Matek Q8M no GPS fix on flight controller

Hi everyone,
I am quite new to ardupilot (not to RC though) and I am having a harsh time trying to get a GPS fix with my flight controller.
The hardware I am using is listed below :

To sum up the situation :
When I connect the GPS module to U-center I can modify the different parameters in the configuration view (baud rate, update rate) and I can get a GPS fix in about 1 minute if I put the GPS antenna outside.
Then, when I connect the GPS module to the flight controller, I got “No GPS” error. I found that changing the Baudrate to 57600 solved this issue.
However, now even if the GPS module is recognized by the flight controller, I get no fix (even after 5-10 min). Worse than that, I can see that the sat_count is zero in the menu.
I tried to change different parameters in the configuration menu :

  • I tried : “disable auto config”
  • GPS type : “uBlox”
  • GPS Update rate : “10Hz”

I would greatly appreciate any help or advice on the matter because I must admit that I am quite lost at the moment.
Thank you in advance,
John

Try enable autoconfig, GPS type ublox, update rate 5Hz

Post you related parameters, all GPS* and SERIAL*

Hi,
Thanks for your message.

i tried to change the following settings :

  • enable autoconfig,
  • GPS type ublox,
  • update rate 5Hz
    But I still can’t get any fix.

Bellow are my parameters for GPS and SERIAL at the moment (I changed baudrate to 115) :

Hi,

Just a quick update about the current issue.
Down bellow is a view of the GPS fix I get when using U-center :


After getting this GPS fix in U-center, I proceeded to connect the GPS module to the FC about a minute after disconnecting it from U-center.
Doing so, I obtained a GPS fix in mission planner that lasted about 1-2 minutes. After that, I still get the error no GPS fix and the parameters bellow :

If anyone has an idea on what is causing this issue.
John

Check the power supply voltage. GPS receivers do not like low or fluctuating voltage.

Yes I just checked the voltage and there is indeed a difference :

  • Flight controller voltage outputs 4.5 V
  • YP-05 connector board outputs 5.1 V

I have made some modification to power the GPS module via the YP-05 board. I will keep you updated when I test this configuration.

Hi,

The weather has finally allowed me to test the new configuration outside and it seems to have fixed the problem. Here are the results I get :

I have ordered matek BEC (https://www.mateksys.com/?portfolio=mbec6s) to supply a steady 5V to the GPS module.

Thanks for the helpful advice.,
John