Nevion HD-TD-10GX-8-SFP - Manual (Page 12)

HD-TD-10GX-8 Rev. A
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The operator can select which of the errors are to be counted and which are to be ignored
(masked out). This is done individually for each input or output channel. The error counters
count fields with un-masked errors (for interlaced formats) or frames with un-masked errors
(for progressive formats), not individual errors, of which there can be many in a single field.
The maximum error rate generated in a single channel is thus equal to the field rate or frame
rate. Setting the error rate alarm limit in Multicon below the lowest field/frame rate (20 errors/s,
for instance) will thus guarantee that any permanent error condition will trigger the alarm.
If the input to a channel should disappear altogether, an internal counter with a frequency
slightly above 60 Hz will take over. This guarantees that the error rate from the LOCK error
and VS error bits are always at least as high as the error rate generated by the other types
of errors.
The YCS, CCRC and YCRC error bits have no meaning in SD.
For the output signals, there are only VS and LOCK error bits available. These error indicators
are actually transported from the mux side; to save power there are no actual error detectors
on the de-mux side, except on the 10G fiber transport stream. If errors are indicated on the
10G stream, chances are that one or more of the outputs have also been affected. The error
bits for the fiber transport stream are limited to LOCK error and FF-CRC error. This FF-CRC
bit is not the same as FF-CRC for normal SDI video, but rather a mapping of several internal
checksums into one error bit. This error counter behaves as the others in the sense that the
error count per second is limited to slightly more than 60.
Note that when an input is missing, only the LOCK error bit is set, not the
other error bits. It is therefore advisable to count the LOCK error bit, as the
other error bits will indicate that everything is OK when the input signal has
indeed been lost. Individual reclocker alarms also exist, and while a single
observation of loss of lock is enough to trigger these alarms, the lock status
is only sampled when Multicon asks the card for its current status. The
update frequency will thus depend on how many other cards are in the
system, and glitches in lock status will not necessarily be reported to
Multicon to trigger an alarm there.
3.1.4 Expected video format
In transport products like these it is not always enough to know that video is present and
error-free. It can be equally important to know that the video format is correct. The operator
can select an “Expected video format” for each channel. An input or output signal that does
Illustration 5: Selection of expected video format