Showing papers on "Bessel filter published in 2015"

The radius of convexity of normalized Bessel functions

Abstract: The radius of convexity of two normalized Bessel functions of the first kind are determined in the case when the order is between $-2$ and $-1.$ Our methods include the minimum principle for harmonic functions, the Hadamard factorization of some Dini functions, properties of the zeros of Dini functions via Lommel polynomials and some inequalities for complex and real numbers.

Demonstration of obstruction-free data-carrying N-fold Bessel modes multicasting from a single Gaussian mode

Abstract: By designing and optimizing complex phase pattern combining with axicon phase distribution, we report data multicasting from a single Gaussian mode to multiple Bessel modes using a single phase-only spatial light modulator. Under the obstructed path conditions, obstruction-free data-carrying N-fold Bessel modes multicasting is demonstrated in the experiment. We also experimentally study N-fold multicasting of a 20 Gbit/s quadrature phase-shift keying signal from a single Gaussian mode to multiple Bessel modes and measure the link performance. All the multicasted Bessel modes show relatively low crosstalk from their neighboring modes and achieve a bit-error rate of less than 1e-3.

Simulation of spectral filters used in hyperspectrometer by decomposition on vector Bessel modes

Abstract: The article is devoted to hyperspectrometer modeling based on the use of filters with linearly varying parameters. The point spread function depending on the spectral filter parameters is estimated. The results were obtained by decomposition of the incident radiation on vector Bessel modes. Numerical calculations show that significant deterioration in resolution occurs only in wide-angle optical systems

Method and apparatus for polar receiver with phase-amplitude alignment

Abstract: Systems and methods are provided for aligning amplitude and phase signals in a polar receiver. A receiver generates digital amplitude and phase signals representing the amplitude and phase of a modulated input signal. At least one of the digital signals is filtered using a fractional delay filter with a variable delay. The delay of the fractional delay filter is adjusted to align the amplitude and phase signals. In some embodiments, an error vector magnitude is determined by comparing in-phase and quadrature values of the signal with values corresponding to a constellation point, and the delay is adjusted based on the error vector magnitude. The fractional delay filter may be a finite impulse response filter with coefficients stored in a lookup table that correspond to different delays.

Analog filter group delay optimization using the Vortex Search algorithm

Abstract: In this study, a method based on the Vortex Search algorithm is proposed for analog filter group delay optimization. To measure the performance of the proposed method, a number of all-pass filters are first cascaded to a fifth order Chebyshev low-pass filter and then the optimum parameters of these all-pass filters are searched by using the Vortex Search algorithm. It is shown that, the group delay of the fifth order Chebyshev low-pass filter (2.593s) can be decreased down to 1.547s by using an optimum fourth order all-pass filter.

High rejection stacked bandpass filter optimized by group delay response

Abstract: A new configuration has been used for design of a wideband resonator-coupled bandpass filter with high rejection on both sides of the passband. Corrected group delay in combination with space mapping was used to calculate the initial dimensions, which provides a response that is sufficiently close to ideal response in order to be used in full-wave optimization. The design was fabricated and measurements are in excellent agreement with simulation.

Enhancing amplifiers/filters bandwidth by transfer function zeroes

Abstract: The paper describes an extension, at the approximation level, of shunt-peaking technique to increase the filter/amplifier bandwidth. The frequency dependent delay function of a Bessel filter and the modifications of this function consisting in deleting one or more frequency terms in the delay function numerator are considered as “squared-moduli” for a group of filters with transmission zeroes. Using a standard procedure of restoration one finds the transfer functions of this group. The number of filters in each group is defined by the order of the denominator. The paper provides the transfer functions parameters, frequency properties and the parameters of step-transient responses for the filter orders from two to six.

Conformable Fractional Bessel Equation and Bessel Functions

Abstract: In this work, we study the fractional power series solutions around regular singular point x=0 of conformable fractional Bessel differential equation and fractional Bessel functions. Then, we compare fractional solutions with ordinary solutions. In addition, we present certain property of fractional Bessel functions.

Comparative analysis of different filters in power line harmonic reduction

Abstract: Harmonics are injected in power system due to frequent switching and enormous usage of nonlinear loads. As a consequence, harmonic contamination in power system signals is a matter of major anxiety to electrical engineers. Fast Fourier Transform (FFT) has been adopted as an analytical tool for signal processing purpose. Single phase voltage signal is chosen from a three phase supply sent to motor. Here, power analyzer interfaced with laptop is an arrangement used as data acquisition unit. Obtained wave data of single phase voltage signal is processed through the FFT program in MATLAB. Then, simulation of the voltage signal procured from data acquisition unit is designed in SIMULINK. After that, the simulated signal is filtered by Butterworth filter, Bessel filter and Chebyshev 1 filter to diminish Total Harmonic Distortion (THD) from the output after filtration. THD value is scaled down from 9.08% to 5.40%.

Effect of noise on constellation diagram of 100 Gbps DP-QPSK systems under influence of different digital filters

Abstract: In this paper a DP-QPSK modulation scheme has been used at 100 Gbps for the propagation length 500 km. To mitigate effects of Chromatic dispersion (CD) and Polarization mode dispersion (PMD), constant modulus algorithm (CMA) is used, while to compensate carrier phase estimation (CPE) a modified Viterbi-Viterbi algorithm is used by means of DSP at the receiver end. The comparison of constellation diagrams has been performed by using different digital low pass filters such as Gaussian, Bessel, Butterworth and Chebyshev filters, for order 1st to 6th. It is observed that Bessel filter 6th order is superior, while Gaussian filter 4th order gives second best performance.

Application of Krein’s series to calculation of sums containing zeros of the Bessel functions

Abstract: The Bessel functions of the first kind, J v (z), with v > −1 are considered. On the basis of the general theorem on the representation of the reciprocal of an entire function in the form of Krein’s series, an expansion of the function 1/J v (z) in simple fractions is obtained. This result is used to calculate the sums of series of a certain structure that contain powers of positive zeros of Bessel functions.

An impedance surface-based method for designing wideband reflectarrays

Abstract: This paper presents the design of a reflectarray antenna from the point of view of an impedance surface instead of the traditional array-based methods. The proposed design methodology is based on the Bessel filter with its group delay bandwidth maximized. It will be shown that the reflectarrays can fully capitalize this bandwidth without using true-time-delay devices. A proof-of-concept 1-D reflectarray is designed using the developed methodology. Simulated far-field patterns are shown and compared to a parabolic reflector.

Improved characterization of differential multi-Ghz integrated amplifiers and filters

Abstract: Accurate characterization of fully differential on-chip filters and amplifiers whose bandwidths extend to several GHz is challenging. Measurement using a packaged chip is convenient, but not accurate due to nonidealities of the package. In this work, we demonstrate that the use of on-chip polarity reversal buffers greatly enhances accuracy by reducing the effect of finite package isolation and by mitigating errors due to common-mode to differential mode conversion. Further, the technique also allows differential characterization using only two-port single-ended measurements, without compromising much on accuracy. Measurements on an integrated 7 GHz Bessel filter made using this technique show good consistency up to 20 GHz whether the chip is probed or bench characterized after mounting in a QFN package.

Performance analysis of optical transmission system using fbg and bessel filters

Abstract: The optical fiber has found great application in long distance communications, as light the medium of information transfer attenuates very less compared to electric pulses in cables. However the major issues that limit efficiency are chromatic dispersion and non-linear effects. Fiber Bragg Grating (FBG) is widely used as a component to compensate dispersion on account of its low insertion loss. This paper provides a method of using a combination of FBG as a dispersion compensator and Bessel filter to improve the Q factor of the system and also reduce the noise figure. A 10 Gb/s NRZ pulse is launched into the fiber and the performance of the system is evaluated using Optisystem simulator. The Q factor of the system is then investigated with and without use of Bessel filter. The simulation is analysed with respect to input power, fiber length, and attenuation coefficient.

Implementation of Hyperbolic CORDIC-based VLSI architecture for Kaiser-Bessel Window techniques in spectral analysis

Abstract: In this paper, proposed CORDIC based VLSI architecture for implementing Kaiser-Bessel Window. This proposed architecture is suitable to use before FFT for real time digital spectral analysis system and also can be used for filtering applications to compute Kaiser-Bessel window coefficients and the error analysis has been discussed. The proposed architecture has synthesised in Synopsys design compiler (Design Vision) using TSMC 90 nm technology library.

Nonlinear Dynamics in Signals Derived from Bessel Functions

Abstract: The present work purports to the formulation and characterization of signal based chaos based on Bessel Functions. Specifically, the variable in these functions is viewed as an additively coupled sum of sinusoidal signals, with competing frequencies. By adapting the regular and modified Bessel Functions of the first and second kinds into signals, the derivatives are computed and used to form the corresponding iterative maps, which are studied using phase portraits. It is seen that the phase portraits of the regular and modified Bessel functions of the first kind exhibit rich, ornamental patterns, characteristic of quasiperiodicity and chaos. Using these, the bifurcation diagrams are plotted, and the chaotic behavior is quantitatively characterized using largest Lyapunov Exponents. It is seen that the nature of chaos in the generated signals indeed depend on the frequency ratio of the driving signals, thus pertaining to a case of signal based chaos, which has the key advantage of easy tunability, which forms the novelty of the present work.

Digital All-Pass Filter Modeling Based on Desired Group Delay Using Advanced Material: A Review on the Signal Processing Part

Abstract: This paper presents a review on three types of techniques in designing digital all-pass filters based on group delay. All the three methods use the same basic concept rooting back to the requirement of a stable transfer function of the filter which should be a minimum-phase type, and the denominator group delay. The most optimized of the three is chosen to be implemented in MATLAB in order to decrease the group delay variation of a 5th order Chebyshev low-pass filter with cut-off frequency of 160 MHz. The digital transfer function of the low-pass filter is obtained from the analog transfer function by means of bilinear transformation. The sampling frequency of the digital LPF is 100 times the cut-off ffrequency to retain the response of the analog LPF. Both of the filters are then cascaded together and the overall group delays variations are analyzed. The variations of group delay shows a reduction but the price paid is the increase of the overall group delay of the system.