an “irregularity” of the same dimension of the Fresnel
radius, resulting in both amplitude and phase scintillations,
due to the scattering of the wave encountering it, whose
occurrence is roughly of the same order of magnitude. This
indicates that, from a statistical point of view, the chimney
is almost the sole cause of the ‘perceived’ scintillation
effects along that path.
The different features of the maps described above are
now discussed and re-interpreted by analysing the surroundings of the building of the former IESSG, where
the receiver designated herein as NSF06 was located in
2008. The survey was carried out in February 2011 and
the geo-referencing was carried out by using the “DATALive Ordnance Survey” vector data of the University of
Nottingham campus. Fig. 7 shows the area of the Nottingham campus, together with pictures of some features in
correspondence with their azimuths from the receiver
antenna position. At 171° there is the chimney, whose effect
has been already discussed to explain the pattern of the
data acquired by the NSF06 receiver during 2008 (Fig. 2,
Figs. 4 and 5). Other possible sources of multipath are
the trees in the azimuth range between 230° and 273°,
which were pruned and made much lower after 2008. They
acted as a source of multipath, as shown by the enhancement of both CCSTDDEV and S4 percentage of occur-
rence in Figs. 1 and 3. Similar sources of multipath,
visible in the abovementioned maps and indicated in the
pictures of Fig. 7, are the building at about 50° azimuth
and which span elevation angles between 5° and 20°, and
the GPS antenna on the roof of the building at about
145° azimuth, shown in the same picture of the chimney
(the crane tower seen in the photo was not present in 2008).