Range migration image formation algorithm for linear FM waveform
Single-Look Complex Image from Unfocused LFM SAR Data
Load a file that contains simulated unfocused synthetic aperture radar (SAR) data obtained with a linear frequency modulated waveform. The waveform has a sample rate of 45 MHz, a pulse width of 3 microseconds, a pulse repetition frequency of 960 seconds, and a sweep bandwidth of c/10 Hz, where c is the numerical value of the speed of light.
data = load("RangeMigrationLFMExampleData"); raw = data.raw; wvf = phased.LinearFMWaveform(SampleRate=45e6, ... PulseWidth=3e-6,PRF=960,SweepBandwidth=physconst("LightSpeed")/10);
The system works at an operating frequency of 4 GHz. The platform moves at a velocity of 100 meters per second and the distance between the beam center on the ground and the radar is 1118 meters.
fc = 4e9; v = 100; rc = 1118;
Generate a single-look complex image from the data. Plot the image.
slcimg = rangeMigrationLFM(raw,wvf,fc,v,rc); imagesc(abs(slcimg)) xlabel("Cross-Range Samples") ylabel("Range Samples")
raw — Raw SAR data
Raw SAR data, specified as a matrix. The data is the unfocused in-phase and
quadrature (I/Q) raw data collected by the SAR system. The rows of
raw correspond to the along-range samples. The columns of
raw correspond to the pulses received as the platform moves along
the cross-range direction.
raw must have at least two rows.
waveform — Input waveform
Input waveform, specified as a
fc — Operating frequency
Operating frequency in hertz, specified as a positive scalar.
2.8e9 Hz specifies a typical S-band operating-frequency value for
airport and weather radar systems.
v — Platform velocity
Platform velocity in meters per second, specified as a positive scalar.
rc — Distance between radar and beam center
Distance between radar and beam center on the ground in meters, specified as a positive scalar.
Specify optional pairs of arguments as
the argument name and
Value is the corresponding value.
Name-value arguments must appear after other arguments, but the order of the
pairs does not matter.
SquintAngle — Squint angle
0 (default) | scalar in the range
Squint angle of the antenna from the broadside direction in degrees, specified as a scalar in the range
PropagationSpeed — Signal propagation speed
physconst("LightSpeed") (default) | positive scalar
Signal propagation speed in meters per second, specified as a positive scalar.
343 meters per second approximates the speed of sound at sea level and at a temperature of 20 °C under normal atmospheric conditions.
C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.
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