An HDTV digital video cassette recorder has been experimentally developed, using a 3/4-inch MP tape. This VCR can record 64-minute HDTV signal with 8 channel PCM audio signals at 2 times higher recording density than that of the current HDTV digital VTRs. This VCR is expected to be widely used as an HDTV program production equipment because of excellent picture quality, easy handling and lower operation/maintenance cost. Both improved tape to head contact realized by a newly designed drum structure and development of wideband-amplifier ICs permitted to realize such high density recording.
This report presents various characteristics of folded dipole antennas with a parallel-wire reflector calculated by the method of moment. Firstly, an antenna structure win be shown. Some calculated results of the gain, bandwidth, current distributions and input impedance win be described. Next, for wide frequency band, the radiating element consists of a multiple-wire folded dipole with short-circuits win be shown. Finally, calculted bandwidth results of different folded antennas win be demonstrated.
The demand for wireless high speed data links is growing in indoor local area network applications. This paper describes indoor wireless networks via optical diffuse channel. When an optical signal is transmitted using a diffuse channel, multipath effects occurs. Such effects are characterized by an optical intensity impulse response and a transmission loss. Firstly, we theoretically derive them and discuss. Then, BER of optical BPPM/DD system is theoretically derived, accounting for multipath effects. We also estimate the system coverage, where desired BER is attained. The result indicates that the transmission loss and the background radiation severely degrade the receiver sensitivity and restrict the system coverage.
Digital standard pictures have been produced for evaluation of HDTV These are digital data transferred from nine of the Hi-systems. Vision Standard Test Pictures published by ITE. The process has been designed to transfer the information of slide pictures into HDTV video signals as precisely as possible. The digital data of each picture has 1,920×1,035 Pixels of 10bits in R,G,B and also Y,P_B,P_R.
To select EDTV system, it is necessary to consider not only its improvement but also its compatibility. First, concerning to compatibility with conventional receivers, this paper shows vertical frequency characteristics of cameras. Next, concerning to compatibility with interlaced scan camera, step responses to signals without enhancement components are calculated. And also, a new scan conversion system is proposed.
The second generation EDTV has been developed in Japan. In this system, progressive scan camera might be necessary. Two types of progressive scan equivalent cameras are proposed: 1) dual scan type progressive camera 2) 3 CCD 1 line shifted camera These camera has the advantage that the scanning speed is as the same as the conventional interlaced camera. Thus they have the potential to reduce the cost of the progressive scan equivalent camera.