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NOISY FORCED ZERO PADDED DPCM PREDICTION

ELECTRONICS LETTERS 1992年第13期28卷 1223-1224页

作者： QUINN, D LACY, J NATL UNIV IRELAND UNIV COLL DUBLIN DEPT ELECTR & ELECT ENGNDUBLIN 4IRELAND

An enhanced DPCM compression algorithm is described which combines the use of dither within the predictor feedback loop and a prediction technique called 'forced zero padding' whereby a three level DPCM encode... 详细信息

关键词： IMAGE PROCESSING DATA COMPRESSION pulse-code modulation

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BER IMPROVEMENT DUE TO TRANSVERSAL EQUALIZER IN TRELLIS-codeD MULTILEVEL QAM DIGITAL MICROWAVE RADIO

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ELECTRONICS LETTERS 1990年第6期26卷 406-408页

作者： TAKANASHI, H AIKAWA, S NAKAMURA, Y NTT Radio Commun. Syst. Labs. Kanagawa Japan

Investigates trellis-coded modulation (TCM) on fading channels. It shows that TCM with a transversal equaliser system can achieve improved signature performance and bit error rates (BER) over multipath fading channels.

关键词： BER improvement TCM amplitude modulation bit error rates digital microwave radio digital radio systems error statistics fading microwave links multi-level QAM multipath fading channels pulse-code modulation signature performance transversal equaliser system trellis-coded modulation

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SUBJECTIVE EFFECTS OF DPCM ERRORS AND PREDICTOR LEAK ON VISUAL TELEPHONE PICTURES

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PROCEEDINGS OF THE INSTITUTION OF ELECTRICAL ENGINEERS-LONDON 1977年第9期124卷 737-742页

作者： KITCHEN, JA NICOL, RC CORBETT, JM PO RES CTR SUFFOLK IP5 7REENGLAND

A technique for reducing the visibility of transmission errors in television signals which have been digitally encoded using differential pulse-code modulation(d.p.c.m.) is to weight the predicted value of the signal by a factor less than unity. This prediction ‘leak’ has the effect of reducing the extent of the propagation, and hence the visibility, of transmission errors, but it may also increase the quantising distortion. A closely controlled subjective investigation of this error visibility against quantising distortion trade-off is described. Details of both the equipment and procedure followed are given and a mathematical model is derived to allow the plotting of curves of constant impairment for varying leak factor and error rate. The investigation indicated that for moderate channel error rates, a leak factor of 15/16 is a good compromise between error visibility and quantisation distoration.

关键词： digital encoding mathematical model visual telephone pictures video signals pulse-code modulation television signals moderate channel error rates digital communication systems transmission errors Telephony videotelephony error visibility coding errors predictor leak digital signals quantising distortion Applications of television systems differential pulse code modulation electric distortion modelling encoding

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UNIFIED THEORY OF DIGITAL modulation

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PROCEEDINGS OF THE INSTITUTION OF ELECTRICAL ENGINEERS-LONDON 1974年第2期121卷 109-115页

作者： HAWKSFORD, MJ UNIV ESSEX DEPT ELECT ENGN SCI WIVENHOE PK COLCHESTER CO4 3SQ ENGLAND

A theory of signal quantisation is developed from first principles that describes quantisation using analogue-modulation techniques. The nonlinearities, which are fundamental to digital source encoding, are expressed by two sampling processes, which directly lead to solutions in terms of amplitude and phase modulation. The analysis derives a related set of mathematical models that deter mini stically describe the input/output transfer characteristics of uniform and nonuniform p.c.m., uniform delta modulation (d.m.) and uniform d.p.c.m.

关键词： modulation and coding methods transfer characteristics digital modulation signal quantisation quantisation pulse-code modulation encoding

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COMPONENT codeC STANDARDS FOR HIGH-QUALITY DIGITAL TELEVISION

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ELECTRONICS & COMMUNICATION ENGINEERING JOURNAL 1992年第4期4卷 195-202页

作者： WELLS, ND Research Department British Broadcasting Corporation Tadworth UK

Work towards defining standards for digital television transmission codecs has been proceeding for many years. A draft specification for 140 Mbit/s coding using blanking removal and differential pulse code modulation is given in CCIR Recommendation 721. A draft specification for a codec operating at 30-45 Mbit/s and using the discrete cosine transform has been defined by the European Telecommunications Standards Institute. The paper briefly reviews bit-rate-reduction techniques and describes the 140 and 34 Mbit/s codecs.

关键词： Stations and subscriber equipment ETSI DPCM 140 Mbit/s 30 to 45 Mbit/s video equipment DCT blanking removal codes television standards CCIR Recommendation 721 discrete cosine transform codec standards Television and video equipment, systems and applications encoding pulse-code modulation bit-rate-reduction techniques high-quality digital television codecs differential pulse code modulation European Telecommunications Standards Institute

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SUBOPTIMAL REAL-TIME FREQUENCY INCIDENT-ANGLE ESTIMATOR FOR MULTIPLE RADAR pulseS

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IEE PROCEEDINGS-F RADAR AND SIGNAL PROCESSING 1991年第3期138卷 247-254页

作者： MCCORMICK, WS TSUI, JBY USAF WRIGHT RES & DEV CTRWRIGHT PATTERSON AFBOH 45433

A method is presented that provides numerical estimates of properly paired frequency and incident angles for an arbitrary number of sinusoidal radar pulses incident on a linear array. The key element of the method is a two-stage sub-optimal technique that estimates the angle of arrival of a pulse by using the output of two antenna elements and a previously calculated value of paired frequency. A method of extending the two-element method to multiple elements, by using a noise protected modification of the Chinese remainder theorem (CRT) is also advanced. Owing to its simplicity, the algorithm is appropriate to real-time processing.

关键词： pulse-code modulation

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Conformational Preference and Chiroptical Response of Carbohydrates D-Ribose and 2-Deoxy-D-ribose in Aqueous and Solid Phases

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JOURNAL OF PHYSICAL CHEMISTRY B 2013年第47期117卷 14599-14614页

作者： Mar Quesada-Moreno, Maria Azofra, Luis Miguel Aviles-Moreno, Juan Ramon Alkorta, Ibon Elguero, Jose Jesus Lopez-Gonzalez, Juan Univ Jaen Dept Phys & Analyt Chem E-23071 Jaen Spain CSIC Inst Quim Med E-28006 Madrid Spain Univ Lille 1 CNRS UMR 8523 Lab Phys Lasers Atomes & Mol F-59655 Villeneuve Dascq France

This work targets the structural preferences of D-ribose and 2-deoxy-D-ribose in water solution and solid phase. A theoretical DFT (B3LYP and M06-2X) and MP2 study has been undertaken considering the five possible configurations (open-chain, alpha-furanose, beta-furanose, alpha-pyranose, and beta-pyranose) of these two carbohydrates with a comparison of the solvent treatment using only a continuum solvation model (PCM) and the PCM plus one explicit water molecule. In addition, experimental vibrational studies using both nonchiroptical (IR-Raman) and chiroptical (VCD) techniques have been carried out. The theoretical and experimental results show that alpha- and beta-pyranose forms are the dominant configurations for both compounds. Moreover, it has been found that 2-deoxy-D-ribose presents a non-negligible percentage of open-chain forms in aqueous solution, while in solid phase this configuration is absent.

关键词： AQUEOUS solutions SOLID phase extraction FURANOSIDES pulse-code modulation CARBOHYDRATES SOLVATION

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The effect of halogen substitution on the structure and electronic spectra of fluorone dyes

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OPTICS AND SPECTROSCOPY 2012年第5期112卷 671-678页

作者： Slyusareva, E. A. Tomilin, F. N. Sizykh, A. G. Tankevich, E. Yu. Kuzubov, A. A. Ovchinnikov, S. G. Siberian Fed Univ Krasnoyarsk 660041 Russia Russian Acad Sci Siberian Branch Kirensky Inst Phys Krasnoyarsk 660036 Russia

By means of the B3LYP density functional method with the use of the polarized continuum model PCM, we have performed quantum-chemical computations of the electronic absorption and fluorescence spectra of fluorone dianions: fluorescein, dibromofluorescein, eosin, erythrosine, and Rose Bengal in vacuum and methanol. We have revealed conformational features of the structure of fluorone dianions (charge redistribution, changes in the bond lengths and angles between bonds) second by the halogen substitution, the transition from the ground state to an excited state, and the change of the solvent (vacuum-methanol). Absorption and fluorescence wavelengths, constant dipole moments, transition dipole moments, and oscillator strengths have been calculated. We have showed that, upon halogenation of fluorones, the absorption spectra are redshifted and the Stokes shift decreases, which is qualitatively consistent with experimental results.

关键词： ELECTRONIC spectra DYES & dyeing FLUORESCEIN DENSITY functionals POLARIZATION (Electricity) pulse-code modulation ELECTRIC charge & distribution

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APPLICATION OF DATA COMPRESSION TO AN EXPERIMENTAL 9.6 KBIT-S ADAPTIVE PCM DIGITAL SPEECH SYSTEM

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PROCEEDINGS OF THE INSTITUTION OF ELECTRICAL ENGINEERS-LONDON 1976年第2期123卷 109-114页

作者： TURNER, LF IMPERIAL COLL SCI & TECHNOL DEPT ELECTR ENGNEXHIBITION RDLONDON SW7 2BTENGLAND

The paper deals with an investigation that was carried out to determine whether simple data-compression techniques could be applied successfully to an experimental 9.6 kbit/s adaptive p.c.m. digital speech system: The main aim of the investigation was to ascertain whether compression factors of two or four could be achieved. In the paper, the results of the investigation are presented and it is shown that the adaptive p.c.m. system is converting speech into a 9.6 kbit/s digital form that appears to possess very little redundancy. The results of a statistical analysis of the data are given, and it is shown that a compression factor of two is unlikely to result in a speech quality that is commercially acceptable. The results of an experimental investigation that was carried out in support of the theoretical investigation are presented. The results of the experimental investigation show that although compression by a factor of two results in a speech quality that is commercially unacceptable, a 4/3 compression can be achieved without any serious degradation of the speech quality.

关键词： digital communication systems data compression compression factors statistical analysis Telephony voice communication speech quality pulse-code modulation experimental 9.6 kbit/s adaptive digital speech system pulse code modulation

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NUMERICAL INVESTIGATION OF PCM BASED HEAT SINKS WITH EMBEDDED METAL FOAM/CROSSED PLATE FINS

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NUMERICAL HEAT TRANSFER PART A-APPLICATIONS 2014年第10期66卷 1131-1153页

作者： Srivatsa, P. V. S. S. Baby, Rajesh Balaji, C. Indian Inst Technol Heat Transfer & Thermal Power Lab Dept Mech Engn Madras 600036 Tamil Nadu India

Three-dimensional numerical models for phase change material based heat sinks equipped with thermal conductivity enhancers like aluminum metal foam and crossed plate fins are validated with the experimental data found in literature. For the aluminum metal foam embedded in the heat sink filled with phase change material, the porosity and the pores per inch of the metal foam were varied and natural convection currents were studied. Maintaining the volume fraction of the phase change material as a constant, the thermal performance enhancement as a result of the introduction of thermal conductivity enhancer into the heat sinks is determined.

关键词： NUMERICAL analysis pulse-code modulation HEAT sinks METAL foams PLATES (Engineering) THERMAL conductivity PHASE change materials

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