[FOSS-GPS] New Project with RTKlib & need help.

Mauro Ugarte Avilés mauro.ugarte at cefop.udec.cl
Mon Jan 2 08:58:10 EST 2012

> the goal is to get a better accuracy by merging two GPS information, than
> one.
> [Question 1] Do the RTK and RTKlib are developed for the above reason? My
> goal can be solved by RTKlib?
  If you want better accuracy on the rover, you need to place the base 
receiver's antenna on a previously accurately surveyed spot with known 
coordinates. If you are looking for better precision, RTK gives you that 
even when the base position is not exactly and accurately known (the 
autonomous position delivered by the base u-blox is enough). Please 
refer to the following pic in order to define which of the situations is 
what you are looking for:


> [Question 2] To change the raw output format(what RTKlib required), I run an
> u-center and do the follow settings.
>   a. view ->  Messages view
>   b. UBX ->  CFG ->  PRT
>   c. Target = USB  / Protocol in = UBX+NMEA+RTCM  / Protocol out = raw
>   d. press the "send" button
>   e. close the box
> Is this right? The RTKlib shows nothing.
As Timo said, you need to activate as protocol out = UBX, and output the 
following messages:

base: RXM-RAW (for raw observations) and RXM-SFRB (for satellites 
rover: RXM-RAW (for raw observations). SFRB is not needed on both 
receivers, because it should be the same info on both, and it should 
change almost at the same time for both also. If you want to save 
bandwidth between rover and base PC, just RXM-RAW is what you need on 
the rover.

Best regards,

Mauro Ugarte A.
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