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Communications, IEEE Transactions on

Issue 4 • Date April 1974

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  • [Front cover and table of contents]

    Publication Year: 1974 , Page(s): 0
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  • Historical Background and Introduction to the Special Issue on Extremely Low Frequency (ELF) Communications

    Publication Year: 1974 , Page(s): 353 - 354
    Cited by:  Papers (4)
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  • Dedication to Janis Galejs

    Publication Year: 1974 , Page(s): 355
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  • Guide to Papers in This Issue

    Publication Year: 1974 , Page(s): 356 - 359
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  • The Guest Editor's Past Interest in Extremely Low Frequency (ELF) Electromagnetics

    Publication Year: 1974 , Page(s): 587 - 588
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  • [Back cover]

    Publication Year: 1974 , Page(s): 0
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  • Some Early Historical Aspects of Project Sanguine

    Publication Year: 1974 , Page(s): 359 - 363
    Cited by:  Papers (4)  |  Patents (1)
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    Early extremely low-frequency (ELF) research and the implementation of Project Sanguine to meet the Navy's need for secure transmission to submerged fleet ballistic missile (FBM) submarines are outlined. The 1963 "Intensive Test," which proved the feasibility of ELF reception by a submarine at operational depths, is highlighted. View full abstract»

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  • Early Development of the Project Sanguine Radiating System

    Publication Year: 1974 , Page(s): 364 - 371
    Cited by:  Papers (1)
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    The Project Sanguine system is the result of many years of research and analysis into radiating system configurations. The paper describes the early portions of this search, the recognition of equivalences among several of the candidate systems, the conduct of an early transmission experiment, and the initial efforts at system optimization and choice of the radiating system configuration. The early research and tests provided confirmation of the theory that a vertically polarized E -field propagates through the earth ionosphere cavity at ELF with a slight forward tilt which allows it to enter the sea water and then penetrate to considerable depths. It also verified the behavior of the earth return antenna element through the operation of an experimental system. In addition, a system optimization program was developed to allow the cost of achieving various levels of system performance to be assessed. View full abstract»

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  • A Signaling Scheme and Experimental Receiver for Extremely Low Frequency (ELF) Communication

    Publication Year: 1974 , Page(s): 508 - 528
    Cited by:  Papers (4)
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    The advantages of utilizing the extremely low frequency (ELF) band for communications to submarines are principally the low attenuation rate of ELF signals in seawater and the low attenuation rate in the earth-ionospheric waveguide. ELF transmitters, however, require high input power. Efficient signaling schemes and sophisticated receiver designs help minimize the required transmitter power and hence system cost. One such signaling schemeconvolutional encoding and binary antipodal modulation-and an experimental receiver were successfully field tested and are described. Tests included real-time reception of messages aboard a submerged submarine in the Atlantic Ocean. It is concluded that the receiver, which included adaptive nonlinear noise processing, notch filtering, ocean channel compensation, and sequential decoding makes extremely efficient usage of available signal strength and demonstrates the technical feasibility of communication in the ELF band. View full abstract»

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  • The Electronic Countermeasures Problem for Extremely Low Frequency (ELF) Communications

    Publication Year: 1974 , Page(s): 496 - 503
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    An extremely low frequency (ELF) communication system for military purposes needs specialized engineering techniques, in particular signal bandwidth spreading in order to protect against enemy electronic countermeasures (ECM). Qualitative discussion is presented of the processing which the system must have to make jamming difficult, with qualitative discussion of predictive jamming, repeat-back jamming, and high power brute force jamming by adapting electric power systems. View full abstract»

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  • Optimizing the Current Distribution in a Buried Linear Antenna

    Publication Year: 1974 , Page(s): 409 - 411
    Cited by:  Papers (1)
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    A solution is obtained to the problem of finding the current distribution in a buried linear antenna which minimizes the dissipated power while maintaining the required radiated field. An example shows that such distribution saves about 30 percent on power dissipation compared to an antenna of the same total length having simple bared-end grounding terminations. A practical method using current transformers is proposed for controlling the current distribution. A grounding system using this method has the property that it does not short out adjacent active antenna cables when it is in standby mode. View full abstract»

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  • Project Sanguine Interference Mitigation Research

    Publication Year: 1974 , Page(s): 562 - 569
    Cited by:  Papers (2)
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    The Navy's proposed extremely low frequency (ELF) communications system (Sanguine), which would use an earthreturn circuit to excite the earth-ionosphere cavity, represents a potential electrical interference problem. The electromagnetic fields produced by Sanguine could influence other systems such as power distribution lines and telephone circuits, and other very long electrical conductors. This interference potential and the techniques useful in mitigating it are described. Also, data on power and telephone systems are presented that were useful in communications systems design tradeoff studies. View full abstract»

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  • Propagation Theory and Calculations at Lower Extremely Low Frequencies (ELF)

    Publication Year: 1974 , Page(s): 438 - 451
    Cited by:  Papers (2)
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    Propagation theory along the lines of Budden's terrestrial waveguide formalism is reviewed. Special emphasis is placed on its application to the lower extremely low frequency (ELF) range for which a number of calculations have been made to demonstrate the relationship between propagation parameters and the physical constants of the ionosphere. Calculations performed with diffuse anisotropic ionospheres yield reasonable agreement with ELF test results. View full abstract»

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  • Superconducting Extremely Low Frequency (ELF) Magnetic Field Sensors for Submarine Communications

    Publication Year: 1974 , Page(s): 549 - 554
    Cited by:  Papers (8)  |  Patents (8)
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    The ferromagnetic-core type of solenoid that is used as a trailed antenna for communications reception by submarines has not demonstrated adquate sensitivity to satisfy the performance requirements for deeply submerged submarines receiving extremely low frequency (ELF) transmissions from the planned Sanguine communications system. It is possible, however, that a superconducting quantum interference device (SQUID) can be adapted to this role successfully and can permit all requirements of platform depth, speed, and maneuverability to be met. The present status of SQUID's is described, and some laboratory measurements that prove the potential of these devices for the ELF communications reception capability are presented. The engineering development that must be pursued in the areas of 1) sensor and electronics dynamic range, 2) sensor orthogonality, and 3) refrigeration systems to make SQUID ELF sensors available as operational receiving antennas is also discussed. View full abstract»

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  • Application of Magnetotelluric Techniques at Extremely Low Frequency (ELF) for Sanguine Transmitting Antenna Site Characterization

    Publication Year: 1974 , Page(s): 394 - 398
    Cited by:  Papers (2)
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    Conductivity measurements using the magnetotelluric resistivity method can be used to survey a proposed Sanguine transmitter site for its suitability, and to predict the radiation pattern of the transmitting antenna. The magnetotelluric resistivity method, unlike other conductivity measuring techniques, can account for the anisotropic behavior of the earth, and can obtain measurements rapidly as compared with other techniques. View full abstract»

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  • Bared-End Ground for an Insulated Buried Antenna Cable

    Publication Year: 1974 , Page(s): 404 - 408
    Cited by:  Papers (3)
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    The impedance, effective length, and current distribution of a grounding electrode are examined numerically. Its length varies frown being electrically short to being larger than a skin depth. The electrode is taken to be the bared extension of an insulated buried antenna. It is shown that there is little to be gained in making the electrode longer than a skin depth, unless the current distribution can be forced to spread out further along the electrode. Whether or not the properties of the grounding electrode will be affected by the impedance per unit length of the conductor is an important consideration. A criterion to help in this regard is developed. View full abstract»

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  • Motion-Induced Noise in Electrode-Pair Extremely Low Frequency (ELF) Receiving Antennas

    Publication Year: 1974 , Page(s): 540 - 542
    Cited by:  Patents (3)
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    The pressure fluctuations in the turbulent boundary layer surrounding the towed antenna cable cause it to vibrate in the geomagnetic field and thereby generate noise. This noise mechanism is the dominant one in current long antennas. Its effect can be reduced only by increasing antenna diameter and length. Tension, stiffness, and damping have no effect. Noise voltage spectra derived from pressure fluctuation data show striking agreement with those measured. View full abstract»

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  • Extremely Low Frequency (ELF) Propagation Measurements Along a 4900-km Path

    Publication Year: 1974 , Page(s): 452 - 457
    Cited by:  Papers (5)
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    Extremely low frequency (ELF) electromagnetic wave propagation was investigated by measuring the amplitude of a CW signal transmitted from the Sanguine site in North Carolina to receiving sites located in New York State, Labrador, and Iceland. The attenuation factor α and the reciprocal of the excitation factor h_{i} (\sigma _{e}S_{0})^{1/2} were determined. Data for daytime, nighttime, and sunrise transition paths were obtained. The attenuation factors obtained for 78 and 156 Hz are compared with the value of α obtained from measurements of atmospherics. The attenuation values at 78 Hz of 1.29 and 1.01 dB/1000 km, and a value of 0.75 dB/1000 km at 45 Hz, obtained by interpolation of results of this and other experiments, were used in Sanguine systems analysis. View full abstract»

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  • Design of a Sanguine Noise Processor Based Upon World-Wide Extremely Low Frequency (ELF) Recordings

    Publication Year: 1974 , Page(s): 528 - 539
    Cited by:  Papers (19)
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    This paper describes the design of a candidate noise processor for the Sanguine receiver based on communication theory considerations and detailed experiments using wide-band recordings of extremely low-frequency (ELF) (3-300 Hz) atmospheric noise. This processor consists of the following elements: 1) a compensating (or whitening) filter; 2) nonlinear notch filtering at frequencies of manmade interference; 3) a post-notch filter nonlinearity; and 4) a phase coherent linear matched filter. Due to the impulsive non-Gaussian nature of the noise, nonlinear processing with a bandwidth considerably greater than the 40-80-Hz signal bandwidth is significantly better than a linear receiver (consisting only of a matched filter and appropriate whitening filters). Simulations using noise recordings from a number of widely separated locations in the world have shown improvements of 7 dB to 20 dB at times of high ELF atmospheric noise levels at the receiver input. View full abstract»

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  • Extremely Low Frequency (ELF) Communication to Submarines

    Publication Year: 1974 , Page(s): 371 - 385
    Cited by:  Papers (1)
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    An ELF (extremely low frequency) communication system has been proposed for communication from land to submerged submarines. We present an analytical study of conceptual feasibility of such a system and discuss some of its properties. We find no fundamental technical reason why such a system is infeasible. The present work yields the general structure of the receiver, and estimates for the important parameters of such a system. Nonlinear processing ahead of the FSK (frequency-shift keying) receiver in the submarine appears essential. Such processing greatly reduces the effects of atmospheric noise due to nearby lightning storms, and hence, makes reliable operation possible at much smaller transmitter power. View full abstract»

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  • The Sanguine Biological-Ecological Research Program

    Publication Year: 1974 , Page(s): 570 - 577
    Cited by:  Papers (7)
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    An overview of laboratory and field studies, completed and in progress, which are designed to disclose possible effects on organisms of a Sanguine system, is presented. The extremely low frequency (ELF) electric and magnetic field levels associated with a Sanguine system are about 0.07 V/m and 0.2 G, respectively, at the surface of the earth directly above a buried Sanguine antenna. The Sanguine Division of the Naval Electronic Systems Command initiated research in 1969 to determine whether biological or ecological effects could be expected from exposure to these low levels. The research spans a broad spectrum of biological sciences, from enzymes to mammalian behavior, and from bacteria and slime molds to primates. Results of completed studies are summarized, and those studies still in progress are discussed. Research results to date show no indication that exposure to ELF field levels associated with a Sanguine system would have any effect on biological or ecological systems. Results of research in progress will be reviewed when available to determine future directions of the program. View full abstract»

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  • Far-Field Extremely Low Frequency (ELF) Propagation Measurements, 1970-1972

    Publication Year: 1974 , Page(s): 468 - 474
    Cited by:  Papers (7)
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    For the past 3 years, we have participated in various extremely low frequency (ELF) propagation tests. During these tests, receiving sites were located in Connecticut, North Carolina, Maine, Utah, Nova Scotia, California, Greenland, the Virgin Islands, Alaska, Norway, Hawaii, Greece, and Saipan. Measurements have also been taken sporadically in Connecticut since June 1970. At each location, the horizontal magnetic field strengths were measured at a band of frequencies centered at 45 Hz and 75 Hz in order to determine the average attenuation rates and relative excitation factors for daytime and nighttime propagation conditions. The U.S. Navy ELF Wisconsin Test Facility was the transmission source. The principal results obtained from these measurements were 1) the daytime attenuation rate is usually higher than the nighttime attenuation rate at both 45 and 75 Hz; 2) the relative excitation factors are quite different for daytime and nighttime propagation conditions; 3) nighttime propagation is more variable than daytime propagation; 4) there is a seasonal variation in the ELF propagation parameters; and 5) auroral-zone effects appear to be present at both frequencies. View full abstract»

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  • Ground Anisotropy and Extremely Low Frequency (ELF) Transmitting Antennas

    Publication Year: 1974 , Page(s): 402 - 404
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    The surface impedance concept is used to examine the effect of ground anisotropy on the radiated field and power dissipation of a horizontal ELF transmitting array. The principal result, for a simple homogeneous but anisotropic ground, is that even though the ground skews the antenna pattern, any attempt to reorient the array to steer the pattern peak towards the receiver incurs an increase in power dissipation. In fact, the power dissipation is minimized by steering the pattern peak even further away from the receiver. View full abstract»

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  • Results of the Wisconsin Test Facility Buried Versus Elevated North-South Antennas Test

    Publication Year: 1974 , Page(s): 419 - 421
    Cited by:  Papers (2)
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    In March and April 1973, the 76-Hz magnetic field strength, produced by the Wisconsin Test Facility elevated and (newly installed) buried north-south antennas, was measured in Wisconsin and Texas. The principal result obtained is that there is no measurable difference in performance between the two antennas. View full abstract»

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  • The Influence of Certain Ionoshperic Phenomena on Extremely Low Frequency (ELF) Propagation

    Publication Year: 1974 , Page(s): 484 - 492
    Cited by:  Papers (1)
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    A number of phenomena that may cause irregularities in extremely low frequency (ELF) ionospheric propagation are suggested. Geomagnetic anisotropy, path asymmetry due to different ionospheric characteristics on the darkened and sunlit hemispheres, effects of strong boundary discontinuities such as the twilight zone or northern latitude sporadic E , and the effects of geophysical trauma such as solar particle fluxes are considered. A primitive analysis of ELF propagation data illustrates that an association can be drawn between the effects of solar charged particle emissions and coincident ELF propagation irregularities. Paths that pass through the auroral zone appear to be most severely affected. 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