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S. Lehner et al.
Fig. 15.20 Profiles of the target in sub-look 1 (solid line) and sub-look 2 (dashed line). The profile
is obtained by range averaging and the pixels not belonging to the target are masked
15.5.6 Ship Velocity Estimation on TerraSAR-X (ATI) data
Ground moving target indication is a very difficult problem, due to the difficulty of
separating the signal returned from a moving target from the stationary background
(clutter). A method that can be used to detect ground moving target is Along Track
Interferometry (ATI). Along Track Interferometric Synthetic Aperture Radar systems
use more than one SAR antenna (typically two), mounted on the same platform and
displaced along the platform moving direction. TS-X can acquire images with a split
antenna. The so called Dual Receive Antenna (DRA) Mode allows the use of ATI
methods. The information about the radial velocity of the moving target is estimated
from the interferometric phase of the images using statistical estimation techniques
based on the statistical distribution of the measured phases. The phase is proportional
to the speed, which has zero mean for non-moving target:
φ ATI =
4π
λ
B ATI
v s
v gr sin θ
(15.10)
B ATI is half of the distance between the two antennas, λ is the wavelength, v s is the
sensor velocity, v gr is the target velocity to be estimated and θ is the local incidence
angle. In Fig. 15.21 an example of retrieved ship speed with TS-X ATI Mode data
over Gibraltar is shown.
S. Lehner et al.
Fig. 15.20 Profiles of the target in sub-look 1 (solid line) and sub-look 2 (dashed line). The profile
is obtained by range averaging and the pixels not belonging to the target are masked
15.5.6 Ship Velocity Estimation on TerraSAR-X (ATI) data
Ground moving target indication is a very difficult problem, due to the difficulty of
separating the signal returned from a moving target from the stationary background
(clutter). A method that can be used to detect ground moving target is Along Track
Interferometry (ATI). Along Track Interferometric Synthetic Aperture Radar systems
use more than one SAR antenna (typically two), mounted on the same platform and
displaced along the platform moving direction. TS-X can acquire images with a split
antenna. The so called Dual Receive Antenna (DRA) Mode allows the use of ATI
methods. The information about the radial velocity of the moving target is estimated
from the interferometric phase of the images using statistical estimation techniques
based on the statistical distribution of the measured phases. The phase is proportional
to the speed, which has zero mean for non-moving target:
φ ATI =
4π
λ
B ATI
v s
v gr sin θ
(15.10)
B ATI is half of the distance between the two antennas, λ is the wavelength, v s is the
sensor velocity, v gr is the target velocity to be estimated and θ is the local incidence
angle. In Fig. 15.21 an example of retrieved ship speed with TS-X ATI Mode data
over Gibraltar is shown.