Simrad EY500, Инструкция по эксплуатации

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Theory of operation
P3403E/A
9
3
W
*
10
& U
4
U
2
10
& U
4
U
2
(7)
3
U
' 3
W
*
10
& U
4
U
2
10
& U
4
U
2
2
4
*
(8)
'
3
U
64
3
3
W
*
2 2
U
4
10
2
U
(9)
6
S
'
4
U 2
0
'
3
U
16
2
3
W
*
2
U 2
0
2
U
4
10
2
U
(10)
10
OJ
(
6
S
)
'
10
OJ
(
3
U
)
%
10
OJ
(
U
4
10
2
U
)
&
10
OJ
(
3
W
*
2
U 2
0
2
16
2
) (11)
Received power at the transducer terminals is obtained by multiplying this
power density by the effective receiving area of the transducer, and the complete
equation becomes:
Rearranging the terms a simple expression is obtained for calculating the echo
properties of the target (equation 9):
In hydroacoustics it is common to state the echo properties in terms of
backscattering strength rather than backscattering area, and the equivalent
expression for point backscattering strength becomes (equation 10):
where r
0
= 1 meter is the reference range for backscattering strength. Finally,
the EY 500 implements a logarithmic version of this equation 11:
The left-hand side of this equation is commonly referred to as the target
strength or simply TS. Thus, target strength is obtained by adding a range
dependent term (corresponds to 40-log-r TVG) and a constant (accounts for
equipment parameters) to the received signal power (digital word from
transceiver/digitizer).
It should be observed that many of the internal algorithms of the sounder are
based on the quantity 10log(S
P
); TS echogram generation, size distribution
statistics etc.