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IEEE Transactions on Communications

Issue 5 • Date May 1978

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Displaying Results 1 - 25 of 38
  • [Front cover and table of contents]

    Publication Year: 1978, Page(s): 0
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  • Through the digital processor

    Publication Year: 1978, Page(s):489 - 492
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (551 KB)

    First Page of the Article
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  • Introduction to Papers on TDM/FDM Transmultiplexers

    Publication Year: 1978, Page(s):697 - 698
    Cited by:  Papers (10)
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    Freely Available from IEEE
  • [Back cover]

    Publication Year: 1978, Page(s): 0
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    Freely Available from IEEE
  • Digital TDM-FDM Translator with Multistage Structure

    Publication Year: 1978, Page(s):734 - 741
    Cited by:  Papers (22)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (688 KB)

    In this paper, a new digital signal processing algorithm for the digital TDM-FDM translator is proposed. The digital TDM-FDM translator, which performs a direct translation between two multiplex formats in the telephone network (time-division-multiplexing (TDM) and frequency-division-multiplexing (FDM)) by using digital techniques, has advantages in accuracy and stability of characteristics over e... View full abstract»

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  • Development of a TDM/FDM Transmultiplexer

    Publication Year: 1978, Page(s):726 - 733
    Cited by:  Papers (16)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (672 KB)

    Recently, digital systems such as digital telephone switching systems and digital transmission paths are being introduced more and more into communications networks in which signals are handled with Time Division Multiplex (TDM). There still exists, on the other hand, a number of analog transmission paths in which signals are multiplexed with Frequency Division Multiplex (FDM). Therefore, it is im... View full abstract»

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  • Synthesis of a T-Carrier Bit Stream Processing System: An Integrated Transmission and Switching System

    Publication Year: 1978, Page(s):618 - 625
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (792 KB)

    T-carrier is a point-to-point digital time division multiplex transmission system. It is designed to transmit voice and signaling information with low distortion between two points. T-carrier systems are not required to interpret dialed numbers or make routing decisions. When these switching functions are required, the previous approach has been to demodulate the multiplexed signals into their ori... View full abstract»

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  • A Three-Dimensional Spatial Non-Linear Predictor for Television

    Publication Year: 1978, Page(s):578 - 583
    Cited by:  Papers (12)  |  Patents (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (592 KB)

    This paper presents a three-dimensional non-linear prediction technique for use in differential pulse code modulation systems used to encode television signals. The prediction is a weighted sum of three estimates called representatives. Each representative is a nonlinear estimate based on previous pels in one of three planes containing the pel to be predicted. The paper contains an explanation of ... View full abstract»

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  • Separation of NTSC Signals by Minimum Mean Square Error Filters and Adaptive Filters

    Publication Year: 1978, Page(s):583 - 593
    Cited by:  Papers (7)  |  Patents (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1328 KB)

    Two techniques for separating a composite NTSC signal into luminance and chrominance components are developed and compared. In the first technique, fixed filters, which are based upon minimum mean square error estimators, are designed. It is shown that, when samples from successive lines are used, these filters have a comb structure in the region of the frequency spectrum in which the luminance an... View full abstract»

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  • A Twelve-Channel Digital Echo Canceler

    Publication Year: 1978, Page(s):647 - 653
    Cited by:  Papers (93)  |  Patents (41)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (672 KB)

    We describe a recently constructed 12-channel digital echo canceler that interfaces directly with the 8-bit μ255 PCM now standard for digital transmission in the telephone plant. The four most interesting features of the canceler are time sharing of circuitry to reduce per channel costs, floating-point multiplication, loop-gain normalization, and the use of a test channel for fault detection.... View full abstract»

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  • Notchless Bi-Level Quantizer for Facsimile and Its Effect on Coding Efficiency

    Publication Year: 1978, Page(s):611 - 618
    Cited by:  Papers (5)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (736 KB)

    With a facsimile bi-level quantizer, notches often occur along the white and black borders of a document when the output of a photosensor goes up and down around a threshold. The objects of this work are, first, to present a notchless bi-level quantizer, and secondly, to improve coding efficiency by using the quantizer. It is pointed out that quantization is comprised of many important aspects fro... View full abstract»

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  • Design Technique for Multiplexing Asynchronous Digital Video and Audio Signals

    Publication Year: 1978, Page(s):601 - 610
    Cited by:  Patents (10)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1088 KB)

    To apply digital transmission to the distribution of television program material it is necessary to encode both sound and picture signals, protect them from the effects of transmission errors and multiplex them into a form suitable for the transmission link that is to be used. Coding, error protection and multiplexing have all received extensive study but their combined application in a system has... View full abstract»

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  • Digital Processing Techniques in the 60 Channel Transmultiplexer

    Publication Year: 1978, Page(s):698 - 706
    Cited by:  Papers (48)  |  Patents (10)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (920 KB)

    Techniques applied to the digital processing of speech and signaling in a 60 channel FDM to 30 channel PCM converter are presented. Great efficiency is achieved through connecting a particular type of Fourier Transform computer to a polyphase network in which coefficient symmetries are exploited. Digital processing parameter values have been chosen so as to meet specified performance objectives. R... View full abstract»

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  • Carrier and Clock Recovery for 8 PSK Synchronous Demodulation

    Publication Year: 1978, Page(s):528 - 533
    Cited by:  Papers (6)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (648 KB)

    Synchronous demodulation of Phase-shift-keyed transmissions requires the recovery of carrier and clock timing signals. Envelope detection of the 70 MHz IF signal is used to recover clock, and baseband processing is used to recover carrier for an 8 PSK digital radio with a data rate of 90 Mbits/s in the 11 GHz band. A sequential phase detector is used in a high noise application. Two versions of th... View full abstract»

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  • An Experimental Microprocessor-Implemented 4800 Bit/s Limited Distance Voice Band PSK Modem

    Publication Year: 1978, Page(s):507 - 512
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (584 KB)

    A low-cost 4800 bit/s modem is described which is applicable to limited distance, direct-copper channels. The modulation technique is eight-phase PSK and both the transmitter and receiver algorithms are aimed at economy of implementation in digital circuitry. The transmitter uses digitally stored waveform elements, and the detection and clock recovery techniques are based on received signal polari... View full abstract»

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  • On the Design of Quantizers for DPCM Coders: Influence of the Subjective Testing Methodology

    Publication Year: 1978, Page(s):565 - 572
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (744 KB)

    In the Candy design procedure for DPCM quantizers, the subject is given a specific task to perform. We test the hypothesis that the form of this task influences the results that are obtained. In one experiment the viewers were permitted unlimited time to evaluate noise visibility; in another test using a different testing procedure viewing time was reduced to one second. Visibility functions were ... View full abstract»

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  • TDM-FDM Conversion Requiring Reduced Computation Complexity

    Publication Year: 1978, Page(s):707 - 719
    Cited by:  Papers (13)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (976 KB)

    We present an approach to perform the conversion between two widely used multiplexing techniques in telephony, time division, multiplex (TDM) to frequency division multiplex (FDM), using digital signal processing techniques. By exploiting some results from the theory of computational complexity we reduce considerably the number of computations required. Furthermore the use of only nonrecursive (FI... View full abstract»

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  • A 4800 Bit/s Microprocessor Data Modem

    Publication Year: 1978, Page(s):493 - 498
    Cited by:  Papers (8)  |  Patents (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (768 KB)

    The development of a new 4800 bit/s data modem, based on real-time digital signal processing by program controlled microprocessors, is described. The modem is fully compatible with the CCITT Recommendations V.27 bis and V.27 ter. In the microprocessor modem, all the digital signals are processed by one general purpose microprocessor unit only and no hardware multiplier is employed. A series of pro... View full abstract»

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  • Bit Rate Per Channel Halving in PCM Multiplexes by Speech Interpolation and Adaptive Quantization

    Publication Year: 1978, Page(s):638 - 646
    Cited by:  Papers (5)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (864 KB)

    An all digital system, labeled PCM.RR. is presented, which enables the doubling of traffic capacity of PCM links. This is obtained, although keeping the transmission quality impairment very close to the normal PCM standards, by properly using "Adaptive Quantization" and "Speech Interpolation" performed by means of a "Speech Detector" that works directly on the A View full abstract»

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  • A Microprocessor-Based PSK Modem for Packet Transmission Over Satellite Channels

    Publication Year: 1978, Page(s):552 - 564
    Cited by:  Papers (14)  |  Patents (21)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1312 KB)

    This paper describes a microprocessor-based modem developed for use in a packet switching network over satellite channels. This digital modem can process both BPSK and QPSK packets with near optimum error rate performance over channels with marginal signal energy-to-noise density ratio. Of principal concern is the development of the discrete time algorithms which form the basis of the microinstruc... View full abstract»

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  • A Digital Codec Simulation Facility

    Publication Year: 1978, Page(s):665 - 669
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (568 KB)

    This paper describes a minicomputer facility developed to aid in the evaluation of the grade-of-service impact of digital codecs. Two minicomputers are interfaced with 15 bit A/D and D/A converters so that an analog signal such as speech can be quantized and stored in real time at sampling rates up to 72 kHz. The acquired digital samples can then be processed by various PCM, ADPCM, and ADM algorit... View full abstract»

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  • Tamed Frequency Modulation, A Novel Method to Achieve Spectrum Economy in Digital Transmission

    Publication Year: 1978, Page(s):534 - 542
    Cited by:  Papers (169)  |  Patents (33)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (912 KB)

    This paper describes a new type of frequency modulation, called Tamed Frequency Modulation (TFM), for digital transmission. The desired constraint of a constant envelope signal is combined with a maximum of spectrum economy which is of great importance, particularly in radio channels. The out-of-band radiation is substantially less as compared with other known constant envelope modulation techniqu... View full abstract»

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  • Modulation Considerations for a 91 Mbit/s Digital Radio

    Publication Year: 1978, Page(s):523 - 528
    Cited by:  Papers (9)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (664 KB)

    The DRS-8 is a 91 Mbit/s long haul digital radio system designed for use in the Canadian 8 GHz frequency band. This paper discusses the considerations which lead to the choice of Quadrature Partial Response Signaling (QPRS) for this application. A method of implementing QPRS that circumvents power amplification difficulties and permits the use of simple conventional filtering and equalization is p... View full abstract»

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  • Passband Timing Recovery in an All-Digital Modem Receiver

    Publication Year: 1978, Page(s):517 - 523
    Cited by:  Papers (44)  |  Patents (26)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (624 KB)

    The performance of conventional modem receivers, where adaptive equalization is achieved by a digital transversal filter with tap gains spaced at the symbol interval, depends critically on the choice of the sampling phase. In this paper, a digital timing recovery loop is described and analyzed in the case of passband quadrature amplitude modulated data signals. Under conditions likely to be encoun... View full abstract»

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  • An Improved Method for Digital SSB-FDM Modulation and Demodulation

    Publication Year: 1978, Page(s):720 - 725
    Cited by:  Papers (23)  |  Patents (7)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (584 KB)

    A new method for digital implementation of SSB-FDM modulation and demodulation is presented, which utilizes the FFT algorithm to reduce the multiplication rate. The hardware realization of the presented method is shown to be the simplest; it consists of only an FFT processor and a set of complex bandpass filters which operate at the same rate as the input baseband sequences; no signal conversions ... View full abstract»

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Aims & Scope

IEEE Transactions on Communications focuses on all telecommunications including telephone, telegraphy, facsimile, and point-to-point television by electromagnetic propagation.

 

 

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Naofal Al-Dhahir
University of Texas at Dallas