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Background and Objectives |
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After the beginning of service in Tokyo, Nagoya and Osaka in December 2003, work will proceed on the digitization of broadcasting stations throughout Japan, with the goal being to cover the nation with digital terrestrial broadcast waves by 2006. To deliver these signals to mountainous areas and remote islands, NHK is developing new technologies for upgrading the broadcasting station transmission systems and broadcast-wave relay networks from the master station to the extremities of the service area. |
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Overview |
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The following new technologies will help to realize digital terrestrial broadcasting.
- Digital terrestrial broadcasting transmission system
A system was constructed to transmit diverse services, including data broadcasting and the electronic program guide, to broadcasting stations throughout the country by using a channel equivalent to a single TV link.
- Transmission technology using microwaves
This technology employs microwave transmission for the signal transmission circuit between the broadcasting station and broadcasting transmitter (STL*1) and for the broadcasting transmitter-to-transmitter link (TTL*2). This link can be achieved by transport stream (TS) transmission or intermediate frequency (IF) transmission, depending on relay conditions. NHK fabricated the transmission systems for the respective transmission environments.
- Broadcast-wave relay technology
Although an SFN*3 in which master station signals are received and retransmitted on the same channel after being amplified, can efficiently utilize a frequency, it is prone to signal distortion and noise accumulation. To address these problems, NHK developed countermeasures to a wide variety of interferences, such as multipath in master station signals, signal feedback, and interference caused by the use of the same channel for transmitting and receiving signals.
- Reception characteristic improvement technology
With the aim of maximizing the features of digital terrestrial broadcasting, research is underway on a technology to improve areal reception characteristics. A technology was developed that uses a receiver to equalize multipath disturbances in excess of the limit of orthogonal frequency division multiplexing (OFDM) .
- Optical transmission technology
A countrywide digital terrestrial broadcasting network could be complemented by technologies that will deliver digital terrestrial broadcasting to homes via optical fiber.
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Future Work |
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Along with verification of the developed technologies through field trials, the size, cost, and energy consumption of the equipment will be reduced.
> A large picture
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