Simrad EY500, Инструкция по эксплуатации

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Simrad EY 500
8
P3403E/A
3
W
4
U
2
(4)
3
W
*
10
& U
4
U
2
(5)
3
W
*
10
& U
4
U
2
(6)
where
P
r
and P
t
are the received and transmitted power referred to the transducer
terminals.
G is the transducer gain towards the target.
r is the transducer target range.
"
is the attenuation constant.
F
is the effective backscattering cross-section area of the target.
8
is the wavelength.
This expression can be recognized as the classic radar equation, and its
derivation will be recapitulated.
Assuming an idealized lossless isotropic transducer the transmitted power will
propagate evenly in all directions, and the power density at the transducer-
target range is explained in expression 4:
The real transducer amplifies the radiated signal by a factor G in the direction
of the target, and attenuation occurs while propagating from the transducer to
the target. Hence, the real power density at the target becomes:
The ability of an object to backscatter energy is stated in terms of its effective
backscattering cross section area, henceforth the backscattering area, which
roughly corresponds to the physical cross section area as seen from the
transducer. Introducing this concept in the derivation the real target can be
replaced by an isotropic transmitter of power:
While propagating back towards the transducer attenuation and spherical
spreading occur once more, and the power density at the transducer becomes: