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rangeMigrationFMCW

Range migration image formation algorithm for frequency-modulated CW waveform

Description

example

slcimg = rangeMigrationFMCW(raw,waveform,fc,v,rc) returns a single-look complex image of raw synthetic aperture radar (SAR) data obtained with a frequency modulated continuous wave (FMCW) waveform. The function uses the range migration algorithm.

slcimg = rangeMigrationFMCW(raw,waveform,fc,v,rc,Name=Value) specifies additional inputs using name-value arguments. You can specify the squint angle of the antenna and the signal propagation speed.

Examples

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Load a file that contains simulated unfocused synthetic aperture radar (SAR) data obtained with a frequency modulated continuous wave waveform sampled at 15 MHz. The waveform has a sweep time of 25 microseconds, a sweep bandwidth of 20 MHz, and sweeps in the "Down" direction.

data = load("RangeMigrationFMCWExampleData");
raw = data.raw;

wvf = phased.FMCWWaveform(SampleRate=15e6, ...
    SweepTime=2.5e-5,SweepBandwidth=20e6,SweepDirection="Down");

The system works at an operating frequency of 3 GHz. The platform moves at a velocity of 200 meters per second and the distance between the beam center on the ground and the radar is 46.672 meters.

fc = 3e9;
v = 200;
rc = 46.672;

Generate a single-look complex image from the data. Plot the image and zoom in on the first 20 along-range samples.

slcimg = rangeMigrationFMCW(raw,wvf,fc,v,rc);

imagesc(abs(slcimg(1:20,:)))
xlabel("Cross-Range Samples")
ylabel("Range Samples")

Figure contains an axes object. The axes object contains an object of type image.

Input Arguments

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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.

Data Types: double

Input waveform, specified as a phased.FMCWWaveform object.

Example: phased.FMCWWaveform(SweepBandwidth=100e3,OutputFormat="Sweeps",NumSweeps=2)

Data Types: double

Platform velocity, specified as a positive scalar. Units are in meters per second.

Data Types: double

Operating frequency, specified as a positive scalar. Units are in Hz.

Example: 2.8e9 Hz specifies a typical S-band operating-frequency value for airport and weather radar systems.

Data Types: double

Distance between radar and beam center on the ground, specified as a positive scalar. Units are in meters.

Data Types: double

Name-Value Arguments

Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is 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.

Example: SquintAngle=45,PropagationSpeed=343

Squint angle of the antenna from the broadside direction in degrees, specified as a scalar in the range (-90, 90).

Data Types: double

Signal propagation speed in meters per second, specified as a positive scalar.

Example: 343 meters per second approximates the speed of sound at sea level and at a temperature of 20 °C under normal atmospheric conditions.

Data Types: double

Output Arguments

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Single-look complex (SLC) image, returned as a matrix. slcimg is the same size as raw and contains the focused data processed by the range migration algorithm.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

Version History

Introduced in R2022a