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ISDB-T features

ISDB-T is characterized by the following features:

ISDB-T (Integrated Services Digital Broadcasting-Terrestrial) use UHF470 MHz-770 MHz, bandwidth of 300 MHz, allocate 50 channels, namely ch.13-ch.62, each channel is 6 MHz width  (actually 5.572 MHz effective bandwidth and 430 kHz guard band between channels).
These 50 channels, ch.13-ch.62, are called "physical channel".
ISDB-T single channel bandwidths 5.572 MHz has number of carriers 5,617 with interval of 0.99206 kHz.
ISDB-T allows to switch to two or three SDTV channels instead of one HDTV channel (multiplexing SDTV channels).
Each channel is further divided into 13 segments. 1seg uses only single segment, and the remainder can be allocated as (1) one 12-segments HDTV program, (2) three 4-segments SDTV programs, or (3) one 8-segments (Medium Definition) program and one 4-segments SDTV program, broadcasted from a single TV station as the multiple-program arrangement in simultaneous broadcasting (see figure).
The single segment for 1seg is further divided and broadcasting as multiple-program arrangement.
The combination of these services (1), (2) or (3) can be changed at anytime. Mostly NHK Educational TV and Open University of Japan broadcasts with these 3 modes appropriately.
ISDB-T transmits a HDTV channel and a mobile TV channel 1seg within the 6 MHz bandwidth.
ISDB-T provides interactive services with data broadcasting.
ISDB-T provides EPG (Electronic Program Guides).
ISDB-T supports internet access as a return channel that works to support the data broadcasting. Internet access is also provided on mobile phones.
ISDB-T provides SFN (Single frequency Network) and on-channel repeater technology. SFN makes efficient utilization of the frequency resource (spectrum).
ISDB-T can be received indoors with a simple indoor antenna.
ISDB-T provides robustness to multipath interference ("ghosting").
ISDB-T provides robustness to co-channel analog television interference.
ISDB-T provides robustness to electromagnetic interferences that come from motor vehicles and power lines in urban environments.
ISDB-T is claimed to allow HDTV to be received on moving vehicles at over 100 km/h (this has not yet been proven in real-world operation); DVB-T can only receive SDTV on moving vehicles, and it is claimed that ATSC can not be received on moving vehicles at all (however, in early 2007 there were reports of successful reception of ATSC on laptops using USB tuners in moving vehicles).
1seg is a mobile terrestrial digital audio/video broadcasting service in Japan. Although 1seg is designed for mobile usage, reception has proved problematic in moving vehicles. Because of reception on high speed vehicle, UHF transmission is shaded by buildings and hills frequently, but reported well receiving in Shinkansen as far as run in flat or rural area.

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