L64724 LSI Logic Corporation, L64724 Datasheet - Page 147

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

5.7.1.5 Phase Lock Detection
false locks. The parameters in the above table might have to be adjusted
at very low rates (< 2 MS/s) for optimal performance, depending on the
tuner.
Choose CAR_LSWL and CAR_USWL as given below. Sweeplimit
indicates the upper desired sweep limit in Hz for CAR_USWL and it
indicates the lower limit for CAR_LSWL.
Equation 5.15
In order to initialize the carrier frequency deviation to any desired value,
use the CAR_LF_INIT register from Group 3. In
freqdeviation is the desired frequency deviation in Hz and Fs is the
sampling (A/D) frequency. Calculate CAR_LF_INIT as shown in
Equation
Equation 5.16
The carrier frequency deviation can be read back from CAR_NCOF in
Group 3, APR 7, 8, and 9.
deviation.
Equation 5.17
When the carrier frequency is close enough to the frequency of the
incoming wave, the carrier signal lies in the pull-in range of the phase-
locked-loop. When the loop is phase locked, the phase lock detector sets
the CAR_LC bit (Group 3, APR 11) to 1. To stop the sweep, the
microprocessor must then set the CAR_SW bit (Group 4, APR 41) to 0.
Carrier Recovery Loop
frequencydeviation (Hz)
CAR_XSWL
CAR_LF _INIT
5.16.
=
2
----------------------------------------------
=
16
2
---------------------------------------------------- -
24
sweeplimit
Fs
freqdeviation
=
Fs
--------------------------------------------- -
Fs
Equation 5.17
CAR_NCOF
2
24
is the equation for frequency
Equation
5.16,
5-15