SAA7109 PHILIPS [NXP Semiconductors], SAA7109 Datasheet - Page 54

• Manufacturer Part Number: SAA7109
• Description: PC-CODEC
• Manufacturer: PHILIPS [NXP Semiconductors]

Philips Semiconductors
9.1.3.2
The rejection of the chrominance components within the
9-bit CVBS or Y input signal is done by subtracting the
re-modulated chrominance signal from the CVBS input.
The comb filtered C
(upsampled) by the low-pass 3 block. It’s characteristic is
controlled by LUBW (subaddress 09H, bit 4) to modify the
width of the chrominance ‘notch’ without influencing the
chrominance path. The programmable frequency
characteristics available, in conjunction with the
LCBW2 to LCBW0 settings, can be seen in Figs 20 to 23.
It should be noted that these frequency curves are only
valid for Y comb disabled filter mode (YCOMB = 0).
In comb filter mode the frequency response is flat. The
centre frequency of the notch is automatically adapted to
the chosen colour standard.
2004 Mar 16
PC-CODEC
Luminance path
B
-C
R
components are interpolated
54
The interpolated C
time-multiplexed subcarrier signals from the subcarrier
generation block 2. This second DTO is locked to the first
subcarrier generator by an increment delay circuit
matched to the processing delay, which is different for
PAL and NTSC standards according to the chosen comb
filter algorithm. The two modulated signals are finally
added to create the re-modulated chrominance signal.
The frequency characteristic of the separated luminance
signal can be further modified by the succeeding
luminance filter block. It can be configured as peaking
(resolution enhancement) or low-pass block by
LUFI3 to LUFI0 (subaddress 09H, bits 3 to 0). The 16
resulting frequency characteristics can be seen in Fig.24.
The LUFI3 to LUFI0 settings can be used as a user
programmable sharpness control.
The luminance filter block also contains the adjustable
Y delay part; programmable by YDEL2 to YDEL0
(subaddress 11H, bits 2 to 0).
B
-C
SAA7108E; SAA7109E
R
samples are multiplied by two
Product specification