L64780 LSI Logic Corporation, L64780 Datasheet - Page 47

• Manufacturer Part Number: L64780
• Description: Dvb-t Cofdm Demodulator Technical Manual 2/00
• Manufacturer: LSI Logic Corporation

3.2.3 Access to the FFT Block
Figure 3.18 FFT Input Mapping
3.2.4 Access to the CSI Block
Figure 3.19 CSI Input Mapping
26
DVSP
0
26
START
25
START DV S_NB
25
24
24 23 22 21
0
In this mode, you can select whether the COFDM symbol number comes
from the TPS informations (Frame Number) or from the MUXINBUS
(S_NB). This selection is done through the AFC_MODE bit (address 0x5,
bit 6). If AFC_MODE = 0, the COFDM symbol number comes from the
MUXINBUS (S_NB) or full MUXIN mode; otherwise, it comes from the
TPS register (partial MUXIN mode).
In this mode, the CLKMUXIN signal is configured as a 36 MHz clock
(more precisely, eight times the low IF).
The signals on the bus are I and Q data (in two’s complement format)
and a start pulse (START). These signals are mapped on the
MUXINBUS. See
In this mode, the L64780 can be used as a stand-alone FFT processor
in forward mode (FFT_DIR = 0) or in inverse mode (FFT_DIR = 1). The
FFT_DIR register is located at address 0x11, bit 2.
The CSI block performs the Channel State Information (CSI) processing,
which builds the soft decisions for the Viterbi decoder using a priori
information from the Channel Equalizer (CE). In this mode, CLKMUXIN
is configured as an 18 MHz clock (more precisely: four times the low IF).
The signals on the bus are I and Q data (in twos complement format), a
start pulse (START), a data valid (DV) signal, the COFDM symbol
number (S_NB), and a marker (or data valid) on scattered pilots (DVSP).
These signals are mapped on the MUXINBUS. See
MUXIN Interface
21
20
Figure
Q[10:0]
Q[9:0]
3.18.
11 10 9
11 10
0
Figure
I[10:0]
I[9:0]
3.19.
3-11
0
0