Using different output formats for position and velocity

GNSS-enabled MTi devices can output position and velocity data in different output formats:

  • Floating point 32-bit
  • Fixed point 12.20
  • Fixed point 16.32
  • Floating point 64-bit

The resolution of these output formats varies. This article depicts the differences when an MTi is estimating position data. 

Data is outputted at 10 Hz with reasonable view on the sky (next to a building). The data plotted spans exactly 1 minute. The green rectangle stretches over 2.7 meter in longitude and 2.2 meter in latitude. Although not ideal antenna placement, the accuracy usually stays within a few meters with a few detours and a maximum displacement during the entire trial between the extreme positions of 14 meter. 

Important to note is that the absolute accuracy of the position is always the same, regardless of the output format. Consider that when traveling at a velocity of 50 m/s, a 50 cm displacement is reached within 1 data message when outputted at 100 Hz. 50 cm is approximately the resolution of the 32-bit float output format. This means that using a coarser output format, this may not give bad results in a specific application. 


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