adv7189b Analog Devices, Inc., adv7189b Datasheet - Page 33

• Manufacturer Part Number: adv7189b
• Description: Multiformat Sdtv Video Decoder
• Manufacturer: Analog Devices, Inc.

CG[11:0] Chroma Gain, Address 0x2D[3:0];
Address 0x2E[7:0]; CMG[11:0] Chroma Manual Gain,
Address 0x2D[3:0]; Address 0x2E[7:0]
Chroma Gain[11:0] is a dual-function register. If written to, a
desired manual chroma gain can be programmed. This gain
becomes active if the CAGC[1:0] mode is switched to manual
fixed gain. Refer to Equation 2 for calculating a desired gain. If
read back, this register returns the current gain value. Depending
on the setting in the CAGC[1:0] bits, this is either
x
x
Table 41. CG/CMG Function
CG[11:0]/CMG[11:0]
CMG[11:0]
CG[11:0]
For example, freezing the automatic gain loop and reading back
the CG[11:0] register results in a value of 0x47A.
1.
2.
CKE Color Kill Enable, Address 0x2B[6]
The color kill enable bit allows the optional color kill function
to be switched on or off.
For QAM-based video standards (PAL and NTSC) as well as
FM-based systems (SECAM), the threshold for the color kill
decision is selectable via the CKILLTHR[2:0] bits.
Chroma manual gain value (CAGC[1:0] set to chroma
manual gain mode)
Chroma automatic gain value (CAGC[1:0] set to any of the
automatic modes)
Convert the readback value to decimal
0x47A = 1146d
Apply Equation 2 to convert the readback value
1146/1024 = 1.12
Chroma
_
Gain
Read/Write
Write
Read
0
CG
1024
d
4095
Manual gain for chroma
path.
Currently active gain.
Description
0
...
4
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If color kill is enabled and if the color carrier of the incoming
video signal is less than the threshold for 128 consecutive video
lines, color processing is switched off (black and white output).
To switch the color processing back on, another 128 consecutive
lines with a color burst greater than the threshold are required.
The color kill option only works for input signals with a modu-
lated chroma part. For component input (YPrPb), there is no
color kill.
Setting CKE to 0 disables color kill.
Setting CKE to 1 (default), enables color kill.
CKILLTHR[2:0] Color Kill Threshold, Address 0x3D[6:4]
The CKILLTHR[2:0] bits allow the user to select a threshold
for the color kill function. The threshold applies to only QAM-
based (NTSC and PAL) or FM-modulated (SECAM) video
standards.
To enable the color kill function, the CKE bit must be set. For
settings 000, 001, 010, and 011, chroma demodulation inside
the ADV7189B may not work satisfactorily for poor input
video signals.
Table 42. CKILLTHR Function
CKILLTHR[2:0]
000
001
010
011
100 (default)
101
110
111
SECAM
No color kill.
Kill at < 5%.
Kill at < 7%.
Kill at < 8%.
Kill at < 9.5%.
Kill at < 15%.
Kill at < 32%.
Reserved for ADI
internal use only. Do
not select.
Description
NTSC, PAL
Kill at < 0.5%
Kill at < 1.5%
Kill at < 2.5%
Kill at < 4.0%
Kill at < 8.5% (default)
Kill at < 16.0%
Kill at < 32.0%
ADV7189B