17 
ae centre. 
s to determine one or 
mique and then use a 
rame. Of course this 
ie case of accessibility 
around the antenna 
zenith angle is wide 
could be very high 
his could cause some 
le antenna frame with 
1 DGPS or precision 
¡termine at least one 
and then fast-static 
r er) may be used for 
n a good orientation, 
i cost, particularly in 
DGPS techniques. 
• network, where the 
oth static and non- 
to the Medicina 
Engineering Tower 
tal station and MDL 
e the orientation and 
h have been pointed 
Sta 30 
Fig. 6 - Stadio GPS network respect to Medicina permanent 
Station and Faculty of Engineering - TORR (known station). 
The ellipses error related to the adjusted co-ordinates. 
S. Transformation of co-ordinates into the Italian 
National system 
As mentioned above we can use a set of parameters for co 
ordinates transformation from WGS84 to the Italian national 
system (Gauss Boaga co-ordinates). In the area of Bologna we 
have used eight IGM95 stations (Fig. 8) to calculate the set of 
parameters, where their co-ordinates are known in the 
Fig. 7 - Local stadio network . Classical measurements by 
using MDL and Total Station 
National system and in WGS84 system. The reasons for using 
a unique set of parameters are: 
a- the difficulties to obtain and determine the nearest 
IGM95 station for each antenna, since there is a high 
number of IGM95 stations in each zone and this could 
create confusion when using transformation parameters, 
b- The use of a particular set of parameters for each zone 
does not give remarkable differences in the final co 
ordinates respect to the requested precision, as shown in 
the table 2, where the differences tend to be systematic. 
on instruments. The 
nents, in our case, is 
ifferent stations and 
ficulty in using this 
■ch elements of the 
ffore maximum care 
with them. 
neasurements at the 
radiation surveying 
juish between the 
lassical techniques 
instruments). The 
n-precision DGPS, 
iinates of one point 
ian National system 
:e in order to obtain 
survey, one has to 
Fig. 8 - The IGM95 vertices used for calculating the transformation parameters 
in the area of Bologna. Bologna GPS Network (Al-Bayari et al., 1997).