DATA SHEET
VSP 94x2A
Table 2–2:
Clamping Adjustment
Signal
CLMPST1
CLMPD1
CLMPST1S
CLMPD1S
CLMPST2
CLMPD2
CLMPST2S
CLMPD2S
Description
Measurement pulse start for ADC1
Measurement pulse duration for ADC1
Clamping pulse start for ADC1
Clamping pulse duration for ADC1
(Measurement pulse start for ADC2)
(Measurement pulse duration for ADC2)
Measure and clamp start for RGBF-ADC (clamping start for ADC2)
Measure and clamp duration for RGBF-ADC (clamping duration for ADC2
2.1.4. Synchronization
After elimination of the high frequent components of
the CVBS signal by a low pass filter, horizontal and
vertical sync pulses are separated. Horizontal sync
pulses are generated by a digital phase locked loop.
The time constant can be adjusted between fast and
slow behavior in four steps (PLLTC) to accommodate
different input sources (e.g. VCR). The time-constant
can be changed during normal operation without visi-
ble picture degradation. A fine tuning of the PLL time
constant can be done by
NSRED.
Additional weak input signals from a satellite dish
(’fish’) become more stable when
SATNR
is enabled.
Vertical sync pulses are separated by integration of
equalizing pulses. A vertical flywheel mode improves
vertical sync separation for weak signals (VFLYWHL,
VFLYWHLMD).
Additionally, v-syncs may be gated by
VTHRL
and
VTHRH
to reject invalid v-syncs (independently adjust-
able for 50 and 60 Hz sources) if no input signal is con-
nected the device switches to a freeruning mode. The
device can be configured to switch-on background
color when no or only a weak signal is applied (NOS-
IGB).
50 Hz or 60 Hz operation for sync separation
may be forced separately or selected to work automat-
ically (FLNSTRD).
2.1.5. Chroma Decoder
The digital multistandard chroma decoder is able to
decode NTSC and PAL signals with a subcarrier fre-
quency of 3.58 MHz and 4.43 MHz (PAL B
*
/N/
60
†
,NTSC M/4.4) as well as SECAM signals with auto-
matic standard detection. Alternatively a standard can
be forced. The demodulation is done with a regener-
ated color-carrier. To enable a factory adjustment of
the crystal frequency, the frequency of the regenerated
subcarrier can be adjusted via
SCADJ.
For this pur-
pose the crystal deviation (SCDEV) can be read out
via I
2
C after chroma PLL locking (indicated by
SCOUTEN)
and can be stored in
µC
ROM for
SCADJ.
For test purposes,
CPLLOF
allows the opening of the
chroma PLL loop.
For adjustment to the specific operational area an
automatic norm detection is selectable. Available
50 Hz color standards are PAL B, PAL N and SECAM.
Available 60 Hz color standards are NTSC M, PAL M,
PAL60 and NTSC44. For each line standard, one or
more color standards can be enabled for automatic
chroma standard detection. Please refer to
and
for allowed combinations.
The standard detection process can be set to slow or
fast behavior
(LOCKSP).
In slow behavior, 25 fields
are used to detect the standard, whereas 15 fields are
used in fast behavior.
If the detection was not success-
ful during this time frame, the system will switch to the
next enabled TV Standard.
* PAL B is representative for PAL B/G/H/I/N
† PAL60 and NTSC44 are nonstandard signals which
are generated by some VCR or DVD player
Micronas
Aug. 16, 2004; 6251-552-1DS
9
MICRONAS [ MICRONAS ]
