L64780 LSI Logic Corporation, L64780 Datasheet - Page 51

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

3.3.4 Channel Equalizer (CE) Output
Figure 3.26 CE Output Mappings
3.3.5 CSI Output
Figure 3.27 CSI Output Mappings
36 MHz CLK START DV
18 MHz CLK
26
26
START DV
25
25
24 23
The Channel Equalizer (CE) output lets you probe data after channel
equalization or the frequency response of the channel. After channel
equalization, you can display the constellation by feeding I and Q data
into two DACs. For constellation display purposes, the DACs require only
8-bit resolution.
The signals at this point are I and Q data in two’s complement format, a
start pulse that delimits the COFDM symbols (START), a data valid (DV)
signal that accompanies valid data, and a 36 MHz clock. These signals
are mapped on the MUXOUTBUS. See
The I and Q data available on the bus represent either the equalized data
or frequency response of the channel depending upon the CE_SELECT
bit (address 0x11, bit 3). When CE_SELECT = 0, equalized data are
present on the MUXOUT bus; otherwise, the MUXOUT bus contains the
channel response in the frequency domain.
The CSI output provides an averaged measure per carrier on the
confidence to be placed on the hard decision.
The signals present at this point are the degree of confidence (CSI), a
start pulse that delimits the COFDM symbols (START), a data valid (DV)
signal that accompanies valid data, and an 18 MHz clock. These signals
are mapped on the MUXOUTBUS. See
A high value on the CSI bus indicates a low level of confidence, and vice-
versa. The CSI word is nonsigned data, which can be used to drive a
bar graph representing the quality of reception in a channel.
MUXOUT Interface
24 23
Q[11:0]
0
12 11
11 10
Figure
Figure
3.26.
3.27.
CSI[10:0]
I[11:0]
3-15
0
0