IEEE Transactions on Communications

Issue 2 • February 1974

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Displaying Results 1 - 25 of 29
  • [Front cover and table of contents]

    Publication Year: 1974, Page(s): 0
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    Freely Available from IEEE
  • Editorial

    Publication Year: 1974, Page(s): 97
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    Freely Available from IEEE
  • A Queueing Model for Radio Nets - Part III: Validation and Refinement

    Publication Year: 1974, Page(s):106 - 123
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1647 KB)

    In Parts I and II of this paper a generalized analytical queueing methodology for studying the performance of radio nets was presented and the methodology was applied to a number of net systems. In this part the methodology is refined and its assumptions and definitions are validated. It is important to emphasize that several of the refinements introduced here alter the methodology for multiplefre... View full abstract»

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  • Real-Time Minimal-Bit-Error Probability Decoding of Convolutional Codes

    Publication Year: 1974, Page(s):146 - 151
    Cited by:  Papers (39)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (578 KB)

    A recursive procedure is derived for decoding of rateR = 1/nbinary convolutional codes which minimizes the probability of the individual decoding decisions for each information bit, subject to the constraint that the decoding delay be limited to Δ branches. This new decoding algorithm is similar to, but somewhat more complex than, the Viterbi decoding algorithm. A "real-time," i.e.... View full abstract»

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  • Digital Amplitude-Phase Keying with M-Ary Alphabets

    Publication Year: 1974, Page(s):168 - 180
    Cited by:  Papers (111)  |  Patents (12)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1121 KB)

    Signal sets employing amplitude and phase keying (APK) with large alphabets conserve bandwidth and do not require as high a signal-to-noise ratio (SNR) as phase-shift keying (PSK). Twenty-nine empirically generated APK sets withM-ary alphabet sizes from 4 to 128 are investigated to determine optimum designs. Selected sets are compared on the basis of a symbol-error-probability bound for... View full abstract»

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  • Negatively Correlated Branches in Frequency Diversity Systems to Overcome Multipath Fading

    Publication Year: 1974, Page(s):180 - 190
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1082 KB)

    In multipath environments in which there is a compact concentration of the values of time-delay-difference (TDD) between signals arriving over each of the indirect paths and the direct path, it is possible, by suitably choosing frequency differences, to design a frequency diversity system in which the diversity branches are negatively correlated. This results in a reduced probability of simultaneo... View full abstract»

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  • Static and Dynamic Equalization of the L5 Repeatered Line

    Publication Year: 1974, Page(s):212 - 217
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (761 KB)

    The residual transmission deviation of the L5 repeatered line can be divided into two categories, static or time invariant and dynamic or time variant. The static deviation, which is due to design limitations and manufacturing deviations of the basic and regulating repeaters, is compensated for by manually adjustable equalizers designatedE1andE2. These equalizers are composed... View full abstract»

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  • Jumbogroup Frequency Supply

    Publication Year: 1974, Page(s):239 - 242
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (412 KB)

    The jumbogroup frequency supply provides the jumbogroup multiplex terminals with signals having the frequency accuracy(Delta F/F < 1/10^{8})required for frequency multiplexing 10 800 message channels. In addition to frequency precision, reliability is of utmost importance since many jumbogroup multiplex terminals are to be supplied by one jumbogroup frequency supply. Protection switc... View full abstract»

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  • Comments on "Spectrum of Manchester Coded FSK

    Publication Year: 1974, Page(s):270 - 271
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (134 KB)

    Hartmann [1] and Shehadeh and Chiu [2] have derived expressions for the spectrum of Manchester coded frequency-shift keyed (FSK) signals. The expressions are compared and the conditions under which they coincide are discussed. View full abstract»

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  • [Back cover]

    Publication Year: 1974, Page(s): 0
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    Freely Available from IEEE
  • Bounds to Probability of Error in Binary Communication Systems with Intersymbol Interference and Dependent or Independent Symbols

    Publication Year: 1974, Page(s):251 - 254
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (312 KB)

    Upper and lower bounds to the probability of error in a binary communication system with intersymbol interference and independent noise are computed. The symbols may be dependent or independent. The bounds are tight and practically coincide for a proper choice of certain parameters. View full abstract»

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  • Staged Fault and Laboratory Tests on a Cable Pair Protection System Designed to Serve Power Stations

    Publication Year: 1974, Page(s):193 - 199
    Cited by:  Papers (11)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (728 KB)

    Cable pairs entering power stations may be subjected to ground potential rise (GPR) and/or induction of several thousand volts during power system faults. A cable protection system designed to give a high degree of reliability is described, and the results of staged fault and laboratory tests are discussed. An analysis of neutralizing transformer transient performance shows how the transformer's b... View full abstract»

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  • A Centralized and Automated Transmission Surveillance System

    Publication Year: 1974, Page(s):230 - 234
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (544 KB)

    Continuous verification of the transmission integrity of a complex broadband network such as the L5 coaxial system requires many repetitive measurements at different locations and considerable processing of the measured data. To minimize the cost and time for these maintenance operations and to provide the best system reliability, a centralized, automated transmission surveillance system has been ... View full abstract»

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  • Main Station, Line Interconnection, and Signal Administration

    Publication Year: 1974, Page(s):221 - 225
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (416 KB)

    The L5 line connecting equipment fulfills several functions, including the routing of jumbogroup signals for through, branched, or terminal connections of the message service on the line. Any combination of three jumbogroup signals may be sent along the through route, branched directly to another route, or dropped locally to a multiplex terminal. Line pilots for dynamic equalization, temperature r... View full abstract»

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  • Carrier Synchronization and Detection of QASK Signal Sets

    Publication Year: 1974, Page(s):98 - 106
    Cited by:  Papers (63)  |  Patents (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (824 KB)

    A carrier regeneration loop which generates highly coherent quadrature reference signals for quadrature amplitude-shift keying (QASK) demodulation is presented. The loop employs the principle of decision feedback and has a structure analogous to a decision feedback loop for quadriphase signals suggested earlier in the literature. The error probabihty performance of QASK is computed in the presence... View full abstract»

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  • A New Type of VF Repeater for Two-Wire Transmission Loops

    Publication Year: 1974, Page(s):242 - 250
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (816 KB)

    Power loss at voice frequencies in two-wire telephone lines is presently overcome by employing electronic repeaters which produce bidirectional amplification without undue interaction between the outgoing and incoming paths. This isolation between the directional gain elements is achieved by employing balanced transformer windings or negative impedance transformations. Both methods rely heavily on... View full abstract»

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  • Atmospheric Propagation and Communication Channel Model for Laser Wavelengths: An Update

    Publication Year: 1974, Page(s):265 - 270
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (584 KB)

    Excellent reveiw papers on the state of the art of propagation through the atmosphere at laser wavelengths have been published during and prior to 1970. This concise paper gives a brief update of major developments that took place since 1970. Covered are the saturation phenomenon, heterodyne receiver performance, atmospheric turbulence model, and transmitter-aperture averaging effect. View full abstract»

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  • Estimation of the Average Density of a Nonuniform Poisson Process

    Publication Year: 1974, Page(s):162 - 167
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (480 KB)

    The average densitylambda (t)of a Poisson process is estimated by a nonstationary shot noise processs(t). The processs(t)is generated by a time-varying system whose impulse responseh (t, alpha)is so determined as to minimize the mean-square (ms) estimation error. It is shown that, under realistic assumptions,h (t, alpha )is a truncated parabol... View full abstract»

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  • Comparison of Time Codes for Source Encoding

    Publication Year: 1974, Page(s):151 - 162
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1016 KB)

    The time information for source-encoded, or compressed, sampled time functions is treated as a two-symbol source, the symbols corresponding to redundant and nonredundant samples. The entropy of this source for both the statistically independent symbol model and the Markov model is used as a reference for the comparison of time codes. Time encoding schemes are classified into two categories: total ... View full abstract»

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  • Fresnel-Corrected Second-Order Interfrequency Correlations for a Surface-Scatter Channel

    Publication Year: 1974, Page(s):138 - 145
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (816 KB)

    The correlation of the transfer function taken simultaneously at two different frequencies is computed for a random surfacescatter channel. The analysis is limited to transmission in the specular direction but uses a Fresnel-corrected model. It is therefore applicable to channels excited by a wide beam transmitter. Using this model it is possible to explain why in certain circumstances channel act... View full abstract»

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  • Low-Noise Ultralinear Line Repeaters for the L5 Coaxial System

    Publication Year: 1974, Page(s):206 - 211
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (648 KB)

    Two major characteristics of the coaxial cable that are of paramount importance in the design of coaxial line repeaters are the nominal cable loss and the variation in the cable loss due to seasonal variations in cable temperature. As a result, there are two types of line repeaters used to equalize for the cable loss characteristics. One is a low-noise ultralinear fixed-gain amplifier. It is desig... View full abstract»

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  • Discrete Time Analyses of Nonuniform Sampling First- and Second-Order Digital Phase Lock Loops

    Publication Year: 1974, Page(s):123 - 137
    Cited by:  Papers (81)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1080 KB)

    The present paper considers discrete time analyses of firstand second-order digital phase lock loops. These loops are characterized by the fact that they track the zero crossings of the incoming signal; consequently, the sampling intervals are nonuniform. The firstorder loop is analyzed for phase step and frequency step inputs; mean time to skip cycle is also considered. For phase step input, appr... View full abstract»

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  • The L5 Coaxial System Transmission System Analysis

    Publication Year: 1974, Page(s):190 - 192
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (336 KB)

    The L5 system design characteristics and features, including the transmission plan, frequency allocation, and predicted noise, intermodulation, and crosstalk performance, are described. The effects of such factors as modulation product addition, misalignment, and mastergroup frogging on system performance are discussed. Signal-signal-to-noise optimization through transmission level shaping is desc... View full abstract»

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  • Markov Process Analysis of PCM Line Monitors

    Publication Year: 1974, Page(s):261 - 265
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (544 KB)

    In PCM transmission systems, ensuring repeater timing and regenerative capabilities requires monitored enforcement of the ones density of the line waveform. One possible corrective monitor action is to pre-empt information bits and insert ones when necessary, and thus introduce errors into the pulse stream. The analysis of the resultant error rates for classes of digital and analog implementations... View full abstract»

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  • Line Protection Switching for the L5 Coaxial System

    Publication Year: 1974, Page(s):217 - 220
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (472 KB)

    A new 1-for-10 line protection switching system called LPSS-3 has been developed for the L5 coaxial system. Reliability and economic considerations dictate maximum switching spans of 150 mi. Control is primarily by integrated-circuit logic. The line switches use microwave switching diodes to achieve the required pass, modulation, and isolation characteristics. Switching is initiated when temperatu... 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