21-06-2012, 02:16 PM
RETRIEVING EVAPORATION DUCT HEIGHTS FROM RADAR SEA CLUTTER USING PARTICLE SWARM OPTIMIZATION (PSO) ALGORITHM
[attachment=24992]
INTRODUCTION
Atmospheric duct is an anomalous condition of atmosphere, which
leads to the trap of electromagnetic waves within a certain atmosphere
of ducting on electromagnetic wave. m and M are
presented meters and modi¯ed refractivity, respectively.
radar is e®ectively blind and an increase in the sea clutter. Hence,
radio systems/radar systems operating in these environments would
bene¯t from knowing the e®ects of the environment on their system
SIMULATION OF THE RADAR SEA CLUTTER POWER
A forward simulation of received radar sea clutter power has to be
performed, and its accuracy determines the veracity of evaluating the
performances of radar systems and a®ects the precision of retrieved
duct parameters. Using the classical radar equation, received radar
clutter power can be calculated as follows (in dB) [2]:
Scattering Coe±cient at Grazing Angle
In reality, radar scattering coe±cient (radar cross section) is a
function of grazing angle, the e®ective clutter height, range and
duct parameters. The grazing angle is usually less than 0.8±, and
almost constant for long ranges. There are many techniques to
compute scattering coe±cient [17{20], such as classical Kirchho®
approximation (KA), phase perturbation technique (PPT), and small
slope approximation (SSA). Unfortunately, all of them can not
calculate the scattering coe±cient properly at a low grazing angle.
Thus, one uses the assumptions of ¾0 / µ0 and ¾0 / µ4, where µ is the grazing angle.
Evaporation Duct Model
Normally, the atmospheric refractivity has a negative slope of the
altitude. In this condition, electromagnetic waves would slowly move
away from the surface. If the negative slope is stronger than the
curvature of the earth, the wave will be partially trapped and forced
to bend downward, and an atmospheric duct is formed.
Retrieval Algorithm: Standard PSO
Actually, the technique used to retrieve atmospheric ducts from radar
sea clutter is a minimum problem which estimates the ¯t of simulated
and measured radar sea clutter power. PSO method can solve the
problem e®ectively. Thus, a standard PSO algorithm is introduced.
[attachment=24992]
INTRODUCTION
Atmospheric duct is an anomalous condition of atmosphere, which
leads to the trap of electromagnetic waves within a certain atmosphere
of ducting on electromagnetic wave. m and M are
presented meters and modi¯ed refractivity, respectively.
radar is e®ectively blind and an increase in the sea clutter. Hence,
radio systems/radar systems operating in these environments would
bene¯t from knowing the e®ects of the environment on their system
SIMULATION OF THE RADAR SEA CLUTTER POWER
A forward simulation of received radar sea clutter power has to be
performed, and its accuracy determines the veracity of evaluating the
performances of radar systems and a®ects the precision of retrieved
duct parameters. Using the classical radar equation, received radar
clutter power can be calculated as follows (in dB) [2]:
Scattering Coe±cient at Grazing Angle
In reality, radar scattering coe±cient (radar cross section) is a
function of grazing angle, the e®ective clutter height, range and
duct parameters. The grazing angle is usually less than 0.8±, and
almost constant for long ranges. There are many techniques to
compute scattering coe±cient [17{20], such as classical Kirchho®
approximation (KA), phase perturbation technique (PPT), and small
slope approximation (SSA). Unfortunately, all of them can not
calculate the scattering coe±cient properly at a low grazing angle.
Thus, one uses the assumptions of ¾0 / µ0 and ¾0 / µ4, where µ is the grazing angle.
Evaporation Duct Model
Normally, the atmospheric refractivity has a negative slope of the
altitude. In this condition, electromagnetic waves would slowly move
away from the surface. If the negative slope is stronger than the
curvature of the earth, the wave will be partially trapped and forced
to bend downward, and an atmospheric duct is formed.
Retrieval Algorithm: Standard PSO
Actually, the technique used to retrieve atmospheric ducts from radar
sea clutter is a minimum problem which estimates the ¯t of simulated
and measured radar sea clutter power. PSO method can solve the
problem e®ectively. Thus, a standard PSO algorithm is introduced.