QUESTION

Question

Hi,

I have mounted a M20050-1 module on my board. I make my test in France.

Board picture:

module picture:

The module is working but I observe a bad accuracy, with a very good hdop (< 0.7), and a lot of sat (> 12)
sometime the gps position is about 50 meters from the real position !

I have tested a lot of init sequence but I don't observe any change from the accuracy :(

Init :

$PMTK225,0*2B //normal mode
$PMTK314,0,1,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0*28 //ouput RMC GGA
$PMTK286,1*23 //AIC  enabled
$PMTK313,1*2E //SBAS enabled
$PMTK319,1*24 //SBAS mode 1
$PMTK301,1*2D //DGPS enabled
$PMTK386,0*23 //static THD OFF
$PMTK869,1,1*35 //EASY enabled

Is my init sequence good ?

Please can you confirm that if hdop and sat number are good, that module placement is godd and antenna matching is good ?

Best regards,

Gaétan

Edit: I tired to replace M20050 with a M20048 and result are the same...

Answer 1

Hi Gaétan,

It looks most likely that this is due to a layout problem, due to not enough ground to the left and right of the module - see section 10.5 of the data sheet. It's also possible the external antenna to the left of the module in your image is having some effect. We offer a free design review service and can evaluate your design in more detail, please contact techsupport@antenova.com to get in touch with your regional representative who can guide you through the process. 

Many Thanks

Steve