MSP4458 datasheet(74/85 Pages) MICRONAS

74 / 85 page

MSP 44x8G

PRELIMINARY DATA SHEET

Micronas

6.2. DSP Write and Read Registers for Manual Mode

6.3. Manual Mode:

Description of Demodulator Write Registers

6.3.1. Automatic Switching between NICAM and

Analog Sound

In case of bad NICAM reception or loss of the

NICAM-carrier, the MSP 44x8G offers an Automatic

Switching (fall back) to the analog sound (FM/AM-

Mono), without the necessity of the controller reading

and evaluating any parameters. If a proper NICAM sig-

nal returns, switching back to this source is performed

automatically as well. The feature evaluates the NICAM

ERROR_RATE and switches, if necessary, all output

channels which are assigned to the NICAM source, to

the analog source, and vice versa.

An appropriate hysteresis algorithm avoids oscillating

effects (see Fig. 6–1). STATUS[9] and C_AD_BITS[11]

(Addr: 0023hex) provide information about the actual

NICAM-FM/AM-status.

Fig. 6–1: Hysteresis for automatic switching

6.3.1.1. Function in Automatic Sound Select Mode

The Automatic Sound Select feature (MODUS[0]=1)

includes the procedure mentioned above. By default, the

internal ERROR_RATE threshold is set to 700dec. i.e.:

–NICAM

→ analog sound if ERROR_RATE > 700

– analog sound

→ NICAM if ERROR_RATE < 700/2

Table 6–3: DSP-Write Registers; Subaddress: 12hex, all registers are readable as well

Write Register

Address

(hex)

Bits

Operational Modes and Adjustable Range

Reset

Mode

Page

Additional Channel Matrix Modes

00 08

00 09

00 0A

00 41

00 0B

00 0C

[7:0]

[SUM/DIFF, AB_XCHANGE, PHASE_CHANGE_B,

PHASE_CHANGE_A, A_ONLY, B_ONLY]

00hex

FM Fixed Deemphasis

00 0F

[15:8]

[OFF, 50

µs, 75 µs]

OFF

FM Adaptive Deemphasis

[7:0]

[OFF, WP1]

OFF

Identification Mode

00 15

[7:0]

[B/G, M]

B/G

Table 6–4: DSP Read Registers; Subaddress: 13hex, all registers are not writable

Additional Read Registers

Address

(hex)

Bits

Output Range

Page

Stereo detection register for

A2 Stereo Systems

00 18

[15:8]

[80hex ... 7Fhex]

8 bit two’s complement

DC level readout FM1/Ch2-L

00 1B

[15:0]

[8000hex ... 7FFFhex]

16 bit two’s complement

DC level readout FM2/Ch1-R

00 1C

[15:0]

[8000hex ... 7FFFhex]

16 bit two’s complement

ERROR_RATE

Selected Sound

NICAM

analog

Sound

threshold

threshold/2

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