Philips Semiconductors
Preliminary specification
PAL/NTSC/SECAM video decoder with adaptive PAL/NTSC
comb filter, VBI-data slicer and high performance scaler
SAA7114H
Remark: Due to bandwidth considerations XPSC[5:0] and
XACL[5:0] can be chosen different to the previous
Where:
2XDCG[2:0] ≥ DC gain
mentioned equations or Table 11, as the H-phase scaling
is able to scale in the range from zooming up by factor 3 to
DC gain = (XC2_1 + 1) × XACL[5:0] + (1 − XC2_1).
down-scale by a factor of 1024
⁄
.
8191
For example, if XACL[5:0] = 5, XC2_1 = 1, then
DC gain = 10 and the required XDCG[2:0] = 4.
Figs 26 and 27 show some resulting frequency
characteristics of the prescaler.
The horizontal source acquisition timing and the
prescaling ratio is identical for both luminance path and
chrominance path, but the FIR filter settings can be
defined differently in the two channels.
Table 11 shows the recommended prescaler
programming. Other programmings, than documented in
Table 11, may result in better alias suppression, but the
resulting DC gain amplification needs to be compensated
by the BCS control, according to the equation:
Fade-in and fade-out of the filters is achieved by copying
an original source sample each as first and last pixel after
prescaling.
2XDG[2:0]
DC gain × 64
CONT[7:0] = SATN[7:0] = lower integer of
----------------------------------
Figs 24 and 25 show the frequency characteristics of the
selectable FIR filters.
Table 10 FIR prefilter functions
PFUV[1:0]A2H[7:6]
PFY[1:0]A2H[5:4]
LUMINANCE FILTER COEFFICIENTS
CHROMINANCE COEFFICIENTS
00
01
10
11
bypassed
1 2 1
bypassed
1 2 1
−1 1 1.75 4.5 1.75 1 −1
1 2 2 2 1
3 8 10 8 3
1 2 2 2 1
MHB543
handbook, full pagewidth
6
V
3
(dB)
0
−3
−6
(1)
−9
(2)
−12
−15
−18
−21
−24
−27
−30
−33
(3)
−36
(1) PFY[1:0] = 01.
−39
−42
(2) PFY[1:0] = 10.
(3) PFY[1:0] = 11.
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
f_sig/f_clock
Fig.24 Luminance prefilter characteristic.
43
2000 Mar 15
NXP [ NXP ]
