ADVANCE INFORMATION
VDP 313xY
2.4.7. Automatic standard recognition
2.4.8. PAL Compensation/1-H Comb Filter
The burst-frequency measurement is also used for
automatic standard recognition (together with the sta-
tus of horizontal and vertical locking) thus allowing a
completely independent search of the line and color
standard of the input signal. The following standards
can be distinguished:
The color decoder uses one fully integrated delay line.
Only active video is stored.
The delay line application depends on the color stan-
dard:
– NTSC:
– PAL:
1-H comb filter or color compensation
– PAL B,G,H,I
– NTSC M
– SECAM
– NTSC 44
– PAL M
color compensation
– SECAM: crossover-switch
In the NTSC compensated mode, Fig. 2–5 c), the color
signal is averaged for two adjacent lines. Thus,
cross-color distortion and chrominance noise is
reduced. In the NTSC combfilter mode, Fig. 2–5 d), the
delay line is in the composite signal path, thus allowing
reduction of cross-color components, as well as
cross-luminance. The loss of vertical resolution in the
luminance channel is compensated by adding the ver-
tical detail signal with removed color information. If the
2-H adaptive comb filter is used, then the 1-H NTSC
comb filter should not be used.
– PAL N
– PAL 60
For a preselection of allowed standards, the recogni-
tion can be enabled/disabled via I2C bus for each stan-
dard separately.
If at least one standard is enabled, the VDP 313xY
checks regularly the horizontal and vertical locking of
the input signal and the state of the color killer. If an
error exists for several adjacent fields a new standard
search is started. Depending on the measured line
number and burst frequency the current standard is
selected.
CVBS
Luma
8
Notch
filter
Y
Y
For error handling the recognition algorithm delivers
the following status information:
8
chroma
Chroma
Process.
Chroma
Process.
CRCB
CRCB
– search active (busy)
– search terminated, but failed
– found standard is disabled
– vertical standard invalid
– no color found
8
a) conventional
b) S-VHS
CVBS
Notch
filter
Y
8
Chroma
Process.
1H
Delay
CRCB
– standard switched
c) compensated
Notch
filter
Y
CVBS
1H
Delay
8
Chroma
Process.
CRCB
d) comb filter
Fig. 2–5: NTSC color decoding options
Micronas
11
MICRONAS [ MICRONAS ]
