Graphics Programs Reference
In-Depth Information
Fig. 7.3
shows a block diagram of a coherent MTI radar. Coherent transmis-
sion is controlled by the STAble Local Oscillator (STALO). The outputs of the
STALO, , and the COHerent Oscillator (COHO), , are mixed to produce
the transmission frequency, . The Intermediate Frequency (IF),
, is produced by mixing the received signal with . After the IF
amplifier, the signal is passed through a phase detector and is converted into a
base band. Finally, the video signal is inputted into an MTI filter.
f
LO
f
C
f
LO
+
f
C
f
C
±
f
d
f
LO
Pulse modulator
f
LO
+
f
C
f
LO
+
f
C
duplexer
power amplifier
f
LO
+
f
C
±
f
d
f
LO
f
LO
mixer
STALO
mixer
f
C
±
f
d
f
C
IF amplifier
COHO
f
C
f
C
±
f
d
to dete
ctor
phase detector
MTI
f
d
Figure 7.3. Coherent MTI radar block diagram.
7.3. Single Delay Line Canceler
cancelerÓs impulse response is denoted as . The output is equal to the
convolution between the impulse response and the input . The single
delay canceler is often called a Ðtwo-pulse cancelerÑ since it requires two dis-
tinct input pulses before an output can be read.
h
()
y
()
h
()
x
()
The delay
T
is equal to the PRI of the radar (
1
⁄
f
r
). The output signal
y
()
is
y
()
x
()
xt T
=
(
)
(7.4)
The impulse response of the canceler is given by
h
() δ() δ
tT
=
(
)
(7.5)
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