Graphics Programs Reference
In-Depth Information
T
1
T
2
n
1
n
2
-----
=
-----
(7.25)
where
n
1
and
n
2
are integers. The first true blind speed occurs when
n
1
T
1
n
2
T
2
-----
=
-----
(7.26)
This is illustrated in
Fig. 7.10
for and . Note that if
, then the process of PRF staggering is similar to that discussed in
Chapter 3
. The ratio
n
1
=
4
n
2
=
5
n
2
=
n
1
+
1
n
1
n
2
k
s
=
-----
(7.27)
is known as the stagger ratio. Using staggering ratios closer to unity pushes the
first true blind speed farther out. However, the dip in the vicinity of
1
⁄
T
1
becomes deeper, as illustrated in Fig. 7.11 for stagger ratio
k
s
=
63
⁄
64
. In
general, if there are
N
PRFs related by
n
1
T
1
n
2
T
2
n
N
T
N
-----
===
----- …
------
(7.28)
and if the first blind speed to occur for any of the individual PRFs is
v
blind
1
,
then the first true blind speed for the staggered waveform is
n
1
+++
N
n
2
…
n
N
v
blind
=
-----------------------------------------
v
blind
1
(7.29)
7.7. MTI Improvement Factor
In this section two quantities that are normally used to define the perfor-
mance of MTI systems are introduced. They are ÐClutter Attenuation (CA)Ñ
and the MTI ÐImprovement Factor.Ñ The MTI CA is defined as the ratio
between the MTI filter input clutter power
C
i
to the output clutter power
C
o
,
CA
=
C
i
⁄
C
o
(7.30)
The MTI improvement factor is defined as the ratio of the Signal to Clutter
(SCR) at the output to the SCR at the input,
-----
S
i
S
o
C
o
----
I
=
⁄
(7.31)
C
i
which can be rewritten as
Search WWH ::
Custom Search