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GPs Issues

Posted by Richard Evans on August 28, 2014 at 6:38am

It seems that I have a chronic problem getting the GPS to lock in. Often when powering up with the PIxhawk, I get hdop 100 and 0 satellites. After waiting anywhere from 3 to 10 minutes, It may or may not begin working and I get a 3D fix. sometimes I just give up because It seems to be totally dead other than seeing the the red LED is lit.

I have tried another Compas/GPS module, but the same thing happens.  I am using 1.58GB video, 1000 mw.   Could it be overdriving the GPS?

I am using the Compass/GPS ordered with the PIXHAWK.

I also am unable to write the new beta firmware to the board. I am using the USB serial, and it usually will do the erase, then will begin writing but at some point the progress bar is showing that it is writing, but randomly will stop progress and then give a timeout error.
So it leaves the board dead, but I can then load and write the 3.1 current flying firmware and bring it back to life.. I have tried different USB cables, any ideas for me to try?

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Replies

  • Admin
    Thomas J Coyle III August 28, 2014 at 7:10am

    @Richard,

    You might try using a powered USB Hub as some PCs/Laptops do not supply enough current for a full up Pixhawk configuration.

    Regards,

    TCIII AVD 

    • Charles K Taylor > Thomas J Coyle III August 28, 2014 at 8:13pm
      It is definitely possible the video tx is interfering with GPS since L1 GPS is 1575mhz, not to far from 1258. Try killing the power to the transmitter and see if GPS improves. I had a 2w on 1258 over a foot away and it still severely impacted GPS.
    • Richard Evans > Thomas J Coyle III August 28, 2014 at 2:36pm

      Thanks, I'll give that a shot.   That is a great suggestion.  

      Do you have any ideas about the GPS issue?  , I have two Pixhawks and both seem to have flacky GPS performance.

      sometimes I power up and they work fine, but often, they take time and multiple power ups to begin making satellite connections.  the will begin showing my position in MP thousands of miles away, and keep moving every refresh until after a few minutes MP finally shows my position in my neighborhood.. Today though, after ten minutes I had to give it up and go to work..

      Thanks for any ideas..

      RE

      • Richard Evans > Richard Evans August 28, 2014 at 2:49pm

        Well, some success I finally got the 3.2rc5 to load, I just kept trying to upload, and it failed three times, each time the progress bar went part of the way, finally the 4th time it went all the way. 

        Now I will have to get outdoors to try to figure out the GPS issue.

        Thanks

        • Charles K Taylor > Richard Evans August 28, 2014 at 6:19pm

          Depending on your configuration it could be interference from your setup.  Mount the GPS up and away from the body.  I had the same issues until I shielding the plate my GPS mounts on with copper tape.

          • Richard Evans > Charles K Taylor August 28, 2014 at 7:33pm

            I will give that a try, on both my quads I have the GPS/Compass in front of the Pixhawk, then in front go the GPS/Compass is my Video Xmitter (1.258 GHZ)   I have been wondering about that.

            RE

            • Richard Evans > Richard Evans August 29, 2014 at 6:07am

              I did find that the location of the GPS/compass was the problem.  I moved it to a "Tower" that elevated it about 6 inches, and moved it to behind the AP, further from the Antenna for the video transmitter. It now immediately acquires satellites.  moving it back to the location where is was mounted before, causes it to lose the satellites immediately.

              Thanks for the tip!

              RE

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