L64704 LSI Logic Corporation, L64704 Datasheet - Page 122

• Manufacturer Part Number: L64704
• Description: Satellite Decoder Technical Manual 5/97
• Manufacturer: LSI Logic Corporation

Figure 5.8
Carrier Loop Filter
Schematic
Equation 5.11
5-18
5.6.2.2 Loop Characteristics
To set the parameters of the carrier recovery loop (natural frequency and
damping factor), you must select both the values the microcontroller
writes into the registers CAR_KD (Group 4, APR 26) and CAR_KP
(Group 4, APR 25), and the values of the resistors and capacitors of the
external active filter (shown in
The natural frequency
determined by the following equations.
K
NDAML is selected.
detectors as a function of the Carrier to Noise ratio (C/N).
Demodulator Module Functional Description
D
=
is the Phase Detector Gain and it depends on whether DDML or
CAR_VCO1P
CAR_VCO1N
L64704
2 CAR_KD
n
Figure 5.9
R
R
T
CAR
CAR
n
(rad/s) and the damping factor of the loop are
,
n
Figure
=
presents the gains of the two phase
C
------------------------------------------------------------ -
R
CAR
CAR
C
5.8).
3.3 K
CAR
+
C
–
CAR
D
K
CARVCO
CAR_KP
VCO
To ADC