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Technology of Q 2500 colour TV set
1. Half picture
100Hz Indicator
50%
50Hz
1.Half picture
Indicator
Centre of
picture
100%
1. Half picture
50Hz
Indicator
4.4.2 Conversion of signals in 100 Hz in
memory 1
Frequency doubling takes place in the half
picture memory 1 (in I 2311), as it is read at
double speed. This means it is possible to
read the memory twice, whilst it is only written
to once. The first reading of a half picture al-
ways starts when a little over half the picture
is in memory. Due to the double speed, writing
to and reading out end at about the same
time. As the return times at 100 Hz are also
twice as fast, reading out starts before writing
to. The picture is therefore read out for the
second time and during this time up to half of
the next half picture is written to memory.
Document Q 2500
50/100Hz write/read cycle
50Hz Indicator
Start
2. Half
1st Half
picture
Memory content
picture
picture
read
start
50Hz
Indicator
100Hz Indicator
1.Half picture
1x read from
2. Half picture
100Hz Indicator
1. Half picture
2.x read from
1. Half picture
50Hz Indicator
50%
2. Half picture
50%
1. Half picture
100Hz Indicator
1.Half picture
2x read from
4.4.3
Half picture memory 2 and 3
In this half picture writing to and reading out of
memory take place at the same speed. The
half picture is read to memory a second time
and so delayed by a half picture. This means
that half picture A can be written to and read
from memory, whilst the same is happening in
memory 1 for half picture B.
4.4.4
Control pulses
The memory is controlled by the following
pulses:
pin 22: SWCK (Serial Write Clock)
Cycle for reading in the Y/C signals to the
memory.
pin 23: RSTW (Reset Write)
The address counter for writing at the start of
the memory area is set at H level.
92
2. Half picture
50%
2. Half picture
50%
1. Half picture
100%
2. Halbbild
50Hz
Indicator
© Loewe ProCollege
100Hz Indicator
Start
2.Half picture
1.x read from
100Hz
Indicator
2.Half picture
1x read from
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