Tektronix MTD200, User Manual

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Measurement Functions
2–20
MTD200 MPEG Test Decoder User Manual
Unreferenced PID (3rd priority)
The Program Map Table (PMT) contains a complete list of all program
definitions contained in the transport stream. In turn, each program definition
contains the information on all PIDs of the elementary stream packets of this
program. This means that by evaluating the PMT one obtains the PIDs of all
transport stream packets which are permitted to convey the useful data of the
program. Besides these referenced packets, the transport stream multiplex is only
permitted to contain packets with program-specific information (PSI tables) such
as PAT, CAT, CA-PID, PMT, NIT, BAT, SDT, TDT, TOT, EIT, RST or having
packet numbers reserved by the MPEG-2 standard.
If the program is changed (a new PMT), a nonreferenced PID may be contained
in the transport stream during 0.5 s according to the DVB Measurement
Guidelines (ETR 290). This interval of 0.5 s is preset in the MPEG test decoder
to comply with DVB, but it can be modified according to individual require-
ments in the MONITORING / LIMITS menu (refer to MONITORING / LIMITS
Menu on page 4–15).
In the DVB Measurement Guidelines (ETR 290) the preconditions for an
Unreferenced_PID_Error message are set as follows:
Unreferenced PID ERROR is signaled if
the transport stream contains a packet with a PID which is not the PID of PAT, CAT,
CA-PID, PMT, NIT, BAT, SDT, TDT, TOT, EIT or RST and which is not referenced in a PMT
that is at least 0.5 second old (ES-PID or PCR-PID)
An error of this type is indicated in a cumulative message signaling several
single errors by the LED labeled OTHER lighting (line of LEDs at front panel).
As additional information, the PID of the packet containing the error can be
obtained from the monitoring report.