L64724 LSI Logic Corporation, L64724 Datasheet - Page 139

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

5.5 Matched Filter
Table 5.2
The L64724 implements a matched filter with selectable roll-off factor on
the I and Q branches according to the DVB standard and DSS
specifications, respectively (square root raised cosine shape with roll-off
B = 0.35 or 0.20). The roll-off factor is selected through the configuration
bit MF_20_35 (Group 4, APR 20, bit 0). The filter operates at a constant
input rate of 2/T. The roll-off factor is configured as shown in
Table 5.3
Matched Filter
(Sheet 3 of 3)
MF_20_35
1.7359
1.5781
1.4203
1.2625
1.1047
(MS/s)
Rb
1
0
1
Frequency
Sampling
Decimation Results (Cont.)
Roll-Off Factor
(MHz)
Roll-Off Factor
50
45
40
35
30
30
0.20 (DSS)
0.35 (DVB)
DF_RATIO
8
8
8
8
8
8
Samples
Symbol
28.803
28.515
28.163
27.723
27.157
30.000
per
DF_FILTER
4
4
4
4
4
4
Table
DF_GAIN
8
8
8
8
8
8
5.3.
5-7