By Topic

Broadcasting, IEEE Transactions on

Issue 1 • Date Mar 1991

Filter Results

Displaying Results 1 - 4 of 4
  • π/4-QPSK modems for satellite sound/data broadcast systems

    Page(s): 1 - 8
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (620 KB)  

    The use of π/4 quadrature phase-shift keying(QPSK) modems for satellite sound broadcast systems (SSBS) broadcasting to mobile or portable receivers is proposed. Three different differential detectors (including the FM-discriminator followed by integrate-sample-and-dump filter) and a novel coherent detector are discussed. The degradation caused by the frequency offset between the local oscillator and the unmodulated carrier in the baseband differential detector is studied. The performance of both coherently and differentially detected π/4-QPSK in a Gaussian channel is also studied. It is shown that with a frequency offset of more than 3% of the symbol rate, the performance degradation is more than 1 dB at 10-4. The out-of-band power of the nonlinearly amplified bandlimited π/4-QPSK signals is reduced from -13 dB to -37 dB if a 2-dB output back-off amplifier is used instead of a hardlimiter. The performance of the π/4-QPSK is equivalent to that of QPSK, although the π/4-QPSK has the advantage of less spectrum restoration after nonlinear amplification. The coherent demodulator and differential decoder avoid the three-level detection and achieve the same bit-error-rate (BER) performance as DEQPSK with a simple circuit View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Universal sine squared shaped video syncs

    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (84 KB)  

    A digital method for generating precisely controlled sine-squared shaped video sync pulses of sixteen different wave shapes is reported. The principle involved in the technique is to store 16 sample values of the desired sine-squared shaped signal in programmable read-only memory (PROM) and to release these digital data sequentially to a digital-to-analog converter at a desired speed to produce the sine-squared shaped waveform. The application of this method is discussed View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An improved π/4-QPSK with nonredundant error correction for satellite mobile broadcasting

    Page(s): 9 - 16
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (460 KB)  

    An improved π/4-quadrature phase-shift keying (QPSK) receiver that incorporates a simple nonredundant error correction (NEC) structure is proposed for satellite and land-mobile digital broadcasting. The bit-error rate (BER) performance of the π/4-QPSK with NEC is analyzed and evaluated in a fast Rician fading and additive white Gaussian noise. (AWGN) environment using computer simulation. It is demonstrated that with simple electronics the performance of a noncoherently detected π/4-QPSK signal in both AWGN and fast Rician fading can be improved. When the K-factor (a ratio of average power of multipath signal to direct path power) of the Rician channel decreases, the improvement increases. An improvement of 1.2 dB could be obtained at a BER of 10-4 in the AWGN channel. This performance gain is achieved without requiring any signal redundancy and additional bandwidth. Three types of noncoherent detection schemes of π/4QPSK with NEC structure, such as intermediate frequency band differential detection, baseband differential detection, and FM discriminator, are discussed. It is concluded that the π/4-QPSK with NEC is an attractive scheme for power-limited satellite land-mobile broadcasting systems View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The dual green pickup experiment for a compact HDTV color camera with three-2/3 inch CCDs

    Page(s): 17 - 22
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (444 KB)  

    A design concept for compact HDTV cameras is proposed. An experimental camera that has been developed in order to verify this concept is described. Since no 2/3-in HDTV charge-coupled devices (CCDs) suitable for compact HDTV cameras have been developed, 2/3-in CCDs (pixels: 766(H)×980(V), aspect ratio: 4:3) developed for a high-quality picture NTSC camera have been used as substitutes. The developed camera employs the three CCDs with spatially offset imaging between two green channels to improve resolution. Horizontal limiting resolution is over 900 TV lines, and vertical limiting resolution is about 800 TV lines. It is concluded that resolution deterioration due to the shortage of pixels can be compensated for with an adequate image pickup method and that it is possible to produce an HDTV camera that has relatively few pixels but has a well-balanced relationship between characteristics and resolution 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