L64704 LSI Logic Corporation, L64704 Datasheet - Page 118

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

Equation 5.8
5-14
CAR_VCOF f
If the CAR_RP register is set to 8, the reference period is 8192 reference
clock cycles (for instance, at 10 MHz), and the upper and lower sweep
limits must have the following values:
5.6.1.2 Carrier VCO Frequency Measurement
The L64704 puts the result of the VCO frequency measurement into the
16-bit CAR_VCOF register (Group 3, APR 6:7) for the microcontroller to
read. You must read both nibbles before the L64704 releases this
register for a new value.
The L64704 computes the value that it puts into the CAR_VCOF register
based on
For example, if f
prescaler = 32, then
So that the value each bit in the CAR_VCOF register is given by the
following:
Therefore if prescaler = 16, then the value for each bit in the CAR_VCOF
register is 14.5 kHz.
Demodulator Module Functional Description
CAR_LSWL
CAR_USWL
CAR_VCOF
------------------------------- -
CAR_VCOF
f
CAR_VCO
Equation
=
=
=
=
xo
14.90625
f
--------------------------------------------------------------------------- -
480
--------------------- -
15.09375
xo
CAR_VCO
12288
=
= 10 MHz, CAR_RP = 8, f
5.8.
CAR_RP 1024
10
6
=
8192
------------ -
8192
------------ -
CAR_RP 1024
39062 Hz
f
10
10
xo
=
=
12 211
12 365
f
-------------------------
prescaler
CAR_VCO
(lower limit)
(upper limit)
=
CAR_VCO
480 8 1024
-------------------------------------- -
10 32
= 480 MHz, and
=
12288