40 
• two external antennas (Legant microstrip zero 
centered) (Fig. 4) with incorporated choke and 
certificate of calibration on the GPS L1+L2 carriers; 
Fig. 4. The Legant antenna. 
• 32-bit Control Data Unit or Data Logger (CDU-2 - 
Psion 5) (Fig. 5) with 8 Mb of RAM for data storage 
under the Epoch 32 operating system, equipped with 
RTK Field Face software. The software is able to 
manage each measurement and recording function 
and to perform a co-ordinate transformation between 
the datum and different projections; 
Fig. 5. The Psion 5 Data Logger. 
• 433-34 MHz external radio modem (Satel) with 1 W 
of power, approved for use in Italy. 
Finally, the entire GPS+GLONASS RTK system was 
equipped with connecting cables and power supply 
batteries. Figure 6 illustrates the connections of the 
various components both for the Master station and the 
Rover station. 
2. FIELD TEST 
2.1 Marking out transverse sections of a road 
embankment 
The first example of an application of the system involves 
the marking out (Fig. 7 and 8) of transverse sections and 
the surveying of 3 road embankments under construction. 
The purpose was to quantify the volume of fill used in the 
works. 
The transverse sections of the road embankments had the 
geometric characteristics reported in Figure 9. Their 
lengths varied between 1.5 and 2.5 km. 
Fig. 6. Master and Rover receivers of the 
GPS+GLONASS RTK system. 
Fig. 7. View of the road embankment under construction. 
Fig. 8. Positioning of the Rover receiver on the measuring 
point. 
Before the GPS+GLONASS RTK measurements, we 
performed a traditional survey to determine on the ground 
the planned sections of the road embankments (Zero 
survey). The instrumentation used consisted of a Pentax 
PTSV1 integrated electronic theodolite. The 
instrumentation sites were organised planimetrically and 
altimetrically with respect to existing vertices of known 
co-ordinates. From them, we measured, with simple polar 
co-ordinates, some new vertices which were then used to 
perform the operations of plane calibration of the 
GPS+GLONASS measurements. In view of the limited 
area of the zone and the low precision required for 
measurement of the height (rms between 10 and 15 
centimeters), we assumed the relative variations between 
geoid and ellipsoid to be zero.