%, which results in take off at a higher throttle than in STABILIZE. You can read more in the APM wiki.
Regarding the pre-arm checks:
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You need to disable board voltage check, as there is now no way for Navio+ to sense it.
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Compass scaling is most likely off in the current driver as we use a compass with higher resolution. It is on our issue list and will be fixed. Does not affect flight. You can bitmask only two of these prearm checks by setting
ARMING_CHECK 123
@ivereninov thanks for the info, what I found surprising that take off was beginning around 80% throttle more than 60% (i have a deadband of 10% with the THR_DZ parameter at 100). by the way, this afternoon all works fine: the ALT_HOLD and LOITER mode, in AndroPilot i have a lock with 11 satellites and a HDOP around 1.6 (the VTX was on). I dont have tried RTL but I guess it should work. thanks Igor for the help and all the amazing works you have done with this board.
@florent451 Good to hear that you got everything working 
Could you by any chance have throttle expo on your transmitter?
Waiting for you flight videos 
@ivereninov – after a long break from having fun with Navio+, I finally got back to testing gps. I have two boards, the GPS works great on one, and fails on the other with the same antenna. I believe that the first board (the original one discussed in the posts above) has a bad GPS chip. Can you provide info on replacing? I bought the board through your UK distribution.
@capucsc Sure, sending you a PM right now!
I have the same problem with my Navio+
Even though ublox centre shows a gps lock, in mission planner when I run
sudo ArduCopter-quad -A udp:192.168.0.144:14550
i get gpsstatus =0 in mission planner . Please if someone has fixed the problem let me know how.
(In mission planner I have enabled gps … i m not new in mission planner since i also have a pixhawk)
@Yiannis could you please create another thread and provide us the screenshots from U-center and Mission Planner as well as information about what system do you use and what is the version of the arducopter.