11
Fig 2.10.
The RTK GPS base station.
Depending on the conditions on the investigation site the best method is used. Some points to
consider:
If working in an environment with a number of trees, high buildings or others that might disturb
the communication with GPS satellites a Total station is preferred. In these types of
environments it can also be hard to define lines and point features with the GPS.
However, on open ground with lower vegetation or obstacles, the RTK GPS solution most
often is a faster and easier way of positioning.
The Total Station needs line of sight, and by that one extra operator for the Total station if the
tracking fails.
If the investigation area is large, the Total Station needs to be moved and new Total Station
positions need to be defined, which can be more time consuming. However every type of
investigation area can be covered by a Total Station, which is not the case with a GPS.
It should also finally be mentioned, that temporary loss of tracking will not cause the data to be
useless, as long as start and end points of each swath are well defined.
Note!
A GPS is very effective when it works! In order to be 100% sure that you can perform the
investigation a Total station is needed, though.
2.5 Accessories
The target applications for the MIRA systems are radar
surveys over large areas and, practically, it’s
not feasible to move the array manually over thousands of square meters. Some kind of motorized
carrying system is usually necessary. It’s possible to ship the radar parts and accessories and attach
the system to any carrier, but this requires a case by case handling and cannot be described precisely.
For example lawn-mower types of vehicles are very suitable for carrying the MIRA arrays and in
Figure 2.11 below a carrier, including the antenna array box, are shown. This type of arrangement is
highly recommended by MALÅ Geoscience on surfaces like grass and high vegetation. For small size
scanning on concrete and asphalt the antenna box can be attached to a special design of our
standard RTC cart, see example in Figure 2.12.
