Reverberation chamber with variable received signal amplitude distribution

2002 ◽  
Vol 35 (5) ◽  
pp. 376-377 ◽  
Author(s):  
Paul Hallbjörner
Keyword(s):  
Signal Amplitude ◽  
Amplitude Distribution ◽  
Reverberation Chamber

scholarly journals Shaping Code in Conjunction with DCT for PAPR Reduction in Multicarrier System

2021 ◽  
Author(s):  
Younes Aimer ◽  
Boubakar Seddik Bouazza ◽  
Smail Bachir ◽  
Claude Duvanaud
Keyword(s):  
Power Amplifier ◽  
Power Efficiency ◽  
Average Power ◽  
Nonlinear Behavior ◽  
Signal Amplitude ◽  
Amplitude Distribution ◽  
Papr Reduction ◽  
Radio Link ◽  
Error Vector Magnitude ◽  
Multicarrier System

Abstract Nonlinear behavior and power efficiency of the Power Amplifier (PA) contradictorily depend on the input signal amplitude distribution. The transmitted signal in multi-carrier modulation exhibits high Peak-to-Average Power Ratio (PAPR) and large bandwidths, leading to the degradation of the radio link and additional generation out-of-band interferences, which degrade the quality of the transmission. Practical solutions exist, like a power back-off, but with unacceptable efficiency performances of the transmitter. This paper deals with efficiency and linearity improvement using a new PAPR reduction method based on the combination of Discrete Cosine Transform (DCT) and shaping technique. The main principle is to determine an optimal coding scheme according to a trade-off between coding complexity and performance benefits in the presence of PA non-linearities. Simulation and experimental results in the context of OFDM signal and using a 20W - 3.7GHz Radio-Frequency Power Amplifier (RF-PA) show an improvement on PAPR reduction of about 3.25dB. Also, the communication criteria like BER (Bit Error Rate) and EVM (Error Vector Magnitude) are improved by about one decade and a half and 8%, respectively.

Acoustic Emission From Simple Upsetting of Solid Cylinders

1982 ◽  
Vol 104 (2) ◽  
pp. 145-152 ◽  
Author(s):  
David A. Dornfeld ◽  
Edward Diei
Keyword(s):  
Plastic Deformation ◽  
Acoustic Emission ◽  
Count Rate ◽  
Effective Strain ◽  
Signal Amplitude ◽  
Amplitude Distribution ◽  
Degree Of Deformation ◽  
Surface Cracking ◽  
Cumulative Count ◽  
Ae Signals

Acoustic emission (AE) generated during simple upsetting (forging) of solid cylinders contains information that could potentially be used to separate the upsetting process into a range of zones of plastic deformation and a zone of both plastic deformation and cracking. This investigation monitored the AE signals during the upsetting of cylindrical specimens of 7075-T6 Aluminum from the start of plastic deformation through eventual cracking. The count rate (N˙) and cumulative count (N) as a function of effective strain were determined. The count rate data are characterized by three distinct regions, an initial peak during yielding of the material, a period of gradual increase during the progression of plastic deformation and the accompanying changes in specimen geometry, and finally a region of rapid increase in N˙ as cracking begins. The cumulative count and rms data follow similar patterns. An analysis of the amplitude distribution of the cumulative count data over a range of strain was made, and in the region of higher amplitude emissions, changes in the distribution of up to two orders of magnitude are observed for data obtained during plastic deformation and surface cracking compared to that from the region of pure deformation only. If plotted as log count (N) versus signal amplitude, the resulting data can be fit with a line using least squares methods yielding a power law relationship sensitive to the degree of deformation.

scholarly journals Amplitude Distribution of Partial Discharge Signals on Tunnel-Installed High-Voltage Cables

2019 ◽  
Vol 9 (21) ◽  
pp. 4595 ◽  
Author(s):  
Yong Qian ◽  
Xiaoxin Chen ◽  
Yiming Zang ◽  
Hui Wang ◽  
Gehao Sheng ◽  
...  
Keyword(s):  
High Voltage ◽  
Partial Discharge ◽  
Current Method ◽  
Signal Amplitude ◽  
Amplitude Distribution ◽  
Xlpe Cable ◽  
Bonding Wires ◽  
Cable Laying ◽  
Cable Systems ◽  
The Cross

For 110 kV and above tunnel-installed high-voltage (HV) cross-linked poly-ethylene (XLPE) cable systems, it is a normal procedure to adopt a cross-bonding scheme. The high-frequency current method is frequently used in the cross-bonded cable systems for on-site or online partial discharge (PD) detection by monitoring the signals on the cross-bonding wires. To further study the amplitude distribution characteristics of the PD signals, a parametric characteristic admittance model of a three-phase cable system in a tunnel is established based on Tylavsky’s formulas. The model is used to calculate the amplitude distribution formula of the PD pulse current on the cross-bonding wires. In addition, the influence of cable laying and tunnel environment on the amplitude distribution is also studied. Finally, the correctness of the model and the conclusion are verified by simulation experiments and on-site tests. The results show that the signal amplitude distribution is determined by the ratio of the characteristic admittances. As the distance between the cables and the distance from the inner wall of the tunnel increase, the amplitude difference gradually decreases.

scholarly journals Shaping Code in Conjunction with DCT for PAPR Reduction in Multicarrier System

2020 ◽  
Author(s):  
Younes Aimer ◽  
Boubakar Seddik Bouazza ◽  
Smail Bachir ◽  
Claude Duvanaud
Keyword(s):  
Power Efficiency ◽  
Average Power ◽  
Nonlinear Behavior ◽  
Signal Amplitude ◽  
Amplitude Distribution ◽  
Papr Reduction ◽  
Radio Link ◽  
Error Vector Magnitude ◽  
Multicarrier System ◽  
Cost Efficient

Abstract Nonlinear behavior and power efficiency of the power amplifier (PA) depend in a contradictory way on the input signal amplitude distribution. The transmitted signal in multi-carrier modulation exhibits high peak-to-average power ratio (PAPR) and large bandwidths, leading to the degradation of the radio link and the generation of additional out-of-band interferences, which degrade the quality of the transmission. Practical solutions exist, like a power back-off, but with unacceptable cost-efficient conditions at the transmitter. This paper deals with efficiency improvement using a new PAPR reduction method based on the combination of Discrete Cosine Transform (DCT) and shaping technique. The main principle is to determine an optimal coding scheme according to a trade-off between efficiency performances and coding complexity. Simulation and experimental results in the context of OFDM Signal and in presence of a 20 W - 3,7 GHz RF-PA show an improvement on PAPR reduction of about 3,25 dB. Also, the communication criteria like BER (Bit Error Rate) and EVM (Error Vector Magnitude) are improved of about 2 decades and 8 %, respectively.

scholarly journals Shaping code in conjunction with DCT for PAPR reduction in multicarrier system

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Younes Aimer ◽  
Boubakar Seddik Bouazza ◽  
Smail Bachir ◽  
Claude Duvanaud
Keyword(s):  
Power Amplifier ◽  
Power Efficiency ◽  
Average Power ◽  
Nonlinear Behavior ◽  
Signal Amplitude ◽  
Amplitude Distribution ◽  
Papr Reduction ◽  
Radio Link ◽  
Error Vector Magnitude ◽  
Multicarrier System

AbstractNonlinear behavior and power efficiency of the Power Amplifier (PA) contradictorily depend on the input signal amplitude distribution. The transmitted signal in multi-carrier modulation exhibits high Peak-to-Average Power Ratio (PAPR) and large bandwidths, leading to the degradation of the radio link and additional generation out-of-band interferences, which degrade the quality of the transmission. Practical solutions exist, like a power back-off, but with unacceptable efficiency performances of the transmitter. This paper deals with efficiency and linearity improvement using a new PAPR reduction method based on the combination of Discrete Cosine Transform and shaping technique. The main principle is to determine an optimal coding scheme according to a trade-off between coding complexity and performance benefits in the presence of PA nonlinearities. Simulation and experimental results in the context of OFDM signal and using a 20 W–3.7 GHz Radio-Frequency Power Amplifier show an improvement on PAPR reduction of about 3.25 dB. Also, the communication criteria like Bit Error Rate and Error Vector Magnitude are improved by about one decade and a half and $$8\%$$ 8 % , respectively.

scholarly journals Detection of Wavy Sea Surface Oil-Derivative Contamination with Forward Specular High-Frequency Scattering

2020 ◽  
Vol 27 (1) ◽  
pp. 173-179
Author(s):  
Stanisław Pogorzelski ◽  
Paweł Rochowski ◽  
Maciej Grzegorczyk ◽  
Bogumił B. J. Linde ◽  
Ewa Skrodzka ◽  
...  
Keyword(s):  
Layer Thickness ◽  
Low Frequency ◽  
Signal Amplitude ◽  
Amplitude Distribution ◽  
Sea Surface ◽  
Spectral Energy ◽  
Surface Films ◽  
Distribution Parameters ◽  
The One ◽  
The Baltic

AbstractA spectrum of low-frequency (20–30 Hz) amplitude fluctuations of the ultrasonic (10 MHz) signal specularly scattered from water surfaces covered with monomolecular and thicker crude oil origin films of well-defined, oceanographically relevant viscoelastic properties was examined in laboratory and at-sea conditions. The relationship between the surface water wave (30 Hz) damping coefficient and the oil layer thickness was established, and compared to the one predicted by the classical Stokes theory. The depression of the spectral energy density of wind-driven waves by surface films was inferred from the ratio of acoustic signal fluctuations spectra with/without films, and compared to that resulting from the Marangoni damping theory applicable to monolayers of particular surface viscoelasticity. The agreement between the theory and experimental data was satisfactory. As shown in at-sea experiments performed with a free-floating, buoy-like acoustic system, and an artificial oil slick spread over the Baltic Sea surface, the film’s rheological surface properties can be recovered from acoustic surface probing, as well as oil spill edge detection. Simultaneous statistical analyses of the scattered signal amplitude distribution parameters turned out to be unequivocally related to the oil substance fraction weight, oil layer thickness, and the form of oil contamination.

scholarly journals A Novel Degradation Feature Extraction Technique Based on Improved Base-Scale Entropy

2021 ◽  
Vol 26 (1) ◽  
pp. 41-48
Author(s):  
Zhenyi Chen ◽  
Changzhuan Shao ◽  
Xiong Hu ◽  
Bing Wang ◽  
Daobing Zhang ◽  
...  
Keyword(s):  
Feature Extraction ◽  
Approximate Entropy ◽  
Signal Amplitude ◽  
Amplitude Distribution ◽  
Rolling Bearing ◽  
Performance Degradation ◽  
Entropy Method ◽  
Extraction Technique ◽  
Information Amount ◽  
Feature Extraction Technique

In order to track the performance degradation trend accurately, a novel degradation feature extraction technique is proposed based on improved base-scale entropy. A unified base scale is proposed and a new symbol standard is defined to overcome the disadvantages of the base-scale entropy method, so as to symbolize signal amplitude to characterize information amount under different degradation conditions quantitatively. A lifetime dataset of rolling bearing from the IMS Bearing Experiment Center is introduced. For instance, analysis and some entropy-based techniques including fuzzy entropy, approximate entropy and sample entropy are imported for comparison. The results show that the improved basic-scale technique is able to characterize information amount of the signal amplitude distribution, so that the characterizing performance degradation degree of bearing shows a proportional relationship. When comparing the entropy-based techniques, the improved base-scale entropy technique has a faster calculation speed and better algorithm stability.

scholarly journals On the Relationship between Field Amplitude Distribution, Its Maxima Distribution, and Field Uniformity inside a Mode-Stirred Reverberation Chamber

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
M. A. García-Fernández ◽  
C. Decroze ◽  
D. Carsenat ◽  
N. Arsalane ◽  
G. Andrieu
Keyword(s):  
Communication Systems ◽  
Amplitude Distribution ◽  
Calibration Method ◽  
Field Amplitude ◽  
Wireless Communication Systems ◽  
Reverberation Chamber ◽  
Working Volume ◽  
Field Uniformity ◽  
The Relationship ◽  
Statistical Laws

A mode-stirred reverberation chamber (RC) is nowadays a commonly accepted performing tool for over-the-air (OTA) communication system evaluation, and their standardization is underway. Before performing active measurements of wireless communication systems using an RC, field uniformity inside the RC working volume has to be measured following the calibration method described in IEC standards 61000-4-21 and 61000-4-3, which requires 24 calibration measurements of field amplitude. In this contribution, we present the statistical laws that describe electromagnetic field maxima distribution, and based on them, a novel expression that could be useful to obtain a lower limit for the number of stirrer positions required at least to obtain a specific value for the normalized dispersion used to evaluate field uniformity with the IEC calibration method, being therefore of particular interest for OTA measurements.

Sign in / Sign up

Export Citation Format

Share Document