Triple-Play Service Deployment

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Chapter 6: Troubleshooting Video in the Headend
Within each table, each parameter has an LED to reflect the current
status (red for in error, green for no error) and, in this solution, a
counter to indicate how many errors have been observed in this
test session.
Testing against a TR 101-290 template is an excellent way to get a
rapid yet comprehensive assessment of the health of an MPEG
transport stream, as each parameter in these tables is the
cumulative status of one or more tests. For instance, the PAT
category will reflect an error status if the time between PAT arrivals
has exceeded 0.5 seconds, but it will also reflect an error status if
something other than the PAT table is on PID 0x0000, as that is
reserved for the PAT only, or if the PID 0x0000 has been scrambled,
as that is invalid and would prevent the decoder from being able
to use the PAT.
Ultimately, TR 101-290 provides a validation tool, which is the first
stage of MPEG test. For purposes of rapid QA, turn-up and
provisioning of equipment, validation allows the technician to
confirm that the MPEG system is compliant and be reasonably
confident that there are no obvious MPEG failures at that point in
the network.
MPEG Troubleshooting
The second stage of MPEG testing is troubleshooting. MPEG
transport is highly dynamic and very volatile.The errors that occur
are often transient. Diagnosing problems from the symptoms
alone is difficult as there is rarely a one-to-one relationship. Often
there are multiple problems that will trigger the same symptom,
and there may be multiple potential root causes that could create
one problem. For instance, a loss of audio at the set top box could
mean the audio component has been lost and is not present at the
set top box. But, it could also be caused when the audio PID has
not correctly been identified in the PMT table, or when the PTS
values for the audio and video have been corrupted and are too