Panasonic PT47WXD63 - 47" PROJECTION TV, Техническое руководство

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NTSC and 480i Signal Process
Figure 34
All main NTSC and 480i video signals are converted to digital data by an analog
to digital (A/D) converter circuit located inside the Global Core IC, IC4001. The
comb filter in IC4001 converts the composite video signal of the main picture to Y
and C separated video data. S-Video, which is already Y/C separated, simply
bypasses the comb filter. The chroma information is then applied to the chroma
demodulator circuit that separates the color signal into Pb and Pr data. The
component signal, which is already Y, Pb, Pr separated, simply bypasses the
comb filter and chroma demodulator circuits.
IC4001 outputs the data to the global core IC, IC4002. IC4002 contains a line
doubler circuit that halves the horizontal line period, doubling the horizontal
frequency to 31.468KHz. Using IC4015 as a temporary storage area, IC4002
then converts the digital signal scan format from interlaced to progressive and
sends the 10 bit signals to IC4501.
The noise reduction circuit of IC4501 reduces noise and improves the picture
quality. Using IC4502 as a temporary storage area, IC4501 converts the digital
signal scan format from 480p to 540p. The horizontal frequency of the 540p
signal is 33.75KHz, same as 1080i, therefore eliminating the need for a complex
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