scholarly journals A Truncated Matched Filter Method for Interrupted Sampling Repeater Jamming Suppression Based on Jamming Reconstruction

2021 ◽  
Vol 14 (1) ◽  
pp. 97
Author(s):  
Lu Lu ◽  
Meiguo Gao
Keyword(s):  
Time Delay ◽  
Theoretical Analysis ◽  
Numerical Simulations ◽  
Frequency Modulation ◽  
Pulse Compression ◽  
Matched Filter ◽  
Filter Method ◽  
Matched Filters ◽  
Digital Radio ◽  
Real Target

Interrupted sampling repeater jamming (ISRJ) is becoming more widely used in electronic countermeasures (ECM), thanks to the development of digital radio frequency memory (DRFM). Radar electronic counter-countermeasure (ECCM) is much more difficult when the jamming signal is coherent with the emitted signal. Due to the intermittent transmission feature of ISRJ, the energy accumulation of jamming on the matched filter shows a ‘ladder’ characteristic, whereas the real target signal is continuous. As a consequence, the time delay and distribution of the jamming slice can be obtained based on searching the truncated-matched-filter (TMF) matrix. That is composed of pulse compression (PC) results under matched filters with different lengths. Based on the above theory, this paper proposes a truncated matched filter method by the reconstruction of jamming slices to suppress ISRJ of linear frequency modulation (LFM) radars. The numerical simulations indicate the effectiveness of the proposed method and validate the theoretical analysis.

scholarly journals SIMULATION MODELING OF THE INTERFERENCE IMMUNITY OF THE RADARS OPERATING WITH COMPRESSED SIGNAL

2020 ◽  
Vol 8 (12) ◽  
pp. 799-804
Author(s):  
Sevdalin Ivanov Spassov ◽  
Keyword(s):  
Simulation Modeling ◽  
Pulse Compression ◽  
Matched Filter ◽  
Chirp Signal ◽  
Interference Immunity ◽  
Matched Filters ◽  
Matlab Software ◽  
Interference Signals

The immunity to the interference of a radar operating with a pulse compression signal is an important feature. The matched filter is one of the elements of the radar, providing resistance to interference. A model of a matched filter to chirp signal has synthesized using the Simulink tool of the Matlab software. Two types of interference signals have fed to the matched filter input, and the output signals are measured. The matched filters degree of suppression against these two interference signals has been assessed. Inferences about the interference immunity of the radars operating with compressed signals have been made.

scholarly journals Dynamics of a Discrete Internet Congestion Control Model

2011 ◽  
Vol 2011 ◽  
pp. 1-12
Author(s):  
Yingguo Li
Keyword(s):  
Time Delay ◽  
Theoretical Analysis ◽  
Numerical Simulations ◽  
Periodic Solutions ◽  
Control Model ◽  
Bifurcation Parameter ◽  
Single Source ◽  
Internet Congestion Control ◽  
Single Link ◽  
The Stability

We consider a discrete Internet model with a single link accessed by a single source, which responds to congestion signals from the network. Firstly, the stability of the equilibria of the system is investigated by analyzing the characteristic equation. By choosing the time delay as a bifurcation parameter, we prove that Neimark-Sacker bifurcations occur when the delay passes a sequence of critical values. Then, the explicit algorithm for determining the direction of the Neimark-Sacker bifurcations and the stability of the bifurcating periodic solutions is derived. Finally, some numerical simulations are given to verify the theoretical analysis.

scholarly journals Implementation of Multi-Objective Grey Wolf Optimizer to Minimize The Sidelobes And Reduce Mainlobe Width

2018 ◽  
Vol 7 (2.20) ◽  
pp. 219
Author(s):  
K Ravi Kumar ◽  
Prof. P. Rajesh Kumar
Keyword(s):  
Frequency Modulation ◽  
Pulse Compression ◽  
Matched Filter ◽  
High Energy ◽  
Grey Wolf Optimizer ◽  
Grey Wolf ◽  
Compression Technique ◽  
Range Resolution ◽  
Multi Objective ◽  
Small Targets

Range resolution in radar can be achieved by splitting the long pulse of high energy into the high bandwidth of short pulses using pulse compression technique. Frequency modulation (Linear frequency modulation (LFM)) signal is used to improve range resolution. To get better range resolution, frequency step is introduced between a train of LFM pulses known as stepped frequency pulse train (the SFPT). The SFPT suffers from grating lobes when the product of sub-pulse duration and frequency step becomes more than one. The grating lobes and sidelobes present in the vicinity of the mainlobe. It can cause the false alarm detection and hide the small targets. In this work, Multi-Objective Grey Wolf Algorithm (MOGWO) is used to set the parameters of SFPT to mitigate the grating lobes and minimize the sidelobes at the matched filter output. Trade-off solutions between sidelobes versus grating lobes and mainlobe width versus sidelobes are obtained using the Pareto front for different ranges of SFPT parameters.  

scholarly journals CHIRP FILTER JAMMING IMMUNITY RESEARCH

2021 ◽  
Vol 9 (01) ◽  
pp. 966-971
Author(s):  
Sevdalin Ivanov Spassov ◽  
Keyword(s):  
Pulse Compression ◽  
Matched Filter ◽  
Chirp Signal ◽  
Echo Signal ◽  
Matched Filters ◽  
Compression Technique ◽  
Matlab Software

The pulse compression technique uses a matched filter to extract an echo signal in the radars receiver. A model of a matched filter for a chirp signal was synthesized using the Simulink Tool of the MATLAB software. Pulse jamming and chirp jamming signals were feed to the input of the matched filter. The output signals were measured. The matched filters degree of suppression of these jamming signals was assessed. Conclusions were made about the jamming immunity of a radar operating with a Chirp matched filter.

Synchronization and anti-synchronization of a fractional order delayed memristor-based chaotic system using active control

2018 ◽  
Vol 32 (14) ◽  
pp. 1850142 ◽  
Author(s):  
Dawei Ding ◽  
Xin Qian ◽  
Nian Wang ◽  
Dong Liang
Keyword(s):  
Time Delay ◽  
Theoretical Analysis ◽  
Numerical Simulations ◽  
Active Control ◽  
Fractional Order ◽  
Chaotic System ◽  
Control Strategy ◽  
Active Control Strategy

In this paper, the issue of synchronization and anti-synchronization for fractional-delayed memristor-based chaotic system is studied by using active control strategy. Firstly, some explicit conditions are proposed to guarantee the synchronization and anti-synchronization of the proposed system. Secondly, the influence of order and time delay on the synchronization (anti-synchronization) is discussed. It reveals that synchronization (anti-synchronization) is faster as the order increases or the time delay decreases. Finally, some numerical simulations are presented to verify the validity of our theoretical analysis.

scholarly journals JAMMINGIMMUNITYRESEARCH OF A RADAR OPERATING WITH BARKER CODED PHASE MODULATED SIGNAL

2020 ◽  
Vol 8 (12) ◽  
pp. 738-743
Author(s):  
Sevdalin Ivanov Spassov ◽  
Keyword(s):  
Pulse Compression ◽  
Matched Filter ◽  
Interference Immunity ◽  
Matched Filters ◽  
Compression Technique ◽  
Matlab Software ◽  
Interference Signals

The matched filter is one of the most important elements in the pulse compression technique. Pulse compressed signal enhances the interference immunity of a radar operating with such a signal. A model of the matched filter for a Barker coded phase modulated signal was synthesized using the Simulink tool of the Matlab software. Interference signals were feed to the input of the matched filter and output signals were measured. The matched filters degree of suppression of these interference signals was assessed. Conclusions were made about the jamming immunity of radars operating with Barker coded phase modulated signal.

scholarly journals The Effect of Time Delay on Dynamical Behavior in an Ecoepidemiological Model

2012 ◽  
Vol 2012 ◽  
pp. 1-18
Author(s):  
Changjin Xu ◽  
Yusen Wu
Keyword(s):  
Hopf Bifurcation ◽  
Time Delay ◽  
Theoretical Analysis ◽  
Numerical Simulations ◽  
Local Stability ◽  
Time Delays ◽  
Dynamical Behavior ◽  
Positive Equilibrium ◽  
Predator Prey ◽  
Predator Prey Model

A delayed predator-prey model with disease in the prey is investigated. The conditions for the local stability and the existence of Hopf bifurcation at the positive equilibrium of the system are derived. The effect of the two different time delays on the dynamical behavior has been given. Numerical simulations are performed to illustrate the theoretical analysis. Finally, the main conclusions are drawn.

RT-EQcorrscan: Near-Real-Time Matched-Filtering for Rapid Development of Dense Earthquake Catalogs

2020 ◽  
Vol 91 (6) ◽  
pp. 3574-3584
Author(s):  
Calum John Chamberlain ◽  
John Townend ◽  
Matthew C. Gerstenberger
Keyword(s):  
Real Time ◽  
Template Matching ◽  
Matched Filter ◽  
Rapid Development ◽  
Geographic Region ◽  
High Rate ◽  
Filter Method ◽  
Matched Filtering ◽  
Matched Filters ◽  
Earthquake Catalogs

Abstract Matched-filtering (template-matching) is an effective method for detecting clustered seismicity such as aftershocks, low-frequency earthquakes, repeating earthquakes, and tectonic and volcanic swarms. Several groups have developed efficient codes implementing matched-filter methods and demonstrated that earthquake catalogs can be substantially expanded using these methods. Here, we present a near-real-time implementation of the matched-filter method, designed to be used in response to ongoing seismicity. Its near-real-time capabilities enable dense catalogs of seismicity to be constructed rapidly, providing input into real-time seismic hazard and forecasting and thus informing the earthquake response and scientific understanding. Such rapid development of detailed earthquake catalogs has similar application in volcano monitoring, monitoring of induced seismicity, and for online construction of slow-earthquake catalogs. Our software package, RT-EQcorrscan, is an open-source extension of the EQcorrscan Python package. The package can either be deployed to apply near-real-time matched-filters to a specific geographic region or sequence on a continuous basis, or configured to respond to large earthquakes or high-rate sequences by automatically starting a matched-filter run in response to these events. The system relies on, and maintains, a constantly updated template database of waveforms and event metadata, which is then queried for the specific target region. This template database can be updated while the matched-filter is running to enable the set of templates to expand in response to previous results. Multiple region-specific matched-filters can be run in parallel, allowing the system to respond to distinct trigger events.

scholarly journals JAMMINGIMMUNITY RESEARCH OF A RADAR OPERATING WITH CHIRP SIGNAL

2020 ◽  
Vol 8 (12) ◽  
pp. 731-737
Author(s):  
Sevdalin Ivanov Spassov ◽  
Keyword(s):  
Pulse Compression ◽  
Matched Filter ◽  
Chirp Signal ◽  
Matched Filters ◽  
Compression Technique ◽  
Matlab Software ◽  
Interference Signals

Pulse compressed signal enhances the jamming immunity of a radar operating with such a signal. The matched filter is one of the most important elements in the pulse compression technique. A model of a matched filter for a chirp signal was synthesized using the Simulink tool of the Matlab software. Interference signals were feed to the input of the matched filter and output signals were measured. The matched filters degree of suppression of these interference signals was assessed. Conclusions were made about the jamming immunity of radar operating with chirp signal.

scholarly journals Theoretical Analysis and Design of an Innovative Coil Structure for Transcranial Magnetic Stimulation

2021 ◽  
Vol 11 (4) ◽  
pp. 1960
Author(s):  
Naming Zhang ◽  
Ziang Wang ◽  
Jinhua Shi ◽  
Shuya Ning ◽  
Yukuo Zhang ◽  
...  
Keyword(s):  
Electromagnetic Field ◽  
Transcranial Magnetic Stimulation ◽  
Theoretical Analysis ◽  
Numerical Simulations ◽  
Magnetic Stimulation ◽  
Influential Factors ◽  
Intersection Angle ◽  
Electromagnetic Field Distribution ◽  
Analysis And Design ◽  
Coil Structure

Previous research showed that pulsed functional magnetic stimulation can activate brain tissue with optimum intensity and frequency. Conventional stimulation coils are always set as a figure-8 type or Helmholtz. However, the magnetic fields generated by these coils are uniform around the target, and their magnetic stimulation performance still needs improvement. In this paper, a novel type of stimulation coil is proposed to shrink the irritative zone and strengthen the stimulation intensity. Furthermore, the electromagnetic field distribution is calculated and measured. Based on numerical simulations, the proposed coil is compared to traditional coil types. Moreover, the influential factors, such as the diameter and the intersection angle, are also analyzed. It was demonstrated that the proposed coil has a better performance in comparison with the figure-8 coil. Thus, this work suggests a new way to design stimulation coils for transcranial magnetic stimulation.

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