Summary:
The interferometric process implemented is a sequence of algorithms for the generation of Digital Elevation Models (DEMs) starting from two SAR images. A diagram describing the interferometric process is shown in next figure. Each step of the procedure is described in the following. All the algorithms are written in FORTRAN and they are running in an ALPHA VAX Station.
The different modules of the process can be adapted to different SAR sensors and formats. However, at present, the interferometric algorithms are tailored to the ERS-1/2 SAR interferometric product i.e. the Single Look Complex (SLC) format. This kind of SAR image contains, for each image pixel, amplitude and phase of the radar signal. Actually, for each image pixel the SLC image contains a complex number. During the acquisition the received signal is demodulated to remove the carrier wave which is useful only for transmission and does not contain useful information. Then, the so-called complex voltage is generated. Its two components are the in-phase (I) and the in-quadrature (Q) components:
I=A (t) sin F(t) in phase (1).
Q=A (t) cos F(t) in-quadrature (2).
Where A(t) is the signal amplitude and fi(t) the signal phase.