MSP3410B View Datasheet(PDF) - Micronas

Part Name

Description

Manufacturer

MSP3410B

Multistandard Sound Processor

Micronas 

MSP 3410 B

PRELIMINARY DATA SHEET

VREFTOP

AD_CV[7:1]

ANA_IN1+

ANA_IN2+

AGC

AD

AD_CV[8]

ANA_IN-

FRAME

NICAMA

DCO2

Pins

Internal signal lines (see fig. 4–5)

Control registers

Fig. 4–2: Demodulator architecture

DCO1

Oscillator

FIR_REG_1

MODE_REG[6,7,10]

Phase

DQPSK

Decoder

Mixer

Lowpass

CORDIC

MSP sound IF channel 1 Amplitude

Differen-

tiator

Carrier

Detect

NICAM

Decoder

Mute

AD_CV[9]

MSP sound IF channel 2 Amplitude

Carrier

Detect

Mixer

Lowpass

Oscillator

FIR_REG_2

CORDIC

Differen-

tiator

Phase

Mute

MODE_REG[8]

DCO2

N_DA

N_CL

FRAME

CW_DA

CW_CL

NICAMA

NICAMB

Lowpass

FM2

Mixer

IDENT

Lowpass

FM1/AM

4.1.3. Lowpass Filtering Block for Mixed Sound IF

Signals

By means of decimation filters the sampling rate is re-

duced. Then, data shaping and/or FM bandwidth limita-

tion is performed by a linear phase Finite Impulse Re-

sponse (FIR-filter). Just like the oscillators’ increments

the filter coefficients are programmable and are written

into the IC by the CCU via the control bus. Thus, for ex-

ample, different NICAM versions can easily be implem-

ented. Two not necessarily different sets of coefficients

are required, one for channel 1 (NICAM or FM2) and one

for channel 2 (FM1=FM-mono). In section 11.2.3. sever-

al coefficient sets are proposed.

Since both MSP channels are designed to process the

German FM Stereo System with the same FIR coeffi-

cient set (despite 7 dB power level difference of the two

sound carriers), the MSP channel 1 has an internal over-

all gain of 6 dB. To process two carriers of identical pow-

er level these 6 dBs have to be taken into account by de-

creasing the values of the channel 1 coefficient set,

which has already been done in table 11–7.

4.1.4. CORDIC Block

The filtered sound IF signals are demodulated by trans-

forming the incoming signals from Cartesian into polar

format by means of a CORDIC processor block. On the

output, the phase and amplitude is available for further

processing. AM signals are derived from the amplitude

information whereas the phase information serves for

FM and NICAM (DQPSK) demodulation.

4.1.5. Differentiators

FM demodulation is completed by differentiating the

phase information output of the CORDIC block.

4.1.6. Lowpass Filter Block for Demodulated

Signals

The demodulated FM and AM signals are further low-

pass filtered and decimated to a final sampling frequen-

cy of 32 kHz. The usable bandwidth of the final base-

band signals is about 15 kHz.

4.1.7. High Deviation FM Mode

By means of MODE_REG [9], the maximum FM-devi-

ation can be extended to approximately ±360 kHz. Since

this mode can be applied only for the MSP sound IF

channel 2, the corresponding matrices in the baseband

processing must be set to sound A. Apart from this, the

coefficient sets 380 kHz FIR_REG2 or 500 kHz

FIR_REG2 must be chosen for the FIR_REG_2. In rela-

tion to the normal FM-mode, the audio level of the high-

deviation mode is reduced by 6 dB.

10

ITT Semiconductors

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