Sadashi Kageyama

An Extended Definition Television System Using Quadrature Modulation of the Video Carrier with Inverse Nyquist Filter

A QUadrature Modulating Extended definition television system -QUME- , which enhances NTSC to higher definition , is proposed. The QUME system uses quadrature modulation of video carrier with inverse nyquist filter and creates an independent transmission channel (Bandwidth : 1MHz) without using additional channel resources. One of the features of QUME is that the multiplexed signal hardly interferes with the conventional TV receivers, and another is that there is no crosstalk between the multiplexed signal and the main NTSC signal. These features enable a wide aspect ratio image to be transmitted as well as high frequency components of luminance and/or chrominance signals, while keeping compatibility with the NTSC system.

Encoding and decoding in the 6-MHz NTSC-compatible widescreen television system

The Matsushita 6-MHz NTSC-compatible widescreen television system using quadrature amplitude modulation (QAM) of the video carrier and inverse Nyquist filtering is an advanced television system using the side panel method. The principle of QAM is reviewed, and the encoding and decoding processes are discussed. Methods for time expansion and time compression for each panel and very-low-frequency frequency splitting (e.g., 0.1 MHz) at a sampling frequency of 14.3 MHz are detailed. Transmitting and regenerating the colour subcarrier for a multiplex signal and a method of preventing noticeable differences between panels are also described. >

A wide aspect ratio television system with full NTSC compatibility

A description is given of a system that uses quadrature modulation of the video carrier with inverse Nyquist filter and transmits side panels, keeping full NTSC compatibility without using additional channel resources. Two techniques are disclosed for realizing side panel transmission on the quadrature channel, and one of them is implemented in an experimental system. The experimental results show smoothness of the moving images and continuity between center and side panels. >

An NTSC compatible wide screen television system with evolutionary extendibility

A review is presented of the role of the inverse Nyquist filter in quadrature amplitude modulation (QAM) technology and an outline of studio and network issues of this system is given. For two of the problems concerned, i.e., (a) crosstalk caused by ghosting and (b) interference from conventional TV receivers, the authors propose a two-dimensional waveform equalizer, with processing in the time and frequency domain at a transmitter. The encoding and decoding for this wide-screen television system, and the evolutionary extendibility of QAM technology toward further improvement of image and sound quality in a compatible fashion are also discussed. >

NTSC compatible wide-screen TV system with PCM sound using QAM

A CATV (cable television) transmission experiment proved the complete compatibility of a wide-screen QAM (quadrature amplitude modulation) based TV system with CATV. Even under the worst CATV conditions (50 dB CTB, 38 dB C/N, slight annoying reflections), no specific impairment or degradation was perceived in the wide-screen TV or the NTSC. As a result of a subjective estimation of interference to conventional NTSC TV sets, it is shown that there is no need for a guard band between NTSC- and QAM-based TV channels. The system is capable of transmitting PCM (pulse-code-modulated) stereo sound. 320-kHz, 16 bit/sample data are efficiently band-compressed into about 250 kb/s using subband coding, and transmitted during some parts of the vertical blanking and vertical overscanning periods through the QAM channel. >

Waveform equalization for EDTV systems using QAM

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. >