Nevion FRS-HD-CHO - Manual (Page 19)

FRS-HD-CHO Rev. 9
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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.
5.5 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.
5.5.1 Frame sync mode
If a sync input (B&B or Tri-level) is present, the frame synchronizer will output a signal that
has a delay relative to this signal. Two parameters can be set; "Phase delay" and "Video
delay".
Figure 10: Gyda view of the video delay settings
Let us first focus on the phase delay , which also may be called “output phase delay”. This
parameter can be positive or negative, and determines the relationship between the outgoing
video and the sync signal. The parameter really determines a delay on an internal sync
signal, isync
5 . The output is synchronous with isync, see Figure 11.
Figure 11: Positive phase delay
Figure 11 show how the sync signal and the isync signal would look on an oscilloscope, if
converted to analogue signals. The delay of isync can be given in frames, lines, and
samples. The delay can be negative, see Figure 12.
5
Note that isync is not a physical entity, but a term used in this context to explain the delay process
and the use of the configurable parameters related to this process.