TDA9874H datasheet(28/56 Pages) PHILIPS

28 / 56 page

1998 Apr 27

Philips Semiconductors

Preliminary speciﬁcation

Digital TV sound demodulator/decoder

TDA9874H

7.3.11

NICAM CONFIGURATION REGISTER (NCONR)

The default setting at power-up is 00000000.

Table 34 NICAM Conﬁguration Register (subaddress 14)

Table 35 Description of NCONR bits

7.3.11.1

Notes

The decision of whether auto-muting is permitted shall be taken by the controlling microprocessor based on information

contained in the TDA9874H’s status registers. Thus, it depends on the strategy implemented in the software whether the

auto-mute function is in accordance with

“NICAM 728 ETS Revised for Data Applications” or any other preference.

The NICAM de-emphasis gain is 0 dB at 40 Hz.

The AMSEL bit has only an effect on the analog sound outputs (OUTL and OUTR). With regard to the digital sound

output (I2S), the auto-mute will only switch between NICAM and the first sound carrier.

When carrier 2 is in FM mode, the TIMPOL bit should be set HIGH, to achieve the best S/N performance with the current

oscillator application proposal (see Chapter 9).

76543210

−−

TIMPOL

DOUTEN

−

AMSEL

NDEEM

AMUTE

BIT

SYMBOL

DESCRIPTION

−

These 2 bits are not used and should be set to logic 0.

−

TIMPOL

Timing loop polarity. TIMPOL = 1, inverts the polarity. This feature can be used to

compensate for the phase shift that is introduced by an external inverting ampliﬁer at

the pin Vtune. Such an ampliﬁer could be used to provide a larger tuning voltage swing

for the VCXO. TIMPOL = 0, sets the NICAM timing loop to normal polarity.

DOUTEN

Data output enable. DOUTEN = 1, enables the output of the NICAM serial data stream

from the DQPSK demodulator and of the associated clock, PCLK. DOUTEN = 0, both

outputs will be 3-stated.

−

This bit is not used and should be set to logic 0.

AMSEL

Auto-mute select. AMSEL = 1, the auto-mute will switch between NICAM sound and

the analog mono input. This bit has only an effect when the auto-mute function is

enabled and when the DAC has been selected in the Analog Output Select Register

(see Section 7.3.17). AMSEL = 0, the auto-mute will switch between NICAM sound and

the sound on the ﬁrst sound carrier (i.e. FM mono or AM).

NDEEM

De-emphasis on/off. NDEEM = 1, switches the NICAM J17 de-emphasis off.

NDEEM = 0, switches the NICAM J17 de-emphasis on.

AMUTE

Auto-muting on/off. AMUTE = 1, automatic muting is disabled. This bit has only an

effect, when the second sound carrier is set to NICAM. AMUTE = 0, enables the

automatic switching between NICAM and the program on the ﬁrst sound carrier (i.e. FM

mono or AM), dependent on the NICAM bit error rate.

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