Introduction

The Integrated Services Digital Broadcasting for Terrestrial Television Broadcasting (ISDB-T) was conceived in Japan to broadcast digital television signals. It allows high-definition television (HDTV) to be accessible for users of the mobile and wireless receivers, with high or low image definition.

The ISDB-T standard can be analyzed as the transformation of a binary signal, which is the digital signal generated by the television operators formatted by MPEG-2, into electromagnetic waves. These waves travel in the air until they reach the ISDB-T receivers, which have the function of executing the reverse process i.e. turning electromagnetic waves into digital signals that the television decoders will understand: the video and audio signals.

The transformation process is complex and attempts to guarantee a perfect signal at the receiver, which implies high quality of sound and image.

ISDB transmission

The ISDB transmission can be divided into two main phases, called channel encoding and modulation, as shown in Figure 8.1.

The first block of the system is called the channel encoder and has the function of encoding the bits to minimize the destructive effects of the communication channel. The input of this block is fed by an MPEG-2 stream. The first alteration suffered by the signal is structural, i.e. the MPEG-2 stream is rearranged in groups of predefined sizes that remain unchanged until they reach the transmission subsystem.

The method used to arrange the data accepts the implementation of special services, such as hierarchic transmission. The ISDB-T uses a multicarrier modulation method for data transmission, which has advantages over the single-carrier mode.