cx25840 Conexant Systems, Inc., cx25840 Datasheet - Page 111

• Manufacturer Part Number: cx25840
• Description: Video Decoder And Broadcast Audio
• Manufacturer: Conexant Systems, Inc.

CX25840/1/2/3 Data Sheet
Table 3-39. Analog De-Emphasis Filtering for Audio Standards
Figure 3-32. NICAM De-emphasis Filter
102284B
8/3/05
A1 (aka FM-I)
A2-M
A2-BGDK
BTSC
BTSC-SAP
EIAJ
FM-Radio (µs)
FM-Radio (Europe)
Standard
De-emphasis On Mono Channel
–10
–15
–20
–20
–40
–60
–5
0
0
10
10
The first de-emphasis filter block provides the inverse of the pre-emphasis that was
applied by the transmission system. The input is always the output from the final filter
in the demodulator. Since the amount pre-emphasis is dependant on the system, the
filter characteristics are programmable.
for each audio standard.
75 µs (mono BTSC)
1
1
50
75
50 µs
75 µs
75 µs
75 µs
50 µs
µ
µ
s
s
10
10
Nicam Deemphasis (Magnitude)
2
2
Nicam Deemphasis (Phase)
Conexant
De-Emphasis on Stereo/second
10
10
3
3
dbx for SAP
Language
75 µs
50 µs
75 µs
75 µs
50 µs
dbx
Table 3-39
10
10
4
4
summarizes the de-emphasis filter
(L+R)/2, (L-R)/2 or LangA, LangB
(L+R)/2, R or LangA, LangB
(L+R)/2, (L-R)/2
(L+R)/2, (L-R)/2 or langA, LangB
LangA, LangB
(L+R)/2, (L-R)/2
(L+R)/2, (L-R)/2
10
10
Detailed Functional Description
5
5
Matrix
102284_035
3-85