scholarly journals A Novel Technique for Achieving the Approximated ISI at the Receiver for a 16QAM Signal Sent via a FIR Channel Based Only on the Received Information and Statistical Techniques

Entropy ◽  
2020 ◽  
Vol 22 (6) ◽  
pp. 708
Author(s):  
Hadar Goldberg ◽  
Monika Pinchas
Keyword(s):  
Edgeworth Expansion ◽  
Finite Impulse Response ◽  
Signal To Noise Ratio ◽  
Signal Transmission ◽  
Entropy Density ◽  
Approximation Technique ◽  
Novel Technique ◽  
Input Multiple Output ◽  
Source Signal ◽  
Single Input

A single-input-multiple-output (SIMO) channel is obtained from the use of an array of antennas in the receiver where the same information is transmitted through different sub-channels, and all received sequences are distinctly distorted versions of the same message. The inter-symbol-interference (ISI) level from each sub-channel is presently unknown to the receiver. Thus, even when one or more sub-channels cause heavy ISI, all the information from all the sub-channels was still considered in the receiver. Obviously, if we know the approximated ISI of each sub-channel, we will use in the receiver only those sub-channels with the lowest ISI level to get improved system performance. In this paper, we present a systematic way for obtaining the approximated ISI from each sub-channel modelled as a finite-impulse-response (FIR) channel with real-valued coefficients for a 16QAM (16 quadrature amplitude modulation) source signal transmission. The approximated ISI is based on the maximum entropy density approximation technique, on the Edgeworth expansion up to order six, on the Laplace integral method and on the generalized Gaussian distribution (GGD). Although the approximated ISI was derived for the noiseless case, it was successfully tested for signal to noise ratio (SNR) down to 20 dB.

scholarly journals Improved Approach for the Maximum Entropy Deconvolution Problem

Entropy ◽  
2021 ◽  
Vol 23 (5) ◽  
pp. 547
Author(s):  
Shay Shlisel ◽  
Monika Pinchas
Keyword(s):  
Maximum Entropy ◽  
Density Function ◽  
Edgeworth Expansion ◽  
Entropy Density ◽  
Point Of View ◽  
Convergence Time ◽  
Approximation Technique ◽  
Gaussian Density ◽  
Deconvolution Problem ◽  
Equalization Method

The probability density function (pdf) valid for the Gaussian case is often applied for describing the convolutional noise pdf in the blind adaptive deconvolution problem, although it is known that it can be applied only at the latter stages of the deconvolution process, where the convolutional noise pdf tends to be approximately Gaussian. Recently, the deconvolutional noise pdf was approximated with the Edgeworth Expansion and with the Maximum Entropy density function for the 16 Quadrature Amplitude Modulation (QAM) input but no equalization performance improvement was seen for the hard channel case with the equalization algorithm based on the Maximum Entropy density function approach for the convolutional noise pdf compared with the original Maximum Entropy algorithm, while for the Edgeworth Expansion approximation technique, additional predefined parameters were needed in the algorithm. In this paper, the Generalized Gaussian density (GGD) function and the Edgeworth Expansion are applied for approximating the convolutional noise pdf for the 16 QAM input case, with no need for additional predefined parameters in the obtained equalization method. Simulation results indicate that improved equalization performance is obtained from the convergence time point of view of approximately 15,000 symbols for the hard channel case with our new proposed equalization method based on the new model for the convolutional noise pdf compared to the original Maximum Entropy algorithm. By convergence time, we mean the number of symbols required to reach a residual inter-symbol-interference (ISI) for which reliable decisions can be made on the equalized output sequence.

scholarly journals SCaLAr – A surrounding spherical cap loudspeaker array for flexible generation and evaluation of virtual acoustic environments

Acta Acustica ◽  
2020 ◽  
Vol 4 (5) ◽  
pp. 19
Author(s):  
Florian Pausch ◽  
Gottfried Behler ◽  
Janina Fels
Keyword(s):  
Performance Metrics ◽  
Transfer Functions ◽  
Finite Impulse Response ◽  
Signal To Noise Ratio ◽  
Signal Transmission ◽  
Sound Field ◽  
Low Noise ◽  
High Signal ◽  
Spherical Cap ◽  
Channel Separation

Introduction: Surrounding spherical loudspeaker arrays facilitate the application of various spatial audio reproduction methods and can be used for a broad range of acoustic measurements and perceptual evaluations. Methods: Installed in an anechoic chamber, the design and implementation of such an array of 68 coaxial loudspeakers, sampling a spherical cap with a radius of 1.35 m on an equal-area grid, is presented. A network-based audio backbone enables low-latency signal transmission with low-noise amplifiers providing a high signal-to-noise ratio. To address batch-to-batch variations, the loudspeaker transfer functions were equalised by individually designed 512-taps finite impulse response filters. Time delays and corresponding level adjustments further helped to minimise radial mounting imperfections. Results: The equalised loudspeaker transfer functions measured under ideal conditions and when mounted, their directivity patterns, and in-situ background noise levels satisfy key criteria towards applicability. Advantages and shortcomings of the selected decoders for panning-based techniques, as well as the influence of loudspeaker positioning errors, are analysed in terms of simulated performance metrics. An evaluation of the achievable channel separation allows deriving recommendations of feasible subset layouts for loudspeaker-based binaural reproduction. Conclusion: The combination of electroacoustic properties, simulated sound field synthesis performance and measured channel separation classifies the system as suitable for its target applications.

scholarly journals Edgeworth Expansion Based Model for the Convolutional Noise pdf

2014 ◽  
Vol 2014 ◽  
pp. 1-19
Author(s):  
Yonatan Rivlin ◽  
Monika Pinchas
Keyword(s):  
Probability Density Function ◽  
Lagrange Multipliers ◽  
Conditional Expectation ◽  
Edgeworth Expansion ◽  
Entropy Density ◽  
Approximation Technique ◽  
Density Approximation ◽  
Mean Square ◽  
Simulation Results ◽  
Probability Density Function Pdf

Recently, the Edgeworth expansion up to order 4 was used to represent the convolutional noise probability density function (pdf) in the conditional expectation calculations where the source pdf was modeled with the maximum entropy density approximation technique. However, the applied Lagrange multipliers were not the appropriate ones for the chosen model for the convolutional noise pdf. In this paper we use the Edgeworth expansion up to order 4 and up to order 6 to model the convolutional noise pdf. We derive the appropriate Lagrange multipliers, thus obtaining new closed-form approximated expressions for the conditional expectation and mean square error (MSE) as a byproduct. Simulation results indicate hardly any equalization improvement with Edgeworth expansion up to order 4 when using optimal Lagrange multipliers over a nonoptimal set. In addition, there is no justification for using the Edgeworth expansion up to order 6 over the Edgeworth expansion up to order 4 for the 16QAM and easy channel case. However, Edgeworth expansion up to order 6 leads to improved equalization performance compared to the Edgeworth expansion up to order 4 for the 16QAM and hard channel case as well as for the case where the 64QAM is sent via an easy channel.

scholarly journals Free Space Optic Receiver with Strongly Overlapped Photodetectors’ Field of View

2019 ◽  
Vol 9 (2) ◽  
pp. 343 ◽  
Author(s):  
Karel Witas ◽  
Jan Nedoma
Keyword(s):  
Free Space ◽  
Additive Noise ◽  
Noise Suppression ◽  
Signal To Noise Ratio ◽  
Optical Channel ◽  
Electrical Signals ◽  
Free Space Optic ◽  
Input Multiple Output ◽  
Single Input ◽  
Areas Of Interest

In this study, we designed a mobile free space optic receiver that uses several photodetectors to provide omnidirectional receiving capability. Assuming only one transmitter, it is a receiver which builds a single input multiple output optical channel. The photodetectors are fixed to truncated pyramid walls. Electrical signals from the photodetectors are processed using an equal gain combining technique. This architecture allows simple circuits and enables additive noise suppression. The minimum angle between the pyramid base and the direction of falling rays was calculated to determine the threshold for additive noise suppression. Two areas of interest presented themselves: the processing of very weak electrical signals often drowned in noise, and optimization of the number of photodetectors whose fields of view overlapped strongly. We outline the design of the optical receiver circuitry and provide some practical hints concerning its assembly. The receiver was evaluated using bit error rate measurements and comparing signal-to-noise ratio parameters for various photodetector numbers. The measured data confirm the theoretical assumptions.

scholarly journals 16QAM Blind Equalization via Maximum Entropy Density Approximation Technique and Nonlinear Lagrange Multipliers

2014 ◽  
Vol 2014 ◽  
pp. 1-5
Author(s):  
R. Mauda ◽  
M. Pinchas
Keyword(s):  
Maximum Entropy ◽  
Lagrange Multipliers ◽  
Signal To Noise Ratio ◽  
Minimum Mean Square Error ◽  
Blind Equalization ◽  
Entropy Density ◽  
High Signal ◽  
Approximation Technique ◽  
Density Approximation ◽  
Simulation Results

Recently a new blind equalization method was proposed for the 16QAM constellation input inspired by the maximum entropy density approximation technique with improved equalization performance compared to the maximum entropy approach, Godard’s algorithm, and others. In addition, an approximated expression for the minimum mean square error (MSE) was obtained. The idea was to find those Lagrange multipliers that bring the approximated MSE to minimum. Since the derivation of the obtained MSE with respect to the Lagrange multipliers leads to a nonlinear equation for the Lagrange multipliers, the part in the MSE expression that caused the nonlinearity in the equation for the Lagrange multipliers was ignored. Thus, the obtained Lagrange multipliers were not those Lagrange multipliers that bring the approximated MSE to minimum. In this paper, we derive a new set of Lagrange multipliers based on the nonlinear expression for the Lagrange multipliers obtained from minimizing the approximated MSE with respect to the Lagrange multipliers. Simulation results indicate that for the high signal to noise ratio (SNR) case, a faster convergence rate is obtained for a channel causing a high initial intersymbol interference (ISI) while the same equalization performance is obtained for an easy channel (initial ISI low).

scholarly journals Imbalanced post- and extrasynaptic SHANK2A functions during development affect social behavior in SHANK2-mediated neuropsychiatric disorders

2021 ◽  
Author(s):  
Ahmed Eltokhi ◽  
Miguel A. Gonzalez-Lozano ◽  
Lars-Lennart Oettl ◽  
Andrey Rozov ◽  
Claudia Pitzer ◽  
...  
Keyword(s):  
Synaptic Plasticity ◽  
Social Interaction ◽  
Social Behavior ◽  
Ampa Receptors ◽  
Signal To Noise Ratio ◽  
Signal Transmission ◽  
Neuropsychiatric Disorders ◽  
Autism Spectrum ◽  
Strong Impact ◽  
Odor Processing

AbstractMutations in SHANK genes play an undisputed role in neuropsychiatric disorders. Until now, research has focused on the postsynaptic function of SHANKs, and prominent postsynaptic alterations in glutamatergic signal transmission have been reported in Shank KO mouse models. Recent studies have also suggested a possible presynaptic function of SHANK proteins, but these remain poorly defined. In this study, we examined how SHANK2 can mediate electrophysiological, molecular, and behavioral effects by conditionally overexpressing either wild-type SHANK2A or the extrasynaptic SHANK2A(R462X) variant. SHANK2A overexpression affected pre- and postsynaptic targets and revealed a reversible, development-dependent autism spectrum disorder-like behavior. SHANK2A also mediated redistribution of Ca2+-permeable AMPA receptors between apical and basal hippocampal CA1 dendrites, leading to impaired synaptic plasticity in the basal dendrites. Moreover, SHANK2A overexpression reduced social interaction and increased the excitatory noise in the olfactory cortex during odor processing. In contrast, overexpression of the extrasynaptic SHANK2A(R462X) variant did not impair hippocampal synaptic plasticity, but still altered the expression of presynaptic/axonal signaling proteins. We also observed an attention-deficit/hyperactivity-like behavior and improved social interaction along with enhanced signal-to-noise ratio in cortical odor processing. Our results suggest that the disruption of pre- and postsynaptic SHANK2 functions caused by SHANK2 mutations has a strong impact on social behavior. These findings indicate that pre- and postsynaptic SHANK2 actions cooperate for normal neuronal function, and that an imbalance between these functions may lead to different neuropsychiatric disorders.

scholarly journals Compensated Single Input Multiple Output Flyback Converter

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3009
Author(s):  
Mohammad Tahan ◽  
David O. Bamgboje ◽  
Tingshu Hu
Keyword(s):  
Transient Response ◽  
Current Mode ◽  
Voltage Regulation ◽  
Buck Converter ◽  
Output Channel ◽  
Flyback Converter ◽  
Input Multiple Output ◽  
Voltage Deviation ◽  
Single Input ◽  
The Cross

A new single-input multiple-output (SIMO) converter is proposed in this work by incorporating flyback and buck converters in a master–slave configuration. The objective of this work is to address the cross regulation problem, achieve tight voltage regulation, improve the circuit form factor and attain a fast transient response for a SIMO flyback converter. The flyback converter maintains the output channels within 10% of their rated voltages and the SIMO buck converter is placed in series with the flyback converter such that it compensates for the output voltage deviation. Moreover, a time multiplexing switching scheme decouples output channel to eliminate the cross-regulation problem and remove the need for an additional winding transformer per each output channel. A type II compensator with a peak current mode controller was designed to achieve faster transient response which is critical for the proposed configuration. A thorough steady-state analysis was carried out on a triple output channel topology to obtain the design criteria and component values. MATLAB/Simscape modelling and simulation was used to validate the effectiveness of the proposed converter with the result yielding satisfactory transience even with load disturbance. Additionally, the result of the proposed converter is compared with previously published works.

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