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Communication Technology, IEEE Transactions on

Issue 4 • Date December 1964

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

    Publication Year: 1964 , Page(s): 0
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    Freely Available from IEEE
  • Editorial [Fields of Interest of Committees and Fields of Communications Technical Committees]

    Publication Year: 1964 , Page(s): 115
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    Freely Available from IEEE
  • Communication with Orthogonal Polyphase Signals over a Noisy Channel with Doppler Frequency Shift

    Publication Year: 1964 , Page(s): 116 - 118
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    A set of N orthogonal signals is constructed with a modulated carrier taking N possible phase values, and the whole class of such sets is described with a coding procedure that employs a permutation of N integers. These signals are used for communication purposes, and it is shown that there exists a simple matchedfilter detector with a coding and decoding scheme that is unaffected by a phase shift and a Doppler frequency shift on the channel. View full abstract»

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  • A Geometrical Study of Transmitted Reference Communication Systems

    Publication Year: 1964 , Page(s): 118 - 123
    Cited by:  Papers (24)
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    Digital communication systems utilizing wide-band carriers require a coherent reference for optimal data processing. This reference may be either locally generated or transmitted simultaneously with the data. The latter system completely avoids the synchronization problem of locally generated reference systems but is degraded by the fact that two receivers are required, excess system dimension must be used, and the transmitter power is diluted by having to transmit the reference. This report is a study of a general transmitted reference (TR) system, with the primary objective of finding bounds on these restrictions. It is based upon geometrical considerations using the fact that a transmitted reference system can be described by vectors in, and linear transformations upon, an N -dimensional Euclidean space. In this way it can be shown, for example, that the dimension of the transmitting channel must be greater than that of the space of carrier signals for unique operation. This increase in dimension need be only slight in the noiseless case, but an advantage is gained by increasing the dimension in noisy operation. An equivalent expression for output SNR is obtained in terms of norms of signal vectors and a comparison is made with that of a locally generated reference (LGR) system. It is shown that a TR system always operates with at least a 3-dB poorer SNR than that of an ideal LGR system, with the bound increasing to 6 dB if the transmitter is power limited, and gets progressively worse as the transmitter power to noisepower ratio decreases below 0 dB. Some curves are plotted to show these relationships quantitatively. View full abstract»

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  • Serial Synchronization of Pseudonoise Systems

    Publication Year: 1964 , Page(s): 123 - 127
    Cited by:  Papers (25)
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    Radar, communications, and ranging systems can use pseudonoise modulated carriers. The extraction of information from the carrier requires the synchronization of a pseudonoise waveform at the receiver for correlation detection. For initial synchronization, the receiver must examine all possible time positions of the incoming pseudonoise waveform. In serial search the time difference between the pseudonoise modulation on the carrier and the pseudonoise waveform generated at the receiver is linearly varied. A continuous decision process determines when synchronization has been achieved. With additive white normal noise interference, the probabilities of false alarm and false dismissal during synchronization for coherent and incoherent detection are computed. The results are dependent on carrier power, noise per unit bandwidth, and search rate. View full abstract»

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  • Correlative Digital Communication Techniques

    Publication Year: 1964 , Page(s): 128 - 135
    Cited by:  Papers (47)  |  Patents (1)
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    A new method for the transmission of intelligence by means of a signal having certain correlation properties has been evolved. The theoretical and practical aspects of this concept are presented. An important advantage of these techniques is that for a fixed performance criteria, considerably higher speeds are possible compared to the presently known methods. In addition, the implementation is simple and straightforward. An unusual property of these techniques is the capability of error detection without the introduction of redundancy into the original data. Finally, expressions for spectral distributions and error performance as well as methods for practical implementation, including the errordetection process, are presented. View full abstract»

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  • An Analysis of Retransmission Systems

    Publication Year: 1964 , Page(s): 135 - 145
    Cited by:  Papers (64)  |  Patents (5)
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    This paper presents an analysis of the throughput rate R and undetected block error rate ρ for each of three basic types of retransmission logics: 1) send and wait for confirmation, 2) send continuously repeating each individual unconfirmed message, and 3) send continuously repeating each unconfirmed message together with those which followed it. Formulas for R and ρ were obtained in terms of the probability of detected block error and the probability of misinterpreted confirmation or retransmission request. Several options for interpreting garbled service information were considered and the corresponding formulas for R and ρ were obtained. Block diagrams are presented which show the possible sequences of events and their probabilities for each type of logic. Analysis of the third logic required models based on seven-state and ten-state Markov processes. Tractable formulas were not obtainable in closed form but only as solutions to matrix equations. Approximate formulas for R and ρ were derived for this case. The results of this paper are used in a companion paper to compare the performance of forward error correcting codes and retransmission systems under various channel conditions. View full abstract»

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  • Comparisons of Error Control Techniques

    Publication Year: 1964 , Page(s): 146 - 154
    Cited by:  Papers (11)
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    The performance capabilities of several retransmission systems are compared with each other and with conventional errorcorrecting codes in hypothetical channels exhibiting independent or dependent errors. These evaluations are based on the analysis in the companion paper which admits errors in the feedback channel and undetectable errors in either channel. The basic problem of deciding whether to use retransmission or forward error-correction for a particular application is investigated. The areas of relative superiority based on throughput rate R and uncorrected error rate ρ for each type of error control are determined for a wide range of codes and channels. It is shown that in almost all burst error cases and in independent error channels with low error probabilities, retransmission sytsems are superior to forward error-correcting systems in both throughput rate R and undetected error rate ρ. In independent error channels with high error rates forward error correction shows substantial improvement over retransmission provided that extremely high reliability is not required. It is shown that in designing a retransmission logic, the decision to interpret garbled messages bearing service information as retransmission requests lowers the throughput rate slightly but improves the reliability considerably. The problem of selecting one of the basic retransmission logics for a particular application is also considered. The systems characteristics of the logics were seen to be the prime consideration in many cases since the differences in R and ρ are generally not substantial. View full abstract»

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  • The Use of Holbrook and Dixon Loading Factors in Setting Receiver Parameters for an FDM-FM Radio Telephone Communication System

    Publication Year: 1964 , Page(s): 155 - 161
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    It is convenient to use a 0-dBm sinusoidal test tone to set the deviation of an FM radio transmitter. It is of interest to know the peak frequency deviation produced by the composite talker signal, relative to the deviation assigned to the 0-dBm test tone. This is necessary to design the equipment with the proper RF bandwidth. If the RF bandwidth is too small, the system will be overloaded and distortion will be produced. If the RF bandwidth is too wide the receiver noise level will be increased. This will cause an unnecessary increase to the amount of time below threshold. The Holbrook and Dixon load factors allow for a practical receiver design, the utilization of which is demonstrated by an illustrative problem. In a particular example the 1.0-Mc/s bandwidth is the limiting parameter and this determines the design value of the test tone frequency deviation. In another system the limiting parameter may be a minimum value for the carrier-to-noise ratio or the voice channel SNR. The inter-relationship of the various receiver parameters is demonstrated here, and design procedures can be evolved from it for any specific requirements. View full abstract»

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  • Dither Signals and Their Effect on Quantization Noise

    Publication Year: 1964 , Page(s): 162 - 165
    Cited by:  Papers (97)  |  Patents (9)
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    In this paper, the conditions a dither signal must meet so that the quantizer noise can be considered independent of the signal are derived for a quantizer having a finite number of levels. An infinite class of dither signals which satisfy these conditions is given. It is seen that the most useful member of this class is one whose probability density function is uniformly distributed over a quantizing interval. It is also shown that a necessary and sufficient condition for the noise n(t) to be independent of the signal x(t) is that a measurable quantity, called the "D" factor, be zero. View full abstract»

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  • New Loop-Around Systems

    Publication Year: 1964 , Page(s): 165 - 175
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    The system described here provides centralized twoway transmission measurements on two-way dial trunks and on one-way incoming dial trunks from remote offices to a control office. View full abstract»

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  • Determination of Long-Term Beyond-The-Horizon Propagation Reliability with Diversity

    Publication Year: 1964 , Page(s): 175 - 178
    Cited by:  Papers (2)
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    A method is presented for determining long-term reliability curves for received signal levels and combined signal levels due to diversity in a scatter communications link. The incoming signals are assumed to be faded and have a Rayleigh distribution. These reliability calculations may be made for any specific time interval or all hours. The method accounts for various orders of diversity, types of signal combining, nonlinear receiver characteristics below threshold, and median variation of the received signal. A concept and method for determining effective diversity reliability curves is also included. The effective diversity arises from the use of a squelch in a receiver located at threshold for improving SNR's. View full abstract»

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  • A 4-Wire Solid-State Switching System: Numbering Plan and Signaling System

    Publication Year: 1964 , Page(s): 179 - 186
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    Signaling is simplified by the adoption of a universal numbering plan. Addressing between centers and from subscriber keysets uses the same inband v-f combinations. Supervision on trunks is accomplished with single frequency tones. For subscribers on local metallic lines advantage is taken of the 4-wire phantom for dc loop supervision and battery feed to normal subscriber instruments. Protection against fading or interruption of the trunk transmission path is achieved by a unique interlocking of all addressing and supervisory signals. Simulation is minimized by using a special grouping of v-f combinations and timed single frequencies. View full abstract»

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  • A 4-Wire Solid-State Switching System: Common Control Equipment

    Publication Year: 1964 , Page(s): 186 - 197
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    The common control equipment of an electronic switching center is described with reference to a block diagram. The progress of a local call is traced. The additional routines required to handle trunk traffic priority calls and stored address operation is then explained. The implementation of some memory and logic functions is highlighted. View full abstract»

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  • A 4-Wire Solid-State Switching System: Time Division Switching Network

    Publication Year: 1964 , Page(s): 197 - 206
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    The transmission path of an electronic switching center utilizing time division multiplexing, its associated contact control circuits, and contact memory are discussed. Line, interhighway, signal injector and highway discharge switches are incorporated in this transmission network. The design of an accurate and flexible transmission measuring device was necessary so that some of the established transmission characteristics could be satisfactorily measured. The transmission characteristics were thus proven to be well within specified limits. View full abstract»

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  • Simplified Relations for Bit and Character Error Probabilities for M-ary Transmission over Rayleigh Fading Channels

    Publication Year: 1964 , Page(s): 207 - 209
    Cited by:  Papers (6)
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  • The equivalence of two test statistics for an optimum differential phase-shift keying receiver

    Publication Year: 1964 , Page(s): 209 - 210
    Cited by:  Papers (1)
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    Two recent papers [by J.J. Bussgang, and M. Leiter, "Error rate approximations for differential phase-shift keying," ibid., vol CS-12, Mar 1964, pp 18-27 and J.G. Proakis, P.R. Drouilhet, Jr., and R. Price, "Performance of coherent detection systems using decision-directed channel measurement," ibid., vol CS-12, Mar 1964, pp 54-63] presented test statistics for an optimum Differential Phase-Shift Keying (DPSK) receiver. In this correspondence the authors show that these test statistics are equivalent. View full abstract»

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  • The signal-suppression threshold of a frequency doubler

    Publication Year: 1964 , Page(s): 210 - 211
    Cited by:  Papers (1)
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    It is the purpose of this note to present a derivation of the signal-suppression threshold of a frequency doubler. The assumed input is a sinusoid in Gaussian noise. The results will not be substantially in error for narrow-band modulated signals. View full abstract»

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  • Band occupancy of digital FM signals

    Publication Year: 1964 , Page(s): 211 - 216
    Cited by:  Papers (3)
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    The theory of the transmission of digital data by frequency-shift methods has recently aroused new interest as a result of the increased requirements for frequency band conservation in telemetering and pulse-code modulation (PCM) applications. Assuming random 8equences of binary FM signals in the form of two equally probable, alternative frequencies for "mark" and "space" with continuous phase transition, the power density spectrum for a large ratio of carrier frequency to bit rate has been derived in closed mathematical form. As one of the surprising results it has been noted that a peak to peak deviation of about 0.6 to 0.7 times the bit ratlee ads to a particularly efficient crowding of the spectrum near the carrier frequency, resulting in a high efficiency of transmission in terms of occupied bandwidth. For many applications a quantitative expression for the cumulative band occupancy is needed which can be derived by integration of the power density function, and evaluation in terms of percentage of total signal power within given band limits. The following covers the results of auch an integration together with an assessment of the effects of pre- and postmodulation band limitation with linear phase Gaussian response filters. As one of the main conclnsions to be drawn from the calculations presented, it is found that in conventional digital FM transmission 99% of the signal power can be confined within a total bandwidth of 1.1 to 1.2 times the bit rate if the peak to peak deviation is kept below a maximum value between 0.6 and 0.7 times the bit rate, depending on the amount of pre- and postmodulation filtering. View full abstract»

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  • Comparison of square-law and majority-count diversity combiners

    Publication Year: 1964 , Page(s): 217
    Cited by:  Papers (3)
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    The purpose of this correspondence is to point out that the performance of a square-law diversity combiner with M branches is the same as that of a majority-count combiner with the same branch SNR and with (2M-1) branches. View full abstract»

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  • Comments on "Bandwidth and spectra of phase-and-frequency-modulated waves"

    Publication Year: 1964 , Page(s): 217 - 218
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    The problem of the evaluation of RF spectra of waves frequency or phase modulated by random noise is of great importance in the design of trunk radio systems. The system designer is particularly interested in the tail region, from the point of view both of bandwidth requirements and of interference considerations. As a consequence, a considerable body of work has been published, and it is disheartening to the commentor to find that Dr. Abramson, in his above-named contribution [ibid., vol CS-11, Dec 1963, pi3 407-414], ignores virtually all the existing detailed treatments. Especially is this so in so far as one of the papers that might have been cited appeared in the same journal as did his own paper, not so very long ago. Spectrum evaluation in practical cases is liable to run into difficnlties, and Dr. Abramson's paper gives, perhaps, a misleading impression as to the universal application of his approach. View full abstract»

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  • Reduction of Impulse Interference in Voice Channels

    Publication Year: 1964 , Page(s): 218 - 220
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  • A simplified physical model for amplitude distribution of impulsive noise

    Publication Year: 1964 , Page(s): 220 - 222
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    Analytic representations for the a,mplitude distribution of impulsive noise have generally been presented as numerical approximations to experimental data. While this provides a satisfactory solution to design problems, it is of some interest to consider a simplified physical model of the impulsive noise sources affecting narrow-band receivers, and to compare the results witht he empirical models. In proposing the following model, four characteristic assumptions apply to ther eceived noise: 1) The disturbance is of short enough duration so that the receiver. 2) Separate responses do not overlap in time. 3) Response amplitude is defined as the absolute maximum voltage occuring at the measuring point in the receiver during the given complete response. 4) A response is only considered to be an impulse noise response when its amplitudee xceeds a certaint hreshold value. The model seems to satisfy a degree of physical intuition and may thus serve as a support to the experimentally formulated approsirnation models. View full abstract»

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  • High-Altitude X-Band Noise Measurements

    Publication Year: 1964 , Page(s): 222 - 227
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  • On Survivability of Communications Systems

    Publication Year: 1964 , Page(s): 227 - 228
    Cited by:  Papers (1)
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Aims & Scope

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

Full Aims & Scope