Pre-Olympic games were held in Nagano from December 1997 to March 1998. Some of these games were held in Hakuba and NHK produced International slgnals of them. We broadcasted four events using New type cameras and tried to produce NTSC signal and HDTV slgnal simultaneously. Under the slogan of "Beyond Lillehammer '94", we tried some new technologies : Bird-cam, Linear-cam, Ice-Zone microphone, Virtual downhill race and Ultra multi-motion for ski jumping.
Nippon Television Network (NTV) has produced new MULTI-OPTICAL TRANSMISSION EQUIPMENT. It performs a long distance transmission tomards both direction with digital signal and LESER beam. The number of the available channels are that 3-videos and 24-audios and 24-tailys for each direction.
Described is a Radio wave recieving system using optical modulator for the TV relay station, which can modulate its optical power by Radio wave signals without electrical power supply. This system in practical use is very effective to prevent lightning damages at TV stations. In addition, use of this system can improve reliability and maintenance work since only passive circuits are used at the recieving station.
A small spiral ring antenna, composed of N turns spiral element with one wave length, is a kind of loop antennas. It is expected that its characteristics are similar to the normal one wave length loop antenns. In this report, the electric far-field is derived from the current distribution on this antenna, and it is also simulated by moment method, then these results are compared with experimental data of this spiral ring antenna.
DTTB (Digital Terrestrial Television Broadcasting) has been studied for mobile reception service. The received signals at mobile station become worse caused by the reflected, diffracted and scattered waves from near buildings. We measured receiving level at mobile station. In this paper, we report accumulated distribution of receiving level and propose a simple model for mobile reception.
OFDM (Orthogonal Frequency Division Multiplexing) is an efficient modulation method for the digital terrestrial broadcasting. We studied FEC (Forward Error Correction) scheme and time-symbol-interleaving method for OFDM system. In this paper we show the results of laboratory experiment OFDM system under rayleigh fading for mobile reception.
Digital transmission signals are distorted by multi-path fading in a mobile radio channel. It is a severe problem especially when they are transmitted at high bit rate such as HDTV digital signals. OFDM (Orthogonal Frequency Division Multiplexing) is a modulation scheme which can mitigate the adverse effect multi-path fading by distributing the transmission data into a large number of carriers of a low bit rate modulation. In order to transmit the compressed HDTV digital data and reduce the degradation due to multi-path fading, we have developed a multi-level OFDM modem, which adopted 16DAPSK (Differential Amplitude Phase Shift Keying) modulation scheme for each OFDM carrier. This paper describes the features of the experimental 16DAPSK-OFDM modem and discusses the aspects of mobile digital FPU (Field Pick-up Unit) of the HDTV digital signals.
In this paper we have examined the major factor in causing digital coding impairment of HDTV video signals. At a lower bit rate than 20Mbps, the number of bits which can be assigned to DCT coefficients will be reduced for B-pictures. Therefore, it is required to suppress the number of bits used for motion vectors and macroblock type information. We propose some technique to improve picture quality by reducing bits of the side information.