<para>
Sometimes there is a discrepancy between the internal clock in the barograph
instrument and GPS time which can result in the altitude and ground positions
not correlating correctly.  This can be corrected manually by passing the time
difference in seconds between the two time domains through the "timeadj"
parameter.  This can be any positive or negative integer:
</para>
<para><userinput>gpsbabel -i gpx -f baro.gpx -i igc -f my2D.igc -o igc,timeadj=27 -F my3D.igc</userinput></para>
<para>
GPSBabel can also attempt to deduce the time difference automatically.  This
is done by comparing the time that it thinks that you landed on the GPS track
and the barograph and adjusting accordingly:
</para>
<para><userinput>gpsbabel -i gpx -f baro.gpx -i igc -f my2D.igc -o igc,timeadj=auto -F my3D.igc</userinput></para>


