scholarly journals A Tensor-based Localization Framework Exploiting Phase Interferometry Measurements

2020 ◽  
Author(s):  
Farzam Hejazi ◽  
Mohsen Joneidi ◽  
Nazanin Rahnavard
Keyword(s):  
Lower Bound ◽  
Sensor Network ◽  
Phase Difference ◽  
Antenna Arrays ◽  
Linear Array ◽  
Tensor Decomposition ◽  
Array Antennas ◽  
Cross Correlations ◽  
Simulation Results ◽  
Phase Differences

In this paper, a framework for localization of multiple co-channel transmitters using phase difference measurements between two antennas mounted on sensors of a sensor network is proposed. To pursue localization, we equip each sensor with two antennas and we use temporal cross-correlations between the received signals of the {two} antennas to extract the phase differences between each antenna pairs, named as phase interferometry measurements (PIMs), provoked by each {transmitters} using tensor decomposition. We calculate Cramer-Rao lower bound of error of localization using PIMs. Our simulation results show that highly accurate estimations can be achieved using PIMs. We also compare the accuracy of our proposed technique with a sensor network that exploits highly directional linear array antennas and show that {our} proposed technique can perform similar to a network that employs very large antenna arrays.

scholarly journals A Tensor-based Localization Framework Exploiting Phase Interferometry Measurements

2020 ◽  
Author(s):  
Farzam Hejazi ◽  
Mohsen Joneidi ◽  
Nazanin Rahnavard
Keyword(s):  
Lower Bound ◽  
Sensor Network ◽  
Phase Difference ◽  
Antenna Arrays ◽  
Linear Array ◽  
Tensor Decomposition ◽  
Array Antennas ◽  
Cross Correlations ◽  
Simulation Results ◽  
Phase Differences

In this paper, a framework for localization of multiple co-channel transmitters using phase difference measurements between two antennas mounted on sensors of a sensor network is proposed. To pursue localization, we equip each sensor with two antennas and we use temporal cross-correlations between the received signals of the {two} antennas to extract the phase differences between each antenna pairs, named as phase interferometry measurements (PIMs), provoked by each {transmitters} using tensor decomposition. We calculate Cramer-Rao lower bound of error of localization using PIMs. Our simulation results show that highly accurate estimations can be achieved using PIMs. We also compare the accuracy of our proposed technique with a sensor network that exploits highly directional linear array antennas and show that {our} proposed technique can perform similar to a network that employs very large antenna arrays.

scholarly journals Principles of adaptive element spacing in linear array antennas

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tanzeela Mitha ◽  
Maria Pour
Keyword(s):  
Antenna Arrays ◽  
Communication Systems ◽  
Linear Array ◽  
Main Idea ◽  
Phase Center ◽  
Array Configuration ◽  
Array Antennas ◽  
Center Location ◽  
Novel Approach ◽  
Array Performance

AbstractA novel approach to linear array antennas with adaptive inter-element spacing is presented for the first time. The main idea is based upon electronically displacing the phase center location of the antenna elements, which determine their relative coordinates in the array configuration. This is realized by employing dual-mode microstrip patch antennas as a constitutive element, whose phase center location can be displaced from its physical center by simultaneously exciting two modes. The direction and the amount of displacement is controlled by the amplitude and phase of the modes at the element level. This in turn facilitates reconfiguring the inter-element spacing at the array level. For instance, a uniformly-spaced array could be electronically transformed into a non-uniform one without any mechanical means. The proposed idea is demonstrated in two- and three-element linear antenna arrays. The technique has the potential to control the radiation characteristics such as sidelobe levels, position of the nulls, and the beamwidths in small arrays, which are useful for adaptively controlling the array performance in emerging wireless communication systems and radars.

An Improved Clutter Suppression Method for Non-Sidelooking Uniform Linear Array Antennas Airborne Radar

2013 ◽  
Vol 681 ◽  
pp. 175-180
Author(s):  
Jun Zhao ◽  
Xu Hang
Keyword(s):  
Linear Array ◽  
Compensation Method ◽  
Airborne Radar ◽  
Clutter Suppression ◽  
Uniform Linear Array ◽  
Array Antennas ◽  
Compensation Methods ◽  
Suppression Method ◽  
Simulation Results ◽  
Independent Identically Distributed

The clutter distribution of airborne radar with non-sidelooking uniform linear array antennas varies with ranges and samples in different range gates are not independent identically distributed vectors, so that the statistical STAP methods degrade greatly. In this paper, an improved clutter range dependence compensation method for airborne radar with uniform linear array is proposed. This method involves in a preprocessing with ADC method to align the mainlobe of clutter spectrum in different range gates and subsequently clutter suppression in other azimuths with EDBU technology. Simulation results show the proposed method can reduce the clutter spectrum dispersion significantly and outperform conventional local compensation methods.

An Elevation Cosine Derivation Based Updating STAP Method for Non-Sidelooking Uniform Linear Array

2014 ◽  
Vol 556-562 ◽  
pp. 3662-3665
Author(s):  
Xing Hui Chen ◽  
Shi Qiao Gao
Keyword(s):  
Linear Array ◽  
Airborne Radar ◽  
Uniform Linear Array ◽  
Array Antennas ◽  
Compensation Methods ◽  
Simulation Results ◽  
Independent Identically Distributed

The clutter distribution of airborne radar with non-sidelooking uniform linear array antennas varies with ranges and interference in different range gates are not independent identically distributed vectors, so the performance of statistical STAP methods degrade heavily. In this paper, the range dependency problem is studied and a clutter nonstationarity reducing method is proposed. This method involves in the pre-processing of elevation cosine based vector extending and subsequently statistical STAP technique. Simulation results show the proposed method can reduce the clutter dispersion significantly and outperform conventional compensation methods.

scholarly journals Flexible Phase Difference of 4 × 4 Butler Matrix without Phase-Shifters and Crossovers

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Ke Han ◽  
Wuyu Li ◽  
Yibin Liu
Keyword(s):  
Closed Form ◽  
Phase Difference ◽  
Return Loss ◽  
Phase Mismatch ◽  
Phase Shifters ◽  
Butler Matrix ◽  
Arbitrary Phase ◽  
Form Design ◽  
Simulation Results ◽  
Phase Differences

This paper proposes a new Butler matrix topology. The proposed Butler matrix consists of only four couplers without phase shifters and crossovers. The output phase difference is relatively flexible. Compared with the phase differences (±45° and ±135°) generated by the conventional Butler matrix, the proposed design can generate different sets of phase differences, which can be realized from −180° to 180°. The proposed new Butler matrix replaces the traditional 90° coupler with arbitrary phase-difference couplers. In this paper, closed-form design equations are derived and presented. A 4 × 4 Butler matrix with output phase differences of −30°, +150°, −120°, and +60° is designed according to equations. The 4 × 4 Butler is meant to operate at 2 GHz. The simulation results show that the amplitude unbalance is less than 0.1 dB, the phase mismatch is within 1°, the return loss is higher than 29 dB, and the isolation is higher than 32 dB.

Transfers with a rendezvous lasting no more than one orbit between close near-circular coplanar orbits

2020 ◽  
pp. 82-93
Author(s):  
Aleksandr F. BRAGAZIN ◽  
Alexey V. USKOV
Keyword(s):  
Key Words ◽  
Relative Velocity ◽  
Free Parameter ◽  
Space Station ◽  
Characteristic Velocity ◽  
Orbital Station ◽  
Orbit Transfer ◽  
Simulation Results ◽  
The Moment ◽  
Phase Differences

Consideration has been given to orbit transfers involving spacecraft rendezvous which belong to a class of coplanar non-intersecting near-circular orbits of a spacecraft and a space station. The duration of the transfer is assumed to be limited by one orbit. The feasibility of a rendezvous using an optimal two-burn orbit-to-orbit transfer is studied. To determine a single free parameter of the transfer, i.e. the time of its start, ensuring a rendezvous at a given time or at a given velocity at the end of transfer, appropriate equations have been obtained To implement in the guidance algorithms optimal three-burn correction programs are proposed to achieve a rendezvous at a given time with a specified relative velocity at the moment of spacecraft contact. A range of phase differences at the start of maneuvering is determined, within which the characteristic velocity of the rendezvous is equal to the minimum characteristic velocity of the orbit-to-orbit transfer. The paper presents simulation results for “quick" rendezvous profiles that use the proposed programs. Key words: spacecraft, orbital station, “quick” rendezvous, orbit transfer, rendezvous program.

scholarly journals Full snapshot reconstruction in hybrid architecture antenna arrays

2020 ◽  
Vol 2020 (1) ◽  
Author(s):  
Maria Trigka ◽  
Christos Mavrokefalidis ◽  
Kostas Berberidis
Keyword(s):  
Antenna Array ◽  
Antenna Arrays ◽  
Communication Systems ◽  
Linear Array ◽  
Research Work ◽  
Hybrid Architecture ◽  
Angle Of Arrival ◽  
Music Algorithm ◽  
Array Structures ◽  
Signal Sources

AbstractIn the context of this research work, we study the so-called problem of full snapshot reconstruction in hybrid antenna array structures that are utilized in mmWave communication systems. It enables the recovery of the snapshots that would have been obtained if a conventional (non-hybrid) uniform linear antenna array was employed. The problem is considered at the receiver side where the hybrid architecture exploits in a novel way the antenna elements of a uniform linear array. To this end, the recommended scheme is properly designed so as to be applicable to overlapping and non-overlapping architectures. Moreover, the full snapshot recoverability is addressed for two cases, namely for time-varying and constant signal sources. Simulation results are also presented to illustrate the consistency between the theoretically predicted behaviors and the simulated results, and the performance of the proposed scheme in terms angle-of-arrival estimation, when compared to the conventional MUSIC algorithm and a recently proposed hybrid version of MUSIC (H-MUSIC).

scholarly journals Combined Reduced Phase Dual-Directional Illumination Digital Holography and Speckle Displacements for Shape Measurement

2019 ◽  
Vol 2019 ◽  
pp. 1-6
Author(s):  
Davood Khodadad
Keyword(s):  
Phase Difference ◽  
Digital Holography ◽  
Relative Phase ◽  
Groove Depth ◽  
Phase Unwrapping ◽  
Shape Measurement ◽  
Phase Ambiguity ◽  
Holographic Method ◽  
Height Range ◽  
Phase Differences

We present a digital holographic method to increase height range measurement with a reduced phase ambiguity using a dual-directional illumination. Small changes in the angle of incident illumination introduce phase differences between the recorded complex fields. We decrease relative phase difference between the recorded complex fields 279 and 139 times by changing the angle of incident 0.5° and 1°, respectively. A two cent Euro coin edge groove is used to measure the shape. The groove depth is measured as ≈300  μm. Further, numerical refocusing and analysis of speckle displacements in two different planes are used to measure the depth without a use of phase unwrapping process.

scholarly journals Current-Mode Third-Order Quadrature Oscillator Using CDTAs

2009 ◽  
Vol 2009 ◽  
pp. 1-5 ◽  
Author(s):  
Jiun-Wei Horng
Keyword(s):  
Theoretical Analysis ◽  
Phase Difference ◽  
Oscillation Frequency ◽  
Current Mode ◽  
Third Order ◽  
Quadrature Oscillator ◽  
Oscillation Condition ◽  
Transconductance Amplifiers ◽  
Simulation Results ◽  
A Current

This paper describes a current-mode third-order quadrature oscillator based on current differencing transconductance amplifiers (CDTAs). Outputs of two current-mode sinusoids with90°phase difference are available in the quadrature oscillator circuit. The oscillation condition and oscillation frequency are orthogonal controllable. The proposed circuit employs only grounded capacitors and is ideal for integration. Simulation results are included to confirm the theoretical analysis.

PERMUTATION ROUTING AND SORTING ON THE RECONFIGURABLE MESH

1998 ◽  
Vol 09 (02) ◽  
pp. 199-211
Author(s):  
SANGUTHEVAR RAJASEKARAN ◽  
THEODORE MCKENDALL
Keyword(s):  
Lower Bound ◽  
Randomized Algorithms ◽  
Linear Array ◽  
Order Term ◽  
Routing Algorithm ◽  
Sorting Algorithm ◽  
Routing Problem ◽  
Reconfigurable Mesh ◽  
Permutation Routing ◽  
Time Bounds

In this paper we demonstrate the power of reconfiguration by presenting efficient randomized algorithms for both packet routing and sorting on a reconfigurable mesh connected computer. The run times of these algorithms are better than the best achievable time bounds on a conventional mesh. Many variations of the reconfigurable mesh can be found in the literature. We define yet another variation which we call as Mr. We also make use of the standard PARBUS model. We show that permutation routing problem can be solved on a linear array Mr of size n in [Formula: see text] steps, whereas n-1 is the best possible run time without reconfiguration. A trivial lower bound for routing on Mr will be [Formula: see text]. On the PARBUS linear array, n is a lower bound and hence any standard n-step routing algorithm will be optimal. We also show that permutation routing on an n×n reconfigurable mesh Mr can be done in time n+o(n) using a randomized algorithm or in time 1.25n+o(n) deterministically. In contrast, 2n-2 is the diameter of a conventional mesh and hence routing and sorting will need at least 2n-2 steps on a conventional mesh. A lower bound of [Formula: see text] is in effect for routing on the 2D mesh Mr as well. On the other hand, n is a lower bound for routing on the PARBUS and our algorithms have the same time bounds on the PARBUS as well. Thus our randomized routing algorithm is optimal upto a lower order term. In addition we show that the problem of sorting can be solved in randomized time n+o(n) on Mr as well as on PARBUS. Clearly, this sorting algorithm will be optimal on the PARBUS model. The time bounds of our randomized algorithms hold with high probability.

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