Installation guide

Technical Overview 11
different types of data packets are Video, Audio, CA, PC compatible serial data and
Program Guide. Video and audio packets contain the visual and audio information of
the program. The CA (Conditional Access) packet contains information that is
addressed to individual receivers. This includes customer E-Mall, Access Card
activation information and which channels the receiver is authorized to decode. PC
compatible serial data packets can contain any form of data the program provider
wants to transmit, such as stock reports or software. The Program Guide maps the
channel numbers to transponders and SCID's (more on this later). It also gives the
customer TV program listing information.
Figure 2 shows a typical uplink configuration for one transponder. In the past, a single
transponder was used for a single satellite channel. With digital signals, more than one
satellite channel can be sent on the same transponder. The example shows three video
channels, five stereo audio channels (one for each video channel plus two extra for
other services such as a second language), and a PC compatible data channel. Audio
and video signals from the program provider are encoded and converted to data
packets. The configurations can vary depending on the type of programming. The
data packets are then multiplexed into serial data and sent to the transmitter.
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Figure 2, Uplink