MSP3410D datasheet(36/83 Pages) MICRONAS

36 / 83 page

MSP 34x0D

PRELIMINARY DATA SHEET

Micronas

Fig. 6–3: CCU software flow diagram: standard B/G

with NICAM or FM-Stereo with Demodulator Short

Programming

After each incrementation, a field strength value is

available at the quasi-peak detector output (quasi-peak

detector source must be set to FM), which must be

examined for relative maxima by the CCU. This results

in either continuing search or switching the MSP 34x0D

back to FM demodulation mode.

During the search process, the FIR2 must be loaded

with

the

coefficient

set

“AUTOSEARCH”,

which

enables small bandwidth, resulting in appropriate field

strength characteristics. The absolute field strength

value (can be read out of “quasi peak detector output

FM1”) also gives information on whether a main FM

carrier or a subcarrier was detected, and as a practical

consequence, the FM bandwidth (FIR1/2) and the

deemphasis (50

µs or adaptive) can be switched auto-

matically.

Due to the fact that a constant demodulation frequency

offset of a few kHz, leads to a DC level in the demodu-

lated signal, further fine tuning of the found carrier can

be achieved by evaluating the “DC Level Readout

FM1”. Therefore, the FM DC Notch must be switched

on, and the demodulator part must be switched back to

FM demodulation mode.

For a detailed description of the automatic search

function,

please

refer

the

corresponding

MSP 34xxD Windows software.

Note: The automatic search is still possible by evaluat-

ing only the DC Level Readout FM1 (DC Notch On) as

it is described with the MSP 34x0B, but the above

mentioned method is faster. If this DC Level method is

applied with the MSP 34x0D, it is recommended to set

MODE_REG[15] to 1 (AM gain = 12 dB) and to use the

new Autosearch FIR2 coefficient set as given in

Table 6–11.

LOAD_SEQ_1/2

NICAM_WAIT

LOAD_SEQ_1

IDENT_CHECK

FM_

LOAD_SEQ_1

NICAM_CHECK

NICAM

Pause

Audio Processing Init

FM_WAIT

START

Yes

Stereo/Biling.

Mono

Set

Sound Standard

0008hex

Set

Sound Standard

0003hex

Set

Sound Standard

0008hex

MSP3410D Datasheet(PDF) 36 Page - Micronas

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