Nevion FRS-HD-XMUX4 - Manual (Page 16)

FRS-HD-XMUX4 Rev. C
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Automatic selection mode
Figure 6: Multicon GYDA view of the input selection
If the Video in mode selector is set to auto in Multicon GYDA, three input choices can
be made for each of the three priority levels: electrical, optical, mute or generator.
When the selected signal on the Main level is lost, the change over will switch to the
signal selected on the next priority level (backup 1) and so on. If the third priority level
is not needed, backup 2 can be set to
‘–‘.
The switching between these priority levels is controlled by rules.
The available rules are:

Lol = loss of lock

Los = loss of signal
Hold time and lock time for the signals can also be set.
When using the rule loss of signal, switching function can be selected as either latched
or non-latched.
Non-latched switching function is only possible with rule loss of signal.
5.3 De-glitcher
The de-glitcher corrects timing errors within a single video line. The de-glitcher has a
2048 samples buffer. When the first signal is present,
we call it the “initial phase
signal”, data is taken from the centre of this buffer. If the timing reference of the video
signal changes, when for instance a new source being switched into the signal path,
the timing errors occurring by this change will be corrected if the new timing reference
is within +/-1024
samples of the “initial phase signal”. This also goes for all consecutive
timing references.
If a signal is more than +/-1024 samples off relative to the “initial phase signal”, the
output will repeat the last frame, refill the 2048 samples buffer and take out data from
th
e centre of the buffer. This new signal is now considered the “initial phase signal”.
Audio will fade out when a frame repeat is being done, and fade in at the new frame.
Hence, it produces an error free video output without frame wrapping when the video
input comes from a router with synchronous input video signals that all lies within +/-
1024 samples of each other.
The de-glitcher output is always seamless. When a signal is repeated the
audio is faded out. It fades in at the new frame.
5.4 Frame synchronizer
The frame synchronizer consists of a frame store buffer and some control logic. The
frame store buffer can store up to 8 full HD frames. Data is fetched from this buffer
according to the user settings by force of the control logic. The control logic sets the
frame synchronizer into different modes dependent on the presence of a sync input.