[FOSS-GPS] Differential GPS with RTKLIB 2.4.2

rolf.elsing at online.de rolf.elsing at online.de
Wed Jun 5 21:23:56 PDT 2013

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I’am trying to build a differential GPS using RTKLIB 2.4.2.
The accuracy that I can achieve is around +/-2 m.
Which is about the same that one of my sensor achieves in PPP kinematic mode.
My expectation is to achieve something around +/- 5 cm.
The set up:
Sensors2 UBLOX NEO6P 
AntennaTrimble Bullet III
The sensors are installed on the roof with a free 360 °view. RTKLIB indicates that 6 to 8 Satellites are visible. The distance between both sensors is < 20 cm.

Ublox Center Configuration:
NEMA Child Messages Disabled
UBX Child Messages Enabled
RXM-RAW Enabled
RXM SFRB Enabled
RXM-RATE 200ms
Dynamik Mode Pedestrian
RTKLIB Configuration
Input Streams
Rover Serial COM 1, UBLOX
Base Serial COM 2, UBLOX
Log Streams
Rover to File
Base to File
Solution Log
Solution 1 toFile
Solution 2 to File
Base Station Position is acquired by 10hour static measurement.

So, with this setting I usually get FLOAT (90%) and intermediate FIX (10%) soloutions with an accuracy of +/- 2m.
My expectation is to achieve something around +/- 5 cm.
Is my expectation wrong?
Have I selected the correct configuration?
When I run the sensors stand alone in PPP Kinematic mode I also get around +/- 2m accuracy which matches the manufacturer provided data.So I assume that my Antenna, Sensor are working fine.
Can somebody HELP ?

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