MSP3438G datasheet(10/84 Pages) MICRONAS

10 / 84 page

MSP 3438G

PRELIMINARY DATA SHEET

MICRONAS INTERMETALL

2.2.3. Preprocessing of Demodulator Signals

All demodulated signals must be processed by a

deemphasis filter and adjusted in level (analog signals

must also be dematrixed). The correct deemphasis fil-

ters 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 set 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

interaction 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 stan-

dards: D/K1-FM, D/K2-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 34x8G 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 2–3). By choosing one of the

four demodulator channels, the preferred sound mode

can be selected by means of the Source Select regis-

ters, independent for all MSP-outputs.

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 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

the section “Demodulator Source Channels in Manual

Mode” on page 80. Fig. 2–3 and Table 2–2 show the

source channel assignment of the demodulated sig-

nals 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 contains

the signal of the second FM carrier, the L

−R signal of

the MPX carrier, or the SAP signal.

Fig. 2–2: Source channel assignment of demodulated

signals in Manual Mode

Fig. 2–3: Source channel assignment of demodulated

signals in Automatic Sound Select Mode

2.3. Preprocessing for SCART and

I2S Input Signals

The SCART and I2S inputs need only be adjusted in

level by means of the SCART and I2S prescale regis-

ters.

Prescale

primary

channel

secondary

channel

NICAM A

NICAM B

FM/AM

Prescale

NICAM

FM/AM

(Stereo or A/B)

FM-Matrix

NICAM

LS Ch.

Matrix

SC2 Ch.

Matrix

Output-Ch.

Matrices

must be set

according

the standard

Prescale

Automatic

Sound

Select

NICAM A

NICAM B

FM/AM

Prescale

NICAM

FM/AM

Stereo or A/B

Stereo or A

Stereo or B

primary

channel

secondary

channel

LS Ch.

Matrix

SC2 Ch.

Matrix

Output-Oh.

Matrices must

be set once to

stereo

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