GDC21D003 Datasheet, PDF (48/77 Pages) Hynix Semiconductor – VSB Receiver

10
Comb
Filter
GDC21D003
10
Multiplexer
Reference
Generation
MSE
&
Comparator
Combstat
Figure 6.3.16 The Block Diagram of NTSC Rejection
When NTSC co-channel interference is checked,
Comb Filter ON/OFF timing can be changed
through I²C bus. Its control signal is
NoCombgain[1:0](in I²C bus register5) and
controls this by changing error gain which doesn’t
use Comb Filter. When NoCombgain[1:0] is “00”,
gain is ‘1’. As a result, sum of error value during
PN511 section, which doesn’t use Comb Filter is
compared with the sum of the other during PN511
section, passed through Comb Filter. When it is
“01”, each error that doesn’t use Comb Filter is
multiplied by the gain of ‘1.125’(1.023dB) and the
results are compared. When it is “10”, gain is
‘1.1875’ (1.493dB), and when “11”, gain is ‘1.25’
(1.983dB). By this manner, it is determined
whether Comb Filter will be used or not. The signal
to inform this to the next part is Combstat. And it
can be read through I²C bus. (in I²C bus register8)
Various controls can be done through I²C bus as
shown in Table 6.3.5.
Table 6.3.5 Comb Filter Control through I²C Bus
NCombW
(in I²C bus register5)
‘1’
‘1’
‘0’
NComb
(in I²C bus register5)
‘1’
‘0’
don’t care
Combstat
(in I²C bus register8)
‘1’(Comb filter OFF)
‘0’(Comb filter ON)
Internally detected signal
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