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Communications, IEEE Transactions on

Issue 2 • Date February 1976

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Displaying Results 1 - 23 of 23
  • [Front cover and table of contents]

    Publication Year: 1976 , Page(s): 0
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    Freely Available from IEEE
  • Editorial

    Publication Year: 1976 , Page(s): 153
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    Freely Available from IEEE
  • Correction to "Short Constraint Length Rate 1/2 ́Quick-Looḱ Codes"

    Publication Year: 1976 , Page(s): 286
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (66 KB)  

    First Page of the Article
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  • [Back cover]

    Publication Year: 1976 , Page(s): 0
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    Freely Available from IEEE
  • An Efficient Parity Checking Scheme for Random and Burst Errors

    Publication Year: 1976 , Page(s): 249 - 254
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (536 KB)  

    In this concise paper we describe an efficient scheme for random and burst error checking by a combination of serial parity checking and convolutional interleaving. The framing for interleaved blocks is shown possible by a simple implementation, and the error detection capability is better than other schemes similar in complexity. The proposed scheme has useful applications for digital transmission. View full abstract»

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  • A Model for Evaluating the Performance of an Integrated Circuit- and Packet-Switched Multiplex Structure

    Publication Year: 1976 , Page(s): 195 - 202
    Cited by:  Papers (61)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (680 KB)  

    Recent papers have introduced a multiplexing structure for mixing voice and data traffic in an integrated telecommunications system. This structure utilizes a master frame format of a time division statistical multiplex facility. A certain portion of the frame is allocated to voice calls, and data traffic is assigned to the remaining frame capacity. To achieve a high transmission utilization, data are allowed to use any residual voice capacity momentarily available due to statistical variations in the voice traffic. The voice traffic is treated as a loss system and data packets are buffered. In this paper we derive exact analytical expressions for the key system perfomance measures, the probability of loss for voice calls, and the expected waiting time for data packets. Actually, two cases are considered, the one discussed above, called the movable boundary case, and one where the boundary is fixed; i.e., data are not allowed to utilize the residual voice capacity. The computational aspects of calculating actual numbers are discussed in some detail, and results are presented for typical cases. View full abstract»

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  • Power Spectra of Sinusoidal Amplitude-Modulated Binary Signals

    Publication Year: 1976 , Page(s): 284 - 286
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (232 KB)  

    Power spectra for binary phase-shift keyed (PSK) and frequency-shift keyed (FSK) signals with combined sinusoidal amplitude modulation by the bit rate clock are presented. Such signal formats have application in "burst" communication systems wherein reliable bit synchronization is provided with relative receiver simplicity. Effects of the clock amplitude modulation index and phase are considered, and corresponding power spectra are illustrated. Further, effects of the clock parameters on the rate of spectral rolloff are given and compared with those of conventional PSK and FSK spectra. View full abstract»

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  • A New Translation Procedure for the C-60M System

    Publication Year: 1976 , Page(s): 230 - 238
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    This paper proposes a new translation procedure which is based on a jumbogroup constitution for simultaneous multiplex transmission of telephone and videophone signals over a coaxial 60-MHz system and describes transmission characteristics of the C-60M system using the translation procedure. The translation procedure reduces group-delay distortion harmful to video transmission without changing telephone transmission capacity or without degrading telephone transmission characteristics. It is also capable of transmitting either 36 videophone signals with 1 MHz bandwidth or nine videophone signals with 4.3 MHz bandwidth. View full abstract»

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  • Stored Channel Simulation of Tactical VHF Radio Links

    Publication Year: 1976 , Page(s): 154 - 163
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1088 KB)  

    This paper discusses the theory and design of a tactical channel simulator (TCS) built to simulate land-mobile VHF radio links. The instrument is one of the first such units based on the stored channel principle, which permits the actual medium to be recorded and played back. The key application of the TCS simulator is to realistically reproduce field conditions in a laboratory. Tests on the TCS simulator should be in good accord with performance encountered in the field, unlike results obtained in the standard back-to-back tests which ignore effects of the propagation channel. Experimental results show that the evaluation of modem performance must take into account the effects of propagation over the VHF channel, as data tests are measurably affected by channel conditions. The TCS simulator will be particularly useful in the comparative evaluation of various highspeed, high-performance modems now being introduced into the inventory. View full abstract»

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  • Thermal Heating Contribution to Intermodulation Fields in Coaxial Waveguides

    Publication Year: 1976 , Page(s): 238 - 243
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (584 KB)  

    We investigate intermodulation (IM) production due to the thermal heating of coaxial waveguide walls. Two impressed signals are assumed to propagate in a coaxial cable in the TEM mode. The resulting power developed in the IM product is found to depend upon the thermal coefficient of the electrical conductivity of the metal squared, and is inversely proportional to the conductivity itself. View full abstract»

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  • Linear Detection in a Poisson Regime with Random Pulse Heights

    Publication Year: 1976 , Page(s): 254 - 259
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (616 KB)  

    The detection of light signals using photomultipliers is presented in terms of an idealized model in which the received signal consists of a series of pulses of random height with arrival times that are Poisson distributed with an instantaneous rate proportional to transmitted signal intensity. Linear detection, effected through multiplication by locally generated functions followed by integration, is considered. An optimization algorithm based on Chernoff bounds for the error probability is developed. For the standard Poisson regime with constant pulse heights this algorithm derives correctly the logarithmic local functions predicted rigorously for maximum likelihood detection. For random pulse heights the functions resemble smoothly truncated logarithmic functions of the transmitted signal intensities, and the logarithmic singularity for zero values of the signal is either removed or greatly weakened. Calculations for several classes of pulse height distributions show that the degradation in performance caused by pulse height fluctuations can be predicted with fair accuracy from an "excess noise factor" defined in terms of the ratio of pulse height variance to the square of its mean. View full abstract»

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  • Computation of Interference into Angle-Modulated Systems Carrying Multichannel Telephone Signals

    Publication Year: 1976 , Page(s): 259 - 263
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (432 KB)  

    It is commonly known that, in order to calculate the demodulated noise power of the wanted frequency division multiplexedfrequency modulated (FDM-FM) signal due to interference, the convolution between the power spectra of the wanted FM signal and interference is required to be obtained. This concise paper shows a simple approach to calculate this convolution without direct calculation of the power spectrum of the FDMFM signal when the power spectrum of the interference is given (by measurements or calculation) and the highest and lowest channel frequencies of the baseband signal and rms frequency deviation of the wanted FDM-FM signal are known. Since the calculation of the FDM-FM signal power spectrum is not an easy problem in some cases, this approach makes much simpler an accurate evaluation of the output noise power due to interference. View full abstract»

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  • The Performance of Quantizers for a Class of Noise-Corrupted Signal Sources

    Publication Year: 1976 , Page(s): 184 - 189
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (568 KB)  

    An investigation is made of the performance of quantizers used as source encoders for noise-corrupted signal sources. The developmerit is pertinent to discrete-time, memoryless, signal-signal-sourse-independent noise sources with a given amplitude bound. A functional analysis approach is adopted to formulate the problem and derive the results. The derivations and intermediate results are in terms of an arbitrary quantizer and, consequently, are applicable to any quantizer and allow quantizer performance comparisons in the worstcase corrupting-noise source context. Examples are presented with this type of comparison in mind. These examples instructively illustrate the application of the results as well as file performance of the uniform quantizer and others under their worst-case additive noise conditions. View full abstract»

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  • An Approximate Time-Delay Analysis for Packet-Switching Communication Networks

    Publication Year: 1976 , Page(s): 210 - 222
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1104 KB)  

    A technique is presented for the derivation of approximate average packet time-delay formulas in a packet-switching store-and-forward network. The approximation technique appropriately incorporates arrival and departure packet interferences with the recent queueing results in a noninterfered communication path. Simulation results, for basic flow configurations, show the approximate timedelay function to constitute a very close lower bound over wide range of traffic intensities. The resulting average time-delay approximation when a Poisson assumption is made, is shown to constitute an upper bound. A procedure for approximate network time-delay analysis is then presented. View full abstract»

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  • Maximum Likelihood Receiver for Multiple Channel Transmission Systems

    Publication Year: 1976 , Page(s): 276 - 283
    Cited by:  Papers (113)  |  Patents (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (568 KB)  

    A maximum likelihood (ML) estimator for digital sequences disturbed by Gaussian noise, intersymbol interference (ISI) and interchannel interference (ICI) is derived. It is shown that the sampled outputs of the multiple matched filter (MMF) form a set of sufficient statistics for estimating the input vector sequence. Two ML vector sequence estimation algorithms are presented. One makes use of the sampled output data of the multiple whitened matched filter and is called the vector Viterbi algorithm. The other one is a modification of the vector Viterbi algorithm and uses directly the sampled output of the MMF. It appears that, under a certain condition, the error performance is asymptotically as good as if both ISI and ICI were absent. View full abstract»

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  • Study and Fabrication of a Frequency Divider-Multiplier Scheme for High-Efficiency Microwave Power

    Publication Year: 1976 , Page(s): 243 - 249
    Cited by:  Papers (16)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (808 KB)  

    The design, fabrication, and experimental evaluation of an exploratory 8.2 W, microwave FM power amplifier for the 4-GHz band are presented. It operates on a frequency divide, amplify, and multiply scheme receiving about 2-4 dBm of FM signal in the 4-GHz band, divides the frequency coherently by two, amplifies the modulated signal to about 10.4 W, and doubles the frequency coherently, yielding about 8.2 W into standard 50-ω 4-GHz load, with an overall efficiency of about 30 percent. Frequency halving is accomplished by a wideband regenerative frequency divider yielding about 1-2 dBm of signal at 1995 MHz. The signal is amplified by commercial class C amplifiers and is restored to the 4-GHz band by a stacked varactor containing two 0.32 ω, 15-pF chips in a coaxial embodiment. This entire ensemble, with a total breakdown of 160 V, serves as a frequency doubler. View full abstract»

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  • New Technique for Generating and Detecting Multilevel Signal Formats

    Publication Year: 1976 , Page(s): 263 - 267
    Cited by:  Papers (22)  |  Patents (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (520 KB)  

    A new modem circuit technique is proposed for multilevel signal transmission to utilize frequency bandwidth efficiently in high-speed digital carrier transmission systems. With this technique a multilevel amplitude and phase-keying (APK) signal is generated as the sum of the outputs of two multiphase modulators and is detected by tandem phase demodulators. This "superposed modem has a simple circuit configuration. It is constructed from phase-shift-keying (PSK) modems. It appears advantageous for realizing high-baud-rate multilevel transmission of severalhundred Megabauds (MBd). Experimental results show the feasibility of a 16-level modem with performance degradation of only about 1 dB from the theoretical predictions. View full abstract»

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  • Single-Message Communication

    Publication Year: 1976 , Page(s): 190 - 194
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (536 KB)  

    When a communication system is used to transmit many short messages, it is important to reduce the amount of control overhead for creation and destruction of logical process-to-process connections and for reliable communication. Different end-to-end control procedures are described, and they are studied with respect to the possibility of losing a message or accepting a duplicate. It is shown (under certain assumptions about the communication network) that all end-to-end protocols either allow for loss of a message or can deliver duplicates of a message. View full abstract»

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  • Nonadaptive DPCM Transmission of Monochrome Pictures Over Noisy Communication Channels

    Publication Year: 1976 , Page(s): 173 - 183
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1360 KB)  

    The present study is a sequel to the authors' 1972 paper [1] where the output signal-to-noise ratio SNRois obtained for nonadaptive differential pulse-code modulation (DPCM) systems with an arbitrary linear predictor operating on noisy digital channels. Important stability constraints for an arbitrary linear predictor are obtained. A complete analytical study of previous line-line-and-sample feedback systems is presented. The SNRoimprovement over previoussample feedback is found to increase from approximately 2.6 dB for error-free channels to 4.1 dB for noisy channels. Optimization of the predictor for noisy channel usage is shown to greatly reduce the sensitivity of SNRoto variations in message and channel parameters, while use of the resulting predictor on error-free channels yields SNRovalues which are almost as good as those obtained when the predictor is optimized for error-free channels. Reduction of the effects of digital channel errors on SNRousing various methods, including periodic or pseudorandom resetting are considered briefly. Hardcopy results from computer-simulated DPCM monochrome image transmission systems corroborate our analytical results. View full abstract»

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  • Mutual Impedances for Parallel Wires Over a Two-Layer Earth

    Publication Year: 1976 , Page(s): 222 - 230
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (632 KB)  

    J. R. Wait developed an analytical formulation for the fields of an infinite line source above a stratified earth which can be extended to include any number of layers. This formulation is numerically evaluated using Filon's method to give results on the mutual impedance between two long conductors above a stratified earth. To demonstrate the usefulness of this formulation, numerical results are compared to the experimental results of Bowen and Gilkeson in which the mutual impedance was observed in both its reactive and resistive components at Cross Keys, NJ. View full abstract»

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  • Power Control Algorithms for Satellite Communication Systems

    Publication Year: 1976 , Page(s): 267 - 275
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1136 KB)  

    Three different ground terminal transmit power control concepts for a Satcom system are examined. The effectiveness of constant satellite power (CSP) sharing among the carriers and adaptive satellite power (ASP) sharing is compared with constant ground terminal transmit power (CTP). It is shown that ASP offers substantial advantages over CSP in combating environmental degradations and that both can increase link availability with respect to the constant power (CTP) case. The effectiveness of the ASP control technique is shown to depend on the interconnectivity of the network if multidestinational carriers are used. The measurements required for system control, as well as their accuracies, are described. View full abstract»

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  • Digital Signal Design Concepts for a Time-Varying Rician Channel

    Publication Year: 1976 , Page(s): 164 - 172
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (752 KB)  

    The problem of transmitting digital data reliably over a Rician channel, which is used to model the aircraft-satellite link, is treated by an integrated coding and modulation design approach. The results presented enable one to show that it is quite possible to achieve robust signaling which is fairly insensitive to the channel's surface scatter parameters, such as scatter path energy and Doppler spreads. These results illustrate that the scatter energy need not limit the effectiveness of transmitting digital data and, in fact, can improve the performance when operating in the region of low direct path SNR's. These concepts are exemplified by performance curves for frequencyshift keying (FSK) and differential phase-shift keying (DPSK) modulation formats combined with efficient channel measurement decoding algorithms. In addition, general analytical results for evaluating the bit error probability for binary and channel measurement decoders are presented. View full abstract»

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  • Chaining in a Loop System

    Publication Year: 1976 , Page(s): 203 - 210
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (744 KB)  

    This paper offers an approximate analysis of the chaining operation in a loop system. The system consists of a central processor and N terminals linked by a common communication channel. Chaining refers to the service protocol whereby the channel is assigned in sequence to each of the terminals. Messages from terminals to the central processor are sent as chains of segments. The object of the analysis is to display the relationships between the arrival processes, the channel allocation, and the response of the system. 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.

 

 

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Meet Our Editors

Editor-in-Chief
Robert Schober
University of British Columbia