Theory of GNSS Reflectometry - GNSS Remote Sensing: Theory, Methods and Applications - page 186

Fig. 8.10 Delay and Doppler frequency properties at each point on the reflecting surface, here
given with respect to the specular point (coordinates: 0,0), under the form of iso-value contour lines
(locci: ellipsoidal for iso-delay lines, parabolic-like for iso-frequency lines). The scattering plane
is the Y-Z plane, the receiver laying in the positive side of the Y-axis, transmitter towards negative
Y. Iso-delay contours given at 1 C/A code chip intervals (0.978 s delay, or 293.26 m range). Earth
curvature has been taken into account. ( left ) Aircraft scenario at 10 km altitude, elevation angle
of observation at 60 ı ( top ) and 30 ı ( bottom ). The receiver velocity is 250 m/s pointing towards
45 ı counter-clockwise from X-axis. Iso-frequency lines given at 100 Hz intervals. ( right ) LEO
scenario at 500 km altitude, elevation angle of observation at 60 ı ( top ) and 30 ı ( bottom ). The
receiver velocity is 7 km/s pointing towards 45 ı counter-clockwise from X-axis. Iso-frequency
lines given at 1 kHz intervals
captured in the waveform, filtering out the contributions from other areas. That is,
the technique permits to map the Doppler-frequency space (Fig. 8.12 ). Table 8.1
compiles the size of the Fresnel zone (specular reflection); of the first GPS C/A chip
iso-delay; and of the first Doppler belt under different geometric conditions.