tda9870ah NXP Semiconductors, tda9870ah Datasheet - Page 14

• Manufacturer Part Number: tda9870ah
• Description: Digital Tv Sound Processor Dtvsp
• Manufacturer: NXP Semiconductors

Philips Semiconductors
6.2.1
All input channels to the digital crossbar switch (except for
the loudspeaker feedback path) are equipped with a level
adjust facility to change the signal level in a range from
input channels to be 15 dB below full-scale ( 15 dB
full-scale) under nominal conditions.
6.2.2
A high-pass filter suppresses DC offsets from the
FM demodulator, due to carrier frequency offsets, and
supplies the monitor/peak function with DC values and an
unfiltered signal, e.g. for the purpose of carrier detection.
The de-emphasis function offers fixed settings for the
supported standards (50, 60 and 75 s).
An adaptive de-emphasis is available for
Wegener-Panda 1 encoded programs.
A matrix performs the dematrixing of the A2 stereo, dual
and mono signals.
6.2.3
This function provides data words from a number of
locations of the signal processing paths to the I
interface (2 data bytes). Signal sources include the
FM demodulator outputs, most inputs to the digital
crossbar switch and the outputs of the ADC. Source
selection and data read-out is performed via the I
Optionally, the peak value can be measured instead of
simply taking samples. The internally stored peak value is
reset to zero when the data is read via the I
The monitor function may be used, for example, for signal
level measurements or carrier detection.
6.2.4
The matrix provides the following functions: forced mono,
stereo, channel swap, channel 1, channel 2 and spatial
effects.
There are fixed coefficient sets for spatial settings of 30%,
40% and 52%.
The Automatic Volume Level (AVL) function provides a
constant output level of 23 dB full-scale for input levels
between 0 and 29 dB full-scale. There are some fixed
decay time constants to choose from, i.e. 2, 4 and 8 s.
Pseudo stereo is based on a phase shift in one channel via
a second-order all-pass filter. There are fixed coefficient
sets to provide 90 degrees phase shift at frequencies of
150, 200 and 300 Hz.
1999 Dec 20
15 to 15 dB (see Fig.5). It is recommended to scale all
Digital TV Sound Processor (DTVSP)
L
FM (AM)
M
L
EVEL SCALING
OUDSPEAKER
ONITOR
PATH
(M
AIN
)
CHANNEL
2
C-bus.
2
C-bus
2
C-bus.
14
Volume is controlled individually for each channel ranging
from +24 to 83 dB with 1 dB resolution. There is also a
mute position. For the purpose of a simple control software
in the microcontroller, the decimal number that is sent as
an I
volume setting in dBs (e.g. the I
the new volume value to +10 dB).
Balance can be realized by independent control of the left
and right channel volume settings.
Contour is adjustable between 0 and +18 dB with 1 dB
resolution. This function is linked to the volume setting by
means of microcontroller software.
Bass is adjustable between +15 and 12 dB with 1 dB
resolution and treble is adjustable between
+12 and 12 dB with 1 dB resolution.
For the purpose of a simple control software in the
microcontroller, the decimal number that is sent as an
I
the new contour, bass or treble setting in dBs (e.g. the
I
Extra bass boost is provided up to 20 dB with 2 dB
resolution. The implemented coefficient set serves merely
as an example on how to use this filter.
The beeper provides tones in a range from approximately
400 Hz to 30 kHz. The frequency can be selected via the
I
loudspeaker and headphone channel signals. The beeper
volume is adjustable with respect to full-scale between
0 and 93 dB with 3 dB resolution. The beeper is not
effected by mute.
Soft mute provides a mute ability in addition to volume
control with a well defined time (32 ms) after which the soft
mute is completed. A smooth fading is achieved by a
cosine masking.
6.2.5
The matrix provides the following functions: forced mono,
stereo, channel swap, channel 1 and channel 2
(or C and S in Dolby Surround Pro Logic mode).
Volume is controlled individually for each channel in a
range from +24 to 83 dB with 1 dB resolution. There is
also a mute position.
For the purpose of a simple control software in the
microcontroller, the decimal number that is sent as an
I
volume setting in dB (e.g. the I
the new volume value to +10 dB).
2
2
2
2
C-bus data byte for contour, bass or treble is identical to
C-bus data byte +8 sets the new value to +8 dB).
C-bus. The beeper output signal is added to the
C-bus data byte for volume control is identical to the
2
C-bus data byte for volume control is identical to the
H
EADPHONE
(A
UXILIARY
2
2
C-bus data byte +10 sets
)
C-bus data byte +10 sets
CHANNEL
Product specification
TDA9870A