L64724 LSI Logic Corporation, L64724 Datasheet - Page 249

• Manufacturer Part Number: L64724
• Description: Satellite Receiver
• Manufacturer: LSI Logic Corporation

The loop equations are calculated as shown in
Equation
Equation B.40
Equation B.41
The damping factor (
K
K
get L
shown in
Equation B.42
Equation B.43
CAR_MU_SEL[3:0] and CAR_LAMBDA_SEL[3:0] are defined as shown
in
Equation B.44
Equation B.45
Program the four LSBs of APR 28 with 0x5 and the four MSBs of
APR 28 with 0x8.
QPSK Demodulator and FEC Configuration Example: Low Data Rates
digital
digital
Equation B.45
CAR_MU_SEL
CAR_LAMBDA_SEL
a
b
a
b
car
=
=
=
=
= 10, with the result that K
is chosen from
= Fs/Fb = 60e6/2.0e6 = 30. We can now calculate
-------------------------------------------------------------- -
------------------------------------------------------------------ -
---------------------------
K
---------------------------
K
25 10
2
B.41.
Equation B.42
2
dcar
dcar
n
2
25 10
T
n
0.24 30
L
L
0.24 30
2
3 2
T
car
car
=
and
l og
----------------------- -
2.0 10
3
Equation
2
Table
=
1
----------------------- -
2.0 10
is chosen as 1.0. K
and
l og
t
a
1
6
2
2
5.4, on
2
Equation
6
25
=
b
B.46.
=
1.24 10
=
dcar
2
3.4 10
l og
16
page
= 0.24. Using these values, we
=
2
B.43.
l og
1.24 e -6 2
–
–
6
5-19. For a SNR of 4dB,
3
dcar
2
3.4 e -3 2
= K
Equation B.40
25
digital
=
16
5
x 0.78/32.0.
=
=
0x5
a
8
and
=
and
0x8
b
B-35
as