Synthetic aperture radar interferometry(5)
时间:2025-07-11
时间:2025-07-11
Synthetic aperture radar interferometry is an imaging technique for measuring the topography of a surface, its changes over time, and other changes in the detailed characteristics of the surface. By exploiting the phase of the coherent radar signal, interf
facing toward the radar and is less on slopes facing away from the radar.Also from(16),the fringe frequency is inversely proportional
to
(20)
These equations appear to be nonlinear,but by choosing an
appropriate local coordinate basis,they can be readily solved
for[48].To illustrate,we
let be the platform
position vector and specialize to the two-dimensional case
where
is measured and relates the platform posi-
tion to the target(range sphere)through extension of the unit
look vector.The look
angle
estimated,can be constructed.
It is immediate from the above expressions that re-
construction of the scatterer position vector depends on
knowledge of the platform location,the interferometric
baseline length,orientation angle,and the interferometric
phase.To generate accurate topographic maps,radar inter-
ferometry places stringent requirements on knowledge of
the platform and baseline vectors.In the above discussion,
atmospheric effects are neglected.Appendix B develops
the correction for atmospheric refraction in an exponential,
horizontally stratified atmosphere,showing that the bulk of
the correction can be made by altering the effective speed
of light through the refractive atmosphere.Refractivity
fluctuation due to turbulence in the atmosphere is a minor
effect for two-aperture single-track interferometers[24].
To illustrate these theoretical concepts in a more concrete
way,we show in Fig.13a block diagram of the major steps
in the processing data for topographic mapping applica-
tions,from raw data collection to generation of a digital
topographic model.The description assumes simultaneous
collection of the two interferometric channels;however,
with minor modification,the procedure outlined applies to
processing of repeat-track data as well.
B.Sensitivity Equations and Accuracy
1)Sensitivity Equations and Error Model:In design
tradeoff studies of InSAR systems,it is often convenient to
know how interferometric performance varies with system
parameters and noise characteristics.Sensitivity equations
are derived by differentiating the basic interferometric height
reconstruction equation(6)with respect to the parameters
needed to determine,,
and
,baseline
length
,and position,assuming
that,yields
[24]
,and velocity errors result in position
errors on a vector parallel
to.Since the look vector
in an interferometric mapping system has components both
parallel and perpendicular to nadir,baseline and phase errors
contribute simultaneously to planimetric and height errors.
For broadside mapping geometries,where the look vector is PROCEEDINGS OF THE IEEE,VOL.88,NO.3,MARCH2000341
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