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Proceedings of the IEEE

Issue 6 • June 1969

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Displaying Results 1 - 25 of 98
  • [Front cover and table of contents]

    Publication Year: 1969, Page(s): c1
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    Freely Available from IEEE
  • Scanning the issue

    Publication Year: 1969, Page(s):859 - 860
    Cited by:  Papers (1)
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  • Objectives, history, and principal achievements of the topside sounder and ISIS programs

    Publication Year: 1969, Page(s):861 - 865
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    This paper discusses the ionospheric satellites that have been developed and launched as a result of the topside sounder and ISIS programs. The mission objectives, the feasibility studies, the program coordination, and the more important scientific accomplishments are summarized. View full abstract»

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  • Note on the availability of topside sounding data

    Publication Year: 1969, Page(s): 866
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    A brief explanation is given on where to obtain ionospheric data generally, and specifically ionospheric data which has been observed from space vehicles. The close relations between the World Data Centers and the National Archives is noted. View full abstract»

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  • The development of a series of ionospheric satellites

    Publication Year: 1969, Page(s):867 - 875
    Cited by:  Papers (24)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (977 KB)

    The Alouette-ISIS series of satellites is described, with attention being paid to the engineering and management constraints that were present during the conceptual stages, and it is shown how each succeeding mission meets more fully the objectives of the program. The lessons learnt during the development of this series are finally applied to the conceptual design of ISIS-C, the last satellite in ... View full abstract»

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  • Development of the fixed-frequency topside-sounder satellite

    Publication Year: 1969, Page(s):876 - 881
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1863 KB)

    A fixed-frequency ionosphere sounder satellite, Explorer XX, was developed for the purpose of obtaining pulsed soundings of the topside of the ionosphere. The basic sounder instrumentation comprised a two-frequency transceiver coupled to an electrically short dipole antenna. Three transceivers were used for sounding at six fixed frequencies between 1.50 and 7.22 MHz. A two-frequency sounder payloa... View full abstract»

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  • Mechanical design and dynamics of the Alouette spacecraft

    Publication Year: 1969, Page(s):882 - 896
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1710 KB)

    A general review is presented of the highlights associated with the mechanical engineering of the Canadian Alouette I and II spacecraft. Of special interest was the development of the extendible ionospheric sounding antenna, first used to form 75-ft by 150-ft tip-to-tip crossed dipoles on Alouette I. The use of such long antennas made Alouette I the first earth satellite to be launched that exhibi... View full abstract»

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  • The design of swept-frequency topside sounders

    Publication Year: 1969, Page(s):897 - 929
    Cited by:  Papers (69)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (4669 KB)

    Echo sounding of the ionosphere from below has, for four decades, been a fruitful way of obtaining information about the upper atmosphere and the effects of solar emissions. In the last few years, earth satellites have been used as platforms from which to sound the ionosphere from above. This technique has opened new areas of ionospheric research and has the great advantages of world-wide coverage... View full abstract»

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  • A data acquisition and processing system for mass producing topside ionograms

    Publication Year: 1969, Page(s):929 - 944
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (2317 KB)

    Data telemetered from the Alouette I and II swept-frequency topside sounder ionospheric satellites are collected by a worldwide network of 22 ground stations. To acquire data, each spacecraft is commanded, and its telemetry signals received and recorded, on magnetic tape. The telemetry tapes are then forwarded to processing centers where the ionospheric data are converted into ionograms and stored... View full abstract»

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  • A simple receiving and display system for Alouette I ionograms

    Publication Year: 1969, Page(s):945 - 947
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (540 KB)

    A simple telemetry system was devised soon after the launch of the Alouette I satellite, to obtain topside ionograms directly from the satellite. The video data from a simple receiver are tape-recorded directly with a basic system costing less than $1000. Additional equipment can supplement the basic system to improve the quality of the data and to produce film ionograms. View full abstract»

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  • Quick-look system for virtual real-time telemetry reception of topside ionograms

    Publication Year: 1969, Page(s):947 - 948
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (524 KB)

    A telemetry receiving system that provides a direct readout of ionograms from topside sounders is described. The system is designed to use "off-the-shelf" components. Its most important application is the availability of immediately readable ionograms for short-time corrections of usable frequencies. View full abstract»

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  • The interpretation of topside sounder ionograms

    Publication Year: 1969, Page(s):949 - 960
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (4827 KB)

    Most of the phenomena observed on Alouette I and Alouette II ionograms are identified and interpreted. Simple as well as complex ionograms are treated, but emphasis is placed on ionograms exhibiting very low electron density, spread-F and field-aligned propagation. It is shown that many of the ionograms normally considered too complex for analysis can yield useful geophysical parameters using the ... View full abstract»

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  • The reduction of topside ionograms to electron-density profiles

    Publication Year: 1969, Page(s):960 - 976
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1869 KB)

    The basic principles of the ionosonde technique for ionospheric electron-density determination are reviewed, with special emphasis on the satellite version. It is shown that the lamination method of data reduction, developed initially for the analysis of ionograms obtained with ground-based ionosondes, can be used to calculate the electron density N versus true height h in the topside ionosphere p... View full abstract»

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  • Comparisons between topside and ground-based soundings

    Publication Year: 1969, Page(s):976 - 985
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    Past observations, indicating that electron density profiles derived from topside ionograms have a tendency to be slightly too low, are reviewed and discussed. This problem is then examined in the light of more recent and better controlled experiments in which vertical electron density profiles were obtained essentially simultaneously by topside and ground-based soundings. These new measurements c... View full abstract»

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  • A computer-aided system for scaling topside ionograms

    Publication Year: 1969, Page(s):986 - 989
    Cited by:  Papers (1)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1123 KB)

    A computer-aided data-interpretation system is described that combines the abilities of a human operator for pattern recognition and decision making with those of a digital computer for rapid computation. It is designed for the specific task of converting ionograms to electron density N(h) profiles, but is sufficiently flexible in design and concept to be used, in principle, with any type of compl... View full abstract»

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  • Global electron density distributions from topside soundings

    Publication Year: 1969, Page(s):990 - 1004
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1528 KB)

    A global morphology of electron density distributions in the topside ionosphere during sunspot minimum as deduced from Alouette I and II ionograms is presented. Graphs are shown illustrating the variations of electron density with altitude (400 to 3000 km), dip latitude (±90°), local time (24 hours), and season (December and June solstices; equinox) for both quiet and disturbed geomagnet... View full abstract»

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  • The high-latitude ionosphere

    Publication Year: 1969, Page(s):1005 - 1012
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    This paper reviews information on the high-latitude ionosphere derived from the Alouette-ISIS program. It is primarily descriptive and deals mainly with F-region features. Particle effects in the D region and night E ionization are briefly considered. F-region features include the main trough, maxima and minima in electron density in the polar region, and electron-density irregularities revealed b... View full abstract»

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  • A review of topside sounder studies of the equatorial ionosphere

    Publication Year: 1969, Page(s):1012 - 1018
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (685 KB)

    The structure of the equatorial ionosphere as derived from topside sounder data is reviewed. Shortly after sunrise a single ionization crest occurs above the magnetic equator at all heights, but later during the day an equatorial anomaly develops in the form of an arch along which the ionization is enhanced and which lies along different magnetic field lines at different local times. The arch inte... View full abstract»

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  • Ionospheric irregularities observed by topside sounders

    Publication Year: 1969, Page(s):1019 - 1025
    Cited by:  Papers (17)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1236 KB)

    Topside sounders observe electron-density irregularities in the ionosphere with dimensions of hundreds of meters to many kilometers across the magnetic field. Most irregularities are elongated and may extend thousands of kilometers along the field. The variation of electron density is normally a few percent or less. The irregularities tend to occur in patches, in which the individual irregularitie... View full abstract»

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  • On the prediction of F-layer penetration frequencies

    Publication Year: 1969, Page(s):1025 - 1028
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (335 KB)

    The Comité Consultatif International des Radiocommunications (C.C.I.R.) predictions of F-layer penetration frequencies have been compared with 1963 Alouette topside-sounder data. The data used for these comparisons were collected from 45° to 165°W longitude in the northern hemisphere. It was found that the C.C.I.R. predictions differ by as much as 0.7 MHz from the Alouette data. The... View full abstract»

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  • The topside ionosphere during geomagnetic storms

    Publication Year: 1969, Page(s):1029 - 1036
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    The state of knowledge of ionospheric storms in the topside ionosphere is reviewed. Although much remains to be understood concerning ionospheric storms, many of the storm-time phenomena can be interpreted in terms of drift motions produced by storm-time currents, and by ambipolar diffusion. View full abstract»

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  • Ionospheric ion composition deduced from VLF observations

    Publication Year: 1969, Page(s):1036 - 1041
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (838 KB)

    VLF observations from the Alouette satellites have provided information on the ion composition of the ionosphere. This is derived from two sources: noise bands with a lower frequency cutoff at the lower hybrid resonance (LHR) frequency, and ion whistlers. The LHR frequency depends on the harmonic mean mass of the ionic constituents. Ion whistlers provide good measurements of the relative abundance... View full abstract»

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  • Radio noise levels within and above the ionosphere

    Publication Year: 1969, Page(s):1042 - 1050
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (2982 KB)

    The principal results obtained from the background noise experiment in the Alouette satellites are summarized. The various natural emissions, most of which can reach intensity levels as high as 80 dB above receiver threshold, are identified in the recordings with reference to the characteristic frequencies of the ionosphere local to the spacecraft and are described in turn. Galactic noise is the p... View full abstract»

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  • On the high-latitude limit of closed geomagnetic field lines

    Publication Year: 1969, Page(s):1051 - 1053
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (318 KB)

    One ofthe investigations carried out with the energetic particle experiment on the Alouette satellites has been a study of the high-latitude boundary of 35-keV electrons in the outer radiation zone. A comparison of Λbthe average high-latitude boundary, with solar proton intensity versus latitude profiles, and with the location of the auroral oval, leads to the conclusion that Λ... View full abstract»

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  • Cylindrical electrostatic probes employed on Alouette II and explorer XXXI satellites

    Publication Year: 1969, Page(s):1054 - 1056
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (298 KB)

    The cylindrical electrostatic probes flown on both AIouette II and Explorer XXXl enable intersatellite comparisons of directly measured parameters to be made. The sensors are identical, but differences between the two satellites resulted in differences of data format and probe potential. Interference from the topside sounder on Alouette II has made data processing difficult. View full abstract»

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