Introduction to Radar Basics - MATLAB Simulations for Radar Systems Design - page 4

R

Transmitter /
Modulator

Duplexer

Time
Control

Signal
processor

Signal
processor

Receiver

Figure 1.1. A simplified pulsed radar block diagram.

During each PRI the radar radiates energy only for seconds and listens for
target returns for the rest of the PRI. The radar transmitting duty cycle (factor)
is defined as the ratio

τ

. The radar average transmitted power is d t d t = τ T ⁄

, P av = P t × d t (1.3)

where denotes the radar peak transmitted power. The pulse energy is

.

P t

E p = P t τ = P av T = ⁄ f r

av

The range corresponding to the two-way time delay is known as the radar
unambiguous range, . Consider the case shown in Fig. 1.3 . Echo 1 repre-
sents the radar return from a target at range due to pulse 1. Echo 2
could be interpreted as the return from the same target due to pulse 2, or it may
be the return from a faraway target at range

T

R u

R 1 = c ∆ t ⁄ 2

due to pulse 1 again. In this

R 2

case,

c ∆ t
2

cT ∆ t ( + )

R 2 = -------- or R 2 = ----------------------- (1.4)

2

transmitted pulses

IPP

pulse 2

pulse 1

τ

pulse 3

time

∆ t

τ pulse 1

pulse 3
echo

pulse 2
echo

time

echo

received pulses

Figure 1.2. Train of transmitted and received pulses.