Tektronix MTD200, User Manual

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Glossary
MTD200 MPEG Test Decoder User Manual
Glossary–9
The occurrence frequency of a set transport error indicator is no measure for
the bit error rate on the transmission path. The set transport error indicator
shows that the quality of the transmission path is not sufficient for an
error–free transmission despite error control coding. A slight drop in
transmission quality will already quickly increase the occurrence frequency
of a set transport error indicator and transmission will not take place.
Transport Stream (TS)
The transport stream is a multiplex data stream defined by MPEG2 which
may contain several programs that may consist of several elementary
streams. A program clock reference (PCR) is carried along for each program.
Multiplexing is by forming TS packets for each elementary stream and by
stringing together these TS packets originating from different elementary
streams.
TS Header
The TS header is provided at the beginning of each TS packet and has a
length of four bytes. The TS header always begins with the sync byte 0x47.
Further important elements are the PID and the continuity counter. The TS
header must never be scrambled when it is to be transmitted (see Conditional
Access).
TS Packet
The transport stream is transmitted in packets of 188 bytes (after channel
coding 204 bytes). The first four bytes form the TS header which is followed
by the 184 useful bytes.