9

STOLT INTERPOLATION PROCESSING ON SAR IMAGES

This chapter discusses an alternative approach for processing radar images from the wavenumber (or spatial frequency) domain. Section 9.1 reviews the general background of wavenumber theory. Section 9.2 describes the direct interpolation based on unevenly spaced samples. Section 9.3 reviews the algorithm of Stolt interpolation. Computer simulation for six-target broadside SAR system based on the Stolt interpolation technique is covered in Section 9.4. Computer simulation for six-target squint SAR system is described in Section 9.5. Section 9.6 shows the results of a satellite image file processed by both range–Doppler and Stolt interpolation algorithms. Comparison between range–Doppler and Stolt interpolation algorithms is discussed in Section 9.7.

9.1 WAVENUMBER DOMAIN PROCESSING OF SAR DATA

Several algorithms are used to process SAR image data in wavenumber domains. Examples are direct interpolation from unevenly spaced data, Stolt interpolation (or mapping), time-domain correlation and backprojection, and range stacking.

Consider a group of N targets randomly distributed on the ground with each target located at (x, y) = (xn, yn), n = 1, 2,..., N. Assume that the radar is located at (x, y) = (0, u), and moves at speed V along the y axis. Let p(t) be the transmitting signal; then the total received signal s(t, u) can be expressed as

where s(t, u) is a function of both t and u, and p(t) is the transmitting signal. The Fourier transform ...

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