MSP3407G View Datasheet(PDF) - Micronas
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MSP3407G Datasheet PDF : 81 Pages
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MSP 34x7G
PRELIMINARY DATA SHEET
2.2.3. Preprocessing of Demodulator Signals
The NICAM signals must be processed by a deempha-
sis filter and adjusted in level. The analog demodu-
lated signals must be processed by a deemphasis fil-
ter, adjusted in level, and dematrixed. The correct
deemphasis filters are already selected by setting the
standard in the STANDARD SELECT register. The
level adjustment has to be done by means of the FM/
AM and NICAM prescale registers. The necessary
dematrix function depends on the selected sound
standard and the actual broadcasted sound mode
(mono, stereo, or bilingual). It can be manually set by
the FM Matrix Mode register or automatically by the
Automatic Sound Selection.
2.2.4. Automatic Sound Select
In the Automatic Sound Select mode, the dematrix
function is automatically selected based on the identifi-
cation information in the STATUS register. No I2C inter-
action is necessary when the broadcasted sound
mode changes (e.g. from mono to stereo).
The demodulator supports the identification check by
switching between mono-compatible standards (stan-
dards that have the same FM-Mono carrier) automati-
cally and non-audible. If B/G-FM or B/G-NICAM is
selected, the MSP will switch between these stan-
dards. The same action is performed for the standards:
D/K1-FM, D/K2-FM, D/K3-FM and D/K-NICAM.
Switching is only done in the absence of any stereo or
bilingual identification. If identification is found, the
MSP keeps the detected standard.
In case of high bit-error rates, the MSP 34x7G auto-
matically falls back from digital NICAM sound to ana-
log FM or AM mono.
Table 2–1 summarizes all actions that take place when
Automatic Sound Select is switched on.
To provide more flexibility, the Automatic Sound Select
block prepares four different source channels of
demodulated sound (Fig. 2–2). By choosing one of the
four demodulator channels, the preferred sound mode
can be selected for each of the output channels (loud-
speaker, headphone, etc.). This is done by means of
the Source Select registers.
The following source channels of demodulated sound
are defined:
– “FM/AM” channel: Analog mono sound, stereo if
available. In case of NICAM, analog mono only
(FM or AM mono).
– “Stereo or A/B” channel: Analog or digital mono
sound, stereo if available. In case of bilingual broad-
cast, it contains both languages A (left) and B
(right).
– “Stereo or A” channel: Analog or digital mono
sound, stereo if available. In case of bilingual broad-
cast, it contains language A (on left and right).
– “Stereo or B” channel: Analog or digital mono
sound, stereo if available. In case of bilingual broad-
cast, it contains language B (on left and right).
Fig. 2–2 and Table 2–2 show the source channel
assignment of the demodulated signals in case of
Automatic Sound Select mode for all sound standards.
Note: The analog primary input channel contains the
signal of the mono FM/AM carrier or the L+R signal of
the MPX carrier. The secondary input channel con-
tains the signal of the 2nd FM carrier, the L-R signal of
the MPX carrier, or the SAP signal.
primary
channel
secondary
channel
NICAM A
FM/AM
Prescale
NICAM
NICAM B
Prescale
FM/AM 0
Automatic
Sound
Select
Stereo or A/B 1
Stereo or A 3
Stereo or B 4
LS Ch.
Matrix
Output-Ch.
matrices
must be set
once to
stereo.
Fig. 2–2: Source channel assignment of demodulated
signals in Automatic Sound Select Mode
2.2.5. Manual Mode
Fig. 2–3 shows the source channel assignment of
demodulated signals in case of manual mode. If man-
ual mode is required, more information can be found in
Section 6.7. “Demodulator Source Channels in Manual
Mode” on page 75.
primary
channel
secondary
channel
NICAM A
FM/AM
Prescale
NICAM
NICAM B
Prescale
FM-Matrix
FM/AM 0
NICAM
1
(Stereo or A/B)
LS Ch.
Matrix
Output-Ch.
matrices
must be set
according to
the standard.
Fig. 2–3: Source channel assignment of demodulated
signals in Manual Mode
10
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