Graphics Programs Reference
In-Depth Information
τ'
ξ
=
---------------
=
τ' B
(4.22)
(
1
B
)
is referred to as the compression ratio (also called time-bandwidth product
and compression gain). All three names can be used interchangeably to mean
the same thing. As indicated by Eq. (4.22) the compression ratio also increases
as the radar bandwidth is increased.
ξ
Example:
Compute the range resolution before and after pulse compression corre-
sponding to an LFM waveform with the following specifications: Bandwidth
; and pulsewidth
B
=
1 GHz
τ'
=
ms
.
Solution:
The range resolution before pulse compression is
3 0 8
–
3
c τ'
2
×
×
2
10
×
10
1 0 6
R uncomp
==
------
----------------------------------------------
=
1 . 5
×
meters
Using Eq. (4.21) yields
1
1 0 9
τ n 1
=
-----------------
=
1
ns
×
c τ n 1
2
3 0 8
1 0 9
–
×
×
2
×
.
R comp
=
----------
=
-------------------------------------------
=
1 5
cm
4.2.3. Coherent Pulse Train Ambiguity Function
Fig. 4.7 shows a plot of a coherent pulse train. The pulsewidth is denoted as
and the PRI is
τ'
T
. The number of pulses in the train is
N
; hence, the trainÓs
length is
(
N
–
1
) T
seconds. A normalized individual pulse
s ()
is defined by
1
τ'
t
τ'

------- Rect
-- 
s 1
()
=
(4.23)
τ′
T
(
N
–
1
) T
Figure 4.7. Coherent pulse train. N=5.
 
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