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Ingredients of a CSAR

posted Jan 14, 2009 7:21 AM by Ahmed Fasih   [ updated Jan 14, 2009 7:24 AM ]
clight = 3e8;

elevation_angle = 45/180*pi; % assume this to be constant, but can easily vectorize this for non-flat flightpaths
scene_radius = 2;

range_max = [cos(elevation_angle), sin(elevation_angle)] * [scene_radius; tan(elevation_angle) * 2 * scene_radius];

u_sample_rate = 2 * (range_max / 2 / pi) * cos(elevation_angle);

bandwidth = 600e6;
center_frequency = 10e9;

u_min = (center_frequency - bandwidth/2)*4*pi/clight;
u_number_of_samples = ceil(bandwidth*4*pi/clight * u_sample_rate);
u = (0:u_number_of_samples)/u_sample_rate + u_min;

downrange_resolution = clight / 2 / bandwidth;
azimuth_sample_rate = 2 * (scene_radius/2/pi) * 4 * pi * center_frequency / clight * cos(elevation_angle);

azimuth_extent_min = clight / center_frequency / 2 / downrange_resolution; % for azimuth resolution equal to downrange resolution
azimuth_extent = azimuth_extent_min;

azimuth_number_of_samples = ceil(azimuth_extent * azimuth_sample_rate);
azimuth = ceil((0:azimuth_number_of_samples-1) - azimuth_number_of_samples/2) / azimuth_sample_rate;

boresight_range = norm([6000; 6000]);
platform_velocity = 100;
t = azimuth * boresight_range / platform_velocity;

kx = u(:) * sin(azimuth)        * cos(elevation_angle);
ky = u(:) * cos(azimuth)        * cos(elevation_angle);
kz = u(:) * ones(size(azimuth)) * sin(elevation_angle);

sensor_noise_var = 50;