Scheduled System Maintenance:
On May 6th, single article purchases and IEEE account management will be unavailable from 8:00 AM - 5:00 PM ET (12:00 - 21:00 UTC). We apologize for the inconvenience.
By Topic

Communications, IEEE Transactions on

Issue 10 • Date October 1976

Filter Results

Displaying Results 1 - 25 of 28
  • [Front cover and table of contents]

    Publication Year: 1976 , Page(s): 0
    Save to Project icon | Request Permissions | PDF file iconPDF (181 KB)  
    Freely Available from IEEE
  • Comments on "Calculated channel characteristics of a braided coaxial cable in a mine tunnel"

    Publication Year: 1976 , Page(s): 1212 - 1213
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (185 KB)  

    First Page of the Article
    View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Comments on "Intermodulation Noise and Products Due to Frequency-Dependent Nonlinearities in CATV Sytems"

    Publication Year: 1976 , Page(s): 1213 - 1215
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (307 KB)  

    Some experimental difficulties associated with Chang's "single-frequency-dependent" transfer functions are outlined. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Reply by S.F. Mahmoud [to 'Comments on "Calculated channel characteristics of a braided coaxial cable in a mine tunnel" ']

    Publication Year: 1976 , Page(s): 1213
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (118 KB)  

    SUmmary form only given, as follows. The comments of Prof. Delogne on our paper ("Calculated channel characteristics of a braided coaxial cable in a mine tunnel") seem very appropriate and instructive. I do agree with Prof. Delogne that at low frequencies, questions related to the receiver noise and perhaps the receiver matching become of primary importance. The coupling loss in the aforementioned paper is actually related only to the mutual impedance between the transmitting and receiving antennas but does not include the input resistances of these antennas. This drawback has been repaired in the paper "Calculated transmission loss for a leaky feeder communication systems in a circular tunnel" by Hill and Wait (1976). However, by limiting the antenna input resistance to a certain minimum value at the lower frequencies, the two definitions of the coupling loss in our papers become identical (within a constant). It is interesting to notice that both papers confirm the result that the coupling loss is a very slowly varying function of frequency for frequencies less than about 35 MHz. This is so in spite of the different approaches used in the two papers. Specifically, the coupling loss in Mahmoud and Wait's paper is obtained without assigning any particular location or orientation of the antennas; hence, it can be considered as some kind of average coupling loss over various locations and orientations. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Reply by J.R. Wait [to 'Comments on "Calculated channel characteristics of a braided coaxial cable in a mine tunnel" ']

    Publication Year: 1976 , Page(s): 1213
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (118 KB)  

    Summary form only given, as follows. Prof. Delogne has made some very useful and pertinent comments on the subject of this paper. An improved but, alas, a more complicated approach to the coupling losses is contained in a recent paper, "Calculated transmission loss for a leaky feeder communication system in a circular tunnel," by D.A. Hill and J.R. Wait, Radio Sci., vol. 11, pp. 315-321, Apr. 1976. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Author's reply

    Publication Year: 1976 , Page(s): 1215
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (121 KB)  

    First Page of the Article
    View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • [Back cover]

    Publication Year: 1976 , Page(s): 0
    Save to Project icon | Request Permissions | PDF file iconPDF (201 KB)  
    Freely Available from IEEE
  • Design Criteria for Noncoherent Gaussian Channels with MFSK Signaling and Coding

    Publication Year: 1976 , Page(s): 1078 - 1088
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (928 KB)  

    This paper presents data and criteria to assess and guide the design of modems for coded noncoherent communication systems subject to practical system constraints of power S , bandwidth W , noise spectral density N0, coherence time Tc, and number of orthogonal signals M . Three basic receiver types are analyzed for the noncoherent multifrequency-shift keying (MFSK) additive white Gaussian noise channel: hard decision, unquantized (optimum), and quantized (soft decision). Channel capacity and computational cutoff rate Rcompare computed for each type and presented as functions of the predetection signal-to-noise ratio ST/N_{0} and the number of orthogonal signals M = 2TW . This relates the channel constraints of power, bandwidth, coherence time, and noise power to the optimum choice of signal duration T \leq T_{c} and signal number M . View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Distributed Processing Within an Integrated Circuit/Packet-Switching Node

    Publication Year: 1976 , Page(s): 1089 - 1100
    Cited by:  Papers (1)  |  Patents (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1312 KB)  

    Based on the premise that flexibility is a primary objective for future data networks, it is proposed to integrate circuit switching (CS) and packet switching (PS) in a single network. This paper addresses the switching node in such a network. A novel node concept is presented, imposing PS on a CS structure. Connection management and node control functions on the one hand and packet processing/storing on the other are performed by two groups of modules. The modularity requirement leads to very small, simple processors built into storage modules for packet handling. Considering the high throughput requirement of about 1200 packets/s/node, configurations may exceed 30 packet-handling modules. The wellknown saturation effect of multiprocessor systems, i.e., decreasing incremental throughput with increasing number of processor modules, is overcome by a new concept of intermodule communications, taking advantage of the particular data-communications environment. Intermodule communications-and therefore overhead-have been significantly reduced. As a result, systems throughput for fixed processor module utilization is nearly a linear function of the number of modules, the deviation from linearity being less than 10 percent over the range considered. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Large Time-Bandwidth Product Signaling Technique for Nonwhite Noise Channels

    Publication Year: 1976 , Page(s): 1100 - 1115
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1360 KB)  

    An M -ary, large time-bandwidth product signal design technique is described which is useful for signaling in channels characterized by narrow-band interference and/or wide-band noise impulses. Diversity is also provided, thereby making it a useful signaling technique for dispersive channels. The motivations for choosing this signal format are explained, and design procedures, with two candidate signal designs, are given. The performance of a fast-fast-Fourier-transform-based receiver, which employs an excision algorithm for reducing the effects of narrow-band interference, is investigated through computer simulation. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Image Activity Characteristics in Broadcast Television

    Publication Year: 1976 , Page(s): 1201 - 1206
    Cited by:  Papers (5)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (464 KB)  

    Real-time processing of video waveforms has been implemented for the purpose of analyzing image dynamics. A digital preprocessor yields data sets that describe the difference between selected fields of an input video signal in both the spatial and temporal domains. Further reduction and analysis of the acquired data can provide several measures of image activity such as the frame-to-frame correlation, the frame-difference signal (FDS), and statistics of scene lengths. The results of a series of measurements of the dynamics of typical broadcast television programs are presented. It is demonstrated that image activity is separable into two distinct classes, one caused by image and camera movement, and the other by scene switches. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On Parasitic Correlation Peaks in Cross-Correlation Circuits for Binary Pseudorandom Sequences

    Publication Year: 1976 , Page(s): 1143 - 1148
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (632 KB)  

    Technical applications of binary pseudonoise (PN) sequences frequently utilize correlation procedures. At the output of the post-detection integrator of one form of the correlation circuit, which is often used to obtain initial synchronization of PN spread-spectrum communications systems, parasitic voltage peaks may appear which are not evident from the basic theory of pseudorandom sequences. The origin of these parasitic peaks is explained by the help of the shift-and-add property of binary pseudorandom sequences. Besides, a procedure is given for the approximate calculation of the amplitude of the parasitic peaks. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Evaluation of Decision Feedback Equalization and Viterbi Algorithm Detection for Voiceband Data Transmission--Part I

    Publication Year: 1976 , Page(s): 1130 - 1139
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (960 KB)  

    The application of QAM receivers employing passband decision feedback equalization or Viterbi algorithm detection is considered for high-speed data transmission in voiceband telephone channels. Analytical results for the Viterbi receiver indicate that it can permit digital data transmission with symbol rates exceeding the nominal bandwidth capabilities of the channel. However, it is also shown that the minimum distance of partial response-type impulse responses can substantially decrease due to small demodulation phase errors. Thus, decision feedback receivers may offer more robust performance on channels with phase jitter. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Performance of Multilevel Baseband Digital Systems in a Nonlinear Environment

    Publication Year: 1976 , Page(s): 1166 - 1175
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (712 KB)  

    A good deal of effort has been spent, in the past few years, to devise numerical algorithms for evaluating the performance of digital communication systems over noisy linear channels, i.e., in the presence of intersymbol interference and noise. In this concise paper we present a method for computing the error probability of multilevel baseband digital modulation systems when the channel is nonlinear with memory. The algorithm is based on a Volterra series expansion of the nonlinearity; with this model, we show that the moments of the disturbance can be computed recursively, and the same techniques in use for linear channels can be applied for evaluating the error probability. This approach can be generalized to consider noise entering the nonlinear channel. The computing algorithms are described in detail, and a complete example is worked out. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Wide-Band Phase-Feedback Inverse-Sine Phase Modulator with Application Toward a LINC Amplifier

    Publication Year: 1976 , Page(s): 1139 - 1143
    Cited by:  Papers (6)  |  Patents (49)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (520 KB)  

    A wide-band inverse-sine phase modulator is demonstrated. The modulator has application in a LINC amplifier for linear amplification at microwave frequencies using commonly available saturating amplifiers or injection-locked oscillators. A bandwidth greater than 10 MHz at a carrier frequency of 96 MHz with distortion products 40 dB or greater below desired components has been shown. The distortion behavior as a second-order effect of the loop delay as predicted by analysis has been verified. The output of the inverse-sine phase modulator and its conjugate, generated by a second phase modulator, were subtracted as in a LINC amplifier, to provide at least 40-dB suppression of the zeroth order and even-order components. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Algorithmic Measurement of Digital Instantaneous Frequency

    Publication Year: 1976 , Page(s): 1115 - 1122
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (640 KB)  

    This paper presents an algorithmic method for measuring the instantaneous frequency of a uniformly sampled FM signal. The measured parameter, termed digital instantaneous frequency, is defined in a manner similar to that used to describe frequency-modulated, continuous-time signals. The measurements are derived from an adaptive linear prediction spectral estimates. The proposed algorithm is utilized in the development of a digital processor for FM demodulation which operates on a uniformly sampled FM signal, and its output is a sampled sequence of the estimated demodulated message. The performance of the digital processor is demonstrated and compared with that of a conventional FM discriminator. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Two-Dimensional Markov Representations of Sampled Images

    Publication Year: 1976 , Page(s): 1148 - 1152
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (424 KB)  

    This paper shows that, under certain weak restrictions, a two-dimensional discrete Markov process can be represented either "causally" by a one-sided difference equation, or "noncausally" by a multiple-sided difference equation. The former representation is pertinent to the analysis of image coders and processors that operate sequentially on scanned image data. The latter representation is applicable to the analysis of block coders and processors. The general relation between the two representations is given and the specialized forms resulting under separable scene covariance studied. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Optimum Allocation of Multibeam Communications Satellite Resources

    Publication Year: 1976 , Page(s): 1195 - 1200
    Cited by:  Papers (4)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (568 KB)  

    Future communications satellites can be expected to employ multibeam antennas for both receiving (uplink) and transmitting (downlink). The use of multibeam satellite transmitting antennas raises the question of how to assign the transmitted power and antenna gain to each of the N beams such that optimum use is made of satellite resources. We refer to this problem as the downlink allocation problem; it is part of the larger problem of allocating all satellite network variables. This concise paper deals with both problems. Specifically, we rigorously formulate and solve the downlink problem for an arbitrary number of beams using the Lagrange multiplier technique for constrained extremal problems. We then discuss procedures for incorporating the optimum downlink allocation results into a complete system allocation. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Feedback Receive Amplifier for Optical Transmission Systems

    Publication Year: 1976 , Page(s): 1180 - 1185
    Cited by:  Papers (28)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (600 KB)  

    We consider the design and implementation of a lownoise feedback receive amplifier for use in optical communication systems. The feedback amplifier configuration is advantageous in that it offers a wide bandwidth with good signal to noise ratio. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Topological Design of Teleprocessing Networks Using Linear Regression Clustering

    Publication Year: 1976 , Page(s): 1152 - 1159
    Cited by:  Papers (1)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (792 KB)  

    Cost-effective design of networks linking many remote terminals to a central computer (CPU) involves use of low-speed data lines to link geographically close terminals to concentrators. The concentrators are connected via high-speed data lines to the CPU. A design algorithm based on clustering of terminals followed by optimization of location, capacity and number of concentrators in each cluster is developed and evaluated. Evaluation is based on network designs for sets of 20 randomly (uniformly) generated locations of up to 500 terminals, with specific (realistic) cost versus capacity schedules being used for data lines and concentrators. In comparison with the popular Add algorithm, our linear regression clustering (LRC) algorithm has the following advantages: 1) the total cost of the concentrators, low-speed terminal lines, and high-speed CPU lines is typically 8 percent less; 2) the average transmission time delay at the terminals is typically 40 percent less; 3) the cost of adding low-speed data lines to connect additional terminals to concentrators in existing networks is typically 50 percent less; 4) the computational cost of design is typically 20 times less for 100-terminal networks and 150 times less for 500-terminals networks. Implications of the results and suggestions for further work are discussed. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A 15-Electrode Totally Implanted Time-Multiplex Telemetry Unit

    Publication Year: 1976 , Page(s): 1073 - 1078
    Cited by:  Papers (2)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (736 KB)  

    A 15-electrode totally implanted time-multiplex telemetry unit is described that is powered by two mercury cells in series. Transcutaneous radio frequency (RF) turn-on and magnetic turnoff are used to conserve battery power. The basic cycle rate is 400 Hz, channel rate 6400 Hz. The channel 16 input consists of a 200-Hz 5 mV peak-to-peak (p-p) reference signal, and a 3200-Hz sync signal is added to all channels. The unit is 1.5 \times 2.5 \times 8 cm in size, weighs 41 g, and draws 3.5 mA. Low-frequency cutoff is at 0.2 Hz. The output is FM with a peak deviation of 75 kHz of a 20 MHz carrier at 5 mV peak channel input. The equivalent noise input is 2.8 μV root mean square (rms). The decoder automatically locks on the reference signal square wave with the aid of an exclusive-OR gate. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Buffer Requirements for Intermittent Data Transmission Over a Rayleigh Fading Channel

    Publication Year: 1976 , Page(s): 1122 - 1129
    Cited by:  Papers (2)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (688 KB)  

    Intermittent data transmission, that is, sending data only when the signal strength is above a desired threshold, has been shown to be extremely effective at combatting the effects of signal fading. However, such a system must usually interface with a uniform data source and sink by the use of finite buffers. When the buffer fills, transmission must occur during bad signal conditions and when it empties, no transmission can occur. The effect of such a finite buffer on system performance is derived and these theoretical results are validated using computer simulation. Finally, adaptive methods to improve performance are investigated and two areas of application of an intermittent System are examined. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A Study of Signal Decorrelation Through the Ionosphere

    Publication Year: 1976 , Page(s): 1191 - 1195
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (408 KB)  

    Signals in a satellite-earth communication link pass through the ionosphere where there may exist random irregularities. These random irregularities will scatter and distort the Signal, producing a fading channel. Such a channel is generally characterized by the symmetric and asymmetric correlation functions. Approximate solutions for these functions have been obtained and the results plotted for typical ionospheric parameters. Some of the results are shown in terms of coherence bandwidth. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Subjective Effect of Substituting Lines in a Video-Telephone Signal

    Publication Year: 1976 , Page(s): 1208 - 1212
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (456 KB)  

    In processing video-telephone signals to reduce bandwidth requirements, lines may occasionally be lost due to buffer overflow or DPCM channel errors. The subjective degradation introduced by replacing deleted lines by averaging or repeating adjacent lines (substitution) has been measured. In the test, both skilled and unskilled observers were asked to add white noise to an unimpaired picture until the quality was equal to the same picture in which a number of lines had been randomly substituted. It was found that the more critical skilled observers deemed a picture, degraded by substituting 1 averaged line per frame, comparable to a signal-to-noise ratio of 38.6 dB, a rating of "definitely noticeable but not objectionable" on a 5-point impairment scale. Futhermore, it was found that repeating lines rather than averaging produced more degradation, equivalent to a 4 dB lower signal-to-noise ratio. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Variable Length Encoding of Binary Memoryless Sources with a Fidelity Measure

    Publication Year: 1976 , Page(s): 1185 - 1191
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (656 KB)  

    This concise paper deals with variable length source coding for binary memoryless sources with a fidelity criterion. The encoding scheme under consideration is an ( M_{c}, N, K ) code consisting of a distortionless run-length inner code of size Mcand an outer code that maps each source vector of length N to a codeword of length less than or equal to K . The encoding of the outer code is accomplished by means of a trellis search, and the distortion measure used is a Hamming distance. For composite binary memoryless sources an adaptive ( M_{c}, N ) code can be constructed by varying the constraint K on codeword length according to the source statistics. The ( M_{c}, N, K ), and ( M_{c}, N ) codes are insensitive to the inaccuracy in estimating the source probabilities. Rate-distortion curves, obtained by computer simulation, are plotted along with the theoretical rate-distortion function R(D) . 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