Simrad EY500, Инструкция по эксплуатации

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Simrad EY 500
6
P3403E/A
Transducer
Observer
Electrical
power
Figure 1 The gain concept.
*
( , )
' @ '
( , ) (1)
algorithms of the EY 500 uses the more modern concept of gain in order to
facilitate power budget equations. The gain concept is used widely within many
fields in physics and is accepted internationally as a convenient measure of the
radiation properties.
Gain is defined as the intensity ratio observed at a distant point when using a
real transducer and an idealized lossless omni-directional transducer keeping
the electrical input power constant (see figure.1).
Thus, gain accounts for both directional properties and losses and is indepen-
dent of input power level, impedance and observation point. However, gain must
be referred to a defined point on the terminal side of the transducer in order to
uniquely identify the losses which are to be included. Gain (G) relates to
directivity (D) as shown in equation 1:
where
"
and ß are the directional angles, and
0
is the efficiency of the
transducer. Thus, directivity is a normalized quantity which corresponds to the
gain pattern of an identical but lossless transducer. Whereas gain is used for
describing the radiation properties, it is common to state the receiving
properties in terms of the effective receiving area (A).