Synthetic aperture radar interferometry(9)

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

noise)after the interpolation.If,on the other hand,the unwrapped and the absolute phases differ by an integer number

of

(55)

where we can resample and

phase shift

channel

(56)

Thus

if,

then

two times the range

shift divided by the speed of light)which is:1)constant over

the image processed and2)proportional

to

and should

be identical as well.However,when the transfer functions

of the two channels are different and perhaps varying across

the swath,it is be very difficult to estimate the absolute phase

accurately.A particularly troubling error source is multipath

contamination,as it will cause phase and impulse response

errors which are varying over the swath[51].

Small transfer function differences will have a significant

impact on the absolute phase estimated using the split-spec-

trum method as well,due to the very large multiplier

involved

,defined

as

(57)

where antenna,and an-

gular brackets denote averaging over the ensemble of speckle

realizations.For completely coherent scatterers such as point

scatterers,we have

that,

while when the scat-

tered fields at the antennas are independent.The magnitude

of the correlation