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IEEE Transactions on Communications

Issue 5 • 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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    Freely Available from IEEE
  • 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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  • LSI Processor for Digital Signal Processing and Its Application to 4800 Bit/s Modem

    Publication Year: 1978, Page(s):499 - 506
    Cited by:  Papers (8)  |  Patents (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (946 KB)

    This paper describes a fast data processing LSI unit tailored to the digital signal processing (DSP) applications in the field of electrical communications. The results of successful application to the 4800 bit/s modem are also given. The LSI processor discussed here adopts a firmware control scheme to enhance the flexibility and freedom of application and extensively utilizes the pipeline process... 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 (850 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 theA-law compressed digital si... View full abstract»

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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 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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  • A Practical Design Approach to Decision Feedback Receivers with Conventional Filters

    Publication Year: 1978, Page(s):679 - 689
    Cited by:  Papers (3)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1016 KB)

    A method for designing conventional filters for decision feedback systems is described. Practical considerations, such as error propagation effect, timing inaccuracy and complexity, are incorporated in the design rules. In particular, non-band-limited noisy transmission channels and channels impaired by bandwidth limitation are investigated. In addition, noise and bandwidth limitations are taken i... 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 (29)  |  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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  • Simple Inductorless Automatic Line Equalizer for PCM Transmission Using New Variable Transfer Function

    Publication Year: 1978, Page(s):675 - 678
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (344 KB)

    A new variable transfer function is proposed and its application to digital transmission is investigated. The realization of the new variable transfer function is developed for use in a digital transmission automatic line build out (ALBO) network. A simple inductorless ALBO network having ±15 dB variable range is demonstrated for use in 1.544 Mbit/s PCM transmission. Intersymbol interference ... 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 (52)  |  Patents (27)
    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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  • A Digital Television Sequence Store

    Publication Year: 1978, Page(s):594 - 600
    Cited by:  Papers (13)  |  Patents (49)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (824 KB)

    This paper describes the capabilities and design of a new digital video system which permits a user to record and playback sequences, up to 80 s long, of digitized color television signal. In addition, a user may process the stored video via the associated computer and view the results. The above system, which is called the DVS (Digital Video Store), is intended as a simulation tool for investigat... View full abstract»

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  • A Microprocessor Log PCM/ADPCM Code Converter

    Publication Year: 1978, Page(s):660 - 664
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (416 KB)

    A microprocessor has been used to translate between Log PCM and ADPCM (Adaptive Differential PCM) code forms. This system, in bridging the gap between simulation and prototyping, provides realtime speech processing with user interaction. Continuously coded speech can he subjectively evaluated while switching the values of code word length, step size, or predictor coefficients. Translations of addi... 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 High-Speed FFT Processor

    Publication Year: 1978, Page(s):690 - 696
    Cited by:  Papers (9)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (728 KB)

    A high-speed, low-power, fast Fourier transform (FFT) processor is described in this paper. The FFT processor is designed around parallel arithmetic functions (16 by 16 multiplier and 16-bit adders) and can operate up to a 17.0-MHz clock rate. It performs a 128-point FFT in 250 μs at 16-MHz clock rate and therefore can be used for applications such as frequency-division multiplexing/timedivis... 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: A Functional Relationship Between Visibility, Probability and Masking

    Publication Year: 1978, Page(s):573 - 578
    Cited by:  Papers (33)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (584 KB)

    Visibility functions measure the relative visibility of noise added to a picture at those points where some measure of local activity exceeds a given threshold. The functions are obtained from a series of subjective experiments and vary with the content of the picture. Visibility functions have been used to design quantizing characteristics for DPCM coding of monochrome and color signals and for t... 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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  • A Microprocessor-Based PSK Modem for Packet Transmission Over Satellite Channels

    Publication Year: 1978, Page(s):552 - 564
    Cited by:  Papers (17)  |  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 Twelve-Channel Digital Echo Canceler

    Publication Year: 1978, Page(s):647 - 653
    Cited by:  Papers (120)  |  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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  • A Bandwidth Compressive Modulation System Using Multi-Amplitude Minimum Shift Keying (MAMSK)

    Publication Year: 1978, Page(s):543 - 551
    Cited by:  Papers (25)  |  Patents (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1096 KB)

    A bandwidth compressive modem making use of multiamplitude minimum shift keying (MAMSK) has been designed and implemented in a laboratory environment at microwave frequencies. This system achieves a substantial bandwidth reduction over binary PSK and operates within 0.5 dB of theoretical performance. A number of easily implemented microwave transmitters have been designed to generate the required ... 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 (170)  |  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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  • Analysis of Digitally Generated Sinusoids with Application to A/D and D/A Converter Testing

    Publication Year: 1978, Page(s):669 - 675
    Cited by:  Papers (13)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (608 KB)

    Several aspects of the design of digital frequency synthesizers are considered, and a detailed analysis of the spectral purity of digitally synthesized frequencies is given. These results are then applied to a specific application: the testing of A/D and D/A converters. 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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  • On the Design of Quantizers for DPCM Coders: Influence of the Subjective Testing Methodology

    Publication Year: 1978, Page(s):565 - 572
    Cited by:  Papers (4)
    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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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