Measurement Functions
MTD200 MPEG Test Decoder User Manual
2–5
TS_Sync_Loss (1st priority)
Each packet of the transport stream is preceded by a header consisting of four
bytes. The first byte of the header is the synchronization byte (SyncByte), whose
content is always the hexadecimal value 0x47. In the MPEG-2 decoder, the
SyncByte serves for synchronization with the packetized transport stream. DVB
recommendations define synchronism such that a sequence of at least five
SyncBytes has to be detected by the MPEG-2 decoder. Synchronism is lost if the
SyncBytes in a sequence of at least three TS packets are not detected according
to the DVB recommendations. This status is referred to as TS_Sync_Loss. The
synchronization hysteresis of 5/3 SyncBytes recommended in the DVB
guidelines is also a basic setting in the MPEG test decoder, although it may be
modified for synchronization tests (refer to TS INPUT / SYNC CONDITION
Menu on page 4–28).
In the DVB Measurement Guidelines (ETR290), the preconditions for a
TS_Sync_Loss message are set as follows:
TS_Sync_Loss is signaled if
the content of the synchronization bytes in a sequence of three TS packets does not equal
0
×
47 (hexadecimal)
Two LEDs labeled TS and located one above the other at the very left of the
front panel serve to display the synchronization status. An error (no synchro-
nism) is indicated by the yellow LED (top); synchronism is indicated by the
green LED (bottom) lighting.
Summary of Contents for MTD200
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Page 29: ...Introduction to Digital TV Transmission Technique 1 14 MTD200 MPEG Test Decoder User Manual...
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Page 167: ...Remote Control 5 70 MTD200 MPEG Test Decoder User Manual...
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Page 174: ...Maintenance and Checking 6 6 MTD200 MPEG Test Decoder User Manual...
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