Search Radar

7/29/2019 Search Radar

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BY

H.S.VARA PRASAD


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Introduction

Basic radars.

Types of Radar.

Search Radar

Moving Target

Indication

Scan with search

radar

Search Radar

equation

Conclusion


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MONO STATIC RADAR

BI-STATIC RADAR

CW- RADAR

FM-CW RADAR

PULSED RADAR (search radar)


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R=CTR

2


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Search radars scan a large area withpulses of short radio waves

Targeting radars use the same principlebut scan a smaller area more often

Navigational radars are like searchradar, but use short waves that reflect offhard surfaces. They are used oncommercial ships and long-distance

commercial aircraft


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only detecting target

Operated only in search

or acquisition mode.

it will have knowledgeof other potential target.

An antenna with narrow

pencil beam is sufficient

for finding the target

both detecting and tracking.

Operated in both search

and tracking mode.

in tracking mode , it has noidea of other potential targets

An antenna with narrow

pencil beam is not sufficient for

detecting and ranging. thereforeseparate radar is used for

searching


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-Pulse radar that utilizes doppler frequencyshift as a means of discriminating moving

from a fixed targets is called MTI

-Blind speeds ( ambiguous Doppler

measurement )

-2nd

time around echoes (unambiguous rangemeasurement) depends on p.r.f


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The blind speed is a radial speed of the airplane at which

the phase shifting of the echo-signal has the valuen 360between two pulse periods. With blind speeds

moving targets are suppressed by a MTI system like ground

clutters.

Blind Phases:

It is due to the presenceof sampling pulses at the

point in the Doppler cycle

at each sampling instant


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Block Diagram of MTI


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with power amplifier


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with power amplifier


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Search radars are systems devoted to thesystematic exploration of a large volume ofspace

for typical air search radars, this is performed

over 360 in azimuth and over elevation anglesranging from 20-30 up to almost 90,

processing the echoes over the whole PRI, i.e.

over the whole observable range

a search radar has large beam in elevation

and has a stacked beams in azimuth the beam

steered both in elevation and azimuth in search

radar.

The search volume indicated solid angle


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MODE:

1.Circular scan

2.Sector scan

3.Tracking scan

4.Dopplerscan

Gain

Sweep

frequency

steradiansAZ EL


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R

180

90100

1

2

Search Sector

=azal

steradiansAZ EL

1

2

and the elevation extent goes from

to

.

1

2

and the elevation extent goes from

to

.

=azimuthal

extent from 1

to 2


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The powerP

rreturning to the receiving antenna is

given by the equation:

Where Pt = transmitter power

Gt = gain of the transmitting antenna

Ar= effective aperture (area) of the receiving antenna

= radar cross section, or scattering coefficient, of the target

F= pattern propagation factor

R = distance from the transmitter to the target


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There are several search

radar like surveillance search

radar ,navigation searchradar are extending their

services to both military and

civilian applications


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Search Radar

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