Graphics Programs Reference
In-Depth Information
β
β
Oe n
=
D n
cos
a x
++
vta y
(
D n
sin
+
h
) a z
(12.77)
1
–
2
N
d ;
D n
=
-------------
+
n
=
0 … N
,
–
1
(12.78)
The range between a scatterer
C
within the
k th
range cell and the
n th
element
of the real array is
r 2 t εµ ô
h ô
h ô
) 2
β
(
,,,
;
)
=
D 2
++
v 2 t 2
(
–
+
2 D n
sin
(
–
)
+
(12.79)
n
β
h
tan
(
β k
+
ε
) h
[
tan
(
β k
+
ε
)
–
2 D n
cos
cos
µ
–
2 vt
sin
µ
]
It is more practical to use the scatterer's elevation and azimuth direction-
sines rather than the corresponding increments. Therefore, define the scat-
terer's azimuth and elevation direction-sines as
s
=
sin
µ
(12.80)
u
=
sin
ε
(12.81)
Then, one can rewrite Eq. (12.79) as
r 2 tsu ô
h ô
) 2
(
,,,
;
D n
)
=
D 2
++
v 2 t 2
(
–
+
h 2 f 2 ()
+
(12.82)
h ô
β
β
2 D n
sin
(
–
)
–
(
2 D n h
cos
f ()1
–
s 2
–
2 vhtf () s
)
f ()
=
tan
(
β k
+
asin
u
)
(12.83)
Expanding as a third order Taylor series expansion about incremental
yields
r n
tsu ô
(
,,,
)
ô 2
2
s 2
----
rtsu ô
ô ô
r ô u ô u
-----
(
,,,
;
D n
)
=
r
+++
r u u
+
+ + +
r st st
(12.84)
ô ô
ss
r ô ô ô ô 3
ô 2 u
2
ô u 2
2
t 2
----
u 2
2
r ô st ô st
-----
-----
--------
--------
r tt
+
r uu
+
+
r ô ô u
+
+
r ô uu
+
6
ô s 2
2
r t ô ô t ô 2
r uss us 2
r suu su 2
r utt ut 2
r uuu u 3
r ô ss
--------
+
--------
+
r stu stu
+
--------
+
-------
+
-------
+
-----
2
2
2
2
6
where subscripts denote partial derivations, and the over-bar indicates evalua-
tion at the state
tsu ô
(
,,,
)
=
(
0000
,,,
)
. Note that
{
r s
====== = = = =
=====
r t
r ô s
r ô t
r su
r tu
r ô ô s
r ô ô t
r ô su
r ô tu
(12.85)
r sss
r sst
r stt
r ttt
r tsu
0
}
Section 12.9.8 has detailed expressions of all non-zero Taylor series coeffi-
cients for the
k th
range cell.
ô mx
Even at the maximum increments
t mx
,
s mx
,
u mx
,
, the terms:
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