Page 161 - ITU Journal Future and evolving technologies – Volume 2 (2021), Issue 2

ITU Journal on Future and Evolving Technologies, Volume 2 (2021), Issue 2

Center width, w (c) Center width, w (c) Tail width, w (t)
Tail span, l (t)

(c)
Center height, h
Center height, h (c) Tail height, h (t)
Center length, l (c)
Center length, l (c)
(a) Category 1 (b) Category 2
Wing width, w (w) Wingspan, l (w)
Tail width, w (t)
Center (c) Tail height, h (t) Center width, w (c)
Center height, h (c) Tail span, l (t) Center height, h (c)
width, w

Wing height, h (w) Center length, l (c)
Center length, l (c)
(c) Category 3 (d) Category 4

Fig. 7 – Four categories of the targets based on the shape.

c
th
th
and height of the central section is 2 , , and , respec‑ mesh locations at and ( + 1) steering positions. The
e
tively. instantaneous velocity is represented as ( ) = Δ , +1 .
Δ , +1
th
The wingspan at a mesh from Fig. 6 and Fig. 7 is given Over the steering positions, we can write the maximum
(w)
(w)
as (w) = × ,B , where ,B are the number of blocked velocity as
th
laser beam positions of the mesh at the wings section. Δ
th
The coordinates of the blocked positions at the mesh (max) = max ( , +1 ), ∀ = − , − +1, … , −1, .
for the wingspan are ( (w) , (w) , (w) ). For example in Δ , +1
,o
,o

Fig. 6, the wingspan is 5 . The width of the wings section (8)
th
at the mesh is (w) = e (w) × (w) , where e (w) is a con‑ The trajectory variations of a target in the elevation and
,B azimuth planes can be represented using pitch and drift
(w)
stant value, and for simplicity can be taken as e = , and angles, respectively. Let ( ), and ( ) represent the pitch

coordinates of the blocked positions corresponding to the and drift angles of a target, respectively. If ℎ +1 ( ) and

width of the wings at the th mesh are ( (w) , (w) , (w) ). ℎ ( ) are the estimated heights of the target at + 1 and
,o ,o
The height of the wings section at the th mesh is given steering positions, +1 ( ) and ( ) are the ‑coordinates

(w)
as ℎ (w) = ,B . The coordinates of the blocked mesh of the target at + 1 and steering positions at time , and

positions forming the height of the wings are represented Δ is the distance between two consecutive steering po‑
as ( (w) , (w) , (w) ). The widthand heightof the wingssec‑ sitions shown in Fig. 3, then ( ) and ( ) are given
,o
,o
tion for a given target is shown in Fig. 6, and for Category 3 as [30, 31]
in Fig. 7. In Fig. 6, the width and height of the wings sec‑
(w) −1 ℎ +1 ( ) − ℎ ( )

tion is e , and , respectively. The dimensions of the tail ( ) = tan ( Δ ), (9)
section are obtained similarly as for the wings section.
+1 ( ) − ( )

−1
( ) = tan ( ). (10)
4.2 Velocity, pitch and drift angles, and alti‑ Δ
tude of the target
The maximum altitude of an aerial target contains valu‑
The motion characteristics of a target at a given time de‑ able information characterizing the target. This feature
pends on the velocity, and pitch and drift angles. These can also be determined using our proposed setup. The
three features of a target can be estimated using the pro‑ maximum z‑coordinate value at the intersection pair of
posed framework and can be utilized to classify a target. blocked beams provides the maximum altitude of the tar‑
Let Δ , +1 represent the distance between any two steer‑ get at that location. The maximum altitude of the target
ing positions, and +1, which have one or more blocked from the ground is represented as ℎ (G) . The maximum al‑
intersections due to a target, and Δ , +1 is the corre‑ titude, velocity, pitch and drift angles, and 3D shape fea‑
sponding time difference for a target to move between tures for different types of targets are given in Table 1.
© International Telecommunication Union, 2021 147