The document describes an active cancellation algorithm for radar cross section reduction. The algorithm uses hardware components like receiving and transmitting antennas along with software like MATLAB and C programs. It works by receiving an incoming radar signal, analyzing its parameters, searching databases to find matching echo data, generating a cancellation signal to transmit, and establishing scattering fields to synthesize an empty pattern for the radar receiver. Testing showed the algorithm improved visibility reduction by 25% over conventional methods.
ATI's Radar Systems Analysis & Design using MATLAB Technical Training Short C...Jim Jenkins
This course provides a comprehensive description of radar systems analyses and design. A design case study is introduced and as the material coverage progresses throughout the course, and new theory is presented, requirements for this design case study are changed and / or updated, and the design level of complexity is also increased. This design process is supported with a comprehensive set of MATLAB-7 code developed for this purpose. By the end, a comprehensive design case study is accomplished. This will serve as a valuable tool to radar engineers in helping them understand radar systems design process. Each student will receive the instructor’s textbook MATLAB Simulations for Radar Systems Design as well as course notes.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
In the modern age, High-resolution radar images can be achieved by employing SAR technique. It is well
known that SAR can provide several times better image resolution than conventional radars. The exploration for efficient
image denoising methods still remains a valid challenge for researchers. Despite the difficulty of the recently proposed
methods, mostly of the algorithms have not yet attained a pleasing level of applicability; each algorithm has its
assumptions, advantages, and limitations. This paper presents a review of synthetic aperture radar. Behind a brief
introduction in our work we are especially targeting the noise called backscattered noise in SAR terminology which
causes the appearance of speckle Potential future work in the area of air flight navigation, mapping Weather Monitoring
& during natural disaster like earth quake. The SAR having the capability, to make human visibility beyond optical
vision, is also discussed.
ATI's Radar Systems Analysis & Design using MATLAB Technical Training Short C...Jim Jenkins
This course provides a comprehensive description of radar systems analyses and design. A design case study is introduced and as the material coverage progresses throughout the course, and new theory is presented, requirements for this design case study are changed and / or updated, and the design level of complexity is also increased. This design process is supported with a comprehensive set of MATLAB-7 code developed for this purpose. By the end, a comprehensive design case study is accomplished. This will serve as a valuable tool to radar engineers in helping them understand radar systems design process. Each student will receive the instructor’s textbook MATLAB Simulations for Radar Systems Design as well as course notes.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
In the modern age, High-resolution radar images can be achieved by employing SAR technique. It is well
known that SAR can provide several times better image resolution than conventional radars. The exploration for efficient
image denoising methods still remains a valid challenge for researchers. Despite the difficulty of the recently proposed
methods, mostly of the algorithms have not yet attained a pleasing level of applicability; each algorithm has its
assumptions, advantages, and limitations. This paper presents a review of synthetic aperture radar. Behind a brief
introduction in our work we are especially targeting the noise called backscattered noise in SAR terminology which
causes the appearance of speckle Potential future work in the area of air flight navigation, mapping Weather Monitoring
& during natural disaster like earth quake. The SAR having the capability, to make human visibility beyond optical
vision, is also discussed.
Standard radar detection process requires that the sensor output is compared to a predetermined threshold. The
threshold is selected based on a-priori knowledge available and/or certain assumptions. However, any
knowledge and/or assumptions become in adequate due to the presence of multiple targets with varying signal
return and usually non stationary background. Thus, any predetermined threshold may result in either increased
false alarm rate or increased track loss. Even approaches where the threshold is adaptively varied will not
perform well in situations when the signal return from the target of interest is too low compared to the average
level of the background .Track-before-detect techniques eliminate the need for a detection threshold and provide
detecting and tracking targets with lower signal-to-noise ratios than standard methods. However, although trackbefore-
detect techniques eliminate
the need for detection threshold at sensor's signal processing stage, they often use tuning thresholds at the output
of the filtering stage .This paper presents a computerized simulation model for target detection process.
Moreover, the proposed model method is based on the target motion models, the output of the detection
process can easily be employed for maneuvering target tracking.
Localization of Objects Using Cross-Correlation of Shadow Fading Noise and Co...Rana Basheer
When a radio transmitter is mobile, obstacles in the
radio path can cause temporal variation in Received Signal Strength Indicator (RSSI) measured by receivers due to multipath and shadow fading. While fading, in general, is detrimental to accurately localizing a target, fading correlation between adjacent receivers may be exploited to improve localization accuracy. However, multipath fading correlation is a short range phenomenon that rapidly falls to zero within a wavelength whereas,
shadow fading correlation is independent of signal wavelength and has longer range thereby making it suitable for localization with wireless transceivers that operate at shorter wavelength. Therefore,
this paper presents a novel wireless localization scheme that employs a combination of cross-correlation between shadow fading noise and copula technique to recursively estimate the location of a transmitter. A stochastic filter that models multipath fading as an Ornstein-Uhlenbeck process followed by a Generalized Auto Regressive Conditional Heteroskedasticity (GARCH) filtering is
proposed to extract shadow fading residuals from measured RSSI values. Subsequently, Student-T Copula function is used to create the log likelihood function, which acts as the cost function for localization, by combining spatial shadow fading correlation arising among adjacent receivers due to pedestrian traffic in the area. Maximum Likelihood Estimate (MLE) is used for position estimation as it inherits the statistical consistency and asymptotic
normality. The performance of our proposed localization method is validated over simulations and hardware experiments.
ALTITUDE. Vertical distance of an aircraft or object above a given reference, such as ground or sea level.
AMPLIFIER. An electronic device used to increase signal magnitude or power.
AMPLITUDE MODULATION (AM). A method of impressing a message upon a carrier signal by causing the carrier amplitude to vary proportionally to the message waveform.
ANTENNA SYSTEM. Routes RF energy from the transmitter, radiates the energy into space, receives echoes, and routes the echoes to the receiver.
A presentation prepared by my friend's friend. I have done no editing at all, I'm just uploading the presentation as it is.
Standard radar detection process requires that the sensor output is compared to a predetermined threshold. The
threshold is selected based on a-priori knowledge available and/or certain assumptions. However, any
knowledge and/or assumptions become in adequate due to the presence of multiple targets with varying signal
return and usually non stationary background. Thus, any predetermined threshold may result in either increased
false alarm rate or increased track loss. Even approaches where the threshold is adaptively varied will not
perform well in situations when the signal return from the target of interest is too low compared to the average
level of the background .Track-before-detect techniques eliminate the need for a detection threshold and provide
detecting and tracking targets with lower signal-to-noise ratios than standard methods. However, although trackbefore-
detect techniques eliminate
the need for detection threshold at sensor's signal processing stage, they often use tuning thresholds at the output
of the filtering stage .This paper presents a computerized simulation model for target detection process.
Moreover, the proposed model method is based on the target motion models, the output of the detection
process can easily be employed for maneuvering target tracking.
Localization of Objects Using Cross-Correlation of Shadow Fading Noise and Co...Rana Basheer
When a radio transmitter is mobile, obstacles in the
radio path can cause temporal variation in Received Signal Strength Indicator (RSSI) measured by receivers due to multipath and shadow fading. While fading, in general, is detrimental to accurately localizing a target, fading correlation between adjacent receivers may be exploited to improve localization accuracy. However, multipath fading correlation is a short range phenomenon that rapidly falls to zero within a wavelength whereas,
shadow fading correlation is independent of signal wavelength and has longer range thereby making it suitable for localization with wireless transceivers that operate at shorter wavelength. Therefore,
this paper presents a novel wireless localization scheme that employs a combination of cross-correlation between shadow fading noise and copula technique to recursively estimate the location of a transmitter. A stochastic filter that models multipath fading as an Ornstein-Uhlenbeck process followed by a Generalized Auto Regressive Conditional Heteroskedasticity (GARCH) filtering is
proposed to extract shadow fading residuals from measured RSSI values. Subsequently, Student-T Copula function is used to create the log likelihood function, which acts as the cost function for localization, by combining spatial shadow fading correlation arising among adjacent receivers due to pedestrian traffic in the area. Maximum Likelihood Estimate (MLE) is used for position estimation as it inherits the statistical consistency and asymptotic
normality. The performance of our proposed localization method is validated over simulations and hardware experiments.
ALTITUDE. Vertical distance of an aircraft or object above a given reference, such as ground or sea level.
AMPLIFIER. An electronic device used to increase signal magnitude or power.
AMPLITUDE MODULATION (AM). A method of impressing a message upon a carrier signal by causing the carrier amplitude to vary proportionally to the message waveform.
ANTENNA SYSTEM. Routes RF energy from the transmitter, radiates the energy into space, receives echoes, and routes the echoes to the receiver.
A presentation prepared by my friend's friend. I have done no editing at all, I'm just uploading the presentation as it is.
A primeira pessoa que curei fui eu mesmo. A esquizofrenia eh facilmente curavel mediante uma mudanca de paradigma. Ela jamais sera curavel por meio de drogas antipsicoticas. Mostra-se cientificamente que os antipsicoticos so mantem o esquizofrenico em seu estado patologico. A esquizofrenia pode ser abordada em diferentes contextos: o familiar, o psicologico, o medicamentoso, o social, o politico. Trata-se de um problema multifacetado que pode ser resolvido pelo proprio esquizofrenico, ja que ninguem mais se propoe a faze-lo de modo razoavel e com bom senso. O esquizofrenico pode ser visto como uma pessoa de alto potencial. Este trabalho eh um primeiro esboco de como realizar este potencial.
Since debut of F-117A in Iraq and Yugoslavia, stealth craze has taken the world. Stealth aircraft are appearing - complete with flashy advertising and statements about nigh-invulnerability of these aircraft by defense industry officials - all over the world. But what is the truth?
Race in armaments lasts since dawn of human kind. Many new weapons performed admirably. Many failed miserably. Probably most famous example of latter are German Wunderwaffe from World War II, with whom stealth fighters share their basic belief: that quality can beat the quantity. Is that correct? Find out in this presentation.
Air Combat History describes the main air combats and fighter aircraft, from the beginning of aviation. The additional Youtube links are an important part of the presentation. A list of Air-to-Air Missile from different countries. is also given
For comments please contact me at solo.hermelin@gmail.com.
For more presentations visit my website at http://www.solohermelin.com.
Slides das aulas de Teoria e Prática da Argumentação Jurídica, disciplina ministrada pelo prof. Luís Rodolfo de Souza Dantas em faculdades, empresas e grupos de estudo.
Combat Systems Fusion Engine for the F-35ICSA, LLC
Michael Skaff of Lockheed Martin and the Principal Engineer for the F-35’s pilot vehicle interface explains the combat systems and their integration in the F-35. This capability is inherent in every F-35 or part of the baseline aircraft. In a real sense software development is never done; it is part of the evolving capability of the aircraft.
Curso preparatório de como usar Mapas Mentais para estudar para concursos Públicos.
O curso foi construído utilizando a plataforma de estudos online grátis examtime e a ferramenta de mapas mentais.
International Journal of Engineering Research and Applications (IJERA) is a team of researchers not publication services or private publications running the journals for monetary benefits, we are association of scientists and academia who focus only on supporting authors who want to publish their work. The articles published in our journal can be accessed online, all the articles will be archived for real time access.
Our journal system primarily aims to bring out the research talent and the works done by sciaentists, academia, engineers, practitioners, scholars, post graduate students of engineering and science. This journal aims to cover the scientific research in a broader sense and not publishing a niche area of research facilitating researchers from various verticals to publish their papers. It is also aimed to provide a platform for the researchers to publish in a shorter of time, enabling them to continue further All articles published are freely available to scientific researchers in the Government agencies,educators and the general public. We are taking serious efforts to promote our journal across the globe in various ways, we are sure that our journal will act as a scientific platform for all researchers to publish their works online.
RADAR (RAdio Detection and Ranging) use modulated waveforms and directive antennas to transmit electromagnetic energy into a specific volume in space to search for targets. The targets within the volume reflect echoes back to the radar which are further processed to extract target information. A better SNR (Signal to Noise Ratio) to for radar surveillance is achieved. The results are provided by Matlab simulation.
International Journal of Computational Engineering Research(IJCER) ijceronline
nternational Journal of Computational Engineering Research (IJCER) is dedicated to protecting personal information and will make every reasonable effort to handle collected information appropriately. All information collected, as well as related requests, will be handled as carefully and efficiently as possible in accordance with IJCER standards for integrity and objectivity.
A NEW HYBRID METHOD FOR SYNTHETIC APERTURE RADAR DECEPTIVE JAMMINGjmicro
Based on the synthetic aperture radar (SAR) geometric model, a novel, and fast algorithm of large scene
deceptive jamming against different SAR systems is proposed. First, a template deceptive image is
transformed into the time domain signal using inverse image formation algorithm. Then, the transformed
signal is convolved with enemy’s received SAR signal in order to cope with electronic counter-
countermeasures (ECCM) techniques. Finally, the generated jamming signal is transmitted to enemy’s SAR
system for deceptive purpose. Specifically, we have proposed a hybrid method for SAR jamming, which
uses a digital radio frequency memory (DRFM) system incorporating with SAR raw data simulation
module. The experimental results for the proposed deceptive jammer demonstrate its ability to deceive SAR
system.
A NEW HYBRID METHOD FOR SYNTHETIC APERTURE RADAR DECEPTIVE JAMMINGjmicro
Based on the synthetic aperture radar (SAR) geometric model, a novel, and fast algorithm of large scene deceptive jamming against different SAR systems is proposed. First, a template deceptive image is transformed into the time domain signal using inverse image formation algorithm. Then, the transformed signal is convolved with enemy’s received SAR signal in order to cope with electronic countercountermeasures (ECCM) techniques. Finally, the generated jamming signal is transmitted to enemy’s SAR system for deceptive purpose. Specifically, we have proposed a hybrid method for SAR jamming, which uses a digital radio frequency memory (DRFM) system incorporating with SAR raw data simulation module. The experimental results for the proposed deceptive jammer demonstrate its ability to deceive SAR system.
A NEW HYBRID METHOD FOR SYNTHETIC APERTURE RADAR DECEPTIVE JAMMINGjmicro
Based on the synthetic aperture radar (SAR) geometric model, a novel, and fast algorithm of large scene deceptive jamming against different SAR systems is proposed. First, a template deceptive image is transformed into the time domain signal using inverse image formation algorithm. Then, the transformed signal is convolved with enemy’s received SAR signal in order to cope with electronic countercountermeasures (ECCM) techniques. Finally, the generated jamming signal is transmitted to enemy’s SAR system for deceptive purpose. Specifically, we have proposed a hybrid method for SAR jamming, which uses a digital radio frequency memory (DRFM) system incorporating with SAR raw data simulation module. The experimental results for the proposed deceptive jammer demonstrate its ability to deceive SAR system.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
The peer-reviewed International Journal of Engineering Inventions (IJEI) is started with a mission to encourage contribution to research in Science and Technology. Encourage and motivate researchers in challenging areas of Sciences and Technology.
Similar to International Journal of Computational Engineering Research(IJCER) (20)
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The publishing industry has been selling digital audiobooks and ebooks for over a decade and has found its groove. What’s changed? What has stayed the same? Where do we go from here? Join a group of leading sales peers from across the industry for a conversation about the lessons learned since the popularization of digital books, best practices, digital book supply chain management, and more.
Link to video recording: https://bnctechforum.ca/sessions/selling-digital-books-in-2024-insights-from-industry-leaders/
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International Journal of Computational Engineering Research(IJCER)
1. International Journal of Computational Engineering Research||Vol, 03||Issue, 7||
www.ijceronline.com ||July ||2013|| Page 19
Active Cancellation Algorithm for Radar Cross Section
Reduction
Isam Abdelnabi Osman1,
Mustafa Osman Ali2
Abdelrasoul Jabar Alzebaidi 3
1, 3
Electronics Engineering School, 2
Electronics & Communication Engineering Department
1, 3
Sudan University of Science and technology, 2
Osmania University.
1, 3
Khartoum - Sudan, 2
Hyderabad - India
I. INTRODUCTION
Radar cross section reduction techniques generally fall into one of four categories [1]; target shaping,
materials selection and coating, passive cancellation, and active cancellation. The phased-array antenna
techniques, high-speed microelectronic devices, and computer processing have made active cancellation
technique more feasible and practical. An active cancellation algorithm for radar cross section reduction can
readapt to protect any object, such as aircraft. An active cancellation algorithm for radar cross section reduction
uses the coherent signal interference. To avoid target detection, the target must transmit a cancellation signal at
the same time with an incoming pulse, providing the required phase and amplitude to cancel the reflected energy
from detecting radar. The difficulty in implementing such a system is the need to obtain the parameters of
cancellation signal in real time, and to achieve precise adjustment of the phase and amplitude of the cancellation
waveform. Active cancellation algorithm for radar cross section was based on adaptive real-time adjustment of
electromagnetic (EM) signal within a three-dimensional space. The echo signals are produced by the target,
when a radar target is illuminated. According to Electromagnetic inverse scattering theory, if the source of
radiation field distribution is known, scatter characteristics and distribution of the scattering can be known. If
the radar signals are limited within a small precise angle for the EM wave cancellation, the target can be
invisible to radar's receiver system. An important part of the development of Active cancellation system for
radar cross section understands a particular goal, which is the comparison between the energy density scattered
on the radar receiver with incident energy density in the target. The formal definition of the RCS [2],[3],[4] is in
(1): )1(]/)ˆ.[(2lim irS
R
EeER
Where is the target RCS complex root, Ei is the electric field strength of the incident signal on the
target, R is the distance between the target and the radar, êr is aligned unit vector along electric polarization of
the receiver, and ĒS is the vector of the scattered field. Using active cancellation means, reducing the strength
incident field on the target to reduce the reflected power to the radar receiver. A target’s RCS can be reduced by
reducing the target scattering intensity. According to (1); target's RCS can be measured for many scattering
directions and a radar target’s scattered field direction can be identified as in (2):
ABSTRACT:
Abstract - Modern components for signal processing make it possible to achieve radar
visibility reduction, that requires reduce the radar cross section (RCS) of an aircraft or a system
because it seems to be on the enemy's radar detection capabilities. To achieve this goal, this paper
proposed an Active cancellation algorithm for radar cross section reduction using MATLAB, C
language program, digital radio-frequency memory (DRFM), and phased array technology to generate
the desired signal to cancel the reflected radar returns. The algorithm depends on a pre calculation
approach in which an omni direction RCS, clutter, and noise databases generated in advance. Signal
processing system function analysis parameter of the measured radar signal. Then find the
corresponding echo data (amplitude and phase parameters of the coherent echo) in the target RCS
database through real-time amendment. Through the establishment of a target scattering field with the
abolition of a coherent signal in the direction of the radar system detection, the radar receiver stays in
empty pattern synthesis. The result achieved by the proposed method improves visibility reduction by
25% compared to conventional methods.
KEYWORDS: Active cancellation, coherent, Echo, radar cross section, MATLAB, Phased array
antenna, and Stealth.
2. Active Cancellation Algorithm For Radar…
www.ijceronline.com ||July ||2013|| Page 20
)2(]2ˆ.[lim ReEE ri
R
S
II. METHODOLOGY
Active cancellation algorithm for radar cross section reduction consists of two elements:
A. Hardware components:
Receiving antenna, used to receive a radar signal.
Transmitting antenna, used to transmit a cancellation signal.
Reconnaissance receiver used to stores a precision copy a received signal with aide of (DRFM).
B. Software(MATLAB/C functions and databases):
Signal processing and control function (SPC), used to storing a received signal, database searches, signal
analysis, processing, and control of other elements.
Doppler frequency shift modulation function (DFSM), used to superimposes the Doppler frequency on the
output signal.
Power synthesis and beam forming function (PSBF), used to form the modified beam to transmit.
Target RCS database, is related to frequency, direction, and polarization, power, for incident signal.
Noise database, is related to the effective noise temperature, input noise power, etc.
Clutter database, is related to aircraft speed, airborne, carrier frequency, radar point, altitude radar, distance
to target and radar pulse repetition frequency (PRF).
The method based on generation an anti phase electromagnetic signal to a target’s scattered signal. The
effectiveness of this method depends on the knowledge of its real-time characteristics, the measurement
precision of the radar signal, and the accuracy of the generated cancellation signal, among other factors. Fig. 1
shows the principle process of the algorithm and Fig. 2, shows the flowchart of an active cancellation algorithm
for radar cross section reduction. The incident radar phase, amplitude, frequency, polarization, radar space
position and waveform characteristics are accurately and quickly measured on the target platform by SPC, and a
reconnaissance receiver. The characteristics of target reflection that correspond to the incident radar waveform
will be extracted from the target's RCS database controlled by the computer processing system. By generating a
signal (waveform) with the appropriate parameters, including phase, intensity, polarization and frequency, the
target's echo can be cancelled when the wave returns to the radar receiving antenna. If we can solve the target to
separate N scattering centers, then a radar return on a specific frequency is (3):
)3(.)(
2
1
5.0 nj
N
n
n
e
Where σn is the Nth scatter RCS and φn is the phase due to the physical location of scatterer’s.
Fig. 1: The principle of an active cancellation algorithm for radar cross section reduction process.
Powersynthesis
andbeam
formingunit
Transmittin
gAntenna
Doppler
frequencyshift
modulationunit
Receiving
Antenna
Signal
Processing
andcontrol
unit
TargetRCS
database
Radar
Receiving/
transmitting
Antenna
Reconnaissa
nceReceiver
Noise
database
Clutter
database
Computer Processing
SystemTarget
Radar
3. Active Cancellation Algorithm For Radar…
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A target with a huge number of scattering centers, several controlling scattering centers will exist for a
specific incident signal angle and operating radar frequency. Reduction of the radar returns from these centers
can reduce the target's RCS. If the original RCS of the target is denoted as σ0, an active cancellation system for
RCS reduction can produced an equivalent RCS scattering center denoted by σ1. The phases are φ0 and φ1,
respectively of scattering centers. The superposition σ0 and σ1 is given by (4):
)4()()( 10 5.0
1
5.0
0
jj
ee
By analyzing (4), (5) will get as following:
)5()][cos()/(2/1 01
5.0
1010
Controlling σ1 and φ1 can optimize those parameters to get (6):
)6(
)()12(01
01
Integeriskwherek
When σ = 0, this indicates that stealth in the direction of the enemy's radar has been achieved.
Compiling the target's RCS database is an important step in designing an active cancellation algorithm
for RCS reduction. The RCS entry is a function, rather than just varied number with different frequency,
direction, and polarization for incident signal. It is necessary to establish an RCS database due to different
frequencies, polarizations, and directions, according to real-time measurements for frequency, direction, power,
and polarization of incident signal. This database must support real-time modification for the parameter of the
transmitter to produce an effective cancellation signal for transmission.The reconnaissance receiver is used for
reception and reconnaissance signals from enemy's radar transmitters. A received radar signal is applied to SPC
function which stores a precision copy a received signal with aide of (DRFM) and alternately, it analyzed for
amplitude and phase adjustment to generate anti phase signal with same amplitude. By comparing the stored
signal with the wave signal generated by SPC function, the result from this comparison is checked to obtain a
minimum output value (zero balance), when this happen, the SPC function will send the radar signal to the
DFSM function, with coherent superposition of clutter and noise. The transmitting antenna and PSBF function
are used to form and transmit the active cancellation signal.
Yes
Store a precision copy a received signal on (DRFM).
Receive radar signal
Add stored signal to generated one
Search database to extract amplitude, phase and other wave parameters.
Addition result =
zero
Adjusts signal parameters togenerate anti phase signal
Start
Send the radar signal to the Doppler frequency
shift modulation function
No
Superimposes the Doppler frequency on the signal
Send the radar signal to the power synthesis and
beam forming function
Superimposes the clutter and noise signal to the cancellation signal
Transmits the modified signal by transmitting antenna
Doppler frequency shift
modulation function
Signal processing function
Power synthesis and beam
forming function
End
No
Fig. 2: An active cancellation algorithm for radar cross section reduction flowchart.
4. Active Cancellation Algorithm For Radar…
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The system’s memory is used for storing the databases, including the noise database, target echo
database, and the clutter database. The algorithm work with the assumption that an echo signal consists of three
parts: noise, clutter, and target echo so a radar echo can be as follows (7):
)7()()()()( tCtNtStX
Where S(t) is target's echo signal, N(t) is the noise signal, and C(t) is the clutter signal.
Due to a great deal of calculation and processing power that required to determine the radar's
cancellation signal; it is difficult to achieve calculations in real-time without pipeline delays. For this, an offline
calculation is used to build a target RCS database. Approximation prediction method is the based method for
obtaining a complex target RCS [5],[6],[7].The database for noise and clutter usually uses a distribution of
Gaussian for White noise, which can be produced by the Monte Carlo method [8][9]. Clutter data is related to
aircraft speed, airborne, carrier frequency, radar point, altitude radar, distance to target and radar pulse repetition
frequency (PRF). When clutter data are calculated, reduction of large amount of data is done because the speed,
radar frequency, and aircraft altitude are fixed, and only PRF and radar point are changed [10].Signal processing
and control function is the core of an active cancellation algorithm for radar cross section reduction, which used
for storing a received signal, database searches, signal analysis, processing, and controlling the other elements.
The Doppler shift in the radar wave is produced due to superimpose of the Doppler frequency by the Doppler
frequency shift modulation function. The power synthesis and beam forming function, used to form the
modified beam to transmitted via the transmitting antenna under control of signal processing and control
function.
III. TEST AND RESULTS:
An active cancellation algorithm for radar cross section reduction was tested with the following conditions
for evaluation purpose:
1. A coherent pulse train with 1 MHz modulation rate for radar transmit signal.
2. The signal has PRF of 1 kHz and a pulse width of 4 μs.
3. Uniform speed for the target movement with 100 km initial distance away from the radar transmitter, 300
m/s initial radial velocity, 0 deg of both azimuth and elevation angles and 2 m2
target's RCS according to
the Swelling model II.
4. The reference pattern function for reconnaissance is described by (8):
)8(
)]2/(/)([
])2/(/[
)(
1022
101
akaaBSa
akaASa
F
Where κ0 = (cosθ0)0.5
is the control factor for phased-array antenna modified beam gain with variation
of scanning angle, θ0 is the beam of scanning angle, θ1 is the unbiased-beam main-lobe beam width of 3 dB, θ2
is the unbiased-beam first side-lobe 3-dB beam width, AS is the unbiased-beam main-lobe gain value, BS is the
unbiased-beam first side-lobe gain value, a = 2.783, (a1 = πθ1/a) is first zero unbiased-beam (in rads), and (a2 =
π(θ1 + θ2/a ) is the unbiased-beam first side-lobe peak point of view (in rads).The 3D Electromagnetic pattern
can be simplified into an elevation and azimuth multiplication pattern result as shown in (9).
)9()()(),(
FFF
Where Fφ(φ) is the elevation pattern and Fθ(θ) is the azimuth pattern. Assuming that the radar antenna
vertical main-lobe beam-width is 2 degree, the main-lobe gain is 40 dB, the gain is 9 dB, and the first side-lobe-
width is 1 degree, the 3D antenna pattern shown in Fig. 3 will be generated.
Fig. 3: Three dimensional (3D) antenna's pattern.
The algorithm can used for (ECM) Electronic countermeasures function using rectangular array antenna M x N
pattern function described below as (10):
)10(),(),(),(),( eEGg
Where g(θ, φ) is the pattern of the antenna, G(θ, φ) is the factor of the directivity, E(θ, φ) is the array factor for
the beam shape determines, e(θ, φ) is the factor of the array element with (e(θ, φ) ≈ 1), φ is the elevation angle
5. Active Cancellation Algorithm For Radar…
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on spherical coordinates array, θ is the azimuth angle on spherical coordinates array, (φ ∈ [0, π/2] ), and(θ ∈ [0,
2π] ). Adjacent-array element spacing of d = λ/2 can be described in the x and y directions, E(θ, φ) as (11):
)11(])([exp),(
1 1
M
m
N
n
yxmn
nmjkdIE
Where k = 2π/λ is the wave number and Imn is the weighting coefficient.
)12(
cossincossin
cossincossin
00
00
Y
x
Where (θ0, φ0) is a beam pointing vector. If M = 51, N = 21, θ0 = 30 deg., φ0 = 20 deg, the (51 x 21) will result
array antenna pattern shown in Fig. 4.
Fig. 4: Pattern from multiple-element array antenna.
Fig. 5, shows the result obtained from the algorithm, (a) shows the a coherent pulse train spectrum, (b)
shows superimposed of coherent pulse train on the noise and clutter waveform, with completely target signal
submerged under noise and clutter, (c) shows a signal spectrum contains added noise and clutter with the target
signal, and (d) shows the contrast before (top) the cancellation signal and (bottom) after the cancellation signal
has been added to radar return.
The cancellation signal can be described as (13):
Where ΔĒ is the cancellation residual field and ĒS is the target's scattering field. Complete stealth is realized
when S = 0, From Fig. 5 (d), it can be seen that corresponding cancellation signal, S to ΔĒ max (6 x 10−2dB) is
0.51 dB, so the reduction of radar detection maximum range is 25% of original value.
IV. CONCLUSION:
From the results, an active cancellation algorithm for radar cross section reduction reduces the target
detectability. This approach can be used with different number of others radio echo scenarios.
)13(]/1log[20 S
EES
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REFERENCES
[1] Eugene F. Knott, John F. Shaeffer, and Michael T. Tuley, Radar Cross Section, SciTech Publishing, Inc., 2004.
[2] David C. Jenn, Radar and Laser Cross Section Engineering, American Institute of Aeronautics and Astronautics, Inc.2005
[3] Bassem R. Mahafza, Radar Systems Analysis and Design using MATLAB, Chapman& Hall/CRC, 2000.
[4] Merrill I. Skolnik, Radar Handbook, McGraw-Hill, third edition, 2008.
[5] Michael O. Kolawole, Radar Systems, Peak Detection and Tracking, Newns, 2002.
[6] Fred E. Nathanson and J. Patrick Reilly, Radar Design Principles, McGraw-Hill, 1999.
[7] V. G. Nebabin, Methods and Techniques of Radar Recognition, Artech House, 1995.
[8] David K. Barton and Sergey A. Leonov, Radar Technology Encyclopedia, Artech House, 1998.
[9] Yakov D. Shirman, Computer Simulation of Aerial Target Radar Scattering, Recognition, Detection, and Tracking, Artech
House, 2002.
[10] Merrill I. Skolnik, Introduction to Radar Systems, McGmw-Hill, 2001.