surfacegamma

Gamma value for different terrains

Since R2021a

Syntax

G = surfacegamma(TerrainType)

G = surfacegamma(TerrainType,FREQ)

surfacegamma

Description

G = surfacegamma(TerrainType) returns the γ value for the specified terrain. The γ 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 γ values. These γ values are for an operating frequency of 10 GHz.

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')

Input Arguments

TerrainType — Terrain type

"Sea State 3" | "Sea State 5" | "Woods" | "Metropolitan" | "Rugged Mountain" | "Farmland""Wooded Hill""Flatland"

Terrain type, specified as one of these:

• "Sea State 3"

• "Sea State 5"

• "Woods"

• "Metropolitan"

• "Rugged Mountain"

• "Farmland"

• "Wooded Hill"

• "Flatland"

Data Types: char | string

FREQ — Operating frequency of radar system

10e9 (default) | scalar | vector

Operating frequency of radar system in hertz, specified as a scalar or a vector.

Data Types: double

Output Arguments

G — Gamma value

scalar

Gamma value, γ, in decibels, for constant-γ clutter model, returned as a scalar.

More About

Gamma

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

Algorithms

The γ values for the terrain types "Sea State 3", "Sea State 5", "Woods", "Metropolitan", and "Rugged Mountain" are from [2]. The γ values for the terrain types "Farmland", "Wooded Hill", and "Flatland" are from [3].

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

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

where γ₀ 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.

Version History

Introduced in R2021a