C1851BCU 데이터 시트보기 (PDF) - NEC => Renesas Technology
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C1851BCU Datasheet PDF : 60 Pages
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µPC1851B
2.3 dbx Noise Reduction Block
All the filters required for TV-dbx Noise Reduction are incorporated. These filter responses are adjusted by
setting all the FILTER SETTING bits (Write register, subaddress 02H, bits D0 to D5).
(1) LPF
This LPF has traps at fH and 24 kHz each. The fH trap filter minimizes interference by the fH signal which is not
synchronized with the pilot signal (for example, leakage of the synchronous idle and buzz from the video signal).
(2) 408-Hz LPF
This filter is a de-emphasis filter. Its transfer function is as follows:
1+j
T(f) =
1+j
f
5.23k
f
408
(3) Variable Emphasis
It is also called the spectral VCA. It is controlled by the spectral RMS. The transfer function is as follows:
1+j
S–1 (f, b) =
1+j
f
20.1k
f
20.1k
1 + 51b
x
b+1
1 + 51
x
b+1
where “b” is the variable transferred from the spectral RMS for controlling.
(4) Wide-band VCA
A VCA whose operating frequency range is mainly low to mid frequencies and controlled by the wide-band RMS.
The transfer function is as follows:
W–1 (a) = a
where “a” is the variable transferred from the wide-band RMS for controlling.
(5) 2.19-kHz LPF
This filter is a de-emphasis filter. Its transfer function is as follows:
1+j
T(f) =
1+j
f
62.5k
f
2.19k
(6) Spectral RMS Filter
A filter that limits the band width of the signal input to the RMS which controls the variable emphasis. The
transfer function is as follows:
T (f) =
f
(j
7.66k
f
1+j
7.31k
)2
+ ( j f )2
7.66k
f
j
3.92k
x
f
1+j
3.92k
20
Data Sheet S13417EJ2V0DS00
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