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M20050-1 accuracy


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,


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

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1 Answer

answered by

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 to get in touch with your regional representative who can guide you through the process. 

Many Thanks


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