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.
The side‐looking radar image of time‐variant scenes
The image formed by a side-looking radar system of a scene characterized by a temporally and spatially varying reflectivity density effectively distributed over a plane is given. The implied spectral density transformation, with its intrinsic distortion of the scene's wave number spectral density, is noted. In the remainder it is assumed that the temporal and spatial behaviors are connected via a dispersion relation. It is shown that the image is a linear, space-variant transformation of the scene at, say, t = 0, which can be described as the concantenation of three linear transformations: the first two are space-invariant, one being the system transformation for a time-invariant scene, and the third is space-variant and gives a geometric distortion, most simply a scaling and skewing, which is present in any system using a side-looking scan. Sufficient conditions are given for faithful imaging and spectral density mapping; those for the latter are more easily met.
Calculation of Complex Radiant Heat Load From Surrounding Radiator Surface Temperatures
Abstract A method for calculating the radiant heat exchange between an absorber and individual radiating components in its surroundings is reported. Radiator surface temperatures, ambient and absorber temperatures, and configuration factors for radiating components in the surroundings are used in the customary radiant heat exchange formulae. Simplified methods for calculating or estimating configuration factors for radiators of various shapes solely from angles, subtended at the absorber by the radiators are presented. The method has been verified in the laboratory under controlled conditions and has been used to advantage in the field studies. The method has advantages over the globe therometer method in certain applications.