MSP3410D datasheet(11/83 Pages) MICRONAS

11 / 83 page

PRELIMINARY DATA SHEET

MSP 34x0D

Micronas

4.1.2. Quadrature Mixers

The digital input coming from the integrated A/D con-

verter may contain audio information at a frequency

range of theoretically 0 to 9 MHz corresponding to the

selected standards. By means of two programmable

quadrature mixers, two different audio sources, for

example NICAM and FM-Mono, may be shifted into

baseband position. In the following, the two main

channels are provided to process either:

– NICAM (MSP-Ch1) and FM/AM mono (MSP-Ch2)

simultaneously or, alternatively:

– FM-Mono (Ch2)

– FM2 (MSP-Ch1) and FM1 (MSP-Ch2).

Two programmable registers, to be divided up into a

low and a high part, determine frequency of the oscilla-

tor, which corresponds to the frequency of the desired

audio carrier.

4.1.3. Low-pass Filtering Block

for Mixed Sound IF Signals

Data shaping and/or FM bandwidth limitation is per-

formed by a linear phase finite impulse response (FIR)

filter. Just like the oscillators’ frequency, the filter coeffi-

cients are programmable and are written into the IC by

the CCU via the control bus. Thus, for example, differ-

ent NICAM versions can easily be implemented. Two

not necessarily different sets of coefficients are

required, one for MSP-Ch1 (NICAM or FM2) and one

for MSP-Ch2 (FM1 = FM-mono). In a corresponding

table several coefficient sets are proposed.

Fig. 4–2: Architecture of demodulator and NICAM decoder section

Phase and

AM Dis-

crimination

MSP sound IF channel 1

(MSP-Ch1: FM2, NICAM)

MSP sound IF channel 2

(MSP-Ch2: FM1, AM)

VREFTOP

ANA_IN1+

ANA_IN2+

ANA_IN-

AD_CV[8]

AD_CV[7:1]

AGC

DCO1

Oscillator

Mixer

FIR1

Lowpass

MODE_REG[6]

Amplitude

DQPSK

Decoder

Phase

Differen-

tiator

Carrier

Detect

AD_CV[9]

Mute

NICAM

Decoder

Mixer

Lowpass

ADR

NICAMA

NICAMB

FM2

IDENT

Carrier

Detect

Mute

Lowpass

FM1/AM

MODE_REG[8]

Differen-

tiator

Phase

FIR2

Lowpass

Phase and

AM Dis-

crimination

Amplitude

Mixer

Oscillator

DCO2

Pins

Demodulator Write Registers

FRAME

NICAMA

DCO2

Internal signal lines (see fig. 4–2)

MSP3410D only

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