TMC22x5yA
PRODUCT SPECIFICATION
TMC22x5yA Functional Description
Input Processor
LPF Output
Input
LPF
The input processor selects between the two external video
sources on VIDEO A and VIDEO B. If the TRS stripper or
GRS stacker is active, then the user must select the input
with either the GRS (in genlock mode) or with the embedded
TRS words as output VA. If the input data are separate luma
HPF Output
–
and chroma orY and C C data the input processor must be
B R
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programmed to put the chrominance or C C onto output
B R
VB and the luminance or Y onto VA.
Figure 12. Complementary Bandsplit Filter
To ensure that the chrominance data or the C C data are in
B R
The complementary bandsplit filter separates the base band
composite video into two bands by passing it through a low
pass filter and subtracting the low pass (luma) data from the
composite video to produce the high pass (chroma) data. As
the base bandwidths and subcarrier frequencies of the differ-
ent NTSC and PAL video formats are so different, and the
decoder has to be capable of working over a large frequency
range, it is necessary to provide two low pass filters. These
filters are selectable by the BSFSEL register bit and are inde-
pendent of the video standard. A comparison of the different
data rates to normalized subcarrier frequencies is provided in
Table 2.
two’s complement arithmetic format, the register bit MSBI
inverts the msb of the DB input. For composite inputs, the
IPCMSB register bit should be set LOW, as the ABMUX
register bit is used to select the input(s) to the comb filter.
Bandsplit Filter (BSF)
In its simple mode of operation, the TMC22x5yA uses a
complementary bandsplit filter, instead of a notch filter for
the luma and a bandpass for the chroma. The notch and
bandpass filter technique, removes frequency bands from the
composite video spectrum which can never be retrieved.
The complementary bandsplit filter technique, shown in
Figure 12, allows the decoded component video signals to be
re-encoded into a composite video signal with the minimum
of losses to the composite video spectrum.
The complementary bandsplit low pass frequency response
is shown in Figure 13 and Figure 14.
msb
x
Input Processor Control Register
IPMUX IP8B TDEN TBLK
lsb
ICPMSB ABMUX CKSEL
TRS Stripper (D1/D2/D3)
and
GRS Stacker (TMC22071)
VA
DA
Primary Data
to Comb Filter
VideoA
2:2 MUX
2:2 MUX
VB
DB
Secondary Data
to Comb Filter
MSB
Invert
VideoB
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Figure 11. Input Processor
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REV. 1.0.0 2/4/03
CADEKA [ CADEKA MICROCIRCUITS LLC. ]
