Notification:
We are currently experiencing intermittent issues impacting performance. We apologize for the inconvenience.
By Topic

Communications, IEEE Transactions on

Issue 6 • Date June 1977

Filter Results

Displaying Results 1 - 12 of 12
  • [Front cover and table of contents]

    Publication Year: 1977 , Page(s): 0
    Save to Project icon | Request Permissions | PDF file iconPDF (146 KB)  
    Freely Available from IEEE
  • [Back cover]

    Publication Year: 1977 , Page(s): 0
    Save to Project icon | Request Permissions | PDF file iconPDF (320 KB)  
    Freely Available from IEEE
  • A Theory of Impulse Noise in Telephone Networks

    Publication Year: 1977 , Page(s): 577 - 588
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1344 KB)  

    This paper presents a physical theory of impulse noise in telephone networks based on the assumption that impulsive disturbances can reverberate through a network for very long periods of time. A mechanism of regeneration and propagation of disturbances through signaling circuits is proposed, and the resulting reverberation is modeled as a random walk in one dimension. Theoretical results agree surprisingly well with empirical probability distributions of inter-error intervals in data transmission. However, direct experimental evidence is lacking to substantiate (or disprove) the physical mechanism on which the theory is based. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Photoelectron Counter Dead Time Effects on Direct Detection Optical Communication Systems

    Publication Year: 1977 , Page(s): 615 - 621
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (696 KB)  

    The effects of photon counter dead time on a direct detection binary pulse position modulation optical communication system are computed for both a free space optical channel and an atmospheric channel subject to clear air turbulence. The degradation in the performance of an optimum receiver structure due to dead time losses was found to be typically 1 dB for the free space channel and less than 1 dB for the atmospheric fading channel, even at the large value of the ratio of counter dead time to counting interval length of ten percent. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Echo Canceler with Two Echo Path Models

    Publication Year: 1977 , Page(s): 589 - 595
    Cited by:  Papers (43)  |  Patents (33)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (696 KB)  

    An adaptive echo canceler with two echo path models is proposed to overcome the false adaptation problem for double-talking. The echo canceler possesses two separate echo path models (EPMs), one (background EPM) for adaptively identifying echo path transfer characteristics and the other (foreground EPM) for synthesizing an echo replica to cancel out echo. The parameter values of the foreground EPM are refreshed by those of the background EPM, according to a transfer control logic, when the logic determines that the background EPM is giving a better approximation of echo path transfer characteristics than the foreground EPM. Completely digital hardware implementation is described. Using the hardware, it is shown that virtually complete double-talking protection is actually realizable by the new method. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Design and Performance of a Digital Multifrequency Receiver

    Publication Year: 1977 , Page(s): 608 - 615
    Cited by:  Papers (8)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (864 KB)  

    An experimental multifrequency receiver for recognition of digitally encoded multifrequency signaling was designed, constructed and tested. The receiver is based on a quadrature detection technique that consists of digital demodulation followed by second-order, lowpass digital filtering. The post filtering processing produces an estimate of the amplitude of each of the six multifrequency tones and provides suitable information for thresholding and timing measurements. The receiver performs correctly even when subjected to severe environmental conditions including an analog signal range of 23 dB, 10 ms signal interruptions ('hits') and 20 ms signal spacings. The receiver's operation demonstrates the robustness of the digital signal processing techniques employed. The design of the receiver exploits the use of subsampling techniques to increase the efficiency of the hardware through greater multiplexing. When using subsampling, 128 multifrequency receivers with 16-bit words are realized with 6.5 dual-in-line packages per receiver; commercial TTL logic circuits, a 4-bit serial-parallel pipeline multiplier circuit, serial data and a 16.384 MHz clock are assumed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Communications Processor System Study

    Publication Year: 1977 , Page(s): 604 - 608
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (568 KB)  

    The activities and results of the Communications Processor System (CPS) study, performed at both North Electric Company and Data System Analysts, Inc., under the auspices of Rome Air Development Center (RADC), are described in this paper. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • 400 Mbit/s Digital Repeater Circuitry Provided by a New Design Method and Beam Lead GHz Transistors

    Publication Year: 1977 , Page(s): 595 - 601
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (800 KB)  

    A stable, compact, and high-performance regenerative repeater circuitry, suitable for digital transmission systems up to several hundred Mbit/s, has been provided through utilization of new devices, such as 7 GHz beam lead shielded junction transistors, and through a new computer-aided design method, and has been successfully applied to the 400 Mbit/s experimental coaxial cable PCM system. Major features of this repeater circuitry are: (1) an equalizing amplifier with low noise figure (7.6 dB), small intersymbol interference (12%), and automatic line equalization of 21 dB tracking range at 200 MHz; (2) a regenerative output circuit with bipolar pulses of 2.4 Vop amplitude and 700 ps rise time; and (3) total performance with sufficient noise margin (10 dB for error rate 10-11over a line of 56 dB loss at 200 MHz), small static pattern jitter (20°pp), smaller size ( 270 \times 160 \times 52 mm), and lower power (5.8 W). These have been achieved by use of: (1) new devices such as beam lead transistors with fTof 7 GHz, Le of 0.2 nH and Cob of 0.4 pF and tantalum thin film hybrid integrated circuits; and (2) a new CAD system including block simulation, network design/ simulation, layout design subsystems which use transmission quality (error rate and jitter) as a design criterion, and which can also be directly connected to the manufacture automation systems, e.g., for mask preparation, and transistor mounting by bonding. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A New Phase Modulator

    Publication Year: 1977 , Page(s): 602 - 604
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (288 KB)  

    A phase modulator is described which deviates from perfect linearity by ± 1 degree maximum in the range± 90 degrees. It can be adjusted to eliminate third order distortion. A digital application is illustrated. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The Effects of Bandpass Limiters on n-Phase Tracking Systems

    Publication Year: 1977 , Page(s): 569 - 576
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (712 KB)  

    The combination of a bandpass limiter and an nthpower tracking loop is considered. It is shown that the performance of the combination does not depend on the form of the nonlinear function used to create the nthharmonic signal as long as some energy in that zone is produced. Furthermore, the order in which the limiter and n power nonlinearity occur is unimportant so that the results apply equally well to the n -phase Costas type of implementations of the nthpower loops. Closed form expressions for the signal suppression factors are obtained, and it is shown that the coherent and noncoherent SNR's out of the nthpower-limiter combination can be expressed in terms of two of these suppression factors. This latter point enables one to estimate the loop SNR of an nthpower-limited phase locked loop by simply calculating the suppression factors for nthand ( (2n)^{th} ) power loops. Finally, n thpower phase locked loops without limiters are compared with similar loops with limiters where it is shown that the presence of the limiter can actually enhance the output SNR at moderate to large values of input SNR. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The Autocorrelation Function of the Output of an N-Level Quantizer with an Angle-Modulated Input Signal

    Publication Year: 1977 , Page(s): 621 - 627
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (488 KB)  

    A readily computable formula is given for the autocorrelation function of the output of an arbitrary time-invariant nonlinearity with an arbitrary angle-modulated input. The general result is specialized to the case of an odd-symmetric, but otherwise arbitrary, quantizer. It is shown that to evaluate the output autocorrelation the second-order characteristic function (SOCF) of the modulation is required. Using previously derived SOCFs for a constant, a Gaussian random process, and a generalized random telegraph wave (RTW), the output autocorrelation is given explicitly. Using the SOCF for a binary phase-shift keyed (BPSK) signal, derived here for the first time, the output autocorrelation with BPSK modulation is also presented. Finally, the autocorrelation functions of the modulated input processes are given by reducing the quantizer to a linearity, with the results for the generalized RTW and BPSK modulations being new. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Design of a C-Message Weight Digital Filter

    Publication Year: 1977 , Page(s): 628 - 630
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (176 KB)  

    This note describes an 8.0 kHz sampling rate discrete implementation of the C-message weight filtering characteristic. Included for this filter are the filter coefficients for an eight-bit realization and a tabulation and graph of the frequency response. 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