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Search Results: 1 - 10 of 1369 matches for " Chakrabarti Indranil "
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A New High-Performance Digital FM Modulator and Demodulator for Software-Defined Radio and Its FPGA Implementation
Indranil Hatai,Indrajit Chakrabarti
International Journal of Reconfigurable Computing , 2011, DOI: 10.1155/2011/342532
Abstract: This paper deals with an FPGA implementation of a high performance FM modulator and demodulator for software defined radio (SDR) system. The individual component of proposed FM modulator and demodulator has been optimized in such a way that the overall design consists of a high-speed, area optimized and low-power features. The modulator and demodulator contain an optimized direct digital frequency synthesizer (DDFS) based on quarter-wave symmetry technique for generating the carrier frequency with spurious free dynamic range (SFDR) of more than 64?dB. The FM modulator uses pipelined version of the DDFS to support the up conversion in the digital domain. The proposed FM modulator and demodulator has been implemented and tested using XC2VP30-7ff896 FPGA as a target device and can operate at a maximum frequency of 334.5?MHz and 131?MHz involving around 1.93?K and 6.4?K equivalent gates for FM modulator and FM demodulator respectively. After applying a 10?KHz triangular wave input and by setting the system clock frequency to 100?MHz using Xpower the power has been calculated. The FM modulator consumes 107.67?mW power while FM demodulator consumes 108.67?mW power for the same input running at same data rate. 1. Introduction In the prevalent audio broadcasting applications like private mobile radio (PMR) and digital audio broadcasting-terrestrial (DAB-T) standards, excellent clarity along with the source stability is required for the voice transmission. Frequency modulation (FM) scheme is used in most of these standards. Traditionally, FM signal generation was performed using some analog components to support the audio broadcasting standards. But difficulties arose in analog FM modulation scheme due to the use of the voltage-controlled oscillator (VCO). Using the VCO, it is very difficult to obtain a good clarity as well as source stability in FM-modulated or demodulated signal as VCO suffers from lack of linearity over the desired frequency range. Therefore, digital implementation of FM modulation scheme has evolved to replace the traditional analog counterpart. Nowadays, to get superior performance and good voice clarity in any audio broadcasting system, digital FM modulation and demodulation technique is widely used. To ensure linearity over the entire frequency range, designers choose to replace the VCO by a DDFS, sometimes referred to as a numerically controlled oscillator (NCO). Considerable research has been performed on different digital FM modulator architecture. Some of these have laid stress on reducing the distortion effects of quantization noise,
Multi-Standard Programmable Baseband Modulator for Next Generation Wireless Communication
Indranil Hatai,Indrajit Chakrabarti
International Journal of Computer Networks & Communications , 2010,
Abstract: Considerable research has taken place in recent times in the area of parameterization of software definedradio (SDR) architecture. Parameterization decreases the size of the software to be downloaded and alsolimits the hardware reconfiguration time. The present paper is based on the design and development of aprogrammable baseband modulator that perform the QPSK modulation schemes and as well as its otherthree commonly used variants to satisfy the requirement of several established 2G and 3G wirelesscommunication standards. The proposed design has been shown to be capable of operating at a maximumdata rate of 77 Mbps on Xilinx Virtex 2-Pro University field programmable gate array (FPGA) board.The pulse shaping root raised cosine (RRC) filter has been implemented using distributed arithmetic (DA)technique in the present work in order to reduce the computational complexity, and to achieveappropriate power reduction and enhanced throughput. The designed multiplier-less programmable 32-tap FIR-based RRC filter has been found to withstand a peak inter-symbol interference (ISI) distortion of-41 dBs.
Multi-standard programmable baseband modulator for next generation wireless communication
Indranil Hatai,Indrajit Chakrabarti
Computer Science , 2010, DOI: 10.5121/ijcnc.2010.2406
Abstract: Considerable research has taken place in recent times in the area of parameterization of software defined radio (SDR) architecture. Parameterization decreases the size of the software to be downloaded and also limits the hardware reconfiguration time. The present paper is based on the design and development of a programmable baseband modulator that perform the QPSK modulation schemes and as well as its other three commonly used variants to satisfy the requirement of several established 2G and 3G wireless communication standards. The proposed design has been shown to be capable of operating at a maximum data rate of 77 Mbps on Xilinx Virtex 2-Pro University field programmable gate array (FPGA) board. The pulse shaping root raised cosine (RRC) filter has been implemented using distributed arithmetic (DA) technique in the present work in order to reduce the computational complexity, and to achieve appropriate power reduction and enhanced throughput. The designed multiplier-less programmable 32-tap FIR-based RRC filter has been found to withstand a peak inter-symbol interference (ISI) distortion of -41 dBs
Shannon entropy: axiomatic characterization and application
C. G. Chakrabarti,Indranil Chakrabarty
International Journal of Mathematics and Mathematical Sciences , 2005, DOI: 10.1155/ijmms.2005.2847
Abstract: We have presented a new axiomatic derivation of Shannon entropy for a discrete probability distribution on the basis of the postulates of additivity and concavity of the entropy function. We have then modified Shannon entropy to take account of observational uncertainty.The modified entropy reduces, in the limiting case, to the form of Shannon differential entropy. As an application, we have derived the expression for classical entropy of statistical mechanics from the quantized form of the entropy.
Boltzmann Entropy : Probability and Information
C. G. Chakrabarti,Indranil Chakrabarty
Physics , 2007,
Abstract: We have presented first an axiomatic derivation of Boltzmann entropy on the basis of two axioms consistent with two basic properties of thermodynamic entropy. We have then studied the relationship between Boltzmann entropy and information along with its physical significance.
Effects of the composition on transonic properties of accretion flows around black holes
Indranil Chattopadhyay,Sandip K. Chakrabarti
Physics , 2013, DOI: 10.1142/S0218271811019487
Abstract: We study the properties of a steady, multi-species, low angular momentum accretion flow around a Schwarzschild black hole. Each species is described by a relativistic equation of state. We find that the transonic properties depend strongly on the composition of the flow. We find that an electron-positron pair plasma is the least relativistic one. This flow produces only one sonic point very close to the event horizon and does not show multiple critical points for any angular momentum or energy. When the baryons are present, the number of critical points depend on the specific energy content. Since the number of critical points decide whether the flow will have non-linearities or shock waves, our results implies that whether or not standing shocks forms will depend on the flow composition. Thus, for instance, a pure electron-positron pair plasma will never undergo a shock transition, while mixing it with some baryons (common in outflows and jets, for example) as in a completely ionized gas, will have shocks. We study in detail how the baryon loading affects the shock properties and discuss implication in astrophysical observations.
Boltzmann-Shannon Entropy: Generalization and Application
C. G. Chakrabarti,Indranil Chakrabarty
Physics , 2006, DOI: 10.1142/S0217984906011529
Abstract: The paper deals with the generalization of both Boltzmann entropy and distribution in the light of most-probable interpretation of statistical equilibrium. The statistical analysis of the generalized entropy and distribution leads to some new interesting results of significant physical importance.
Shannon Entropy: Axiomatic Characterization and Application
C. G. Chakrabarti,Indranil Chakrabarty
Physics , 2005,
Abstract: We have presented a new axiomatic derivation of Shannon Entropy for a discrete probability distribution on the basis of the postulates of additivity and concavity of the entropy function.We have then modified shannon entropy to take account of observational uncertainty.The modified entropy reduces, in the limiting case, to the form of Shannon differential entropy. As an application we have derived the expression for classical entropy of statistical mechanics from the quantized form of the entropy.
Generation and Acceleration of Jets from Effective Boundary Layer around Black Hole
Indranil Chattopadhyay,Sandip K. Chakrabarti
Physics , 2000,
Abstract: We propose the processes of generation and radiative acceleration of jets from the centrifugal pressure dominated boundary layer around a black hole.
On Radiative Acceleration of Jets and Outflows from Advective Disks
Indranil Chattopadhyay,Sandip K. Chakrabarti
Physics , 2000, DOI: 10.1063/1.1370888
Abstract: Jets and outflows are known to form out of advective accretion flows around black holes. Hard photons from the centrifugal barrier directly hit the electrons and deposit momentum on them. For optically thick flows such deposition is not efficient, but for optically thin flows matter could be accelerated to relativistic speed. In fact, even bound matter could be made free through successive deposition. We discuss these possibilities.
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