Title :
Waveform equalization for EDTV systems using QAM
Author :
Kageyama, S. ; Uwabata, H. ; Bowser, T. ; Inoue, S. ; Yasumoto, Y.
Author_Institution :
Matsushita Electr. Ind. Co. Ltd., Osaka, Japan
fDate :
11/1/1991 12:00:00 AM
Abstract :
A modified waveform equalizer for a terrestrial QAM (quadrature amplitude modulation) transmission system that is tolerant against ghosts is described. In order to improve the performance of ghost and crosstalk reduction in the QAM subchannel, eight-field sequence reference signals, which are compatible with the GCR (ghost cancel reference) signal proposed by the BTA (Broadcasting Technology Association), and automatic gain control by a CPU are employed. Moreover, modified synchronous demodulation with automatic carrier phase control by a CPU is useful to upgrade (by about 5 dB under a heavy ghost condition) the equalization performance and to reduce the quadrature distortion of the subsignal. The crosstalk in the subchannel can be reduced to a level of 36-40 dB D/U. The QAM technology can be fully applied for terrestrial broadcasting even under significant ghost conditions
Keywords :
amplitude modulation; equalisers; high definition television; telecommunications computer control; television broadcasting; BTA; Broadcasting Technology Association; CPU; EDTV system; QAM subchannel; automatic carrier phase control; automatic gain control; crosstalk reduction; eight-field sequence reference signals; ghosts; quadrature amplitude modulation; quadrature distortion; synchronous demodulation; terrestrial broadcasting; terrestrial transmission system; waveform equalizer; Broadcast technology; Broadcasting; Crosstalk; Demodulation; Equalizers; Gain control; HDTV; Phase control; Phase distortion; Quadrature amplitude modulation;
Journal_Title :
Consumer Electronics, IEEE Transactions on
