Download DATcomp.PLX (11 Kb)

Requires Perl Support package.


PERL -W DatComp <Truth Viewdat> <Compare ViewDat> [Elevation Mask]

DatComp compares two ViewDAT (ViewDAT -D17 -X) output files that should be identical and makes sure they are. This is most useful when you are testing other systems that are creating DAT files. Normally for truth a DAT file downloaded from the receiver is used, but any trusted source can be used.



  1. Phase and Range Measurements
  2. Clock Offsets
  3. Slip indications
  4. SV’s in both files
  5. Code type indications
  6. Missed Epochs

The system works around the know differences that are expected between DAT files.

These are

  1. Slightly different clock values, RINEX files have the clock calculated during the conversion to DAT. This calculation is not the same as in the reciever.
  2. Phase and Range differences, the Phase and Range measurements in the DAT file from a receiever with file compression is different than that of the RT-17 data. RT-17’s are not compressed, the compression system is uses less resolution (which is more than enough for all applications) which causes differences.
  3. Elevation and Azimuth differences, there is upto 2 degrees of difference is allowed. While this is a lot, all applications that do tropo modeling have to calc the elevation angle as a degree resolution for elevation angle is not suitable for the most precise tropo modeling.