By Topic

Communications, IEEE Transactions on

Issue 6 • Date June 1973

Filter Results

Displaying Results 1 - 24 of 24
  • [Front cover and table of contents]

    Page(s): 0
    Save to Project icon | Request Permissions | PDF file iconPDF (169 KB)  
    Freely Available from IEEE
  • Error-Correcting Codes, Second Edition

    Page(s): 782
    Save to Project icon | Request Permissions | PDF file iconPDF (100 KB)  
    Freely Available from IEEE
  • [Back cover]

    Page(s): 0
    Save to Project icon | Request Permissions | PDF file iconPDF (152 KB)  
    Freely Available from IEEE
  • A General Queuing Model for Buffer Storage Problems

    Page(s): 744 - 747
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB)  

    A mathematical model for a general buffered telecommunication system with the output channel available only periodically is constructed and analyzed in this paper. Under the assumptions that certain system parameters are continuous variables, it is shown that the probability density functions for the peaks and valleys of the buffer content are exactly the same as the density functions for the response time and the waiting time, respectively, for aGI/G/1queuing system, with the density functions for the arrival processGIand the service processGobtained from the statistical functions for the parameters of the original buffered system. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Two Problems in Simultaneous Communications

    Page(s): 763 - 767
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (624 KB)  

    Recent extensions of information and communication theoretic concepts to simple systems involving a single transmitter and several receivers are described and compared in an intuitive and tutorial manner. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Bandwidth Compaction Codes for Communications

    Page(s): 687 - 695
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (768 KB)  

    The familiar error-correction codes allow a reduction in the required signal-to-noise ratio at the expense of an increase in bandwidth. Here we reverse the problem and investigate codes that permit a reduced bandwidth at the expense of an increase in the required signal-to-noise ratio. Theoretical properties of these bandwidth compaction codes have been published previously. This paper emphasizes the tradeoff between bandwidth and signal-to-noise ratio when the codes are used. The inherent error detection and error correction properties of the codes are also explored. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Comparison of Optimum and Logarithmic Quantization for Speech PCM and DPCM Systems

    Page(s): 752 - 757
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (648 KB)  

    Two quantization rules, optimum (minimum mean-square error) and logarithmic companding, are compared for application to digital speech transmission. Comparison is made on the basis of signal-to-quantizing noise ratio (S/N), subjective quality judgments, idle channel noise, and dynamic range. These quantizers are considered in both PCM and differential PCM configurations. A computer algorithm is described that yields the optimum quantizer levels for a given speech record. It has been found that the improvement in S/N which optimum quantization affords over conventional logarithmic quantization is offset by the greater idle channel noise and smaller dynamic range (range of talker volumes handled with a lower limit on S/N) of the optimum law. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Error Rates on a Data Link with Nonlinear Regeneration

    Page(s): 671 - 679
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (688 KB)  

    A model of nonlinear data wave regeneration without retiming is analyzed. Attention is focused on performance after regeneration and subsequent detection. The communication model consists of a pseudoternary signal that is regenerated at one data station, but not retimed prior to retransmission to another station. The signal regeneration is accomplished by a three-level slicer, and this nonlinear transformation degrades the overall system performance in the presence of noise. The extent of this degradation is our subject matter. The formulation and analysis are constructed so that one can put to effective use the fact that, for a certain Gaussian process, one can give definite expressions for the chance that its sample paths lie below a piecewise linear curve on an appropriately restricted time interval. We are able to use events of this type to give upper and lower bounds for the error rate. The bounds are compared with the error rate that would have been obtained had detection been accomplished before the nonlinear regeneration. We hope that the techniques employed here may be of use in other nonlinear communication problems. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An Approach to the Analysis of Performance of Quasi-Optimum Digital Phase-Locked Loops

    Page(s): 733 - 738
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (512 KB)  

    An approach to the analysis of performance of quasioptimum digital phase-locked loops (DPLL's) is presented. An expression for the characteristic function of the prior error in the state estimate is derived, and from this expression an infinite dimensional equation for the prior error variance is obtained. The prior errorvariance equation is a function of the communication system model and the DPLL gain and is independent of the method used to derive the DPLL gain. Two approximations are discussed for reducing the prior error-variance equation to finite dimension. The effectiveness of one approximation in analyzing DPLL performance is studied. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • High-Capacity Digital Line Links

    Page(s): 680 - 686
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (568 KB)  

    A hybrid digital transmission system of the kind originally proposed by Chang and Freeny [4], [6] is considered. Based on predictions about cable and repeater costs around 1980, an investigation of a certain economic measure of goodness is performed. Specifically, the influence on the system cost of the choice of certain fundamental system parameters like repeater spacing, symbol rate, and number of signal levels is studied. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Interference into Angle-Modulated Systems Carrying Multichannel Telephony Signals

    Page(s): 714 - 727
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (952 KB)  

    An investigation of interference between angle-modulated systems carrying multichannel telephony, which is directly applicable to existing satellite and terrestrial radio-relay systems, has been undertaken. This study includes a general solution for arbitrary narrow-band interference into an angle-modulated system with arbitrary modulation. The algorithm has been implemented on a digital computer to provide calculations of interference between two FDM/FM systems. The analysis is valid for all modulation indices, and may be applied to any PM, FM, or preemphasized FM baseband. A comparison of calculated results and experimental measurements shows good agreement. An extensive investigation, covering a wide range of modulation indices and basebands, has been conducted for the particular case of preemphasized FDM/FM signals. Wherever possible, a generalized presentation of interference results is given. Interleaving criteria are also presented for certain cases of interference involving two identical signals. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On Moments and Walsh Characteristic Functions

    Page(s): 768 - 770
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB)  

    This correspondence treats the derivation of natural moments from their corresponding Walsh characteristic function via the dyadic derivative operator. The derivation of a result concerning Walsh transforms of dyadic derivatives of functions is also considered. However, some established ideas such as Walsh transform, dyadic stationarity, and dyadic correlation are introduced first. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Low Bit Rate Differential PCM for Monochrome Television Signals

    Page(s): 706 - 714
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1032 KB)  

    This paper contains an examination of the performance of low bit rate differential PCM systems when used to encode monochrome National Television System Commission (NTSC) television pictures. 12 different encoders with various sampling rates and numbers of quantizing levels operating at bit rates from 9 to 24 Mb were considered. The differential PCM systems were implemented by using an 8-b PCM A/D converter followed by digital logic that performed the differential operation in a simple previous sample feedback loop. The subjective performance of these encoders was determined using an anchored seven-point quality rating scale and equipreference contours were plotted in a plane whose axes are sampling rate and quantizing bits. Entropy measurements were made on the output of the differential PCM encoders. These entropy measures were compared with the subjective performance of encoding systems operating at the same transmission rate. The encoding systems studied produced television pictures of medium quality in which quantizing noise and bandwidth limitations were apparent. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Clipping and Signal Determinism: Two Algorithms Requiring Validation

    Page(s): 738 - 744
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (640 KB)  

    Two algorithms are proposed for recovering signals subjected to bandpass clipping and related types of nonlinear transformations. Both are based on contraction mapping principles and both seem to work experimentally, but neither has been validated formally. The conditions on signal determinism suggested by the algorithms have interesting practical implications. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An Experimental Study of Roundoff Effects in a Tenth-Order Recursive Digital Filter

    Page(s): 757 - 763
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (576 KB)  

    This paper reports experimental measurements of limitcycle amplitude and period in digital recursive filters. The results that were obtained on two cascaded forms of a tenth-order filter show good agreement with existing theoretical bounds. (The bounds only apply to single second-order sections because analysis of cascaded sections is difficult.) Roundoff noise of the filter was measured and it agreed both in spectral shape and total power with that predicted by computer simulation. Some preliminary observations on relative magnitude of limit cycle and roundoff noise were made. In addition, the gradual buildup of a signal through a limit cycle was observed and 1 bit of noise in the least significant bit (LSB) in the filter was seen to break up limit cycles. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Some Optimum and Suboptimum Frame Synchronizers for Binary Data in Gaussian Noise

    Page(s): 770 - 772
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB)  

    In this correspondence we investigate the performance of several optimum and suboptimum devices for locating a sync word in data corrupted by Gaussian noise. One suboptimum synchronizer, which is extremely simple to instrument, is shown to perform virtually optimally over the entire range of interesting signal-to-noise ratios. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Pseudonoise Code Acquisition Using Majority Logic Decoding

    Page(s): 772 - 774
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (272 KB)  

    This paper considers the use of majority logic decoding as a pseudonoise code acquisition technique. A bound on the probability of code acquisition is derived and it is shown that the probability of acquiring an 8191 code in one attempt can be made nearly one at -10-dB SNR. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The New-Word Policy and Decision Feedback in Loop Data Communication Networks

    Page(s): 727 - 730
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (472 KB)  

    The new-word policy with decision feedback is shown to improve the efficiency of loop data communication with noisy links to the extent that the average number of loop transmissions per new word increases only linearly with the number of identically noisy links. This compares to an exponential increase in more conventional acknowledge-or-retransmit systems. Also, in the (almost) noiseless case, a greater number of word transfers per loop transmission can be achieved. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Method for Synchronous Data Transmission Between Electronic Data Switching Exchanges

    Page(s): 730 - 733
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (456 KB)  

    In electronic data switching (EDS) exchanges through connection is performed according to the asychronous time-division multiplex principle. In an input code converter, a polarity reversal on a connected subscriber line or trunk is converted into a line address. With the aid of the central control/storage unit this line address is translated into the address of the serving line; via an output code converter a polarity reversal is effected on the respective line and transmitted to the receiving subscriber. The paper describes how the circuitry in the peripheral equipment of the EDS exchange can be reduced if on the trunks between the EDS exchanges line addresses are transmitted instead of single polarity reversals. To enable a good utilization of the transmission link, the addresses are intermediately stored in a parallel-serial converter and provided with an additional time address in order to recover the original instants at which the polarity reversals have occurred. The principle is illustrated by means of an example, and the possibilities of using PCM channels are outlined. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Comparing Bandwidth Requirements for Binary Baseband Signals

    Page(s): 776 - 781
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (400 KB)  

    The percentage of total power passed through ideal bandlimited channels with bandwidths equal to various multiples of the bit rate is examined for 14 unique binary baseband signaling schemes. The channel bandwidth required to pass 5 percent of the total power is determined as a measure of the need for near-dc channel response. Conclusions are reached as to which signals would be most suitable for high-rate magnetic tape recording. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Techniques for Reducing the Visibility of Transmission Errors in Digitally Encoded Video Signals

    Page(s): 695 - 706
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2200 KB)  

    This paper is concerned with the problem of transmission errors in digitally encoded television signals. Various techniques for reducing the visibility of transmission error effects in the reconstructed signals have been evaluated using computer-produced film sequences. It is found that the visibility of errors in element difference coders is sharply reduced if an erroneous line is replaced by an average of adjacent lines. It is shown that the visibility of errors in two coders that use spatial prediction is low and can be further reduced by using a "leaky" predictor. The implications of these results for in-frame, interframe, and facsimile encoders are discussed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On the Utility of Chirp Modulation for Digital Signaling

    Page(s): 748 - 751
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (368 KB)  

    The issue of signal selection in binary data transmission is presented. The question of the relative utility of linear frequency sweeping (LFS or chirp), compared to PSK and FSK, in terms of error probability and spectrum usage, is discussed. The transmission media considered are the coherent, partially coherent, Rayleigh, and Rician channel models. Theoretically, LFS has unconditionally superior characteristics in the partially coherent and fading cases, for certain ranges of channel conditions. This is due to the more negative values of cross-coherence parameters possible with the LFS signal set over the FSK signal set. For the fading channel, theoretical supremacy of LFS over FSK depends upon the specular-to-Rayleigh signal power ratio and the adjustability of in-phase cross coherence, with a constraint upon quadrature phase cross coherence. From a practical standpoint, coherent reception of the LFS signal set has severe limitations. These are manifested primarily in two aspects: the need for phase synchronization of a chirp signal set, and the fact that the optimum value of cross coherence is highly sensitive to synchronization channel signal-to-noise ratio (SNR), and/or spectral-to-Rayleigh signal power ratio. The latter would require that modulation characteristics track the channel conditions in order to achieve the supremacy in performance theoretically predicted by optimization of the cross-coherence parameter in LFS. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Compression of Weather Charts by the Segmented Lynch-Davisson Code

    Page(s): 774 - 776
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (256 KB)  

    The Lynch-Davisson (L-D) code is shown to be efficient for compressing line-scanned weather charts wherein each line is divided into equal-length segments, and a separate L-D code is generated for each segment. As the number of segments increases, the L-D code length decreases appreciably, thereby simplifying the encoding and decoding operations. However, the accompanying decrease in the overall compression ratio is relatively small. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An Investigation of Telephone-User Habits by Means of Computer Techniques

    Page(s): 663 - 671
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (720 KB)  

    This paper presents a study of traffic data collected at the telephone exchange (PABX) of The Norwegian Institute of Technology. A recording system primarily designed for accounting purposes [1] collects a set of data for each outgoing call and stores it on digital magnetic tape. Based on these data a statistical study is carried out emphasizing the properties of traffic sources, single subscriber sources, as well as groups of subscribers. After a survey of the system and the general traffic situation, studies of the call-generation process follow. Called number repertoires are treated, using the concept of entropy. The major part of the paper is devoted to the study of repeated calls. Comparisons are made with results from France and the U.S.A. An important scope of the paper is to point out the potentials of the applied method, implying the high efficiency of data collection as well as processing by means of computer techniques. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

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
Robert Schober
University of British Columbia