1,519 research outputs found

    Development of a dc-ac power conditioner for wind generator by using neural network

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    This project present of development single phase DC-AC converter for wind generator application. The mathematical model of the wind generator and Artificial Neural Network control for DC-AC converter is derived. The controller is designed to stabilize the output voltage of DC-AC converter. To verify the effectiveness of the proposal controller, both simulation and experimental are developed. The simulation and experimental result show that the amplitude of output voltage of the DC-AC converter can be controlled

    A survey of digital television broadcast transmission techniques

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    This paper is a survey of the transmission techniques used in digital television (TV) standards worldwide. With the increase in the demand for High-Definition (HD) TV, video-on-demand and mobile TV services, there was a real need for more bandwidth-efficient, flawless and crisp video quality, which motivated the migration from analogue to digital broadcasting. In this paper we present a brief history of the development of TV and then we survey the transmission technology used in different digital terrestrial, satellite, cable and mobile TV standards in different parts of the world. First, we present the Digital Video Broadcasting standards developed in Europe for terrestrial (DVB-T/T2), for satellite (DVB-S/S2), for cable (DVB-C) and for hand-held transmission (DVB-H). We then describe the Advanced Television System Committee standards developed in the USA both for terrestrial (ATSC) and for hand-held transmission (ATSC-M/H). We continue by describing the Integrated Services Digital Broadcasting standards developed in Japan for Terrestrial (ISDB-T) and Satellite (ISDB-S) transmission and then present the International System for Digital Television (ISDTV), which was developed in Brazil by adopteding the ISDB-T physical layer architecture. Following the ISDTV, we describe the Digital Terrestrial television Multimedia Broadcast (DTMB) standard developed in China. Finally, as a design example, we highlight the physical layer implementation of the DVB-T2 standar

    Design and Simulation of a 3rd-order Discrete-Time Time-Interleaved Delta-Sigma Modulator with Shared Integrators between Two Paths

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    This paper presents the design and simulation of a 3rd-order two-path Discrete-Time Time-Interleaved (DTTI) ΔΣ modulator. By exploiting the concept of the time-interleaving techniques and time domain equations, a conventional 3rd-order Discrete-Time (DT) ΔΣ modulator is converted to a corresponding 3rd-order two-path DTTI counterpart. For the sake of saving power and silicon area, the integrators between the two paths of the DTTI ΔΣ modulator are shared. Using one set of integrators makes the DTTI ΔΣ modulator robust to path mismatch effects compared to the typical DTTI ΔΣ modulator which has individual integrators in all paths. A problem arises out of sharing integrators between paths which we call the delayless feedback problem. A solution for this problem is proposed in this paper and for an OverSampling Ratio (OSR) of 16 and a clock frequency of 320MHz, a maximum SNR of 76.5dB is obtained

    Design of a Delayless Feedback Path Free 2nd-order Two-Path Time-Interleaved Discrete-Time Delta-Sigma Modulator- a New Approach

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    This paper presents the design procedure for a 2nd_order two-path Discrete-Time Time-Interleaved (DTTI) ΔΣ modulator from a conventional single-loop 2nd-order Discrete-Time (DT) ΔΣ modulator through the use of time domain equations and time-interleaving concepts [1]. The resulting modulator is free from the delayless feedback path and has only one set of integrators. The delayless feedback path issue in Time-Interleaved (TI) ΔΣ modulators is a critical restriction for the implementation of TI ΔΣ modulators and is effectively eliminated through the use of the approach proposed in this paper. The DTTI ΔΣ modulator requires only three op-amps and two quantizers both of which work concurrently, in comparison to the single-loop DT counterpart that also deploys two op-amps. For an OverSampling Ratio (OSR) of 16 and a clock frequency of 640MHz, our simulation results show a maximum Signal-to-Noise Ratio (SNR) for the DTTI ΔΣ modulator to be 70.5dB with an input bandwidth of 20MHz which has 15dB improvement in comparison to its single-loop, single-path DT counterpart

    Enhancing MB-OFDM throughput with dual circular 32-QAM

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    Quadrature Phase Shift Keying (QPSK) and Dual Carrier Modulation (DCM) are currently used as the modulation schemes for Multiband Orthogonal Frequency Division Multiplexing (MB-OFDM) in the ECMA-368 defined Ultra-Wideband (UWB) radio platform. ECMA-368 has been chosen as the physical radio platform for many systems including Wireless USB (W-USB), Bluetooth 3.0 and Wireless HDMI; hence ECMA-368 is an important issue to consumer electronics and the users experience of these products. To enable the transport of high-rate USB, ECMA-368 offers up to 480 Mb/s instantaneous bit rate to the Medium Access Control (MAC) layer, but depending on radio channel conditions dropped packets unfortunately result in a lower throughput. This paper presents an alternative high data rate modulation scheme that fits within the configuration of the current standard increasing system throughput by achieving 600 Mb/s (reliable to 3.1 meters) thus maintaining the high rate USB throughput even with a moderate level of dropped packets. The modulation system is termed Dual Circular 32-QAM (DC 32-QAM). The system performance for DC 32-QAM modulation is presented and compared with 16-QAM and DCM1

    Optically Enabled ADCs and Application to Optical Communications

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    Electrical-optical signal processing has been shown to be a promising path to overcome the limitations of state-of-the-art all-electrical data converters. In addition to ultra-broadband signal processing, it allows leveraging ultra-low jitter mode-locked lasers and thus increasing the aperture jitter limited effective number of bits at high analog signal frequencies. In this paper, we review our recent progress towards optically enabled time- and frequency-interleaved analog-to-digital converters, as well as their monolithic integration in electronic-photonic integrated circuits. For signal frequencies up to 65 GHz, an optoelectronic track-and-hold amplifier based on the source-emitter-follower architecture is shown as a power efficient approach in optically enabled BiCMOS technology. At higher signal frequencies, integrated photonic filters enable signal slicing in the frequency domain and further scaling of the conversion bandwidth, with the reconstruction of a 140 GHz optical signal being shown. We further show how such optically enabled data converter architectures can be applied to a nonlinear Fourier transform based integrated transceiver in particular and discuss their applicability to broadband optical links in general
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