Digital Terrestrial Television Broadcasting (DTTB)

A report on the digital terrestrial television broadcasting system (ISDB-T: Integrated Services Digital Broadcasting-Terrestrial) was presented to the Minister of Post and Telecommunication by the Telecommunications Technology Council (TTC) in May 1999 after the largescale field trials conducted by the Association of Radio Industries and Businesses (ARIB). At the ITU-R Study Group 11 Meeting in February 2000, ISDB-T was approved as one of its international standards. Our laboratories have consistently contributed to the system's development from system proposal through field trials. Using the segmented BST (Band Segmented Transmission)-OFDM scheme, the ISDB-T is capable of providing a variety of services from Hi-Vision (HDTV) for fixed reception to mobile-multimedia broadcasting. The outline and transmission parameters of the DTTB are listed in Table 1. The large-scale field trials utilizing Tokyo Tower and UHF Channel 15 with a 100W output showed that to realize a reception ratio of 99% or more, the minimum field strength of fixed reception must be approximately 57dB V/m in 64QAM modulation. SFN experiments using the Sawara relay station yielded fundamental knowledge on SFN, and the relationships between bit-error rates and active multipath signals within an SFN service area. To clarify technical requirements for the introduction of DTTB stations, protection-ratios between current analog TV and DTTB were measured using the prototype hardware. The measured interference data showed that the co-channel DU ratio from DTTB to analog TV was 45dB, and that the DU ratio of lower adjacent-channel interference was 0dB and that of upper-adjacent channel interference was 10dB. These results were adopted as the interference DU ratios of "Technical Requirements for the Establishment of Digital Terrestrial Television Broadcasting Stations" by the TTC. A field strength of 60dB V/m or greater was established to define the DTTB service area of fixed reception. In addition to the efforts of the DTTB systemstandardization in Japan, the STRL provided instruction for and cooperated in ISDB-T experiments in Singapore, Hong Kong, China, and Brazil which were carried out by the DiBEG (Digital Broadcasting Expert Group).