Philips Semiconductors
Product specification
9-bit video input processor
SAA7113H
handbook, full pagewidth
ANALOG INPUT
ADC
1
0
NO BLANKING ACTIVE
VBLK
<- CLAMP
GAIN ->
1
1
0
0
HCL
HSY
0
1
1
0
1
0
CLL
SBOT
WIPE
slow + GAIN
NO CLAMP
+ CLAMP
− CLAMP
fast − GAIN
+ GAIN
− GAIN
MGC647
WIPE = white peak level (254); SBOT = sync bottom level (1); CLL = clamp level [60 Y (128 C)];
HSY = horizontal sync pulse; HCL = horizontal clamp pulse.
Fig.8 Clamp and gain flow.
• Luminance contrast and brightness
8.3
Chrominance processing
• Limiting YUV to the values 1 (minimum) and 254
(maximum) to fulfil CCIR-601 requirements.
The 9-bit chrominance signal is fed to the multiplication
inputs of a quadrature demodulator, where two subcarrier
signals from the local oscillator DTO1 are applied
(0 and 90° phase relationship to the demodulator axis).
The frequency is dependent on the present colour
standard. The output signals of the multipliers are
low-pass filtered (four programmable characteristics) to
achieve the desired bandwidth for the colour difference
signals (PAL, NTSC) or the 0 and 90° FM signals
(SECAM).
The SECAM-processing contains the following blocks:
• Baseband ‘bell’ filters to reconstruct the amplitude and
phase equalized 0 and 90° FM signals
• Phase demodulator and differentiator
(FM-demodulation)
• De-emphasis filter to compensate the pre-emphasized
input signal, including frequency offset compensation
(DB or DR white carrier values are subtracted from the
signal, controlled by the SECAM switch signal).
The colour difference signals are fed to the
Brightness/Contrast/Saturation block (BCS), which
includes the following five functions:
The burst processing block provides the feedback loop of
the chrominance PLL and contains:
• AGC (automatic gain control for chrominance
PAL and NTSC)
• Burst gate accumulator
• Chrominance amplitude matching (different gain factors
for (R − Y) and (B − Y) to achieve CCIR-601 levels
CR and CB for all standards)
• Colour identification and killer
• Comparison nominal/actual burst amplitude (PAL/NTSC
standards only)
• Chrominance saturation control
1999 Jul 01
13
NXP [ NXP ]
