Comparison Test Results in Brazil

- Clear Superiority of the ISDB-T system -

In order to select the most suitable digital terrestrial broadcasting system for Brazil, Brazilian broadcasters carried out comparison tests of three systems recommended in ITU-R Recommendation BT.1306-1. The systems tested were ATSC of the United States, DVB-T of Europe and ISDB-T of Japan. The results were recently published in the ABU Technical Review*1. A summary of the paper is reported.

From October 1999 to April 2000, ABERT(Brazilian Association of Television and Radio Broadcasters) / SET (Brazilian Society of Television Engineering) Group, which is a technical study group on digital television for planning the introduction of digital television broadcasting in Brazil, conducted the first scientific tests anywhere in the world to evaluate all of the three digital terrestrial television systems, namely ATSC, DVB-T and ISDB-T, using 6MHz channels.

A laboratory was set up in the Machenzie Institute (a private university), in which the comparison tests were conducted under identical conditions. In the laboratory test, performance was measured with various types of interference and under multipath conditions, in reception, transmission and mobile reception.

Field tests were carried out in So Paulo. These included outdoor coverage, indoor reception and mobile reception.

The paper discusses the findings in depth and presents its technical conclusions as follows:
Technical analysis of the results led to the assessment that the ATSC system (8VSB) was inadequate for Brazil. This was mainly due to its deficient performance in multipath conditions and mobile reception, as measured both in the laboratory and in the field. It had the poorest field results among the proposed standards. Even in a city such as So Paulo, the advantage of the ATSC system regarding carrier-to-noise ratio did not obtain better coverage. The DVB-T and the ISDB-T systems maintain a 10% coverage advantage for the whole area of the test. The better performance of the ISDB-T and the DVB-T systems in highly populated areas, namely the first areas to be served with digital television, is a strong competitive advantage. Additionally, the technical analyses show that the DVB-T and ISDB-T systems permit adequate implementation of an HDTV transmission model. The ISDB-T system presents the best global performance in indoor reception, has good advantages in performance under impulse noise conditions and for mobile reception, and is, as a whole more flexible.
(One of the key tables is shown in Table 1.)

Table 1 Mobile field test result (* - Long term failure)

The paper concludes that the technical superiority of the ISDB-T system and its robustness and flexibility are clear. ISDB-T's great flexibility turns out to be an important competitive advantage, enabling a more flexible business model. Brazilian broadcasters are focusing on the simultaneous transmission of an HDTV signal and a robust signal for mobile reception. The ABERT/SET tests clearly indicate that this can be best achieved by the ISDB-T system. The performance of ISDB-T is much better than that of the other systems, since the maximum payload for reliable reception is significantly higher. This is mainly due to the time-interleaving established in the ISDB-T standard.

*1: Ana Eliza Faria e Silva et. al., "BRAZILIAN DIGITAL TELEVISION TEST RESULTS," ABU Technical Review, No.190, pp.14-26 (September - October issue 2000)
(Courtesy, Asia-Pacific Broadcasting Union)

ITU-R Adopts ISDB-TSB as Draft Recommendation

-International standardization of Japanese digital terrestrial sound broadcasting system-

Masayuki TAKADA,
Digital Broadcasting

ITU-R Study Group 6 (SG6) meetings were held from September 13 to 25, 2000, in Geneva, Switzerland. The SG6 meeting approved the ISDB-TSB (Integrated services Digital Broadcasting for Terrestrial Sound Broadcasting) digital terrestrial sound broadcasting system proposed by Japan as the ITU-R draft recommendation.
The International Telecommunication Union (ITU) is a special United Nations organization established to promote the global standardization of telecommunications. The SG6 of the ITU Radiocommunication Sector (ITU-R), which contains 7 Working Parties (WPs), is in charge of the international standardization of broadcasting services. Each working party specializes in examining a specific field such as broadcasting systems/production, digital coding, multimedia, terrestrial broadcasting, and satellite broadcasting.

Digital terrestrial sound broadcasting ISDB-TSB , which has commonality with the ISDB-T digital terrestrial television broadcasting system, was developed in Japan. The transmission parameters are shown in the table below. This system adopts the OFDM modulation scheme, a high-efficiency audio compression coding scheme and a time interleaving technique to ensure good performance in mobile reception. ISDB-TSB was proposed to the ITU-R to be recommended for international use. The SG6 approved it as a draft recommendation because ISDB-TSB is a sufficiently flexible transmission scheme for use in various receiving conditions. In addition, it has been shown to achieve superb performance through numerous experiments. It is now scheduled to be officially recommended by the ITU Member States.

ISDB-TSB transmission parameters
Transmission bandwidth 430kHz/1.3MHz
Moduletion Segmented OFDM
Carrier Modulation DQPSK,QPSK,16QAM,64QAM
Error correction Convolutional code and Reed-Solomon code
Multiplexing MPEG-2 Systems
Audio coding MPEG-2 AAC

The 2nd NHK-KBS* Digital Group Meeting
The 2nd NHK-KBS Digital Study Society meeting was held at the NHK Science & Technical Research Laboratories on October 25, 2000. This society is responsible for digital broadcasting technology information sharing between NHK and KBS.
Four engineers who handle the development of digital broadcasting at KBS participated in the meeting. NHK and KBS each gave three presentations, and a lively discussion ensued. With regard to data broadcasting, KBS presented the concept of equipping a TV with the functions of a personal computer, with the establishment of a project named iPCTV. It also reported that program production making good use of CG was being carried out.
NHK gave a report regarding ISDB-S (satellite), ISDB-T (terrestrial), ISDB-C (cable), and a digital production information system for efficient program production. NHK also presented demonstrations of a coupling canceller, which is important in digital terrestrial broadcasting, and of digital satellite data broadcasting.
*KBS: Korean Broadcasting System, a special corporation funded by the South Korean government.
(Toshiyuki MATSUI, Planning & Coordination)

The 37th ABU General Assembly and Engineering Committee

Between November 2 and November 11, 2000, the ABU General Assembly and Committee Meetings were held in Manila, Philippines. President EBISAWA of NHK, who is the president of ABU, served as the chairman of the assembly, and made the following address:

Address of President EBISAWA
With the 21st century around the corner, the world of broadcasting has entered into a significant era of revolution, accompanied by the advance of digitization. In Japan, BS satellite broadcasting will start digital services on December 1, 2000. These will enrich broadcasting services by providing high quality picture and sound in Hi-Vision, and interactive data broadcasting.
While the digitization of broadcasting will provide a big business opportunity to related industries, I believe that we should never forget that, at the same time, broadcasting creates culture based on technology. Technology gains its true value when used to enrich people's hearts and minds. We hope to contribute to the coexistence of a comfortable society and an energetic economy, by positively integrating technological reform accomplishments with broadcasting.
The digital divide in the advance of digitization has been pointed out. The rectification of this situation has become a global concern. We believe that it is a basic mission of broadcasting to allow people equal information access regardless of their abilities, income, or educational background. As for NHK, looking toward the realization of more human-friendly broadcasting, technology is being developed to produce automatic closed-captioning for the hearing-impaired, and to convert the speech rate of TV and radio broadcasting into slower speeds for the elderly. Such technological developments are the challenges we are tackling to eliminate the digital divide.
Through discussions on occasions such as the ABU General Assembly, we are determined to make our best efforts to overcome these problems.

Engineering Committee
In the Engineering Committee, Senior Research Engineer Mr. MORIYAMA of the STRL, who was selected as a Topic Chairman of Transmission Technology, presented reports regarding worldwide digital terrestrial, data, and Internet broadcasting, etc. The present situations of broadcasters in each country were also reported, and information concerning the latest broadcasting technologies was exchanged. NHK reported on the status of various projects, including ISDB-S, ISDB-T, ISDB-C, Hi-Vision Drama CG composi tion, and the news speech transcription system for broadcasting. In a guest lecture, Mr. KATO of the STRL talked about a television home server for the digital broadcasting services of TV anytime.
At the Asia Multimedia and Broadcast Show 2000, which was held together with the General Assembly, a home server exhibition introduced participants to the many convenient functions, such as the ability to retrieve a desired program or desired information instantly.
*ABU: Asia-Pacific Broadcasting Union, participated in by 102 broadcasting institutions from 51 countries and regions.
(Shigeki MORIYAMA, Digital Broadcasting Networks)

ITU-T WP1/9 Agrees on Draft Recommendation J. api
The ITU-T WP1/9 meeting was held in Portland, Oregon, in the United States from November 6 to 10, 2000. Participants agreed on Draft Recommendation J. api, which consists of recommendations on the multimedia coding scheme and API from the viewpoint of the digital receiver.
The Draft Recommendation establishes a framework for the multimedia API core set. It includes the multimedia coding standards (XHTML, CSS, DOM, and ECMAScript), which are introduced in the BML (Broadcast Markup Language) of ARIB STD-B24, "Data coding and transmission specification for digital broadcasting."
The Draft Recommendation is scheduled for approval at the ITU-T SG9 Meeting in March 2001. Further, a Recommendation describing detailed specifications is presently under study.
(Toshiro YOSHIMURA, Multimedia Services)

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