GDC21D003 Datasheet, PDF (65/77 Pages) Hynix Semiconductor – VSB Receiver

6.6.7 Data Derandomizer
The data(excluding Field Sync Data, Segment Sync
Data, and parity bytes) is randomized at the
transmitter by Pseudo Random Sequence(PRS).
The de-randomizer accepts the error-corrected data
bytes from the RS decoder, and applies the same
PRS randomizing code to the data. The PRS code
is generated identically as in the transmitter, using
the same PRS generator feedback and output taps
GDC21D003
as shown in Figure 6.6.7. Since the PRS is locked
into the reliably recovered Data Field Sync(and not
some code words embedded within the potential
noisy data), it is exactly synchronized with the data
and performs reliably. The initialization(pre-load)
to F180H occurs during the Data Segment Sync
interval prior to the first Data Segment. The data
derandomizer can be bypassed for performance
tests by setting the I²C register64[3](Derand_on) to
‘0’.
X
X² X²
X⁴ X^{5 X6}
X⁷
X⁸ X⁹ X¹⁰ X¹¹
X¹²
X¹³
X¹⁴ X¹⁵ X¹⁶
D⁰
D¹
D²
D³
D⁴
D⁵
D⁶
D⁷
Figure 6.6.7 Derandomizer Polynomial
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