surfacegamma

Gamma value for different terrains

Syntax

G = surfacegamma(TerrainType)
G = surfacegamma(TerrainType,FREQ)
surfacegamma


Description

G = surfacegamma(TerrainType) returns the $$\gamma$$ value for the specified terrain. The $$\gamma$$ value is for an operating frequency of 10 GHz.

G = surfacegamma(TerrainType,FREQ) specifies the operating frequency of the system.

surfacegamma displays several terrain types and their corresponding $$\gamma$$ values. These $$\gamma$$ values are for an operating frequency of 10 GHz.

Input Arguments

TerrainType	Character vectors that describe the terrain type. Valid values are: 'sea state 3' 'sea state 5' 'woods' 'metropolitan' 'rugged mountain' 'farmland' 'wooded hill' 'flatland'
FREQ	Operating frequency of radar system in hertz. This value can be a scalar or vector. Default: 10e9

Output Arguments

G	Value of $$\gamma$$ in decibels, for constant $$\gamma$$ clutter model.

Examples

Simulate Constant Gamma Clutter

Determine the γ value for a wooded area, and then simulate the clutter return from that area. Assume the radar system uses a single cosine pattern antenna element and has an operating frequency of 300 MHz.

fc = 300e6;
g = surfacegamma('woods',fc);
clutter = constantGammaClutter('Gamma',g, ...
    'Sensor',phased.CosineAntennaElement, ...
    'OperatingFrequency',fc);
x = clutter();
r = (0:numel(x)-1)/(2*clutter.SampleRate) * ...
    clutter.PropagationSpeed;
plot(r,abs(x))
xlabel('Range (m)')
ylabel('Clutter Magnitude (V)')
title('Clutter Return vs. Range')

More About

Gamma

A frequently used model for clutter simulation is the constant gamma model. This model uses a parameter, $$\gamma$$, to describe clutter characteristics of different types of terrain. Values of $$\gamma$$ are derived from measurements.

Algorithms

The $$\gamma$$ values for the terrain types 'sea state 3', 'sea state 5', 'woods', 'metropolitan', and 'rugged mountain' are from [2].

The $$\gamma$$ values for the terrain types 'farmland', 'wooded hill', and 'flatland' are from [3].

Measurements provide values of $$\gamma$$ for a system operating at 10 GHz. The $$\gamma$$ value for a system operating at frequency f is:

$$\gamma ={\gamma }_0+5\log \left(\frac{f}{f_0}\right)$$

where $${\gamma }_0$$ is the value at frequency f₀ = 10 GHz.

References

[1] Barton, David. “Land Clutter Models for Radar Design and Analysis,” Proceedings of the IEEE. Vol. 73, Number 2, February, 1985, pp. 198–204.

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

[3] Nathanson, Fred E., J. Patrick Reilly, and Marvin N. Cohen. Radar Design Principles, 2nd Ed. Mendham, NJ: SciTech Publishing, 1999.

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

Usage notes and limitations:

Does not support variable-size inputs.