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Communications Magazine, IEEE

Issue 11 • Date Nov. 1993

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Displaying Results 1 - 8 of 8
  • Speech synthesis in telecommunications

    Publication Year: 1993 , Page(s): 46 - 53
    Cited by:  Papers (1)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1241 KB)  

    A text-to-speech synthesis system that synthesizes speech from unrestricted text is discussed. The text analysis system, which includes text preprocessing, phrasing and intonation, and letter-to-phoneme conversion, is described. The analyzed text is represented by phonetic characters, stress values, minor- and major-phrase markers, and intonational descriptors. The synthesizer uses this information to compute a speech signal in several stages. The duration of the different speech events is computed, and the intonational descriptors are converted to a fundamental frequency contour. Loudness control is also generated. After these prosodic parameters have been computed, the synthesis parameters that describe the different sounds or phonemes are generated. These parameters are converted to speech by a waveform synthesizer.<> View full abstract»

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  • Standardizing speech-coding technology for network applications

    Publication Year: 1993 , Page(s): 26 - 33
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1560 KB)  

    The different approaches to the standardization of speech coding technology applications are reviewed. The activities of the International Telephone and Telegraph Consultative Committee (CCITT) are highlighted, although other standards setting bodies often follow a similar process. Standardization of speech coding involves the interaction of various experts, who define performance requirements, design speech coding algorithms to meet these requirements, design test plans to evaluate compliance to the requirements, evaluate implementation aspects, select algorithm implementation formats, and develop verification procedures to guarantee compliance to the speech coding specification.<> View full abstract»

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  • Wideband speech and audio coding

    Publication Year: 1993 , Page(s): 34 - 44
    Cited by:  Papers (34)  |  Patents (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1954 KB)  

    Typical parameters of wideband speech and audio signals, including digitized versions of each, potential applications, and available transmission media, are described. Facts about human auditory perception that are exploited in audio coding and quality measures that play an important role in coder evaluations and designs are reviewed. Techniques for efficient coding of wideband speech and audio signals, with an emphasis on existing standards, are discussed. The audio coding standard developed by the Moving Pictures Expert Group within the International Organization for standardization (ISO/MPEG) is covered in some detail, since it will be used in many application areas, including digital storage, transmission, and broadcasting of audio-only signals and audiovisual applications such as videotelephony, videoconferencing, and TV broadcasting. Ongoing research and standardization work is outlined.<> View full abstract»

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  • Whither speech recognition: the next 25 years

    Publication Year: 1993 , Page(s): 54 - 62
    Cited by:  Papers (6)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1178 KB)  

    The fundamentals of speech recognition are reviewed. The dimensions of the speech recognition task, speech feature analysis, pattern classification using hidden Markov models, language processing, and the current accuracy of speech recognition systems are discussed. The applications of speech recognition in telecommunications, voice dictation, speech understanding for data retrieval, and consumer products are examined.<> View full abstract»

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  • Tools for real-time signal-processing research

    Publication Year: 1993 , Page(s): 64 - 74
    Cited by:  Papers (3)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2310 KB)  

    The use of digital signal processing (DSP) devices for real-time communication applications is discussed. The authors comment on distinguishing aspects of DSP architecture, describing not so much individual processors as those features common to DSPs and distinct from modern general-purpose processors. They describe three DSP32xx-based machines that support DSP algorithm implementation: SURF-board, HoBo, and DSP3. They also described rtpi, a source-code debugger for workstations and for the AT&T DSP32C signal-processor integrated circuit, and dspx, a collection of subroutines and host programs that provides an execution environment for DSPs akin to the UNIX environment. These tools facilitate the transfer of algorithms from mainframes or workstations to DSP hardware. Included are case studies of two real-time implementations: the low-delay CELP (LD-CELP) speech coder and the decoder side of the perceptual audio coder (PAC), an algorithm that compresses CD-quality audio into a 128-kb/s stream without perceptible distortion.<> View full abstract»

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  • Speech codecs for personal communications

    Publication Year: 1993 , Page(s): 76 - 83
    Cited by:  Papers (7)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1020 KB)  

    Some of the many factors that go into the design of a personal communications system (PCS) are considered. The ways in which these factors affect the speech codec are discussed. Cell size, multiple access methods, and the trade-offs in PCS design are examined. Possible future designs of PCSs and their codecs are described.<> View full abstract»

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  • A synchronous digital hierarchy network management system

    Publication Year: 1993 , Page(s): 84 - 90
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1884 KB)  

    The critical issues in multivendor environments and operation systems of telecommunication networks essential to speeding up the handling of service orders and service restoration after failures are discussed. To overcome these problems as the software backlog grows, the authors propose the application of a telecommunications management network (TMN) architecture together with an object-oriented network resource (ONR) model. The second phase of the synchronous digital hierarchy (SDH) network management system, which is based on the TMN architecture and ONR model, is examined.<> View full abstract»

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  • Defining, designing, and evaluating digital communication systems

    Publication Year: 1993 , Page(s): 91 - 101
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1383 KB)  

    The fundamental relationships in defining, designing, and evaluating digital communication system performance are reviewed. The concept of bandwidth-limited and power-limited systems and how such conditions influence the design when the choices are confined to M-ary phase-shift keying (MPSK) and M-ary frequency-shift keying (MFSK) modulation are examined. The definitions and computations involved in transforming from data bits to channel bits to symbols to chips are discussed. It is suggested that since most digital communication systems share these concepts, understanding them should enable one to evaluate other such systems in a similar way.<> View full abstract»

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Aims & Scope

IEEE Communications Magazine covers all areas of communications such as lightwave telecommunications, high-speed data communications, personal communications systems (PCS), ISDN, and more.

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Osman Gebizlioglu
Huawei Technologies