MC92314 Datasheet, PDF (33/100 Pages) Motorola, Inc – DVB-T Single Chip Demodulator Application Note

Freescale Semiconductor, Inc.
Device Description
Table 3-4 shows the encoding of the rate information into a three bit word. This information is
used for output information when using automatic synchronisation or for control information
when the block is being externally controlled via the I²C interface.
Table 3-4. Rate Encoding
Coding Rate
Data Word
1/2
000
2/3
001
3/4
010
5/6
011
7/8
100
Automatic
111
n Notes:
Automatic rate selection is only used as an input value
tio ^{when internal synchronisation is used. The decoder will}
never output 111 as a coding rate.
a All other states of the 3 bit data word are unused.
rm _{This table is referred to throughout this document when discussing the various rates supported}
fo _{by the decoder.}
y ^In _{3.2.3.2.6 Input Data Format}
ar ^{The I and Q data input to the decoder can be interpreted as either sign-magnitude or offset binary}
in ^{format. The choice of input format is specified by setting the IFS bit in the CONFIG register bank}
of the I2C interface. The default after RESET_N is to use offset binary.
lim^{Table 3-5. I And Q Input Format}
Pre ^{Interpretation}
VC0[2:0]/VC1[2:0]
IFS = 0
IFS = 1
2’s complement
(internal format)
(offset binary) (sign-magnitude)
strong 0
000
011
100
.
001
010
101
.
010
001
110
weak 0
011
000
111
weak 1
100
100
000
.
101
101
001
.
110
110
010
strong 1
111
111
011
3.2.3.2.7 Channel SNR Measurement
The synchroniser generated syndrome sequence (p₀) is used to determine the channel SNR
value.
period
The
and
average value of
is accessible via
the
the
number of 1’s
I²C interface.
accumulated
from
p₀
is
calculated
over
a
known
Single Chip DVB-T Demodulator - Rev. 1.3 (11/30/98)
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MOTOROLA
3-15