Graphics Programs Reference
In-Depth Information
Substituting Eq. (10.1) into Eq. (10.5) yields,
P λ 2 G
4( 2 R 2
1
B J
--------------------
-----
J
=
(10.6)
Thus, S/J ratio for a SSJ case is obtained from Eqs. (10.6) and (10.2),
P t τ G σ B J
ERP
S
---
=
--------------------------------------
(10.7)
) 4( R 2 L
(
and when pulse compression is used, with time-bandwidth-product
G PC
, then
Eq. (10.7) can be written as
P t G σ B J G PC
ERP
S
---
=
--------------------------------------------
(10.8)
) 4( R 2 B r L
(
Note that to obtain Eq. (10.8), one must multiply Eq. (10.7) by the factor
and use the fact that
B r
B r
G PC
=
B r τ
.
The jamming power reaches the radar on a one-way transmission basis,
whereas the target echoes involve two-way transmission. Thus, the jamming
power is generally greater than the target signal power. In other words, the ratio
is less than unity. However, as the target becomes closer to the radar,
there will be a certain range such that the ratio is equal to unity. This
range is known as the cross-over range. The range window where the ratio
is sufficiently larger than unity is denoted as the detection range. In order
to compute the crossover range
SJ
SJ
SJ
R co
, set
SJ
to unity in Eq. (10.8) and solve
for range. It follows that
P t G σ B J
B r L ERP
12
---------------------------------
(
R CO
) SSJ
=
(10.9)
(
)
MATLAB Program Ðssj_req.mÑ
The program Ðssj_req.mÑ implements Eqs. (10.9); it is given in Listing 10.1
in Section 10.5. This program calculates the cross-over range and generates
plots of relative
S
and
J
versus range normalized to the cross-over range, as
illustrated in Fig. 10.1a .
In this example, the following parameters were utilized: radar peak power
, jammer peak power
P t
=
50 KW
P J
=
200 W
, radar operating bandwidth
B r
=
667 KHz
, jammer bandwidth
B J
=
50 MHz
, radar and jammer losses
10. m 2
L
==
0.10 dB
, target cross section
σ
=
, radar antenna gain
J
G
=
35 dB
, jammer antenna gain
G J
=
10 dB
, the radar operating frequency
is
f
=
5.6 GHz
. The syntax is as follows:
Search WWH ::




Custom Search