I recently ordered a pixhawk autopilot along with the ublox GPS with integrated compass module and received it a few days ago.
After assembling the system, I cant seem to get the GPS to acquire a lock anymore. It seemed to work sporadically when I was bench testing the system before I mounted everything on my quad frame.
The GPS module is clearly getting power and is communicating with the Pixhawk controller. I ohmed out the cable and the connections are fine. The magnetometer is working fine and I can see the mission planner update when the GPS module is rotated.
I even hooked up a 3.3V UART to the GPS module tx line and I see data being updated. It even seems to have my location cached in the module (according to the UBLOX software) but none of the satellites seem to have any signal
I have even tried disabling all the transmitters on the quad (Turned off the video and 915mhz data modem) and the module still never gets a blue light.
I have tried just waiting with the quad outside for up to an hour and it never seems to get a lock.
I tried positioning the module in different locations on the quad and it doesnt seem to make any difference. It is already located on the complete opposite side of the quad from any transmitter. Only my Dragon link reciever is on the same side.
I am out of ideas. Anyone have any suggestions?
Replies
I figured it out... Apparently the cheap GAUI speed controls I was using were putting out enough RF pollution to cause the GPS to lose lock. The interesting thing is that it must be coming over the ground because if I ran the system powered by the USB, it would lock up right away. then I unplugged the servo connections between the ESCs and the Pixhawk and plugged in a battery and the GPS lock would immediately drop.
if I plug in another type of ESC, it remains fine. Of course, I dont have 4 matched sets of those...
When I look at the 5v rail with the battery plugged in, I dont see a lot of obvious noise, but my scope is fairly slow and it must be high frequency noise to interfere with the GPS signal.
oh well.. time to buy a new speed controller.