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Ultrasensitive core for magnetooptical fluxgate magnetometer with high space resolution

Procedia Engineering 2010年 5卷 989-992页

作者： Vladimir Skidanov Petr Vetoshko Institute for Design Problems in Microelectronics RAS Sovetskaja st. 3 Moscow 124681 Russia

New type of fluxgate magnetometer core on the basis of magnetooptical uniaxial Bi-substituted garnet film was designed, numerically modeled and investigated experimentally. Magnetooptical garnet film with weak magnetization exhibits extremely high sensitivity with relation to external magnetic field. High sensitivity is achieved by single domain wall displacement in film area restricted by potential barriers. High amplitude magnetooptical response was received from garnet film element with special shape in space region 20–200 mcm. Magnetic field value for sensitive element saturation and garnet film coercive field were found in the same range 20–200 /m. Used in fluxgate regime garnet film sensitive element can provide space resolution better 10 mcm with magnetic field sensitivity higher than that one of traditional fluxgate. Presented approach possesses to avoid temperature adjustment and inductive coils application in high sensitive magnetometers.

关键词： Fluxgate magnetometer Ferrite garnet film Domain wall Faraday rotation Magnetostatic barrier

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Bifurcations in the dynamical system for three-layered magnetic valve 6th

Bifurcations in the dynamical system for three-layered magne...

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6th Moscow International Symposium on Magnetism, MISM 2014

作者： Ostrovskaya, Natalia Skidanov, Vladimir Iusipova, Iuliia Institute for Design Problems in Microelectronics RAS Sovetskaya street 3 Zelenograd Moscow124365 Russia National Research University of Electronic Technology Solnechnaya Alleya 5 Zelenograd Moscow124498 Russia

ISBN: (纸本)9783038354826

Magnetization dynamics in a three-layered nanopillar Co/Cu/Co structure with one fixed and one free layer driven by external magnetic field and spin-polarized electric current was investigated using methods of the theory of bifurcations. Mathematical model is based on the Landau-Lifshits-Gilbert equation with the current term in the Sloncžewski–Berger form. Orientation of applied magnetic field was considered to be parallel to the anisotropy axis. Physical model included the magnetocrystalline anisotropy field and the demagnetizing field. Because of small size of the structure, the space dependence of magnetization, as usually, was not taken into account. The resulting system of equations has the form of the nonlinear dynamical system with the polynomial right sides. Mathematical simulation of magnetization dynamics for several typical values of field and current was performed. The numerical experiments revealed the features of switching process in more detail and permitted to find new regimes of magnetization dynamics, such as incomplete and accidental switching. © (2015) Trans Tech Publications, Switzerland.

关键词： Dynamical systems

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Signal Source Angular Location Tracking Algorithm

Signal Source Angular Location Tracking Algorithm

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Digital Signal Processing and its Applications (DSPA), International Conference on

作者： Victor I. Djigan Department of Integrated Circuits Design Methodology Institute for Design Problems in Microelectronics of RAS Moscow Russia

This paper presents an algorithm of the signal source angular location tracking. The tracking is carried out by means of an antenna array. Traditional angular tracking is based on the usage of a monopulse (sum and difference) architecture which combines the output signals of the directional antennas (with mechanical or electronic steering). This requires the usage of a few antennas and a combiner of the antenna output signals. The algorithm, presented in this paper, allows to find the signal source angular location using only one directional antenna that is the antenna array. It is assumed the usage of the antenna array with the digital beamforming. However, the analog phased array can be used as well. This is because the algorithm is based on the processing of the antenna array output signal estimates after the changing (perturbations) only the phases of the array channel signals. This changing can be done by means of the phased shifters in a phased array or by means of the complex-valued weights with the unity absolute values in an antenna array with the digital beamforming. The paper considers the usage of the algorithm in a linear antenna array. To improve the signal-to-noise ratio, the array output samples are processed by a correlator or a matched filter. For this reason, the measured signal must be a pseudo noise sequence. The paper describes the proposed algorithm and the simulation results that confirm the algorithm's operation and demonstrate its efficiency.

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Features of Cylindric Adaptive Antenna Arrays

Features of Cylindric Adaptive Antenna Arrays

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Antennas design and Measurement International Conference (ADMInC)

作者： Victor I. Djigan Department of Integrated Circuits Design Methodology Institute for Design Problems in Microelectronics of RAS Moscow Russia

An adaptive antenna array based on the usage of the Linearly Constrained Recursive Least Squares algorithm for the weights calculation is considered in this paper. The array has a cylindrical shape. It has been demonstrated that the steering vector used in the formulation of the linear constraints has to take into consideration the radiation patterns of the array antennas. It is because the antennas are usually not omnidirectional ones and they are steered towards the different fixed directions according to their placement over the array surface. Due to the same reason the number of the interference signals, which a cylindrical adaptive antenna array is able to suppress, is much less than the number of the weights of the array. The cylindric array efficiency and the confirmation of the above-mentioned features is demonstrated by means of the simulation.

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Measuring Far-Field Radiation Patterns of Digital Beamforming Antenna Arrays

Measuring Far-Field Radiation Patterns of Digital Beamformin...

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Systems of Signals Generating and Processing in the Field of on Board Communications

作者： V. I. Djigan Department of Integrated Circuits Design Methodology Institute for Design Problems in Microelectronics of RAS Moscow Russia

A method of the antenna array far-field Radiation Pattern (RP) measurement is considered. This method is designed for the usage with the receiving Digital Beamforming Antenna Arrays (DBAA). Such type of antenna arrays typically does not have a radiofrequency output. Hence, the standard methods of the RP measurement, based on the radiation and the reception of the monochromatic probing signal, cannot be used for the DBAA RP measurement. The proposed method assumes the radiation of a probing signal modulated by a pseudo-noise sequence and the base-band processing of the DBAA output signal by means of a matched filter or a correlator. The paper presents the description of the measurement setup and the mathematical explanation of the measuring procedure. It has been shown that the accuracy of the RP measurement depends on the Signal-to-Noise Ratio (SNR) at the outputs of the DBAA channel receivers, the number of the array channels and the number of the pseudo-noise sequence symbols. The accuracy increases on 3 dB each time as the number of the array antennas or the pseudo-noise sequence symbols is doubled. This result is confirmed by the simulation of the RP measurement of the eight and the sixteen channel linear antenna arrays with the usage of the maximum length pseudo-noise sequence of 1023 and 2047 symbols.

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Efficient calculation of cyclic convolution by means of fast Fourier transform in a finite field

Efficient calculation of cyclic convolution by means of fast...

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East-West design & Test Symposium (EWDTS)

作者： V.M. Amerbaev R. A. Solovyev A.L. Stempkovskiy D.V. Telpukhov Institute for Design Problems in Microelectronics Russian Academy of Sciences (IPPM RAS) Moscow

Over a finite field a transformation similar to discrete Fourier transform can be defined that can be efficiently implemented using fast algorithms. One of the main applications of such transformation is calculation of convolutions of long sequences of integers by means of integer arithmetic. In this paper a method of implementation of two vectors convolution using modular arithmetic with Proth-type modulo is considered. A device performing cyclic convolution using modular arithmetic was created. A comparison with binary analogues was carried out.

关键词： Convolution Discrete Fourier transforms Pipelines Galois fields Finite element analysis Equations Mathematical model

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Adaptive Cancellation of Engine Noise in Vehicle Cabin

Adaptive Cancellation of Engine Noise in Vehicle Cabin

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Systems of Signal Synchronization, Generating and Processing in Telecommunications (SYNCHROINFO)

作者： V. I. Djigan Department of Integrated Circuits Design Methodology Institute for Design Problems in Microelectronics of RAS Moscow Russia

This paper presents the adaptive noise canceller for the suppression of noise caused by a rotated engine in a vehicle cabin. The canceller uses two microphones to accept the background signals for the processing. One microphone is installed close to the vehicle engine, i.e. outside the cabin. It allows to isolate this microphone from the near-end speaker's voice which is accepted by the second microphone and is transmitted to the far-end speaker. At the same time, the engine noise penetrates to the cabin and is accepted by the second microphone. As a result, the transmitted voice signal becomes noisy. This noise has to be cancelled priory the voice signal transmitting. Because the engine noise is rather colored than white, the efficiency of usage in the noise canceller the computationally simple adaptive filters based the gradient search is low. This paper considers the usage of the computationally complex but functionally efficient Recursive Least Squares (RLS) adaptive filters in this task. Simulation demonstrates a better performance of the RLS noise canceller comparing to the gradient search based Normalized Least Mean Square (NLMS) noise canceller in the considered scenario.

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Adaptive Antenna Array for Low Signal-to-Noise Ratio Operation

Adaptive Antenna Array for Low Signal-to-Noise Ratio Operati...

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Antennas design and Measurement International Conference (ADMInC)

作者： Victor I. Djigan Department of Integrated Circuits Design Methodology Institute for Design Problems in Microelectronics of RAS Moscow Russia

The adaptive antenna array which operates in the low signal-to-noise ratio (SNR) is presented. In this scenario, the Minimum Mean Squares Error (MMSE) criterion adaptive algorithms cannot be used for the array weight calculation. If the angular location of the signal source is known, it is possible to use the linearly constrained adaptive algorithms. However, this location is often unknown or it is changed if the signal source or the array is moving. At the same time, if the informational signals are the pseudo-noise sequences, they can be pre-processed by the matched filters or by the correlators. In this case the informational signal at the devices output becomes above the noise (the SNR is increased) and the MMSE criterion algorithms can be used for the calculation of the adaptive array weights. The adaptive array based on this criterion is able to suppress the interference signals. Besides, it is also able to steer the beam in the direction of the informational signal source and to track the source. The computational procedures of the two Recursive Least Squares algorithms which process the matched filter output signals for the calculation of the adaptive array weights are considered. One of these algorithms uses the complex-valued arithmetic and other one uses the real-valued arithmetic. The simulation demonstrates that the real-valued arithmetic algorithm has about 3 dB better cancellation of the interference signals at the adaptive array output and about two times shorter transient response.

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Low Complexity Partially Adaptive Antenna Array Based on Recursive Least Square Algorithm

Low Complexity Partially Adaptive Antenna Array Based on Rec...

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Systems of Signal Synchronization, Generating and Processing in Telecommunications (SYNCHROINFO)

作者： V. I. Djigan Department of Integrated Circuits Design Methodology Institute for Design Problems in Microelectronics of RAS Moscow Russia

ISBN: (数字)9781665470643

ISBN: (纸本)9781665470650

The adaptive array with a rectangular aperture, whose antennas are placed in the nodes of the rectangular grid, is considered in the paper. The partial adaptability is provided via the base-band combination of the signals in the rows and in the columns of the array. Opposite to the hybrid arrays, based on the subarray output signals combination, the arrays based on the row and the column signal combination, do not suffer on the grating lobes phenomenon, which restricts the ability of the cancellation of the interferences, whose source spatial locations are coincided with those of the grating lobes. A version of the Matrix Inversion Lemma Recursive Least Squares adaptive algorithm for the partially adaptive narrow-band array weight calculation is presented. The Householder transform or QR decomposition adaptive algorithms can be used as well. The algorithm arithmetic complexity does not depend on the number of the array antennas, but depends on the array columns number and the rows number. The simulation results demonstrate that the steady-state performance of the adaptive array with the partial adaptation is the same as that of the adaptive array with the full adaptation if the number of the received signal sources does not exceed the number of the partially adaptive array weights. The dynamic behavior of the both arrays in the terms of the radiation pattern values in the directions of the received signal sources is differed only at the initial stage of the transient response. The equivalent weights of the full array used for the radiation pattern calculations are reconstructed via the combination of the weights of the crossed rows and the crossed columns of the partially adaptive array. The considered partial adaptation can be used in the large rectangular antenna arrays.

关键词： Transient response Array signal processing Adaptive arrays Adaptive algorithms Transforms Complexity theory Telecommunications

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Adaptive Processing of Matched Filter Output Signals in Antenna Array

Adaptive Processing of Matched Filter Output Signals in Ante...

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Digital Signal Processing and its Applications (DSPA), International Conference on

作者： Victor I. Djigan Department of Integrated Circuits Design Methodology Institute for Design Problems in Microelectronics of RAS Moscow Russia

An Adaptive Antenna Array (AAA) is presented in this paper. The least squares criterion adaptive algorithms are used for the array weights calculation. The informational signal of the AAA is a periodic pseudo random sequence, which is hidden by the noise of the array channels. Such sequences are often used in modern radar, navigation and communication systems. The Matched Filters (MF) or the correlators are used for the processing of the AAA channel signals and this enables the usage of the adaptive algorithms based on the least squares criterion. The output signals of the MF are the cross-correlation functions of the AAA channel signals and the pseudo random sequence. The AAA weights calculation algorithm processes the periodic samples of the maximal values of the MF output signals and processes the error signal between the output and desired signals of the array. The desired signal is also composed using the samples of the maximal values of the auto-correlation function of the pseudo random sequence. The calculation of the AAA weights is provided by the Matrix Inversion Lemma Recursive Least Squares algorithm and its two computationally efficient modifications. The simulation demonstrates that the AAA can suppress the interfering signals and can track the informational signal source angular location simultaneously even if the location is initially unknown. This allows to use the AAA for the signal receiving from a moving source in the presence of the interfering signals.

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