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ADAPTIVE PREDICTIVE IMAGE-CODING USING LOCAL CHARACTERISTICS

IEE PROCEEDINGS-I COMMUNICATIONS SPEECH AND VISION 1989年第6期136卷 385-390页

作者： HSIEH, CH LU, PC LIOU, WG Department of Electrical Engineering Chung Cheng Institute of Technology Ta-Hsi Republic of China

The paper presents an efficient adaptive predictive coding method using the local characteristics of images. In this method, three coding schemes, namely, mean, subsampling combined with fixed DPCM, and ADPCM/PCM, are used and one of these is chosen adaptively based on the local characteristics of images. The prediction parameters of the 2-d linear predictor in the ADPCM/PCM are extracted on a block by block basis using the 2-d lattice filtering method. The order update 2-d lattice model proposed by Parker and Kayran is extended into order update and time update recursion for more efficient computation. Simulation results show that the proposed method is effective in reducing the slope overload distortion and the granular noise at low bit rates, and thus it can improve the visual quality of reconstructed images. Other advantages of this method are the low computational burden and the suitability for the VLSI implementation.

关键词： PCM adaptive differential pulse code modulation DPCM Pattern recognition VLSI implementation granular noise slope overload distortion codes picture processing filtering and prediction theory adaptive predictive image coding encoding pulse-code modulation local characteristics Optical information, image and video signal processing 2D linear predictor low bit rates prediction parameters visual quality reconstructed images differential pulse code modulation adaptive filters 2D lattice filtering time update recursion order update recursion ADPCM/PCM

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NEW STRUCTURE FOR DIGITAL SWITCHING NETWORK

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ELECTRONICS LETTERS 1989年第3期25卷 209-211页

作者： JAJSZCZYK, A Inst. of Electron. & Commun. Tech. Univ. of Poznan Poland

Methods for the design of cost-effective one-stage PCM switching networks composed of digital switching matrices are proposed. These one-stage networks have, in many cases, a more regular structure and contain fewer elements than networks currently known. The proposed one-stage networks can also be used as submodules for multistage networks.

关键词： PCM cost-effective design digital communication systems digital switching network multistage networks one-stage networks pulse code modulation pulse-code modulation regular structure submodules switching matrices switching networks

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LINEAR pulse DISTORTION EFFECTS IN APPLICATIONS OF SEMICONDUCTOR OPTICAL AMPLIFIERS TO LOCAL-NETWORK

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ELECTRONICS LETTERS 1989年第9期25卷 618-619页

作者： ZENTENO, LA Polaroid Corp. Cambridge MA USA

It is shown that residual facet reflectivity in travelling-wave semiconductor optical amplifiers causes cumulative pulse broadening and distortion, hence limiting the maximum number of amplifiers that may be reliably used in a local network. For a TDM network, closed-form expressions are derived for this number in terms of bit rate and amplifier and pulse parameters.

关键词： LAN PCM TDM network bit rate closed-form expressions cumulative pulse broadening digital communication systems linear pulse distortion effects local area network local area networks local network optical communication optical communication optical links optical links pulse parameters pulse-code modulation residual facet reflectivity semiconductor junction lasers semiconductor lasers semiconductor optical amplifiers time division multiplexing travelling-wave

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HIGH-FIDELITY MUSIC CODING AT 4 BITS

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ELECTRONICS LETTERS 1988年第8期24卷 493-495页

作者： SMYTH, SMF MCCANNY, JV Dept. of Electr. & Electron Eng. Queen's Univ. of Belfast

A very high-quality sub-band ADPCM music coding scheme which compresses high-fidelity music signals, bandlimited to 15 kHz, to an equivalent PCM representation of only 4 bits per sample, is described. By processing music sampled at 32 kHz, this coder exhibits a total bit rate of only 128 kbit/s and is consequently applicable to the ISDN. Subjective tests conducted with this coder have shown that music recovered from the compression scheme is essentially indistinguishable from the original material. The results obtained are of major importance, not only for ISDN and broadcasting, but also for other digital audio technology such as compact disc (CD) and digital audio tape

关键词： 128 kbit/s 15 kHz 4 bits per sample ADPCM CD Hi-Fi equipment Hi-Fi technique ISDN ISDN acoustic signal processing bandwidth compression broadcasting broadcasting compact disc compression scheme data compression digital audio tape digital audio technology digital communication systems encoding high-fidelity music signals music music coding pulse code modulation pulse-code modulation subband coding scheme

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NEURAL NET BASED NONSTANDARD A/D CONVERSION

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ELECTRONICS LETTERS 1988年第10期24卷 619-620页

作者： ANASTASSIOU, D COLUMBIA UNIV CTR TELECOMMUN RESNEW YORKNY 10027

A technique for nonstandard A/D conversion of signals subject to a fidelity criterion is described, based on Hopfield neural networks. Switched-capacitor neural networks offer a natural means for efficient implementation of the proposed technique. Applications include all forms of PCM coding, oversampled A/D conversion and digital image halftoning

关键词： Hopfield neural networks PCM coding analogue-digital conversion digital image halftoning encoding fidelity criterion neural nets nonstandard A/D conversion oversampled A/D conversion pulse-code modulation signal quantisation switched capacitor networks switched capacitor neural networks

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COMBINING FAST DPCM COMPRESSION OF PICTURES WITH TREE ENCODING

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ELECTRONICS LETTERS 1988年第18期24卷 1148-1150页

作者： DELAMEILLIEURE, J BRUYLAND, I Commun. Eng. Lab. State Univ. Gent

Presents a fast DPCM coder built around a ROM of feasible size, in which an elementary form of tree encoding is integrated, to improve the quality of the decoded picture. Simulations illustrate the improvements of thi... 详细信息

关键词： ROM data compression decoded image differential PCM coder encoding fast DPCM compression image processing picture processing pictures pulse code modulation pulse-code modulation tree encoding

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ERROR BURST AND GUARD SPACE OBSERVATIONS ON CCITT PCM CHANNELS

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ELECTRONICS LETTERS 1988年第12期24卷 739-740页

作者： HOPE, JF FERREIRA, HC Lab for Cybernetics Rand Afrikaans Univ. Johannesburg

The results of a series of experimental measurements on CCITT type primary PCM channels are presented, with special emphasis on statistics of error bursts and related error-free guard spaces

关键词： CCITT PCM channels digital communication systems error statistics error-free guard spaces experimental measurements primary PCM channels pulse-code modulation statistics of error bursts

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ZERO REDUNDANCY CHANNEL CODING IN VECTOR QUANTIZATION

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ELECTRONICS LETTERS 1987年第12期23卷 654-656页

作者： ZEGER, KA GERSHO, A Department of Electrical & Computer Engineering University of California Santa Barbara USA

Gray-coding of signal amplitudes can protect PCM transmission of analogue signals from the effects of channel bit errors. We generalise this to VQ, and provide a `vector switching?? algorithm that reduces the expected... 详细信息

关键词： electric distortion code-book pulse-code modulation vector quantisation distortion reduction codes zero redundancy channel coding vector switching Other data transmission codes channel bit errors Gray-coding of signal amplitudes PCM transmission of analogue signals

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EMBEDDED ADPCM WITH NOISE SPECTRAL SHAPING FOR PACKET VOICE TRANSMISSION

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ELECTRONICS LETTERS 1987年第5期23卷 239-241页

作者： KIM, HD UN, CK Communications Research Laboratory Department of Electrical Engineering Korea Advanced Institute of Science & Technology Seoul Korea

An embedded adaptive differential pulse code modulation (EADPCM) that may be used for speech coding in a packet network is proposed. In this scheme the quantisation nosie of an ADPCM is reduced significantly by employing an instant-aneously adaptive PCM (ADPCM) as a second-stage coder, and is shaped further to reduce the subjectively annoying effects by a noise-shaping filter. By computer simulation using real speech we show a significant performance improvement (3 to 10dB at rates of 16 to 48 kbit/s) with the proposed scheme.

关键词： EADPCM speech coding adaptive differential pulse code modulation noise spectral shaping modulation and coding methods 16 to 48 kbit/s computer simulation using real speech packet switching subjectively annoying effects instantaneously adaptive PCM voice communication noise-shaping filter pulse-code modulation quantisation noise APCM embedded ADPCM second-stage coder performance improvement packet network packet voice transmission Communication system theory digital simulation

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modulation SCHEME SUITABLE FOR INFRARED BIOTELEMETRY

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ELECTRONICS LETTERS 1985年第14期21卷 601-602页

作者： WELLER, C Division of Bioengineering Clinical Research Centre Harrow UK

Telemetering physiological signals from hospital patients by time-sharing infra-red radiation of fixed wavelength means that the limited time available for encoding each data channel imposes constraints on modulation ... 详细信息

关键词： limited time available for encoding Optical communication Telemetering systems telemetering systems hospital patients codes Patient diagnostic methods and instrumentation telemetering physiological signals infra-red biotelemetry Telemetry biomedical electronics unconventional pulse code IR links pulse-code modulation light emitting diodes Biomedical measurement and imaging patient monitoring constraints on modulation methods time-sharing infra-red radiation of fixed wavelength optical links modulation scheme digital modulation methods analogue modulation

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