By Topic

IEEE Transactions on Broadcasting

Issue 2 • Date Jun 1989

Filter Results

Displaying Results 1 - 21 of 21
  • MF sky-wave propagation: a comparison of measurements made at sunset and sunrise

    Publication Year: 1989, Page(s):200 - 203
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (268 KB)

    The strength of MF skywave signals is greatest at night and weakest during the day. The increase in field strength which occurs at sunset has been extensively studied but less is known about the decrease which occurs at sunrise. A description is given of a series of measurements made by members of the European Broadcasting Union (EBU), which cover both the sunrise and sunset periods. The results s... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A high power solid-state medium wave broadcast transmitter

    Publication Year: 1989, Page(s):118 - 120
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (204 KB)

    The factors leading to the choice of an all-solid-state 50-kW medium-wave broadcast transmitter are examined, and its advantages over vacuum-tube-type transmitters of the same power are discussed. The installation and operation of the transmitter are described. The transmitter has demonstrated high levels of performance and reliability. Energy savings and reduction of maintenance times have been a... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Directional MF antennas using self-supporting towers with driven wire cages

    Publication Year: 1989, Page(s):193 - 199
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (480 KB)

    An examination is made of the synthesis of directional high-power MF antennas that comprise grounded self-supporting steel towers with driven wire cages as radiating elements. Advantages of this radiator concept are discussed. Computer models of such radiator for the method of moments (MM) analysis of synthesis for an antenna of n radiators is achieved by (1) MM analysis of the antenna fo... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Impedance stability and bandwidth considerations for elevated-radial antenna systems

    Publication Year: 1989, Page(s):167 - 171
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (268 KB)

    An examination is made of the variations in feed-point impedance that occur in an elevated antenna system due to changes in the electrical characteristics of the underlying soil. The bandwidth of such antennas is also investigated by looking at deviations in the input impedance as the operating frequency is varied about its nominal value. In all cases, results for the elevated antenna are compared... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Relationship between the electrical height of medium-wave antenna and its mechanical dimensions

    Publication Year: 1989, Page(s):241 - 247
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (468 KB)

    The design is studied of the mechanical element implementing the wanted height, once the optimum electrical height of an antenna for medium-wave transmission is determined. The problem of how to determine the velocity factor is complex and not yet completely solved in mathematical terms, particularly as regards nonresonant antennas and having a height near to the half wave. The mean factor of velo... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Medium wave skywave beams

    Publication Year: 1989, Page(s):223 - 226
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (204 KB)

    The author discusses the advantages and drawbacks of skywaves and why they are avoided by domestic medium-wave broadcaster. He reports some results of a computer investigation of problems encountered with medium-wave antennas coupled to a skywave propagation medium. Experimental results are given showing skywave patterns for broadcasts from Alaska, one using a horizontal and the other a vertical a... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Moment method predicted impedances compared to actual measured impedances of directional arrays

    Publication Year: 1989, Page(s):190 - 192
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (184 KB)

    A comparison is made of the self and mutual impedances predicted by a moment method program to show how it derives the Z matrix. A discussion of the theory of these impedances if offered as a foundation to analyze the results. The comparison shows that the field measurements support the data generated by the program View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A proposal of a traffic information signalling compatible with AM-MF broadcasting

    Publication Year: 1989, Page(s):156 - 166
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (716 KB)

    The possibilities for information signaling through two additional tones, coherent with the usual AM stereo pilot tone used in the present USA AM stereo systems, are investigated. Two criteria are defined: an objective one, based on US Federal Communications Commission rules, and a subjective one, based on average human audio perception levels. On the basis of these criteria, the width of the inje... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Solar activity and MF skywave propagation

    Publication Year: 1989, Page(s):204 - 207
    Cited by:  Papers (7)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (240 KB)

    An examination is made of the effect of solar activity on MF skywave propagation, and quantitative expressions describing the effect are presented. It is shown that these equations are valid for all latitudes and for the two commonly used reference hours, two and six hours after sunset. Until recently, it has been assumed that the effect of solar activity was more or less the same for all hours of... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Broadcasting with megawatts of power: the modern era of efficient powerful transmitters in the Middle East

    Publication Year: 1989, Page(s):121 - 130
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (880 KB)

    A description is given of the 1- and 2-MW transmitters developed, built, and installed in the Middle East to satisfy requirements that provide for coverage of vast areas that can best be reached with high-power AM transmissions. The discussion also covers: early high-power developments; the Doherty high-efficiency screen-modulated amplifier; the overall power amplifier circuit and its operation; t... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Matrix method for relating base current ratios to field ratios of AM directional stations

    Publication Year: 1989, Page(s):172 - 175
    Cited by:  Papers (3)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (216 KB)

    A matrix method for relating the field ratios to the voltage sources is presented. As a moment-method program is running, the field and base current for each tower is recorded. Matrices that relate base currents to field ratios, can be extracted from this data or by inverting a matrix. This method is an exact solution and requires only one run of the moment-method program. For this reason, it is s... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Computer analysis of vertical radiation patterns of dipole panel array antennas

    Publication Year: 1989, Page(s):227 - 236
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (396 KB)

    A GW BASIC computer program has been developed to analyze any azimuth vertical radiation pattern of a dipole panel array antenna, fixed on a square tower structure, under different conditions of horizontal progressive quadrature current phase shifting, mechanical panel displacement, beam tilt, feeding current coefficients (null filling) and asymmetric arrangements with and without panel centering.... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Prudent frequency management through accurate prediction of skywave field strengths

    Publication Year: 1989, Page(s):208 - 217
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (748 KB)

    A nonexhaustive chronological summary of the advances made in MF skywave propagation studies is presented with emphasis on progress made in the United States. A qualitative analysis of the documented methods for calculating skywave field strengths and a quantitative comparison of selected methods with measured data are also included. Methods compared include the FCC clear-channel curves (the metho... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Digital AM transmitters

    Publication Year: 1989, Page(s):131 - 133
    Cited by:  Papers (3)  |  Patents (10)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (164 KB)

    Digital amplitude modulation (AM) generates a high-quality AM signal with an overall efficiency of greater than 80%. Digital AM was introduced in March 1987 with a 10-kW solid-state transmitter. Also completed are 25-kW and 50-kW transmitters, and plans exist for transmitters up to 2000 kW. The digital AM system utilizes a high-speed 12-bit analog-to-digital converter (A/D), a digital modulation e... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Relative tower currents and fields in an AM directional array

    Publication Year: 1989, Page(s):176 - 184
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (640 KB)

    With the help of method-of-moments techniques, the antenna monitor parameters that give the correct pattern can be calculated from the field parameters. The base voltages can be computed from the linear relationship between the relative fields and the base voltages. The computed voltages can then be used as sources for MININEC III. The base currents computed by MININEC III for those base voltages ... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Short low loss AM antenna

    Publication Year: 1989, Page(s):237 - 240
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (296 KB)

    An exploration is made of ways to improve the performance of a relatively small transmitting or receiving AM antenna system. Short vertical towers can be top-loaded to increase the radiation resistance and lower the base input capacitive reactance. An insulated counterpoise is connected to the coupling unit and to ground through an inductance which is tuned so as to maximize the field strength rad... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Medium-frequency skywave propagation at high latitudes: results of a five-year study

    Publication Year: 1989, Page(s):218 - 222
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (264 KB)

    Skywave transmission from selected standard AM broadcasting stations in the northern tier of the contiguous United States, Alaska and Canada were monitored near Fairbanks, Alaska from late 1981 to 1987. The objective of this work was to better understand, among other things, the effect of latitude on MF skywave propagation. A modern stable and selective receiver was electronically scanned continuo... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Dynamic carrier control, DCC, a valuable method to save input power of medium wave transmitters

    Publication Year: 1989, Page(s):134 - 138
    Cited by:  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (344 KB)

    A description is presented of the method of dynamic carrier control (DCC), which is characterized by a high margin of safety against adjacent-channel and common-channel interferences, together with remarkable savings in consumption. The special characteristics of this method are presented, along with the technical solutions for PSM and class B modulated transmitters. Examples of recent modificatio... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Analysis of a sectionalized tower as an element in a medium wave phased array using the method of moments

    Publication Year: 1989, Page(s):185 - 189
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (364 KB)

    The use of method-of-moments techniques to obtain operating base parameters for a medium wave directional array is described. The array incorporates a 130' tall antenna element that is sectionalized 75' above the base. A matrix of impedance measurements is used to obtain input data for the MININEC analysis of the array. The MININEC output provides base operating parameters for the appropriate fiel... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Implementation of amplitude modulation companding in the BBC MF national networks

    Publication Year: 1989, Page(s):139 - 146
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (684 KB)

    The design and development of a modulation-controlled system known as amplitude modulation companding (AMC) is described. In this method both carrier and sideband levels are progressively reduced as the modulation level is increased, this effect being compensated in the receiver by the normal action of the automatic gain control circuit. Extensive trials of a fully developed system for 50-kW MW tr... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Performance measurement and test techniques for modern AM broadcast transmitters

    Publication Year: 1989, Page(s):147 - 155
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (568 KB)

    The numerous tests required in evaluating the performance of a modern AM transmitter are discussed. Both laboratory tests of novel products and environmental tests are covered. The latest attainable performance measurements, environmental testing requirements, and field condition simulation tests are examined 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 Broadcasting covers the field of broadcast technology, including the production, distribution, transmission, and propagation aspects of broadcasting.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Yiyan Wu
Communications Research Ctr Canada