Introduction to Brazilian Digital TV

Since 2007, Brazil utilizes a nationwide digital terrestrial television system. In this article we'll look at the history and specifications of the Brazilian Digital Television System.

Brazilian Digital TV History

Research for the implementation of Digital Television in Brazil dates back to the 1990’s, when Brazilians institutions started analysis on multiple TV signal transmission systems to determine which would better fit the country’s needs and purposes in the future. In 2003, a committee formed by the National Telecommunications Agency, or Anatel, and the Telecommunication Research and Development Center named CPqD, was assigned the task of choosing and developing the system which the Digital TV transmissions would be based upon.

The choice relied upon a number of parameters, most notably the capabilities to allow for high-quality transmission, content interaction, e-government procedures and mobile reception. Such rigour regarding the new television system was a result of the dissemination of TV devices across the country, and the supposed use of these devices as interactive platforms in the future. By that year, more than 90% of Brazilian households had a TV set, while only 11% had a computer with access to the internet.

In 2006 the Brazilian Digital TV System was announced to be based on japanese standard called ISDB-T, an abbreviation for Integrated Services Digital Broadcast-Terrestrial. As opposed to the North-American Advanced Television Systems Committee Standards, or ATSC and European Digital Video Broadcasting-Terrestrial, or DVB-T, the japanese ISDB-T was chosen as the format for Brazilian TV for offering of features like signal stability for mobile devices and superior indoors reception. The Brazilian government was also exempted from paying royalties for the use of technology to Japanese authorities.

As of 2014, approximately 62% of the country’s population is served by Digital TV channels, a number the government expects to rise to 100% in 2016. The Brazilian Digital TV format, known as ISDB-Tb, ISDB-T International or Sistema Brasileiro de Televisão Digital, has also been adopted by other countries like Peru, Ecuador, Argentina and Philippines.

ISDB-Tb Specifications

The Brazilian Digital TV system implemented various additions to the original ISDB-T, like new video compression, interaction middleware and improved framerate for transmission to portable devices.

Transmission Architecture

Brazilian Digital TV System channels use 6 Mhz intervals, divided into 13 segments, and can be transmitted in VHF or UHF spectrums. The multiplexing standard for broadcasts is MPEG-2, with BST-OFDM modulation.

Error correction uses Time Interleaving and Frequency Interleaving processes. A 700 Mhz bandwidth is used exclusively for returned signals used for viewer interaction with the system, while portable device transmissions uses the same 1-seg technology from the japanese standard.

Video Format

ISDB-Tb uses levels 1.3 and 4 MPEG-4/H.264 compression for video transmission to non-portable and portable devices respectively, as opposed to MPEG-2 used in ISDB-T. The format allows for 4:3 or 16:9 aspect ratios for Standard Definition and portable device resolutions and 16:9 for High Definition content.

Supported resolutions for television and non-portable devices include:

• 720x480i SD
• 720x480p SD
• 720x576i SD
• 720x576p SD
• 1280x720p HD
• 1920x1080i Full HD

Supported portable device resolutions include:

• 160x120 or 160x90 SQVGA
• 320x240 or 320x180 QVGA
• 352x288 CIF

Framerates for ISDB-Tb transmission are set at 30 frames/s or 60 frames/s for non-portable device transmissions and maximum 30 frames/s for portable devices.

Audio Format

ISDB-Tb audio transmissions are compressed in MPEG-4 AAC Stereo for portable and non-portable device transmissions and 5.1 multichannel is also available for non-portable devices.

Multiprogram

One special feature of ISDB-Tb is the possibility of multi-program transmission for a single channel. This means that a single broadcaster can divide its programming in up to three video sources, with the most commonly cited example being sports broadcasting where viewers can choose multiple camera angles. To use this feature, channels must be formatted within:

• HD combined with SD resolutions for 2 sources
• SD resolutions for 3 sources

Interaction Middleware

Brazilian Digital TV System has an implemented middleware that provides viewer interaction and application install called Ginga. The technology, solely developed in Brazil, allows for information display, interaction with TV programming such as voting and other general functions like banking and shopping.