PRN 30 is a medium to low elevation satellite, and its maximum elevation is
about 60 degree (see Figure 7). The signal scatter is partially due to low elevation,
but the distortion around 13:20 occurs when the satellite is close to its minimum
elevation, see Figures 6 and 7. In addition the other satellites except PRN 15 and
PRN 25 indicate the same pattern as PRN 30. Unfortunately, we did not give here
all the values of C/N0 for the other satellites due to the lack of space.
Figure 7 - Skyplot of site P1 indicting the obstruction by the building
over 12:25-14:30 UT. Next the diffraction effects on the coordinate results will be investigated. The
results for the height component are displayed in Figure 8a. It shows epoch-toepoch
variation of this component minus the height differences from geometrical
levelling. The corresponding mean values and standard deviations are also provided
in the figure. As it can be seen Figure 8(a), for the line P1-P4, in the 1st, the 3rd and
the 4th intervals (i.e. divided by the vertical dashed lines) the recorded average
PDOP values varied between 2.0 and 5.2. For these intervals, the standard deviation
and mean value of the height differences for P1-P4 are obtained above 1 cm, see
Table 4. However, for the 2nd interval, the standard deviation and mean value of the
height differences for P1-P4 are below 1 cm (Table 4) and the recorded average
PDOP values varied between 1.4 and 2.0.