L64724 LSI Logic Corporation, L64724 Datasheet - Page 219

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

B.2 Demodulator Configuration Tips
B.2.1 CAR_BW (Carrier Loop Bandwidth)
B.2.2 CAR_SWR (Carrier Sweep Rate)
6. If all of the flags in the Carrier and FEC Synchronization Status
The following tips help in configuring the demodulator registers. Refer to
the L64724 Satellite Receiver Evaluation Board User’s Guide. The
acquisition process is controlled by the L64724 microcontroller.
For the equations given in the following subsections, the relationship
shown in
Equation B.2
B
damping factor.
Set the carrier loop bandwidth according to
Equation B.3
To provide reliable acquisition at any signal-to-noise ratio, the
microcontroller uses two sweep rates. The fast rate pulls the loop out of
false locks. The parameters in the above table might have to be adjusted
at very low rates (< 2 MSps) for optimal performance, depending on the
tuner.
The sweep rate equations are shown in
Equation B.4
Demodulator Configuration Tips
L
B
carrier_bw (KHz)
fast_sweep_rate[MHz/s]
slow_sweep_rate[MHz/s]
is the loop bandwidth,
register are set to 1, clear the CAR_SW bit in the Carrier Loop
Configuration register to 0b0. The sweep turns off.
L
=
--------- - 1
2
Equation B.2
n
+
CAR_BW
-------- -
4
1
2
=
Rs(MSps)
holds.
=
=
n
M x Rs MS/s
N x Rs MS/s
is the natural frequency, and
Equation
Equation
B.4.
B.3.
is the
B-5