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APEX1000 All-Purpose Edge QAM Software Version 2.4.x • Installation and Operation Manual
254
573408-001-a
Item
Definition
•
Good Frames
Transmitted
•
Error Frames
Transmitted
Last 5 Secs
– shows the number of good frames transmitted during the last
status checking interval (five seconds).
Total
– shows the total number of good frames transmitted since last reset.
UDP Ports Open
Total
– shows the total number of UDP ports currently open.
Number Input TS
Total
– shows the total number of Input TSs currently open.
Reset buttons
Use to
Reset All
(or each individual GigE 1 – 4) totals.
GigE Buffer Statistics
The APEX1000 uses the GigE frame buffer to hold frames while its de-jittering algorithm
performs time-based recovery. This algorithm attempts to correct the timing errors on
the incoming MPEG streams, principally caused by the following factors:
•
PCR Jitter
—
program clock reference
•
Clock Skew
—
the relative difference in clock accuracy of devices in the processing
chain that either creates or alters the PCRs
•
Network Jitter
— a
variation in delay of received packets
The de-jittering algorithm will attempt to determine the intended rate of the incoming
transport stream. The GigE will then de-jitter this stream and make the necessary PCR
corrections in the stream before it is transmitted as an output stream. The de-jittering
algorithm uses incoming PCRs as a variable in the calculation of the intended incoming
stream rate.
Note: If incoming PCRs are incorrect, the de-jittering algorithm will calculate the wrong
stream rate, and the associated frames will be taken out of the buffer at the wrong rate.
•
The
initial frame buffer level
is configured by the user based on the nominal buffer
level setting. The default nominal buffer level is designed to prevent under runs, as
well as be low enough to prevent frame buffer overflows.
•
The
input data rate setting
helps to define the overflow and reset level of each input
buffer. The default input data rate setting is designed to allow for the maximum
amount of MPEG data to be received and buffer each input stream for up to 650ms.
CAUTION
The default configuration settings have been carefully selected to prevent both under
runs and overflows of the GigE frame buffers. Motorola recommends that you do not
change these settings.
The GigE Frame Buffer Status window (illustrated in
) shows information on
the current GigE frame buffer level and input data rates. This window also logs the
maximum values from the last 24 hours.
