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Broadcasting, IEEE Transactions on

Issue 1 • Date March 1989

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Displaying Results 1 - 14 of 14
  • The TV answer viewer response system

    Page(s): 2 - 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (509 KB)  

    A system recently invented to provide two-way interactive capabilities in the broadcast environment is described. The TVA system provides an independent two-way interactive viewer response system which can be used in conjunction with almost any video distribution technology. Its theory of operation is presented. Response transmissions, response pulse propagation, and TV receiver susceptibility are discussed.<> View full abstract»

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  • Reflection and ghosts in a multitower environment

    Page(s): 8 - 22
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    The magnitude of reflections in a multitower TV environment and their delay in microseconds are calculated. The objectives of the study were to determine: (1) the principal source of ghosting on Mt. Wilson Calif.; (2) how the reflection can be reduced: (3) what the optimum antenna/tower characteristics are for a novel installation; (4) the effect of polarization on ghosts; and (5) the impact of HDTV (high-definition television) on the antenna/tower system test methods and test program are presented as well as a detailed analysis of the test result. Over 500 measurements were made at forty different locations. Some conclusions and recommendations for new installations are provided.<> View full abstract»

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  • Spectrally efficient digital broadcast systems operated in a phase noise environment

    Page(s): 31 - 39
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    High spectral efficiency combined with power efficiency, is a requirement for high speed digital broadcast satellite systems. The effect of the recovered carrier phase noise and the nonlinearity on the performance of 16-QAM (quadrature amplitude modulation) and staggered 16-QAM is investigated and compared. It is found that for the phase noise, 16-QAM is more degraded for a roll-off factor of less than 0.4. For roll-off factor of more than 0.8, staggered 16-QAM has superior performance. For the nonlinearity staggered 16-QAM is more sensitive for a roll-off factor of less than 0.4. It is concluded that coincident 16-QAM is suitable for spectrally efficient digital broadcast systems.<> View full abstract»

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  • Theory and methods for design of pulse shapes for broadcast teletext

    Page(s): 40 - 55
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    The theoretical and practical engineering constraints, considerations, and methods for pulse shape design for North American broadcast teletext transmissions are described. The principles and concepts described are for broadcast over-the-air transmission, but they are also applicable to satellite and cable transmission of broadcast teletext signals. Overall objectives of pulse shape design are summarized. Basic constraints and considerations from the Nyquist theory are described. The practical and engineering constraints on teletext pulse shapes are discussed in detail. Pulse shape apportioning and specification are treated. A critical review is provided of the theory and design methods for teletext pulse shaping. A review of analytical and numerical approaches is given. Modelling and simulation approaches are described, including novel comprehensive model. Improved overall and transmitted pulse shapes are evaluated and their performance compared to that obtained with other common pulse shapes.<> View full abstract»

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  • A mobile 12 GHz DBS television receiving system

    Page(s): 56 - 62
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    A practical, mobile, 12-GHz direct broadcast satellite (DBS) television receiving system for receivers on vehicles is described. The system is housed in a cylindrical radome of 350 mm height and 862 mm diameter, and it weighs 50 kg. Two pairs of high performance flat-panel antenna units (640*180 mm each) are used to reduce the system. For rapid recatch of DBS, antenna control is based on a gyroscope that is corrected using a phase-comparison monopulse. To simplify the system, the antenna units and receivers are used for antenna tracking as well as signal reception. The antenna units are in-phase combined to allow electronic tracking, which reduces the influence of pointing error caused by vibration of vehicles. The system maintains a reception rate of more than 90% on expressways.<> View full abstract»

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  • A rejection system for interference in TV reception caused by sporadic-E ionospheric propagation

    Page(s): 63 - 69
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    A method to cancel interference waves by extracting them from TV signals through quadrature synchronous detection and then transforming the signals with a Hilbert transform method is introduced. The system eliminates interference waves at any frequency within the TV signal band. It is easily applied to rebroadcast stations, since it is possible to cancel interference waves at the intermediate-frequency stage. The system automatically eliminates a maximum of five interference waves. It suppresses interference waves by more than 40 dB at a desired-to-undesired signal ratio of 10 dB. The system will greatly contribute to eliminating abnormal interference waves caused by the sporadic-E layer as well as other undesired interference with TV signals.<> View full abstract»

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  • Focus quality assessment. I. Numerical measurement

    Page(s): 74 - 76
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (239 KB)  

    A simple algorithm is described that determines the focus quality of an image by measuring the maximum brightness gradient present in it. Measurements on actual television pictures are correlated with subjective focus evaluations on the CCIR five-point scale. The excellent correlation between measurement and subjective evaluation indicates the usefulness of the algorithm.<> View full abstract»

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  • MF-AM stereo broadcasting: the choice of modulation

    Page(s): 79 - 87
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    Several AM stereo transmitting systems have been applied to local radio-broadcasting networks on the MF (medium-frequency) band in the US. These systems represent a certain compromise between two mutually contrary requirements: (i) that the broadcast spectrum be at the MF carrier within the determined boundaries (the channel occupancy criterion), and (ii) that the transmitted signal be compatible with MF-AM monaural receivers (the compatibility criterion). It is proved that a transmission system that perfectly satisfies both requirements does not exist. A modulation method called modified compatible quadrature amplitude modulation (MC-QAM) is proposed. The system has simpler circuitry and less distortion, and occupies, under many circumstances, a narrower frequency bandwidth. With slight modifications, existing receivers for C-QAM could be used for MC-QAM.<> View full abstract»

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  • An analog binary phase modulator suitable for secondary services broadcast

    Page(s): 88 - 96
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (538 KB)  

    The modulation characteristics of a simple binary phase modulator with a compensated parasitic amplitude modulation is evaluated analytically and numerically. The modulation characteristic slope, giving the modulator circuit sensitivity is obtained analytically. The evaluation is supported by a small personal computer program package written in BASIC, allowing simple and direct use of the phase deviation versus modulation voltage characteristics for Q as a parameter.<> View full abstract»

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  • Plate and grid modulated HF high-power tuned amplifier with increased efficiency

    Page(s): 97 - 107
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    The optimal design of a plate- and grid-modulated high-power tuned HF amplifier with increased efficiency is reported. The increased efficiency is achieved by introducing the third harmonic into the drive and output circuits. The analysis is carried out by applying a linear model of the constant plate current characteristics of an HF high-power triode. The initial CW (continuous-wave) working conditions are selected so that it is possible to realize a 100% modulation. Calculated values are presented graphically as functions of some relevant design parameters. A comparison is made with a tuned high-power amplifier without injection.<> View full abstract»

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  • An approach to the frequency multiplier analysis

    Page(s): 108 - 112
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    A description is given of a linear model of an HF high-power triode which is used in the design of a tuned high-power amplifier that operates as a frequency multiplier. All the expressions necessary for the balance of power are derived in closed form. Results for a frequency doubler and tripler are presented separately. Diagrams that completely depict the operating mode of such an amplifier are given. It is shown that the maximal output power is obtained with conduction angle of pi /2 for the frequency tripler. It is also shown that by combining the operating mode parameters' values, all values of the output current conduction angles cannot be really obtained, because in such a case the output power becomes negative.<> View full abstract»

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  • Implementing FMX broadcasting at your station

    Page(s): 70 - 73
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    A description is given of what FMX stereo radio broadcasting can and cannot do. Encoding specifications, compatibility with other subcarrier services, transmitter tuning, and separation compatibility are discussed. The cause and effect relationships of the various transmission impairments of FMX compatibility are summarized. Reception improvements are identified View full abstract»

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  • A new generation of 90 Mb/s systems: bandwidth efficient, field tested 16-QAM

    Page(s): 23 - 30
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    16-QAM (quadrature amplitude modulation) digital satellite broadcast equipment and satellite communications (SATCOM) systems that double the spectral efficiency of currently operational satellite links is described. It is shown that with this field-proven system, data transmission at a rate of 90 Mb/s (two multiplexed DS-3 signals) is feasible in a transmission bandwidth of 30 MHz. Extensive operational satellite tests performed over the T-303 satellite of AT&T demonstrated a BER <10-10 and no errors for several days. The practical bandwidth efficiency of these SATCOM systems is 3 b/s/Hz, i.e. double the currently used 1.5 b/s/Hz QPSK (quadrature phase-shift keyed) systems. The doubling of the spectral efficiency is attained with advance modem (modulation-demodulation), adaptive equalization robust synchronization, high-power amplifier (HPA) linearization (predistortion), and low redundancy powerful forward-error-correction (FEC) subsystems. The systems may make possible the conversion of currently operational analog FM links into bandwidth efficient digital systems. In one 30 MHz satellite transponder three to four digitized high quality TV signals could be broadcast, or two standard rate DS-3 signals time-division multiplexed with a DS-1 rate signal and additional auxiliary data streams View full abstract»

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  • Focus quality assessment. II. Subjective evaluation

    Page(s): 77 - 78
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (148 KB)  

    For pt.I see ibid., vol.35, no.1, p.74 (1989). Subjective evaluation of 20 actual television pictures using a five-point grading scale is reported. The main purpose of the study was to determine on if subjects could successfully evaluate focus quality on the grading scale and if so, what parameters are used by subjects in the evaluation. Multidimensional scaling was used to determine dimension used in the evaluation. Results show that subjects use only one dimension and that they are able to evaluate pictures very accurately on a five-point grading scale. The results show that the objective evaluation, discussed in part I is valid View full abstract»

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Aims & Scope

IEEE Transactions on Broadcasting covers the field of broadcast technology, including the production, distribution, transmission, and propagation aspects of broadcasting.

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Meet Our Editors

Editor-in-Chief
Yiyan Wu
Communications Research Ctr Canada