2000 Aug 04
27
Philips Semiconductors
Product specication
Digital TV sound demodulator/decoder
TDA9874A
Table 28 Filter bandwidth for channel 1 and channel 2; note 1
Note
1. It is recommended to switch the FM sound mode identification off whenever the received program is not a terrestrial
2-carrier sound. Switching the identification off will reset the associated hardware to a defined state.
7.3.8
FM DE-EMPHASIS REGISTER
This register should not be used when applying ESP. This register is used to select the proper de-emphasis
characteristics as appropriate for the standard of the received carrier. Bits 3 to 0 apply to sound carrier 1, bits 7 to 4 apply
to sound carrier 2. In the event of A2 reception, both groups must be set to the same characteristics.
The default setting after Power-on reset is 0000 0000.
Table 29 FM de-emphasis register (subaddress 10)
Table 30 Description of the FM de-emphasis register bits
FILTBW1
FILTBW0
FILTER BANDWIDTH
FILTER MODES
CHANNEL 1
CHANNEL 2
0
narrow
recommended for nominal terrestrial broadcast
conditions and SAT with 2 carriers
0
1
extra wide
narrow
Recommended for highly overmodulated single
FM carriers. Only channel 1 is available for
FM demodulation in this mode. NICAM can still be
processed on channel 2.
1
0
medium
recommended for moderately overmodulated
broadcast conditions
1
wide
recommended for strongly overmodulated broadcast
conditions
76543210
ADEEM2
FMDSC23
FMDSC22
FMDSC21
ADEEM1
FMDSC13
FMDSC12
FMDSC11
BIT
SYMBOL
DESCRIPTION
7
ADEEM2
Adaptive de-emphasis on/off sound carrier 2: if bit ADEEM2 = 1 it activates the adaptive
de-emphasis function (for Wegener-Panda 1 encoded programs), which is required for
certain satellite FM channels. The standard FM de-emphasis must then be set to 75
s.
If bit ADEEM2 = 0 the adaptive de-emphasis is off.
6
FMDSC23
FM de-emphasis: the state of these bits determines the FM de-emphasis for sound
carrier 2; see Table 31.
5
FMDSC22
4
FMDSC21
3
ADEEM1
Adaptive de-emphasis on/off sound carrier 1: if bit ADEEM1 = 1 it activates the adaptive
de-emphasis function (for Wegener-Panda 1 encoded programs), which is required for
certain satellite FM channels. The standard FM de-emphasis must then be set to 75
s.
If bit ADEEM1 = 0 the adaptive de-emphasis is off.
2
FMDSC13
FM de-emphasis: the state of these bits determines the FM de-emphasis for sound
carrier 1; see Table 31.
1
FMDSC12
0
FMDSC11