Stripmap mode SAR raw data generator for ocean scene with large squint angle
A procedure for synthetic aperture radar (SAR) raw data generation for time-variant ocean surface is proposed. The appropriate ocean reflectivity function that takes account of the electromagnetic-ocean wave interaction is transformed on to SAR raw signal based on the distributed surface (DS) model. An efficient and accurate simulation algorithm with time-domain integration along range dimension for squint SAR raw signal is adopted. Moreover, the ocean's dynamics is accounted by means of interpolation based on the dispersion relationship of the time-variant waves. Simulation results are presented to demonstrate the validity and applicability of the proposed techniques.
A Raw Signal Simulator for Bistatic SAR
Abstract This article proposes a new efficient raw signal simulator for the bistatic synthetic aperture radar (SAR) based on 2D fast Fourier transform (FFT) to deal with cases of both ideal trajectory and trajectory deviation. It begins with analyzing the geometric configuration and the range history of the bistatic SAR in side-looking and squint modes of ideal trajectory as well as trajectory deviation. Then a detailed and mathematical study is conducted on the equivalence relation of bistatic-to-monostatic applications (BTMA) in the case of ideal trajectory and trajectory deviation. Also a set of formulas are derived for the equivalence relation between bistatic SAR and monostatic SAR on some reasonable assumptions. Therefore, the application of the simulation method based on the 2D FFT for the monostatic SAR can be extended to the case of bistatic SAR. Finally, the simulation results prove the validity of this method. By comparing the efficiency of the proposed method with that of the time domain method, it is shown that the former is a few orders of magnitude higher.
Statistical analysis of azimuth streaks observed in digitally processed CASSIE imagery of the sea surface
During the Canberra synthetic-aperture radar sea imaging experiment in 1987 (CASSIE 87), numerous azimuth streaks were observed by the X-band SAR. The authors analyzed the first- and second-order statistical properties of the CASSIE data, containing the images of the sea surface where wave breaking is considered to be present. The probability density function (PDF) and higher order intensity moments are first analyzed for image areas containing few and many streaks. The theoretical PDFs that fit the measured PDFs are identified. The two-dimensional intensity autocorrelation functions (ACFs) of images processed at different processor focal settings are computed and discussed to identify the predominant scatterers' motions. From these experimental results, a scattering model is postulated to account for the non-Rayleigh distribution and correlation of scattering amplitude, and the motion of scatterers. Using the model, the ACF of the range radar cross section is estimated from the image ACF and attempts are made to predict the azimuth component of the image ACF and the scene coherence time. >