Line Interpolation - Loewe Q2500B Serviceanleitung

Technology of Q 2500 colour TV set
K factor
K
factor
1
0,75
0,50
0,25
0
0
Information about the size of movement is
provided by the movement detection. This
occurs only in the Y branch, with which the K
factor is set simultaneously for chroma and Y.
The drawing shows the DNR principle for the
Y path. As already mentioned the circuit in the
chroma path is identical. The K factor can
have a value from 0 to 1. At K = 1, 100% of
the direct signal and 0% of the delayed signal
is switched to the following "And". No noise
suppression is therefore available.
Standard PAL signal
576 lines
visible picture
A standard PAL signal consists of 576 visible
lines. For PALplus, 144 of the lines are dark
sampled and only 432 lines are transferred as
a visible picture. In 16:9 c.r.t's these signals
are shown in the ZOOM mode. In order to
display 576 lines the information for 4 lines
must be determined by 3 lines respectively.
This computer operation is very
Document Q 2500
In the other extreme case K = 0, only the de-
layed signal would be switched, which would
correspond to a freeze frame. To avoid this
the K factor in our TV sets can never be 0.
Otherwise it would only be programmes with a
weak signal that would be incapable of being
displayed.
> 0 Noise
4.5.2
level
The line interpolations circuits allow a situation
to be achieved in which a full-line picture is
written for PALplus signals . The advantage
with respect to a PALplus decoder is that even
without a PALplus signal, the interpolation in
all zoom modes delivers a full-line picture.
This function is explained in the following
paragraphs for PALplus, in the zoom functions
the circuit operates similarly only with other
factors.
PALplus signal
72 lines black bar
432 lines
visible picture
72 lines black bar
complicated and will therefore not be ex-
plained here.
Line interpolation must be carried out both in
chroma as in the Y branch.
98

Line interpolation

PALplus signal on 16:9-
c.r.t. with line interpolation
Interpolation
576 lines
visible picture
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