Handbook of Propagation Effects for Vehicular and ... - Courses

Optical Methods for Assessing Fade Margins 10-9
Percentage of Locations Fade > Abscissa
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10
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7°
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-5 0 5 10 15 20 25 30 35
Fade Depth (dB)
Figure 10-5: Cumulative fade distributions at 1.5 GHz for a family of elevation angles
for urban Japan. Curves were derived using the UTSFM described in text. Indicated
elevation angles are centered within ± 2° intervals.
10.6 Estimation of Urban Fading for the Globalstar Constellation
Akturan and Vogel [1997] and Vogel [1997] estimated urban fading for a real mobile
satellite system using azimuths and elevations for the Globalstar constellation [Schindall,
1995]. This constellation consists of 48 satellites orbiting in eight planes (six satellites
per plane) inclined at 52° with a period of 114 minutes. A satellite is said to be
potentially visible if the elevation angle is above 10°. The azimuths and elevations to
each satellite were calculated at 18-second intervals over a 24-hour period. In other
words a total of 4800 satellite constellations (24x3600/18) were considered for each
photogrammetric image. Since a total of 236 images were taken, the statistical database
in which the cumulative distributions were calculated is comprised of a sample size in
excess of 10 6 constellations (4800x236).