Nevion SDI-TD-MUX-4 - Manual (Page 14)

SDI-TD-MUX-4 / SDI-TD-DMUX-4 Rev. N
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Locate card: See MUX description.
Firmware upgrade: See MUX description.
Input selector: (Stored setting). This control is only available for boards with the optional
optical input. Here the user can select to force the input to be taken from either the electrical
or the optical input, or allow the card to automatically select between them.
In “Auto (pri opt)”, the operation is like this:
1. If there is a carrier on the optical input, this input will always be preferred.
2. If there is no carrier on the optical input, the electrical input will only be selected if it
has got a carrier.
3. There is no check for signal lock and there are no significant delays before swapping
to the other input.
In “Auto (latch)” mode, the operation is like this:
1. On power-on, the board will start with selecting the optical input as default.
2. If, at any time, the lock is lost on the presently selected input, after a ~one second
delay, the board will first check if there is a carrier on the other input. If it isn’t, the
input select will remain unchanged. If there is a carrier on the other input, the board
will swap to that input and try to lock to it.
3. If both inputs have a carrier, but the board is incapable of locking to any of the
signals, the board will toggle between the two inputs until a lockable signal is applied
to either of the two inputs. Then, this input will be selected. The toggling rate is about
once per second while searching for a lockable signal.
4. If none of the inputs has a carrier, the board will remain at its present input selection
(the last one it successfully locked to or tried to lock to).
5. If there is a carrier on only one of the inputs, only this input will be selected as long as
this is the case (no toggling).
6. There will always be a one second delay before giving up the presently selected
signal on loss of lock.
7. There will be no non-volatile memory for keeping the last selected input when in auto
mode. The above algorithm will always start working to find a signal when starting the
board. This means that, after power-on, the optical input will always win if there is a
lockable signal present at that input.
Shuffler: (Stored setting) Each SD output is here assigned to one of the transport streams
(in the SMPTE 346M-2000 compatible HD video) or to one of the onboard generators. Note
that in this particular case a reverse-diagonal is formed, and when combined with the
reverse-diagonal we saw in the MUX, this means that input 1 on the MUX side is routed out
as output 1 on the DMUX side, input 2 is routed out as output 2, and so forth.
The option also exists to force one or more of the outputs to internal generators. This is
primarily useful during site installation, to validate parts of the signal chain.
Fallback (for SD-SDI only): If/when the SD-SDI is lost on the MUX side, or if the HD link
between the MUX and the DMUX breaks down, the DMUX has optional fallback to internal
generators. The video format (525 vs. 625 lines) will then be determined by the last valid
video to be seen by that particular output, while the user selects the video pattern (black
picture or color bars). If no fallback is selected, the output driver will simply be turned off
when the card can no longer output a valid SD signal. This is also the behavior when
transporting DVB-ASI: Since the card has no onboard DVB-ASI generators, and thus no valid
fallback for DVB-ASI, the fallback logic will always treat a DVB-ASI gone missing as if the
fallback option for that particular output was
“None”. In other words, when a DVB-ASI