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rangeMigrationLFM

Range migration image formation algorithm for linear FM waveform

Description

example

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

slcimg = rangeMigrationLFM(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 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")

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.LinearFMWaveform object.

Example: phased.LinearFMWaveform(SampleRate=500e3,'SweepBandwidth',200e3,PulseWidth=1e-3,PRF=1e3)

Data Types: double

Operating frequency in hertz, specified as a positive scalar.

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

Data Types: double

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

Data Types: double

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

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