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IEEE Transactions on Communication Technology

Issue 6  Part 1 • Date December 1971

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  • [Front cover and table of contents]

    Publication Year: 1971, Page(s): 0
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  • Oracular Vision

    Publication Year: 1971, Page(s):870 - 871
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (98 KB)

    First Page of the Article
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  • A 36-Mbit/s Television Codec Employing Pseudorandom Quantization

    Publication Year: 1971, Page(s):872 - 879
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (770 KB)

    The paper describes an experimental system constructed to allow investigation of pseudorandom dither signals for coarse quantization of 625-line monochrome television siginals. The system employs a separate encoder/decoder for the television synchronizing pulses so that the picture signal can be allowed to occupy the full nonsaturating range of the video encoder. Dither samples are added to the vi... View full abstract»

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  • The Effect of Dither on Luminance Quantization of Pictures

    Publication Year: 1971, Page(s):879 - 888
    Cited by:  Papers (37)  |  Patents (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1756 KB)

    This work analyzes the operation of a dithered quantizer of picture luminance. It is shown that the addition of dither before quantization restores some of the pictorial information which a coarse quantizer would otherwise discard. Two-dimensional ordered dither patterns are described which are considerably more effective for this purpose than random distributions of the same dither samples. The p... View full abstract»

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  • Adaptive Variable-Length Coding for Efficient Compression of Spacecraft Television Data

    Publication Year: 1971, Page(s):889 - 897
    Cited by:  Papers (54)  |  Patents (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (941 KB)

    An adaptive variable length coding system is presented. Although developed primarily for the proposed Grand Tour missions, many features of this system clearly indicate a much wider applicability. Using sample to sample prediction, the coding system produces output rates within 0.25 bit/picture element (pixel) of the onedimensional difference entropy for entropy values ranging from 0 to 8 bit/pixe... View full abstract»

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  • Delayed Encoding: Stabilizer for Adaptive Coders

    Publication Year: 1971, Page(s):898 - 907
    Cited by:  Papers (30)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1414 KB)

    The decision process in source encoders can be influenced favorably by anticipating future quantizing errors and modifying the quantizer appropriately. This requires that the signal code be delayed slightly from the corresponding input signal sample. As an adaptation of an existing coder, little advantage is obtained [8]. However, the process has a stabilizing influence so that much stronger adapt... View full abstract»

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  • A Differential Pulse-Code-Modulation Codec for Videotelephony Using Four Bits Per Sample

    Publication Year: 1971, Page(s):907 - 912
    Cited by:  Papers (12)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (635 KB)

    A video codec is described that encodes a 1-MHz analog Picturephone® signal into a 6.312-Mbit/s digital form, suitable for transmission on the Bell System T2 digital facility. Through efficient coding of the horizontal sync format, the bulk of the horizontal blanking period is available for sending active video information. The signal is differentially encoded into 4 bits per sample with a qu... View full abstract»

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  • Transient-Mode Buffer Stores for Nonuniform Code TV

    Publication Year: 1971, Page(s):913 - 922
    Cited by:  Papers (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1093 KB)

    Buffer stores are needed at both sender and receiver whenever a real-time signal is coded into a varying rate sequence of digits and these are transmitted over a channel at a uniform rate. Practical sending stores must be finite in size and therefore are subject to overflow; they thus function in a transient mode. In this paper, deterministic constraints on the operation of sending and receiving s... View full abstract»

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  • Variable-Length Redundancy Removal Coders for Differentially Coded Video Telephone Signals

    Publication Year: 1971, Page(s):923 - 926
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (465 KB)

    A study of the statistics of a differential pulse-code modulation coder for Picturephone® signals which uses a three-bit uniform length code suggests that a higher transmission efficiency can be obtained with a variable word length code. This permits an increase in number of quantizing levels used, thus improving picture quality. A quantizer with 24 levels rather than eight can be used provid... View full abstract»

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  • The Effect of Channel Errors in the Differential Pulse-Code-Modulation Transmission of Sampled Imagery

    Publication Year: 1971, Page(s):926 - 933
    Cited by:  Papers (6)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1123 KB)

    This paper presents an analysis, simulation, and discussion of the effects of communication errors on four-bit differential pulse-code modulation (DPCM) sampled imagery. Simulations are presented that describe the effects of inserting periodic "PCM updates" in order to correct communication errors in the DPCM transmission of photographic scenes that have been scanned and sampled at the Nyquist rat... View full abstract»

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  • An Adaptive Dual-Mode Coder/Decoder for Television Signals

    Publication Year: 1971, Page(s):933 - 944
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1396 KB)

    An adaptive dual-mode coding system for television signals is described. Its main features are a low bit rate (1.5 bits per sample), the high quality of the reproduced picture, and its moderate hardware. The system is based on the statistical properties of video signals. Specifically, it makes use of the nonuniform spectrum of video signals in the form of a differential scheme containing linear pr... View full abstract»

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  • An Edge-Adaptive Three-Bit Ten-Level Differential PCM Coder for Television

    Publication Year: 1971, Page(s):944 - 947
    Cited by:  Papers (7)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (470 KB)

    A modified 3-bit per sample differential PCM coder that is subjectively comparable to a 10-level differential PCM coder is described. The accuracy of coding the signals preceding and following large signal changes is restricted. The bits thus saved are used to improve the coding accuracy of large signal changes. No visible impairments are introduced by this process. The changes in coding strategy ... View full abstract»

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  • Comparison of nth-Order DPCM Encoder With Linear Transformations and Block Quantization Techniques

    Publication Year: 1971, Page(s):948 - 956
    Cited by:  Papers (64)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (866 KB)

    Two important classes of coding schemes that use the spatial correlation of picture elements in reducing data redundancy are the differential pulse-code modulation (DPCM) and the unitary transform coding techniques. We will study the performance of an n th order DPCM system for n ranging from 1 to 22 and compare it to the pe... View full abstract»

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  • Image Coding by Adaptive Block Quantization

    Publication Year: 1971, Page(s):957 - 972
    Cited by:  Papers (39)  |  Patents (14)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (2592 KB)

    A new source encoder called the adaptive block quantizer is proposed for coding data sources that emit a sequence of correlated real numbers with known first- and second-order statistics, Blocks of source output symbols are first classified and then block quantized in a manner that depends on their classification. The system is optimized relative to both the mean square error and the subjective qu... View full abstract»

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  • Frequency Interleaved Sampling of a Color Television Signal

    Publication Year: 1971, Page(s):972 - 979
    Cited by:  Papers (14)  |  Patents (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (959 KB)

    In the transmission of color television signals over a digital communications system, the analog TV signal must first be converted to digital form. This paper treats the first step in this conversion, sampling of the analog waveform. A significant reduction in sampling rate can be achieved by using several properties of the television signal. The spectrum of the TV signal has the energy concentrat... View full abstract»

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  • Spatial Transform Coding of Color Images

    Publication Year: 1971, Page(s):980 - 992
    Cited by:  Papers (38)  |  Patents (18)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (19800 KB)

    During the past few years several monochromeimage transform-coding systems have been developed. In these systems, a quantized and coded version of a spatial unitary transform of an image is transmitted over a channel, rather than an image itself. In this paper the transform-coding concept has been applied to the coding of color images represented by three primary color planes of data. The principl... View full abstract»

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  • Digital Coding of Color Picturephone Signals by Element-Differential Quantization

    Publication Year: 1971, Page(s):992 - 1006
    Cited by:  Papers (14)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (2829 KB)

    An element differential quantizer has been used to encode three baseband components of a color Picturephone® type signal in real time. The first part of this paper is concerned with an investigation of the extra bits required to transmit chrominance information over that required for a high-quality luminance signal (coded to 4 bits per picture element). We have found that a total allocation o... View full abstract»

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  • Focal Points in Speech Communication Research

    Publication Year: 1971, Page(s):1006 - 1015
    Cited by:  Papers (11)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1066 KB)

    Advances in several areas of speech communication research are discussed. Areas selected for comment include: 1) digital encoding and transmission of speech; 2) computer synthesis of speech; 3) automatic speaker verification; 4) speech production; 5) speech perception; and 6) interactive design of digital filters. Advances in these areas have been facilitated by two important tools: a) the growing... View full abstract»

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  • A Hardware Realization of a Digital Formant Speech Synthesizer

    Publication Year: 1971, Page(s):1016 - 1020
    Cited by:  Papers (8)  |  Patents (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (630 KB)

    Terminal analog or formant speech synthesizers have found many applications in speech research. These include investigation of computer voice response, speech synthesis-by-rule, and speech perception studies, among others. Many types of formant synthesizers have been designed and realized either in analog circuitry or as a computer program. In this paper we describe a digital hardware realization ... View full abstract»

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  • An Experimental 9600-bits/s Voice Digitizer Employing Adaptive Prediction

    Publication Year: 1971, Page(s):1021 - 1032
    Cited by:  Papers (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1192 KB)

    An experimental model of a coder for transmission of speech over a 9600-bits/s digital channel was built to demonstrate feasibility of an adaptive prediction-coding technique. After analog-to-digital conversion of the speech input, the coder employs digital processing using a computer type organization. Resonances in the short-term speech spectrum are removed by a nonrecursive digital transmit fil... View full abstract»

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  • A Variable-Step-Size Robust Delta Modulator

    Publication Year: 1971, Page(s):1033 - 1044
    Cited by:  Papers (30)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1576 KB)

    An optimum adaptive delta modulator-demodulator configuration is derived. This device utilizes two past samples to obtain a step size which minimizes the mean square error for a Markov Gaussian source. The optimum system is compared using computer simulations with the linear delta modulator and an enhanced Abate delta modulator. In addition the performance is compared to the rate distortion bound ... View full abstract»

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  • A Comparison of Orthogonal Transformations for Digital Speech Processing

    Publication Year: 1971, Page(s):1045 - 1050
    Cited by:  Papers (23)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (633 KB)

    Discrete forms of the Fourier, Hadamard, and Karhunen-Loève transforms are examined for their capacity to reduce the bit rate necessary to transmit speech signals. To rate their effectiveness in accomplishing this goal the quantizing error (or noise) resulting for each transformation method at various bit rates is computed and compared with that for conventional companded PCM processing. Base... View full abstract»

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  • Systems Analysis of a TDM-FDM Translator/Digital A-Type Channel Bank

    Publication Year: 1971, Page(s):1050 - 1059
    Cited by:  Papers (43)  |  Patents (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (996 KB)

    In keeping with the trend to greater use of digital circuits for signal processing, a project was undertaken to realize in an exploratory way an important telecommunication function using as great a proportion of digital hardware as possible. The function chosen is that of the A -channel bank; viz., the frequency division multiplexing (FDM) of 12 voiceband sign... View full abstract»

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  • Partitioning of Digital Filters for Integrated-Circuit Realization

    Publication Year: 1971, Page(s):1059 - 1063
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (531 KB)

    The details of the partitioning of a digital filter for integrated-circuit realization are discussed. It is shown that the fourth-order filtering requirement of an all digital channel bank serving 24 channels may be implemented with 40 integrated-circuit chips. View full abstract»

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  • Pulse-Code Modulation to Voice Conversion - Binary Rate Multiplier Differential Pulse-Code-Modulation Decoder

    Publication Year: 1971, Page(s):1064 - 1069
    Cited by:  Papers (1)  |  Patents (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (425 KB)

    An experimental and computer investigation of a 9-bit, 16-MHz binary rate multiplier (BRM) used in converting digital signals differential pulse-code modulation (DPCM) to analog signals (voice) is reported in this paper. The physical electronic circuitry was provided with a stream of real-time digital samples at a 32-kHz rate from a magnetic tape which had been generated by a computer simulation. ... View full abstract»

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Aims & Scope

This Transactions ceased publication in 1971. The current retitled publication is  IEEE Transactions on Communications.

Full Aims & Scope