III. Gm-C Filtering - Epublications - Université de Limoges

makes the covering of a large territory easier and less expensive. Indeed, single frequency
networks (known as SFNs) become possible due to the ability to treat echoes of digital
modulations.
Furthermore, up to eight single definition programs can be packed in a single TV
channel with the MPEG-2 norm, where only one analog program was emitted before. This
evolution drastically reduced channels broadcasting costs. Digital standards are also able to
handle more advanced compression formats like MPEG-4, which allow the use of highdefinition
picture and sound formats.
There are four main digital standards across the world, as it may be seen in Figure 9
for terrestrial signals: ATSC for Northern America, ISDB for Brazil and Japan, DMB for
China and finally, DVB for Europe, Australia, India and Russia.
Figure 9. Used digital Standard According to Countries
In France for instance, the analog switch-off has already taken place: only digital TV
is broadcasted. However, it has not yet taken place everywhere in the world. The coexistence
of analog and digital standards will still last for more than a decade in some countries. Hence,
this has to be taken into account when designing the TV receiver.
I.1.c Satellite, Cable & Terrestrial spectra
I.1.c.i TV Transmission Modes
Broadcasted TV signals can be transmitted by three different means, corresponding to
three different reception modes: cable, satellite and terrestrial.
Some TV transmissions take place using cable networks.
Satellite transmissions actually consist in transmitting the TV electromagnetic waves
by a satellite between the emitting and the reception parabolas, as illustrated in Figure 10.
- 13 -