inserted into 6/8MHz channels for transmission over the HFC network to customer STBs. The key impairments that can occur are caused
by micro-reflections, non-linearity problems in the network, and interference from adjacent analog channels (due to higher power levels).
MPEG-2 QoS testing will occur at the Master satellite Headend, or at any other point where the Service Information is changed, and
before insertion into the coaxial plant.
MPEG Network
Test Challenges:
There is no single, simple test solution for MPEG. Terminology is new and confusing for those unfamiliar with digital video with terms such
as Elementary Stream (ES), Packetized Elementary Stream (PES), Transport Stream (TS), Program-Specific Information (PSI), etc. The
best known Test guideline is known as ETSI TR 101 290 Measurement guidelines for DVB systems. The ATSC has also recently
introduced ATSC Recommended Practice: Transport Stream Verification A78.
Things to remember: Fix continuity problems first. Continuity errors create bogus alarms in other areas. Until the continuity problems are
resolved, it will be very hard to determine if there are other problems in the stream. The PAT (Program Associate Table) is on PID 0x00.
This is the first PID a decoder looks at – the MPEG 'Base PID'.
The CX380S-D3.1 can be optioned to perform MPEG analysis of a digital carrier that contains MPEG programs. The following functions
are available under the MPEG Operations menu:
MPEG Explorer
: The MPEG Explorer provides a convenient and practical way to evaluate user quality of experience levels using
objective test data. MOS scores provide a familiar, intuitive representation of picture, audio, and overall audiovisual quality. Metrics
such as Relative MOS and VSTQ can be useful in accurately comparing video quality across different service types.
MPEG Explorer metrics are grouped by:
Video Stream Metrics - Relate to the encoded video stream, including image size, frame rate, GoP structure, etc.
Transmission Metrics - Relate to the performance of the IP network, UDP/TCP and RTP/MPEG Transport protocols
The following functions are available under the MPEG Explorer:
SLM Measurements
- RF Domain
MPEG
Summary
Scan - MPEG Channel Scan
Summary of Contents for VEPAL CX350S-D3.1
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