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Showing papers on "Bessel filter published in 2016"


Journal ArticleDOI
TL;DR: By mapping traditional amplitude modulation to spatial modulation and employing adaptive optics compensation technique, this work proposes and experimentally demonstrate a high-speed Bessel beam encoding/decoding free-space optical link through atmospheric turbulence.
Abstract: By mapping traditional amplitude modulation to spatial modulation and employing adaptive optics compensation technique, we propose and experimentally demonstrate a high-speed Bessel beam encoding/decoding free-space optical link through atmospheric turbulence. The Bessel beam encoding/decoding speed is not limited by the conventional slow switching response of a spatial light modulator (SLM) but is fully determined by the modulation rate of an intensity modulator, which easily supports tens of gigabits per second modulation and resultant encoding/decoding. We use an SLM loaded with a pseudorandom phase mask to emulate atmospheric turbulence in the laboratory environment. An adaptive optics closed loop is used to sense the phase distortion of an extra probe Gaussian beam and then compensate the distorted Bessel beams. A 20-Gbit/s Bessel beam encoding/decoding link with adaptive turbulence compensation is demonstrated in the experiment, showing favorable operation performance.

67 citations


Journal ArticleDOI
TL;DR: In this paper, a scalar impedance surface composed of subwavelength elements, whose response is designed to realize a Bessel filter response, is implemented as a Scalar Impedance Surface (SIS) for wideband reflectarray antennas.
Abstract: This paper develops a framework for designing wideband reflectarray antennas. The proposed reflectarray is implemented as a scalar impedance surface composed of subwavelength elements, whose response is designed to realize a Bessel filter response. The underlying unit cells therefore have maximum group delay bandwidth with no group delay ripples in the passband. It is shown that the reflectarrays designed using this Bessel filter approach exhibit wide bandwidth only limited by the order of the filter used to realize the Bessel filter. Simulated and measured antenna characteristics of the proposed reflectarray are presented for a $C$ -/ $X$ -band reflectarray design. It is shown to have good beam characteristics and ultra-low temporal dispersion from 5 to 10 GHz, two attractive qualities accomplished simultaneously by the proposed reflectarray.

21 citations


Journal ArticleDOI
TL;DR: In this article, a low power communication between two Low Earth Orbiting satellites is proposed for minimum input power of 27.02 dBm and -7.6 dBm, at 2.5Gbps.

21 citations


Journal ArticleDOI
01 Jan 2016

21 citations


Journal ArticleDOI
TL;DR: Theoretical results and numerical examples demonstrate the efficiency and accuracy of the proposed methods for the evaluation of two kinds of highly oscillatory Bessel transforms.

18 citations


Patent
17 Aug 2016
TL;DR: In this paper, an arbitrary waveform generator based on a PXIe bus is presented. But the generator comprises only two parts: a waveform generation part and a wave-form conditioning part, which are used by an upper computer for transmitting waveform data.
Abstract: The invention relates to the field of signal generator, and specifically relates to an arbitrary waveform generator based on a PXIe bus. The generator comprises a waveform generation part and a waveform conditioning part. The waveform generation part comprises an FPGA and a crystal oscillator. The waveform conditioning part comprises a 16-bit DAC, an operational amplifier, an SPI program control amplifier, a filter circuit, an SPI program control DAC, a differential operational amplifier, and a subtracter. The generator employs the PXIe bus as a channel which is used by an upper computer for transmitting waveform data. The FPGA continuously process the waveform data transmitted by the upper computer in a waveform generation process, so as to guarantee the integrity of high-frequency signal quality. In a waveform conditioning process, the generator respectively employs a Bessel filter and an elliptic filter according to the frequency characteristics of signals and the difference of anti-noise capabilities, and meets the filtering requirements of different types of signals. For a signal with the amplitude being less than 50mV, a small signal processing branch circuit is designed, thereby guaranteeing that a signal with a small amplitude value cannot be flooded by noise. The generator employs a mode of internal and external synchronization adjustment for signal amplitude and bias, and guarantees the accuracy of a signal.

8 citations


Proceedings ArticleDOI
TL;DR: The Stratospheric Observatory for Infrared Astronomy (SOFIA) is a 2.5m infrared telescope built into a Boeing 747 SP. In 2014 SOFIA reached its Full Operational Capability milestone and nowadays takes off about three times a week to observe the infrared sky from altitudes above most of the atmosphere's water vapor content as mentioned in this paper.
Abstract: The Stratospheric Observatory for Infrared Astronomy (SOFIA) is a 2.5m infrared telescope built into a Boeing 747 SP. In 2014 SOFIA reached its Full Operational Capability milestone and nowadays takes off about three times a week to observe the infrared sky from altitudes above most of the atmosphere’s water vapor content. An actively controlled 352mm SiC secondary mirror is used for infrared chopping with peak-to-peak amplitudes of up to 10 arcmin and chop frequencies of up to 20Hz and also as actuator for fast pointing corrections. The Swiss-made Secondary Mirror Mechanism (SMM) is a complex, highly integrated and compact flexure based mechanism that has been performing with remarkable reliability during recent years. Above mentioned capabilities are provided by the Tilt Chopper Mechanism (TCM) which is one of the two stages of the SMM. In addition the SMM is also used to establish a collimated telescope and to adjust the telescope focus depending on the structure’s temperature which ranges from about 40°C at takeoff in Palmdale, CA to about −40◦C in the stratosphere. This is achieved with the Focus Center Mechanism (FCM) which is the base stage of the SMM on which the TCM is situated. Initially the TCM was affected by strong vibrations at about 300 Hz which led to unacceptable image smearing. After some adjustments to the PID-type controller it was finally decided to develop a completely new control algorithm in state space. This pole placement controller matches the closed loop system poles to those of a Bessel filter with a corner frequency of 120 Hz for optimal square wave behavior. To reduce noise present on the position and current sensors and to estimate the velocity a static gain Kalman Filter was designed and implemented. A system inherent delay is incorporated in the Kalman filter design and measures were applied to counteract the actuators’ hysteresis. For better performance over the full operational temperature range and to represent an amplitude dependent non-linearity the underlying model of the Kalman filter adapts in real-time to those two parameters. This highly specialized controller was developed over the course of years and only the final design is introduced here. The main intention of this contribution is to present the currently achieved performance of the SOFIA chopper over the full amplitude, frequency, and temperature range. Therefore a range of data gathered during in-flight tests aboard SOFIA is displayed and explained. The SMM’s three main performance parameters are the transition time between two chop positions, the stability of the Secondary Mirror when exposed to the low pressures, low temperatures, aerodynamic, and aeroacoustic excitations present when the SOFIA observatory operates in the stratosphere at speeds of up to 850 km/h, and finally the closed-loop bandwidth available for fast pointing corrections.

7 citations


Journal ArticleDOI
TL;DR: In this paper, the authors extend the results of Christensen et al. to a pair of Bessel sequences in L2(R) having wave packet structure and present sufficient conditions for their extension to wave packet type dual frames.
Abstract: Christensen et al. proved in [Extensions of Bessel sequences to dual pairs of frames, Appl. Comput. Harmon. Anal., 34 (2013), 224–233] that in any separable Hilbert space, any pairs of Bessel sequences (even if the given Bessel system is Gabor system in L2(R) ) can be extended to a pair of dual frames. In this paper, we extend results by Christensen et al. to a pair of Bessel sequences in L2(R) having wave packet structure to a pair of dual frames such that extension have wave packet structure as well. We present sufficient conditions for the extension of a pair of Bessel sequences to wave packet type dual frames for L2(R) . Several examples and counter-examples are given to illustrate our results. Mathematics subject classification (2010): 42C15, 42C30, 42C40.

5 citations


Proceedings ArticleDOI
01 Aug 2016
TL;DR: It is shown that in a finite interval a finite number of such functions that perfectly match Bessel functions of integer order exist and it is proven that the subspace spanned by a set of these functions is able to represent the class of finite duration decaying sequences.
Abstract: Bessel functions have shown to be particularly suitable for representing certain classes of signals, since using these basis functions may results in fewer components than using sinusoids. However, as there are no closed form expressions available for such functions, approximations and numerical methods have been adopted for their computation. In this paper the functions called discrete Bessel functions that are expressed as a finite expansion are defined. It is shown that in a finite interval a finite number of such functions that perfectly match Bessel functions of integer order exist. For finite duration sequences it is proven that the subspace spanned by a set of these functions is able to represent the class of finite duration decaying sequences.

5 citations


Proceedings ArticleDOI
17 Mar 2016
TL;DR: Experimental work in the design of pre-processing module in the Nadi pariksha yantra is presented and Spectral analysis of Tridosha signals and Comparative analysis of Butterworth and Bessel filter has been presented.
Abstract: Nadi pariksha is a very ancient Indian system of Ayurvedic medicine which uses pulse signal from radial artery as means for diagnosis of diseases. It assists the Ayurvedic practitioners in routine diagnostic procedure. This paper presents experimental work in the design of pre-processing module in the Nadi pariksha yantra. Spectral analysis of Tridosha signals and Comparative analysis of Butterworth and Bessel filter has been presented. 8th order Bessel filter retains periodicity and reduces ringing and overshooting effects of the Tridosha signals. Spectral analysis has been implemented to identify the cut-off frequency of acquired Tridosha signal using NI LabVIEW.

5 citations


Proceedings ArticleDOI
27 Jun 2016
TL;DR: In this article, a Duobinary precoder and a duobinary decoder were designed in a cost-effective 0.18-µm CMOS technology fed with 1.8 V, consuming 27.9 mW in total.
Abstract: This work presents a novel CMOS transceiver that enables 50-m 1-mm step-index plastic optical fiber (SI-POF) to increase transmitted data rate up to 3.125 Gbps using amplitude duobinary modulation, in addition to continuous-time equalization. For that purpose, a duobinary precoder and a duobinary decoder have been designed in a cost-effective 0.18-µm CMOS technology fed with 1.8 V, consuming 27.9 mW in total. Additionally, a new model based on low-pass Bessel filter has been proposed to simulate the effect of the equalized channel, achieving excellent agreement with experimental data. Post-layout results validate the advantages of the proposed transceiver.

Proceedings ArticleDOI
01 Jan 2016
TL;DR: In this paper, a mathematical model is used to shape the control algorithm for the dryer and a linear model is prepared for the linear model for the control process, which is shown that the controller is able to control the process in about 50 minutes.
Abstract: Husk rice must be dry before any treatment in industrial processes. For food industries, to preserve the quality of materials, the temperature must remain in a specific domain. So, in this paper, control of the moisture content and temperature of the grains are studied. To this end, a mathematical model is used to shape the control algorithm. In addition, the linear model is prepared for the control process. High-passed Bessel filter, low-passed Butterworth filter, and Linear Quadratic Regulator (LQR) controllers are designed and compared to find the best control gain matrix for the dryer. Using a comprehensive simulation routine, the stated control methods are used to control the final moisture content and the temperature of husk rice grains. It is shown that the controller is able to control the process in about 50 minutes.

Proceedings ArticleDOI
22 May 2016
TL;DR: This paper proposes an optical burst mode receiver with two transfer functions: a fast response Gn(jω/ω1) for receiving the beginning of a burst signal, and a slow response G(sub)n(jω)/ω(sub>2
Abstract: Optical burst mode receivers are an inherent part of the Passive Optical Network (PON) and Optical Switched Access Network (OSAN). We previously implemented optical burst mode receivers with AC-coupling and DC-coupling using off-the-shelf components, and showed that AC-coupling offers better performance. We then proposed an optical burst mode receiver with a transfer function Gn(s)=1-Hn(s) (Hn(s): a Bessel filter transfer function of degree n) by generalizing AC-coupling (n=1), and showed that the proposed receivers have better performance than AC-coupling equivalents. This paper proposes an optical burst mode receiver with two transfer functions: a fast response Gn(jω/ω1) for receiving the beginning of a burst signal, and a slow response Gn(jω/ω2) for the body of the signal. The receiver switches the transfer function from Gn(jω/ω1) to Gn(jω/ω2) just after Gn(jω/ω1) successfully eliminates the DC component of the input burst. We present transfer function design examples, and show that the new proposal offers much better performance.

Journal ArticleDOI
TL;DR: In this paper, a solution to the initial value problem for the third-order partial differential equation, involving the Laplacian, is obtained, and mapping properties such as boundedness and invertibility are investigated for these operators in the Lebesgue spaces.
Abstract: New index transforms, involving the squares of Bessel functions of the first kind as the kernel, are considered. Mapping properties such as the boundedness and invertibility are investigated for these operators in the Lebesgue spaces. Inversion theorems are proved. As an interesting application, a solution to the initial value problem for the third-order partial differential equation, involving the Laplacian, is obtained.

Posted Content
TL;DR: Srivastava and Cetinkaya as discussed by the authors defined a generalized Pochhammer symbol and its applications to hypergeometric functions and obtained properties of the unified family such as generating function, integral representation, Laplace transform and Mellin transform.
Abstract: In the present paper, unification of Bessel, modified Bessel, spherical Bessel and Bessel-Clifford functions via the generalized Pochhammer symbol [ Srivastava HM, Cetinkaya A, K{\i}ymaz O. A certain generalized Pochhammer symbol and its applications to hypergeometric functions. Applied Mathematics and Computation, 2014, 226 : 484-491] is defined. Several potentially useful properties of the unified family such as generating function, integral representation, Laplace transform and Mellin transform are obtained. Besides, the unified Bessel, modified Bessel, spherical Bessel and Bessel-Clifford functions are given as a series of Bessel functions. Furthermore, the derivatives, recurrence relations and partial differential equation of the so-called unified family are found. Moreover, the Mellin transform of the products of the unified Bessel functions are obtained. Besides, a three-fold integral representation is given for unified Bessel function. Some of the results which are obtained in this paper are new and some of them coincide with the known results in special cases.

Posted Content
TL;DR: In this article, the moments of Bessel functions and Bessel-trigonometric functions are analyzed based on the recursive relations of the Bessel function of the first kind and of zero order.
Abstract: The moments of Bessel functions and Bessel-trigonometric functions play a basic role in many practical problems and numerical analysis. This paper presents a complete analysis for these moments based on the recursive relations of Bessel functions. To evaluate the moments of Bessel functions numerically, a fast and efficient scheme is also proposed to approximate the integral of Bessel function of the first kind and of zero order. The moments of Bessel-trigonometric functions are proved to be expressed in a closed form. In the numerical results, the accuracy and efficiency of the proposed analysis for the moments of Bessel functions is validated first and then by comparing the existing methods, a better scheme for the moments of Bessel functions is presented.

Journal Article
TL;DR: In this paper, a generalization of the squared Bessel process with real nonnegative parameter δ by introducing a predictable almost everywhere positive process γ(t, ω) into the drift and diffusion terms is discussed.
Abstract: We discuss a generalization of the well known squared Bessel process with real nonnegative parameter δ by introducing a predictable almost everywhere positive process γ(t, ω) into the drift and diffusion terms. The resulting generalized process is nonnegative with instantaneous reflection at zero when δ is positive. When δ is a positive integer, the process can be constructed from δ-dimensional Brownian motion. In particular, we consider γt = Xt−τ which makes the process a solution of a stochastic delay differential equation with a discrete delay. The solutions of these equations are constructed in successive steps on time intervals of length τ . We prove that if 0 < δ < 2, zero is an accessible boundary and the process is instantaneously reflecting at zero. If δ ≤ 2, lim inft→∞Xt = 0. Zero is inaccessible if δ ≥ 2.

Journal ArticleDOI
TL;DR: In this article, easy-to-compute approximations of modified Bessel functions for any complex order are found for two second-order differential equations with polynomial coefficients.
Abstract: Easy-to-compute approximations of modified Bessel functions for any complex order are found. The case of two second-order differential equations with polynomial coefficients is considered. For approximately solving them, a scheme based on canonical vector-polynomials introduced by the author is proposed. The functions under consideration are of significant interest in light of the introduction of a new class of Yakubovich integral transforms.

Journal ArticleDOI
TL;DR: In this article, the effect of fog, haze, rain and dust on free space optics (FSO) communication has been investigated and it has been shown that with what parameter the communication is possible in this condition.
Abstract: Free space optics is an upcoming field in the communication world. It will provide highest band width, high security, efficient power transmission and less distortion as compared to all other wireless networks, but with all these advantages, free space optics communication is very much affecting with the atmospheric turbulence like haze, rainfall, snow, fall etc. A small amount of dust particle can starch the light beam and provide a high amount of attenuation in the signal. This work tries to reduce the effect of this atmospheric turbulence and make communication as far as possible using optisystem simulator. Signalling rate taken is 2.5GHz, transmitting power is 10 to 30 db and NRZ encoding technique is taken during transmission, transmitter channel is FSO and for reception an avalanche photodiode with Bessel filter is taken .This work also presents the effect of receiving aperture on the signal and shows a communication link more than 180 km in clear weather, 54.5 km in haze with 2.5GHz data rate. INTRODUCTION Free space optics(FSO) is a technique in which a optical communication link is established between two different points wirelessly . This method is a wireless technique so it faces difficulties for the duration of communication like building bend, as transmitter and receiver is positioned at the building and communication link is line of sight so with building bending the line of sight link goes to interrupt, Atmospheric turbulence like fog, haze, rain and dust : as FSO is a optical communication link so communication media is mild and it can travel in a straight line, as any object even a small dust particle is come against the light it will scattered the light due to which the communication link is disturbed or attenuated so during haze, light is attenuated with small dust particles, During rain, light is attenuated with rain drops ,so in these conditions it is very difficult to communicate with FSO. In this work it is shown that with what parameter the communication is possible in this condition. Better conversation gadget needs long distance, minimum scattering, less absorption, minimum misaiming, large laser power & data bits. Device will be cheaper, reliable and easy installable over long distances. To get these and to reduce the effect of these environmental condition, system needs a special quality of FSO link .To do so WDM based FSO link can be used with wide data rate of 2.5 Gbps . A frequency range of 1550 nm with high power laser, a suitable receiver aperture, highly sensitive light detector and better modulation technique is required to improve the device overall performance in terms of excellent of the transmission.

Journal ArticleDOI
TL;DR: In this paper, a novel scheme which can realize high-speed optical signals transmission and reception by using 4-pulsed amplitude modulation (4-PAM) and demodulation in 10 Gb/s passive optical access systems with different bandwidth optical Bessel filter (OBF) is introduced.
Abstract: A novel scheme which can realize high-speed optical signals transmission and reception by using 4-pulsed amplitude modulation (4-PAM) and demodulation in 10 Gb/s passive optical access systems with different bandwidth optical Bessel filter (OBF) is introduced. In this scheme, a PAM sequence generator module, an M-ary pulse generator module and one Mach-Zehnder intensity Modulator (MZM) are employed for generating the 10 Gb/s optical 4-PAM signals. And then, the generated optical 4-PAM signal achieves transmission over 20 km single mode fiber (SMF) for downstream (DS) access links application. Finally, the optical 4-PAM signal after transmission is directly detected and demodulated. We measure time-domain sequential waveform curves, optical spectrum curves, and eye-diagrams, and analyze the receiver sensitivity of 10 Gb/s 4-PAM signals before and after transmission. The received performance of the optical 4-PAM signals after transmission over 20 km single mode fiber (SMF) with different bandwidth OBF has also been analyzed.

Journal ArticleDOI
TL;DR: In this paper, it was shown that the zeros' distribution of the first kind Bessel functions Jν (z) of order ν 1 can be obtained for any integer L 2 provided that ν is half of an odd integer.
Abstract: The aim of this paper is to investigate the zeros’ distribution of the first kind Bessel functions Jν (z) of order ν 1 . The problem arises from the conjecture given by the work [8] which considered the existence of smooth solutions for one-dimensional compressible Euler equation with gravity. In this article we show that Jν (Lθ ) = 0 for any integer L 2 provided that Jν (θ ) = 0 , ν 1 and θ is sufficiently large. Moreover, if ν is half of an odd integer, we can remove the restriction of large θ and show that Jν (Lθ ) = 0 for any integer L 2 .

Journal ArticleDOI
TL;DR: In this paper, the real zeros of the product and cross-product of Bessel and modified Bessel functions of the first kind are studied and the properties and the characterization of real entire functions from the Laguerre-Polya class via hyperbolic polynomials play an important role.
Abstract: The reality of the zeros of the product and cross-product of Bessel and modified Bessel functions of the first kind is studied. As a consequence the reality of the zeros of two hypergeometric polynomials is obtained together with the number of the Fourier critical points of the normalized forms of the product and cross-product of Bessel functions. Moreover, the interlacing properties of the real zeros of these products of Bessel functions and their derivatives are also obtained. As an application some geometric properties of the normalized forms of the cross-product and product of Bessel and modified Bessel functions of the first kind are studied. For the cross-product and the product three different kind of normalization are investigated and for each of the six functions the radii of starlikeness and convexity are precisely determined by using their Hadamard factorization. For these radii of starlikeness and convexity tight lower and upper bounds are given via Euler-Rayleigh inequalities. Necessary and sufficient conditions are also given for the parameters such that the six normalized functions are starlike and convex in the open unit disk. The properties and the characterization of real entire functions from the Laguerre-Polya class via hyperbolic polynomials play an important role in this paper. Some open problems are also stated, which may be of interest for further research.