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Communication Technology, IEEE Transactions on

Issue 3 • Date June 1969

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Displaying Results 1 - 15 of 15
  • [Front cover and table of contents]

    Publication Year: 1969 , Page(s): 0
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    Freely Available from IEEE
  • The 10-C System, a Stored-Program Controlled Reed Switching System

    Publication Year: 1969 , Page(s): 333 - 339
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (822 KB)  

    The 10-C telephone switching system comprises modular multistage link switching networks composed of reed crosspoint matrices, controlled by a stored-program controlled central processor system. In addition to the advantages inherent in the use of sealed contacts, such as high transmission quality, low noise, long life, etc., the following useful system features are obtained: high switching speed, high crosspoint efficiency, optimum match between network and central control, efficient path search and marking procedures, easy extensibility, and integrated quasi-electronic plug-in mounting techniques. The 10-C central processor system is mainly composed of integrated circuit logic and ferrite memory features: high speed, simplicity, compact construction, and high intrinsic reliability. Common storage in extensible randomaccess ferrite memory is provided for program instructions, and translation and parameter tables, as well as variable call data. The duplicate processors working in the load-sharing mode are complemented with a program-reload and automatic recovery system. The first exchange of this type was handed over to the Belgian administration in 1967 and integrated in the Antwerp area automatic telephone network. View full abstract»

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  • Adaptive Routing Techniques for Distributed Communications Systems

    Publication Year: 1969 , Page(s): 340 - 349
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (920 KB)  

    The concept of a netted or distributed communications system is significant because it offers a major advantage over conventional communications systems, i.e., a better chance of providing surviving lines of communication after an attack on the system. During and after an attack, however, an effective adaptive routing technique is necessary to adjust the routing tables of the message-switching control system to the changing situation. Previously investigated adaptive routing techniques are shown to be insufficient for the task, and a number of promising alternatives are formulated and investigated such as some stochastic techniques, which use information on messages passing through the network to adjust the tables, and some deterministic techniques, which use dynamic programming or graph-theoretic algorithms to recalculate changes in the tables from observed changes in the network. Each alternative has operational advantages, which make it good for certain types of communications systems, and certain disadvantages if applied to others. Regions of applicability and inapplicability, with respect to the above system parameters, are given for the various techniques. Recommended techniques are specified for two currently proposed applications of distributed communications systems. A number of research areas are pointed out in which further efforts in the analysis and simulation of adaptive routing techniques will have useful payoffs in the design of future distributed communications systems. View full abstract»

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  • Variable Block Length and Transmission Efficiency

    Publication Year: 1969 , Page(s): 350 - 355
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (596 KB)  

    This work is concerned with the effect of grouping data into blocks for transmission in an error detect-retransmit system. A formula is presented giving transmission efficiency E in data bits per binit. E is a function of the time per bit, block length, nondata bits per block, data bits per word, and average time \bar{T} per block transmission. \bar{T} takes into consideration block length, block starting bit times, mean time to error, turnaround time upon error detection, and correct-block acknowledge time. Using the formula for E and the statistics of the bit error rate distribution, an optimum or even variable block length may be chosen. The variable block length system automatically switches when the present efficiency is estimated, with a given confidence, to be nonoptimum. View full abstract»

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  • Comparison of Diversity, Nondiversity, and Coding on a Parallel FSK HF Channel

    Publication Year: 1969 , Page(s): 355 - 367
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1424 KB)  

    Selected short block and convolutional code improvements using dual inband frequency diversity and nondiversity frequency-shift keyed experimental data obtained on a 2800-km HF path are compared. It is shown that time dispersion techniques (interleaving, diffusion, etc.) are necessary for the short codes to perform measurably better than uncoded dual inband diversity With interleaving, more than two orders of magnitude improvement resulted. The measured binary errors on a nondiversity FSK subchannel (one of 16) are shown to be statistically dependent (nonrandom) for transmission frequencies between the path lowest usable frequency and maximum usable frequency. The range of gap and burst distributions are given indicating the small difference in distribution for the set of frequencies and times on this particular mid-latitude HF path. Comparison of nondiversity and diversity burst distributions present the burst length reductions and change in distribution brought about by diversity. View full abstract»

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  • A New Method for Calculating Probabilities of Errors Due to Impulsive Noise

    Publication Year: 1969 , Page(s): 368 - 379
    Cited by:  Papers (26)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1256 KB)  

    A new approach to the prediction of error rates in digital data transmission systems when the dominant source of errors is given by noise bursts, each having a fiat spectrum across the band of interest, is described. Specifically, a hierarchy of phaseaveraged conditional error probabilities called k th receiver impulse characteristics (RIC) are defined, which depend only on the receiver's structure. Error probabilities are then computed by averaging the RICs over the statistics of the impulsive noise which is characterized at the RF input of the receiver. To illustrate the approach in a practical, interesting situation, a detailed analysis is carried out for a phase-shift keyed system employing either a linear or a hard-limiting receiver, and for impulse rates small enough that errors are essentially caused by single impulses. View full abstract»

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  • Performance of Optimum and Suboptimum Synchronizers

    Publication Year: 1969 , Page(s): 380 - 389
    Cited by:  Papers (26)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (922 KB)  

    The optimum (maximum-likelihood) synchronizer for extracting bit synchronization directly from a binary data stream is presented along with some simple suboptimum synchronizers that perform almost as well. The manner in which the performances of these systems depend on the pertinent system parameters as determined by a combined program of analysis, simulation, and laboratory experimentation are reported. Both synchronizer jitter and the degradation in error rate due to jitter are considered. View full abstract»

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  • Voiceband Four-Phase Data Set for Global Communication

    Publication Year: 1969 , Page(s): 390 - 395
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    A 2400-bit/s four-phase data set with unique clockrecovery and compatible-signal detector circuits is described. It is used as either a terminal set or self-switched regenerative repeater in AUTOVON. View full abstract»

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  • High-Speed Visual Communication over Existing Telephone Networks

    Publication Year: 1969 , Page(s): 395 - 403
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (881 KB)  

    A fully transistorized low-cost visual communication system has been constructed for the high-speed transmission of still two-level pictures (black and white) over the unmodified existing telephone networks. It reduces the transmission times of ordinary facsimile by a factor of from 10:1 to 20:1, still producing readable pictures with a signal-to-noise ratio of 20 dB. The case of short-distance communication (private telephone exchanges) and some other possibilities of particular application are also discussed. Experimental results are shown, recorded under various operating conditions. View full abstract»

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  • Computer-Aided Design Optimization of FDM-FM Communication Systems

    Publication Year: 1969 , Page(s): 403 - 412
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (994 KB)  

    A technique to determine the optimal design of an FDM-FM communications link considering both dollar cost and system performance is established. The four major items of a communications system, transmitter, receiver, transmitting antenna, and receiving antenna, are considered to be stages of a serial-multistage system with the signal-to-noise power ratio as a final boundary value and threshold as a constraint. For eyery combination of the four equipment items, an rms channel modulation index is computed, which for median performance and the system constraint minimizes the required received carrier power. The cost of those combinations of equipment meeting or exceeding the system requirements are computed and compared. Single variable search optimization techniques are used. Rigorous rapid design of analog communications systems is provided. The least cost system and other selected qualifying systems are explicitly determined. View full abstract»

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  • Hidden Residential Telephone Connections Demand in the Presence of Severe Supply Shortage

    Publication Year: 1969 , Page(s): 413 - 414
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (189 KB)  

    A survey in Santiago, Chile, shows a total unsatisfied demand for residential telephone connections which is four times as large as the waiting list. Factors hiding the demand include nonownership of homes and excessive delay in providing new lines. View full abstract»

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  • A Simple Approximation of Data System Error Rate

    Publication Year: 1969 , Page(s): 415 - 417
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    A simple error rate approximation is derived, and bounds on the accuracy are found. The results are applied to the question of how accurately the system error rate may be determined by using nonrandom data. View full abstract»

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  • Receiver Spurious Response Measurements

    Publication Year: 1969 , Page(s): 417 - 419
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (376 KB)  

    Experimental results are presented which demonstrate that significant intermodulation and cross-modulation products are generated in both the RF amplifier and mixer, in a typical receiver. Measured values of four additional spurious response types are given, for the same receiver. The measurement techniques used represent a departure from traditional methods. View full abstract»

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  • Comments on "Communication Nets in Random Behavior"

    Publication Year: 1969 , Page(s): 420
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    Understanding of the basic mathematical model of random communication nets is not possible unless assumptions are made that are both necessary and clear. Redundant and obscure statements of a problem make its solutions meaningless. Some conclusions are reached which conflict with previously obtained results. View full abstract»

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  • [Back cover]

    Publication Year: 1969 , Page(s): 0
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    Freely Available from IEEE

Aims & Scope

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

Full Aims & Scope