Jasvir Singh

Review: VoIP: State of art for global connectivity-A critical review

The Internet has revolutionized the telecommunication systems by supporting new applications and services. Voice over Internet Protocol (VoIP) is one of the most prominent telecommunication services based on the Internet Protocol (IP). The signal quality of the VoIP system depends on several factors such as networking conditions, coding processes, speech content and error correction schemes. The work in the present paper reviewed these issues, used for providing toll-quality communication service to the users over VoIP system. From the very beginning of transferring the voice data over packet switched networks, the journey of the packet based communications to modern VoIP and advancements to improve the service of the VoIP system has been summarized in this work.

Transport and optical properties of hot-wall-grown tin selenide films

Tin selenide (SnSe) films were grown by the hot-wall epitaxy (HWE) technique on glass, mica and KCl substrates. The electrical resistivity and Hall mobility of the films grown on mica and KCl were found to be quite close to the bulk SnSe values. Optical absorption measurements indicated an indirect energy bandgap of about 1 eV and a direct gap of about 1.2 eV.

Cognitive Radio: State of Research Domain in Next Generation Wireless Networks - A Critical Analysis

Radio (CR) is a comparatively new technology in which problems like underutilization of spectrum and spectrum scarcity is solved based on the revolutionary ideas. Cognitive Radio allows group of users to identify and access to available spectrum resources for their optimum use. Recent studies show that most of the assigned spectrum is underutilized. On the other hand, the increasing number of wireless multimedia applications leads to a spectrum scarcity. Cognitive Radio is proposed as a promising technology to solve the imbalance between spectrum scarcity and spectrum underutilization. In Cognitive Radio, spectrum sensing is done in order to locate the unused spectrum segments. This paper show the strength and capabilities of Cognitive Radio processes and what makes it more powerful over the other competitive radio. Main focus is given on Present State of Research, Architecture and Future Scope for CR. Stress is given on Application areas, where Cognitive Radio techniques can be implemented and proved out to have upper-hand than the available Intelligence and adapting Radios.

Computer Modeling & Performance Analysis of VoIP under Different Strategic Conditions

The transmission of the Voice over Internet protocol requires high quality of speech to update this service. VoIP signal quality can be degraded by network layer problems which includes delay, packet loss and jitter. But the frame loss while transmitting voice over internet services may generate audible distortion in the perceived speech quality. The simulation model of VoIP network under impairments is presented in this paper. The results are measured using the perceptual evaluation of speech quality (PESQ). Further spectral analysis of this degraded VoIP speech signal is carried out.

Processing of VoIP Signal Using TMS320C6713 in Digital Domain

The speech of the VoIP system is degraded by network layer problems which include delay, packet loss and jitter. The implementation of signal through digital signal processor can improve the quality of degraded VoIP signal. The work in this paper deals with the implementation of digital filtering algorithm on degraded VoIP speech signal. The results of implementation experiment indicate the improvement of signal quality. The results are validated through the measurement of enhancement signal using perceptual evaluation of speech quality (PESQ) measurement.

Spectral Analysis of Speech Quality in VoIP for G.729A and AMR-WB Speech Coders

The transmission of Voice over Internet protocol requires signal processing for reliable & efficient performance over the computer and the communication platform. Speech quality, as perceived by the users of VoIP telephony, is critically important to the update of the service. Signal quality is degraded by network layer problems including delay, jitter and packet loss. The work presented in this paper presents the spectral analysis of speech quality for narrowband and wideband VoIP. The simulation model of VoIP network under impairments is presented. The VoIP simulations are conducted for G.729A and AMR-WB speech coders at different packet loss rates. The comparison results of various speech analysis algorithms such as power density spectrum FFT etc. for both narrowband and wideband VoIP signals are presented in this paper. The results are also measured using PESQ for narrowband speech signal and WB-PESQ for wideband speech signalIn the flat glass screen panel of CRT forming process, as the wedge-shaped numerical value of it is large, the serious deformation is produced in the inner surface. The design of outer surface curvature of flat glass screen panel is optimized with CAD/CAE, that not only reduce the deformation of inner surface and the weight, but also increase the image brightness of peripheral part of panel and the uniformity of image brightness of the whole panel.

System theoretic modelling and simulation of gall-bladder bile

The study of changes in bile concentration of human gall bladder is an effective method for understanding its overall dynamics. It has been carried out as a function of food intake timings and a mathematical model is suggested to explain the results. Computer simulation gives a good fit. The technique is suitable for detection of abnormalities in gall bladder.

Effect of Cr doping on structural and magnetic properties of ZnS nanoparticles

The structural, optical and magnetic properties of pure and Cr doped ZnS nanoparticles were studied at room temperature. X-ray diffraction analysis confirmed the absence of any mixed phase and the cubic structure of ZnS in pure and Cr doped ZnS nanoparticles. Fourier transfer infrared spectra confirmed the Zn-S stretching bond at 664 cm−1 of ZnS in all prepared nanoparticles. The UV-Visible absorption spectra showed blue shift which became even more pronounced in Cr doped ZnS nanoparticles. However, at relatively higher Cr concentrations a slower red shift was shown by the doped nanoparticles. This phenomenon is attributed to sp-d exchange interaction that becomes prevalent at higher doping concentrations. Further, magnetic hysteresis measurements showed that Cr doped ZnS nanoparticles exhibited ferromagnetic behavior at room temperature.

Analysis of Interpolated FIR Filter for VoIP in Noisy Enviroment

The presence of background noise degrades the quality of speech signal. The speech quality of the VoIP system can be improved by reducing the background noise, codec distortion and various network impairments such as packet loss, delay and jitter. The work in this paper proposes the Interpolated Finite Impulse Response filter (IFIR) based scheme for reduction of noise. The IFIR filter would be applied as post processing after the speech decoding. For various noisy conditions, the quality of speech signal is measured with PESQ measurement to evaluate the performance of the proposed method. The codec tested with proposed method are G.729A and AMR-NB. The performance is evaluated not only for the codec used but also for VoIP system with packet loss in noisy environment. The results show much improvement in speech quality with proposed method

Implementation of FIR Interpolation Filter on TMS320C6713 for VoIP Analysis

In voice over internet protocol (VoIP) system, the speech signal is degraded when passed through the network layers. The speech signal is processed through best effort policy based IP network, which include delay, packet loss and jitter network problems. The quality of VoIP speech signal can be improved by filtering the degraded VoIP speech signal through multirate filters. The work in this paper deals with the implementation of Interpolated finite impulse response (IFIR) filtering algorithm on degraded VoIP speech signal using TMS320C6713 DSP processor. The filter was designed using polyphase structure. The results of implementation experiment indicate the improvement of signal quality. The results are validated through the measurement of enhancement signal using perceptual evaluation of speech quality (PESQ) measurement, which shows the increase in MOS score at different packet loss rates (PLR)Aiming to coordinate power plants planning and power network planning in the electricity market environment, a coordination assessment system is established in this paper. Entropy weight coefficients are utilized to calibrate the weights given by specialists, thus reduced the subjective uncertainty of expertise. Based on the hypothetical ideal solution, the TOPSIS method is adopted to implement multiple attribute decision making (MADM). Its application in a planning case based on Garver-6 system demonstrates the consistency and effectiveness of the aforementioned coordination assessment system.