Simrad EY500, Инструкция по эксплуатации

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Simrad EK 500 / EY 500
P2260/E
9
SIMRAD oct.1991
60 mm COPPER SPHERE
38 kHz PULSE DURATION
ms
1400 1420 1440 1460 1480 1500 1520 1540 1560
SOUND SPEED (m/s)
TA
R
G
E
T
S
T
R
E
N
G
T
H
(dB
)
-3
4.
5-
3
4.
0-
3
3
.5-
3
3
.0
3.0
0.3
(CD3146)
Figure 2 Target strength
of a 60 mm copper sphere.
Reference target.
Simrad supplies copper spheres designed as reference targets for the calibration
of scientific sounders. Copper is selected because it is a metal which can be
made electrolytically with high purity. The spheres are machined to the perfect
spherical form with great accuracy, and a nylon loop is attached. Except for 12
kHz, 49 kHz and 50 kHz, the sphere diameter is different for each frequency in
order to obtain a target strength with minimum dependence of temperature (K.
Foote 1983). A curve showing the variation of the target strength follows each
sphere. The curve for the 38 kHz sphere is shown below as an illustration.
Simrad copper spheres
Frequency
kHz
Diameter
mm
TS sound at speed 1490 m/s
dB
12*
18
27
38
49*
50*
70
120
200
710
45.0
63.0
42.0
60.0
45.0
45.0
32.1
23.0
13.7
10.3 -40.4
-34.4
-37.9
-33.6
-36.4
-36.2
-39.1
-40.4
-45.0
-50.5
* same sphere