Radar System Performance

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Radar System Performance

Analysis under Dynamic JammingHaroon Rashid
http://www.agi.com/http://www.agi.com/


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Motivation Why radar performance analysis under jamming is

critical

Main factors impacting radar performance Radar system noise

Jammer characteristics

Jammers as noise sources Radar system performance parameters


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RAdio Detection And Range


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Radar Equation

43

2

)4( R

LLLLGLGP

r

TxLprrtttP

=

G is Gain, L is Loss, R = Range

Received Power is inversely proportional to the 4th power

of the target range

In order to maintain the same received power level, 16

times transmit power is needed at double the range


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Range Equation

K Ts Bn is the thermal noise power of the receiver

S/N is the signal to Noise ratio

the minimum detectable received power threshold is

)/()4(

43

2

NSBKT

LLLLGLGP

ns

TxLprrtttR

=

)/( NSBKTP nsr =


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Factors Impacting Radar Performance We have little control over these factors.

Radar Cross Section (stealth).

Atmospheric propagation loss, rain attenuation, ...

External noise (Sun, Earth, )

Clutter

Radar system noise

Jamming


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Radar Environmental NoiseSun Noise

Earth Noise

Rain Loss and Noise

Troposphere Loss and Noise

Desired Signal

Polarization

Sun Noise

Earth Noise

Rain Loss and Noise


Desired Signal

Polarization

Sun Noise

Earth Noise

Rain Loss and Noise


Desired Signal

Polarization

Sun Noise

Earth Noise

Rain Loss and Noise


Desired Signal

Polarization

Sun Noise

Earth Noise

Rain Loss and Noise


Desired Signal

Polarization

Sun Noise

Earth Noise

Rain Loss and Noise


Desired Signal

Polarization

Sun Noise

Earth Noise

Rain Loss and Noise


Desired Signal

Polarization

Sun Noise

Earth Noise

Rain Loss and Noise


Desired Signal

Polarization

Sun Noise

Earth Noise

Rain Loss and Noise


Desired Signal

Polarization

Sun Noise

Earth Noise

Rain Loss and Noise


Desired Signal

Polarization


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Radar System Noise

Gain LNA

Loss Antenna CableNoise Figure

LNANoise Temperature


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Jammer Types Wideband, white noise

Wideband, colored noise

Narrowband

Single frequency, Continuous wave (CW)

Pulsed

Transponders with delay


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Jammer Attributes Effective Isotropic Radiated Power (EIRP)

Power amplifier power

Jammer antenna gain in the direction of the radar

Jammer post transmit losses, (hidden behind trees)

Signal characteristics Frequency

Bandwidth

Modulation

Spectrum analyzers let you see and estimatesome of these attributes


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Jammer Power At The Radar

Where

Bn is bandwidth of the radar receiver front end (filters & LNA).

Bj

is the jammer signal bandwidth.

Received jammer power is inversely proportional to the

square of the jammer range

JJ

xenJJ

BR

LLABGP

JPD

= 24


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Jammers As A Source Of Noise

nsSystem BKTNoise =

)1( 10/loss

eTemperatur eKNoise

= o

JJ

xenJJ

BR

LLABGP

JPD

= 2

4

JammerCluttertEnvironmenSystemTotalNoise +++=


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Dynamic Radar Jamming Analysis Account for object movements

Object attitude dynamics

Dynamic antenna gain and EIRP computations System, environmental, and external noise

sources

Frequency and bandwidth overlap, power transfer

as seen by the radar

Dynamic computation of SNRs, S/(N+J),S/(C+N+J), J/S, Pdet,


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Jammer As Seen By The Radar Signal bandwidth overlap

Radar antenna gain in the direction of the jammer

Radar and jammer relative position

Radar attitude

Phased array adaptive nulling antennas

Spectral filters


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S/T Analysis Under Jamming S1/(N+J) and Integrated S/(N+J)

Probability of detection (Pdet) and Integrated Pdet

under jamming. Number of pulses integrated and the integration

time

J/S, jamming power to signal power ratio


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Integ S/(N+J)

Integ SNR

SNR1

S1/(N+J)

dB

SNR1

S1/(N+J)

Integrated

S/(N+J)

Integrated SNR


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J/S

Integrated J/S


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Synthetic Aperture Radar (SAR) Side looking radar

Will generate radar maps of an area

Raster scan is achieved by the forward motion ofthe radar (aircraft and satellite) and azimuth scan

Highly susceptible to clutter.

Higher SNR and SCR will yield a better resolution Jamming reduces the SNR due to addition of the

jamming power, S/(N+J)


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Synthetic Aperture Radar (SAR) Signal to Noise ratio, SNR

Signal to Clutter ratio, SCR

Clutter to Noise ratio, CNR

SAR noise power

SAR noise bandwidth

SAR noise density


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SAR Under Jamming S/(N+J)

S/(C+N+J)

C/(N+J)

J/S

Jamming power

Jamming power density

Jammer bandwidth


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Radar Jamming Coverage Analysis

Integrated S/(N+J)


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Radar Jamming Analysis On An Attitude

Coverage Sphere Direction of arrival of signals and target and

jamming, are critical to a radar

Attitude coverage will analyze the S/T and SARFigures of Merit on a sphere all around a radar

Analyzing jamming FOMs help identify the

direction of attack and its impact

Attitude coverage can help mitigate the threats by

identifying the best direction to steer the antenna

nulls


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Jamming Analysis On Attitude Sphere

Integrated S/(N+J)


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Future Development Direction Radar transmitter spectrum shaping filters

Radar spectral filters

Receiver matched filters

Adaptive phased array antennas

User plug-in radar models


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Thank you for your timeQuestions?

Radar System Performance

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