ABNT NBR 15601 is the technical standard published by the Associação Brasileira de Normas Técnicas (Brazilian Association of Technical Standards) which is responsible for addressing aspects related to transmission in the SBTVD digital television standard, also known as ISDB-Tb.

The document covers a large number of issues relating to the detailed characteristics of transmitters and is essential for the proper understanding and manufacturing of equipment for the digital television market in South America and the Central American countries where it was adopted. The writing and discussion of the technical standard was carried out by the SBTVD Forum.[1]​.

The standard was written by telecommunications and television experts from many countries, their work being coordinated by the SBTVD Forum and covering in detail all transmission aspects that apply to the SBTVD standard.

The transmission aspects of the SBTVD standard are described in the technical standard ABNT NBR 15601:2007 - Digital terrestrial television - Transmission system, a document published by the Brazilian Association of Technical Standards. The broadcast of digital terrestrial television in Brazil is introduced in the VHF and UHF bands and is adjusted to the current 6 MHz channels originally planned for analog television transmission. The Digital Terrestrial Television service will coexist with current analogue television transmissions for a temporary period.

The standard was developed taking into account the simultaneous transmission of a hierarchy of nested levels of broadcast quality, including high definition television (HDTV) and standard definition television (SDTV) within a single band.

The ABNT NBR 15601:2007 Standard describes the modulation and channel coding for the Brazilian system, which is identical to that of the Japanese ISDB-T standard and ITU System C. The transmission system was selected after extensive comparative testing based on the methodology and results of ITU Report BT.2035.

Similar to the European and Japanese approaches, it specifies the digitally modulated signal in order to allow compatibility of equipment developed by different manufacturers.

As a general description, the following processes will be applied to the transport stream: error correction coding, temporal interleaving, and carrier modulation. Channel coding is carried out in OFDM modulation segments as in the ISDB-T standard. A set of segments defines a hierarchical layer, in which the aforementioned parameters can be specified independently. Up to three hierarchical layers can be provided, which include the partial receiving layer defined by the central segment. In addition to the frame information, the Brazilian specification includes the spectral composition of the hierarchical transmission, the means of sending multiple signals and multiple tables in different layers.