Register 4-Demodulator Setup Register - Analog Devices ADF7021-V Manual

REGISTER 4—DEMODULATOR SETUP REGISTER
POST_DEMOD_BW
IF_FILTER _
IFB2 IFB1
BW
0 0 9kHz
0 1
13.5kHz
1 0
18.5kHz
1 1
INVALID
DW10 . DW6 DW5 DW4 DW3
0 . 0 0 0 0
0 . 0 0 0 0
. . . . . .
. . . . . .
. .
. . . .
. . . . . .
1 . 1 1 1 1
•
To solve for DISCRIMINATOR_BW, (Bits[DB19:DB10]),
use the following equation:
DISCRIMINA TOR _ BW
where the maximum value = 660.
For 2FSK,
⎛ ×
3
100 10
⎜
=
K Round
⎜
f
⎝
DEV
For 3FSK,
⎛ ×
3
100 10
⎜
=
K Round
⎜
×
2 f
⎝
DEV
For 4FSK,
⎛
×
100
⎜
=
K Round
⎜
4 FSK ×
4
⎝
DW2 DW1
POST_DEMOD_BW
0 1 1
1 0 2
. .
.
. .
.
. . .
. . .
1 1 1023
TD10 . TD6 TD5 TD4 TD3
0 0
0 . 0 0
0 . 0 0 0 0
. . . . . .
. . . . . .
. . . . . .
. . . . . .
1 . 0 1 0 1
Figure 66. Register 4—Demodulator Setup Register Map
⎛ ⎞
×
DEMOD CLK K
⎜ ⎟
=
⎜ ⎟
×
3
400 10
⎝ ⎠
⎞
⎟
⎟
⎠
⎞
⎟
⎟
⎠
⎞
3
10
⎟
⎟
f
⎠
DEV
DISCRIMINATOR_BW
RI2 RI1
Rx_INVERT
0
0 NORMAL
1
0 INVERT CLK
0
1 INVERT DATA
1
1 INVERT CLK/DATA
TD2 TD1 DISCRIMINATOR_BW
0 1 1
1 0 2
. . .
. .
.
. .
.
. .
.
0 0
660
where:
Round is rounded to the nearest integer.
Round
4FSK
32, 31, 28, 27, 24, 23, 20, 19, 16, 15, 12, 11, 8, 7, 4, 3.
f is the transmit frequency deviation in Hz. For 4FSK,
DEV
f is the frequency deviation used for the ±1 symbols
DEV
(that is, the inner frequency deviations).
•
Rx_INVERT (Bits[DB9:DB8]) and DOT_PRODUCT
(Bit DB7) must be set as indicated in Table 16 and Table 17.
•
POST_DEMOD_BW (Bits[DB29:DB20]) sets the
bandwidth of the postdemodulator filter. To solve for
POST_DEMOD_BW, use the following equation:
POST_DEMOD
where f
CUTOFF
filter) should typically be set equal to 0.75 × the data rate in
2FSK. In 3FSK, it should be set equal to the data rate, whereas
in 4FSK, it should be set equal to 1.6 × the symbol rate.
Rev. 0 | Page 49 of 60
Rx_ DEMOD_
INVERT SCHEME
DP1
DOT_PRODUCT
0
CROSS_PRODUCT
1
DOT_PRODUCT
DS3 DS2 DS1 DEMOD_SCHEME
0 0 0 2FSK LINEAR DEMODULATOR
0 0 1 2FSK CORRELATOR DEMODULATOR
0 1 0
3FSK DEMODULATOR
0 1 1
4FSK DEMODULATOR
1 0 0
RESERVED
1 0 1 RESERVED
1 1 0 RESERVED
1 1 1 RESERVED
is rounded to the nearest of the following integers:
× ×
11
2 π f
= CUTOFF
_BW
DEMOD CLK
(the cutoff frequency of the postdemodulator
ADF7021-V
ADDRESS
BITS