GUIDE TO INSTALLATION AND OPERATION
20
| MDX-3901
To perform a glitch-free switch between two
sources, they must be in the same clean switch
region. A clean switch region is contained within
± ½ line about an H=0 point in the reference
signal, as shown by the dotted lines in the
figure. There is a clean switch region centered
on every H interval. As you can see, vertical
alignment with the reference is not important for
the deglitcher to operate properly.
Referring to the figure on the right, you may
switch between signals A, B or C, without any
glitch, and also between signals D
E and
signals F
G. Any other transition, like A
D,
will cause a vertical image shift for one frame.
To determine whether a clean hot switch is
possible, you need to determine whether the two
input signals lie in the same clean switch region.
There is only one way to measure the position of
the signals with respect to the reference:
Use the deglitcher tab in iControl (Input
Deglitcher)
When the deglitcher mode is on, each of these sources will display the alignment offset between the reference signal
and the input signal. Knowing the offset for both input signals, you can determine if they are in the same clean switch
region. If so, any hot-switch between those two signals will be glitchless.
To determine the limits of a clean swit
ch region, you must know the input’s line length in
s. The first region is delimited
by +½ line and -½ line of the reference. For example, with a 3G 59.94 signal the line length is 14.83
s and so the first
region lies between -7.41
s and 7.41
s. Other regions can be found by adding or removing a multiple of line length to
the two boundaries.
Example: for a 3G 59.94 input signal, we have these clean switch regions:
-1 line and -7.41
s to 0 line and -7.41
s,
0 line and -7.41
s to 0 line and 7.41
s,
0 line and 7.41
s to 1 line and 7.41
s, etc.
…
Ref signal
Signal A
Signal B
Signal C
Signal D
Signal E
Signal F
Signal G
H=½ line
H=½ line
H = 0
Line = x
H = 0
Line = x+1
clean switch region #2
H = 0
Line = x-1
clean switch region #3
clean switch region #1
H=0
V=1
H=0
V=1
H=0
V=1
H=0
V=1
H=0
V=1
H=0
V=1
H=0
V=1
