Pulse Compression - MATLAB Simulations for Radar Systems Design - page 254

Correction for the distortion caused by the target radial velocity can be over-
come by using the following approach. Over a period of a few pulses, the radar
data processor estimates the radial velocity of the target under track. Then, the
chirp slope and pulsewidth of the next transmitted pulse are changed to
account for the estimated Doppler frequency and time dilation.

5.4. ÐMyRadarÑ Design Case Study - Visit 5

5.4.1. Problem Statement

Assume that the threat may consist of multiple aircraft and missiles. Show
how the matched filter receiver can resolve multiple targets with a minimum
range separation of 50 meters. Also verify that the waveforms selected in
Chapter 3 are adequate to maintain proper detection and tracking (i.e., pro-
vide sufficient SNR).

5.4.2. A Design

It was determined in Chapter 3 that the pulsed compressed range resolutions
during search and track are respectively given by

∆ R search = 30 mB search ; = 5 MHz (5.44)

∆ R track = 7.5 mB track ; = 20 MHz

(5.45)

It was also determined that a single search waveform and 4 track waveforms
would be used.

Assume that track is initiated once detection is declared. Aircraft target type
are detected at while the missile is detected at .
It was shown in Section 2.10.2.2 that the minimum SNR at these ranges for
both target types is when 4-pulse non-coherent integration is uti-
lized along with cumulative detection. It was also determined that a single
pulse option was not desirable since it required prohibitive values for the peak
power. At this point one should however take advantage of the increased SNR
due to pulse compression. From Chapter 3, the pulse compression gain, for the
selected waveforms, is equal to 100 (10 dB). One should investigate this SNR
enhancement in the context of eliminating the need for pulse integration.

a m

R max = 90 Km R max = 55 Km

SNR ≥ 4 dB

The pulsed compressed SNR can be computed using Eq. (5.7), which is
repeated here as Eq. (5.46)

P t τ′ G 2 λ 2 σ
4( 3 R 4 kT e FL

SNR = ------------------------------------

(5.46)