An Accurate Operation of Wideband Multi-Port Reflectometer with New Calibration Method implementing Least Mean Square for Microwave Imaging Application

2015 ◽  
Vol 73 (3) ◽  
Author(s):  
Rashidah Che Yob ◽  
Norhudah Seman
Keyword(s):  
Reflection Coefficient ◽  
Calibration Method ◽  
Weight Coefficient ◽  
Calibration Procedure ◽  
Microwave Imaging ◽  
Mean Square ◽  
Least Mean Square ◽  
Calibration Standards ◽  
Imaging Application ◽  
Coefficient Measurement

The wideband operation of multi-port reflectometer may lead to inaccurate reflection coefficient measurement caused by the overlapped phase characteristics of the used calibration standards. Therefore, a calibration procedure implementing Least Mean Square (LMS) is proposed to offer accurate operation of wideband multi-port reflectometer from 1 to 6 GHz. Its well wideband performance is verified by attenuators of 3, 6 and 10 dB that assessed as the device under tests (DUTs). The proposed LMS contains a learning rate, m and updated weight coefficient, W(k+1) to eliminate error and achieve the corrected reflection coefficient of DUT.

Reflection Coefficient Measurement through the Implementation of Wideband Multi-Port Reflectometer with Error Correction for Microwave Imaging Application of Human Head

2013 ◽  
Vol 64 (3) ◽  
Author(s):  
Rashidah Che Yob ◽  
Norhudah Seman
Keyword(s):  
Reflection Coefficient ◽  
Error Correction ◽  
Human Head ◽  
Correction Method ◽  
Microwave Imaging ◽  
Passive Components ◽  
Power Dividers ◽  
Imaging Application ◽  
Coefficient Measurement ◽  
Design Systems

This article presents the reflection coefficient measurement by using a wideband multi-port reflectometer for microwave imaging application of human head. The configuration of the proposed wideband multi-port reflectometer is formed by passive components, which are four couplers and two power dividers operating from 1 to 6 GHz. The investigation is successfully done through simulation using the Agilent’s Advanced Design Systems (ADS) software and practical measurement in laboratory. An error correction method with three standards of match, open and short load is then applied to the constructed wideband multi-port reflectometer to remove its imperfect characteristics. The wideband characteristics of proposed reflectometer are analyzed and verified across the designated frequency band.  Its operation in reflection coefficient is tested with the chosen device under test (DUT).

scholarly journals A CALIBRATION METHOD OF TWO MOBILE LASER SCANNING SYSTEM UNITS FOR RAILWAY MEASUREMENT

2020 ◽  
Vol XLIII-B1-2020 ◽  
pp. 277-283
Author(s):  
K. Yamamoto ◽  
T. Chen ◽  
N. Yabuki
Keyword(s):  
Laser Scanning ◽  
Laser Scanner ◽  
Point Clouds ◽  
Calibration Method ◽  
Railway Vehicle ◽  
Scanning System ◽  
Mean Square ◽  
Least Mean Square ◽  
Linear Type ◽  
Laser Scanning System

Abstract. This paper proposes a methodology to calibrate the laser scanner of a Mobile Laser Scanning System (MLS) with the trajectory of the other MLS, both of which are installed directly above the top of both rails. Railway vehicle laser scanners systems of MLS are able to obtain 3D scanning map of the rail environment. In order to adapt the actual site condition of the maintenance works, we propose a calibration method with non-linear Least Mean Square calculation which use point clouds around poles along rails and sleepers of rails as cylindrical and planner constraints. The accuracy of 0.006 m between two laser point clouds can be achieved with this method. With the common planar and cylinder condition Leven-Marquardt method has been applied for this method. This method can execute without a good initial value for the extrinsic parameter and can shorten the processing time compared with the linear type of Least Mean Square method.

The method of determining the metrological performance of unit reference standards of reflection coefficient in waveguides at millimeter waves

2020 ◽  
pp. 59-63
Author(s):  
A.S. Bondarenko ◽  
A.S. Borovkov ◽  
I.M. Malay ◽  
V.A. Semyonov
Keyword(s):  
Reflection Coefficient ◽  
Millimeter Waves ◽  
Primary Standard ◽  
Reference Standards ◽  
Measurement Scale ◽  
Current State ◽  
Coefficient Measurement ◽  
Mathematical Equations ◽  
Electrodynamic Modeling ◽  
Metrological Performance

The analysis of the current state of the reflection coefficient measurements in waveguides at millimeter waves is carried out. An approach for solving the problem of reproducing the reflection coefficient measurement scale is proposed. Mathematical equations, which are the basis of the reflection coefficient measurement equation are obtained. The method of determining the metrological performance of reflection coefficient unit’s reference standards is developed. The results of electrodynamic modeling and analytical calculations by the developed method are compared. It is shown that this method can be used for reproducing the reflection coefficient unit in the development of the State primary standard.

Improved least mean square adaptive filter algorithm

2013 ◽  
Vol 32 (7) ◽  
pp. 2078-2081
Author(s):  
Cheng-xi WANG ◽  
Yi-an LIU ◽  
Qiang ZHANG
Keyword(s):  
Adaptive Filter ◽  
Mean Square ◽  
Least Mean Square

scholarly journals An Effective Adaptive Combination Strategy for Distributed Learning Network

2021 ◽  
Vol 11 (12) ◽  
pp. 5723
Author(s):  
Chundong Xu ◽  
Qinglin Li ◽  
Dongwen Ying
Keyword(s):  
Minimum Variance ◽  
Iteration Scheme ◽  
Estimation Problem ◽  
Lms Algorithm ◽  
Unbiased Estimation ◽  
Mean Square ◽  
Least Mean Square ◽  
Combination Strategy ◽  
Adaptive Combination ◽  
Diffusion Networks

In this paper, we develop a modified adaptive combination strategy for the distributed estimation problem over diffusion networks. We still consider the online adaptive combiners estimation problem from the perspective of minimum variance unbiased estimation. In contrast with the classic adaptive combination strategy which exploits orthogonal projection technology, we formulate a non-constrained mean-square deviation (MSD) cost function by introducing Lagrange multipliers. Based on the Karush–Kuhn–Tucker (KKT) conditions, we derive the fixed-point iteration scheme of adaptive combiners. Illustrative simulations validate the improved transient and steady-state performance of the diffusion least-mean-square LMS algorithm incorporated with the proposed adaptive combination strategy.

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