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Use GPS Greenwich time as a trace timestamp
– each trace has a timestamp,
it is able to replace by the GMT time received from the GPS/GNSS receiver, for
example, for further synchronization with coordinates after its post-processing in
the third party software.
Note: It is better to use
X-interpolation / by GPS coordinates
processing for the data
analizing and its interpretation (for more details, see page 73) for the GPS positioned
profiles. It is important for velocity analysis of diffracted objects (the permittivity detection
from the found hyperbolas), because the hyperbola may be distorted on non-equidistant
profiles.
Wheel + GPS
- combined Wheel and GPS positioning option, where the
coordinates are recorded in the trace header, but the traveled distance is measured
by the wheel, which is much more accurate than the distance measurements by the
GPS / GNSS receiver.
Note: GPS/GNSS accuracy corresponds to the receiver error, what is a chaotically
fluctuating parameter from the negative to the positive value. It means, that if accuracy,
for instance, is about 5 cm, then measured coordinates are spread around true point in
radius of 5 cm and the maximum difference between measurements on the same point
could be from -5 cm to +5cm, what turns to +10 cm in the distance measurements by
GPS
positioning
. That’s why it is better to use
Wheel+GPS positioning
, if possible.
