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Billingsley’s intrinsic clutter motion (ICM) model

Since R2021a



P = billingsleyicm(fd,fc,wspeed) calculates the clutter Doppler spectrum shape, P, due to intrinsic clutter motion (ICM) at Doppler frequencies specified in fd. ICM arises when wind blows on vegetation or other clutter sources. This function uses Billingsley’s model in the calculation. fc is the operating frequency of the system. wspeed is the wind speed.

P = billingsleyicm(fd,fc,wspeed,c) specifies the propagation speed c in meters per second.


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Calculate and plot the Doppler spectrum shape predicted by the Billingsley ICM model. Assume the PRF is 2 kHz, the operating frequency is 1 GHz, and the wind speed is 5 m/s.

v = -3:0.1:3;
fc = 1e9;
wspeed = 5;
c = physconst('LightSpeed');
fd = 2*v/(c/fc);
p = billingsleyicm(fd,fc,wspeed);
xlabel('Doppler frequency (Hz)')
ylabel('P (dB)')

Input Arguments

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Doppler frequencies in hertz, specified as a scalar or a vector.

Data Types: double

Operating frequency of the system in hertz, specified as a scalar.

Data Types: double

Wind speed in meters per second, specified as a scalar.

Data Types: double

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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Shape of the clutter Doppler spectrum due to intrinsic clutter motion, returned as a scalar or vector. P is the same size as fd.


[1] Billingsley, J. Low Angle Radar Clutter. Norwich, NY: William Andrew Publishing, 2002.

[2] Long, Maurice W. Radar Reflectivity of Land and Sea, 3rd Ed. Boston: Artech House, 2001.

Extended Capabilities

Version History

Introduced in R2021a