MSP3457G datasheet(9/81 Pages) MICRONAS

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PRELIMINARY DATA SHEET

MSP 34x7G

Micronas

2.1. Architecture of the MSP 34x7G Family

Fig. 2–1 on page 8 shows a simplified block diagram of

the IC. The block diagram contains all features of the

MSP 3457G. Other members of the MSP 34x7G family

do not have the complete set of features: The demodu-

lator handles only a subset of the standards presented

in the demodulator block; NICAM processing is only

possible in the MSP 3417G and MSP 3457G (see

dashed block in Fig. 2–1).

2.2. Sound IF Processing

2.2.1. Analog Sound IF Input

The input pins ANA_IN1+ and ANA_IN

− offer the pos-

sibility to connect sound IF (SIF) sources to the

MSP 34x7G. The analog-to-digital conversion of the

sound IF signal is done by an A/D-converter. An ana-

log automatic gain circuit (AGC) allows a wide range of

input levels. The high-pass filter formed by the cou-

pling capacitor at pin ANA_IN1+ (see Section 7.

“Appendix D: Application Information” on page 77) is

sufficient in most cases to suppress video compo-

nents. Some combinations of SAW filters and sound IF

mixer ICs, however, show large picture components on

their outputs. In this case, further filtering is recom-

mended.

2.2.2. Demodulator: Standards and Features

The MSP 34x7G is able to demodulate all TV sound

standards worldwide including the digital NICAM sys-

tem. Depending on the MSP 34x7G version, the fol-

lowing demodulation modes can be performed:

A2-Systems: Detection and demodulation of two sep-

arate FM carriers (FM1 and FM2), demodulation and

evaluation of the identification signal of carrier FM2.

NICAM-Systems: Demodulation and decoding of the

NICAM carrier, detection and demodulation of the ana-

log (FM or AM) carrier. For D/K-NICAM, the FM carrier

may have a maximum deviation of 384 kHz.

Very high deviation FM-Mono: Detection and robust

demodulation of one FM carrier with a maximum devi-

ation of 540 kHz.

BTSC-Stereo: Detection and FM demodulation of the

aural carrier resulting in the MTS/MPX signal. Detec-

tion and evaluation of the pilot carrier, AM demodula-

tion of the (L-R)-carrier and detection of the SAP sub-

carrier. Processing of the DBX noise reduction or

Micronas Noise Reduction (MNR).

BTSC-Mono + SAP: Detection and FM demodulation

of the aural carrier resulting in the MTS/MPX signal.

Detection and evaluation of the pilot carrier, detection

and FM demodulation of the SAP-subcarrier. Process-

ing of the DBX noise reduction or Micronas Noise

Reduction (MNR).

Japan Stereo: Detection and FM demodulation of the

aural carrier resulting in the MPX signal. Demodulation

and evaluation of the identification signal and FM

demodulation of the (L-R)-carrier.

FM-Satellite Sound: Demodulation of one or two FM

carriers. Processing of high-deviation mono or narrow

bandwidth mono, stereo, or bilingual satellite sound

according to the ASTRA specification.

FM-Stereo-Radio: Detection and FM demodulation of

the aural carrier resulting in the MPX signal. Detection

and evaluation of the pilot carrier and AM demodula-

tion of the (L-R)-carrier.

The demodulator blocks of all MSP 34x7G versions

have identical user interfaces. Even completely differ-

ent systems like the BTSC and NICAM systems are

controlled the same way. Standards are selected by

means of MSP Standard Codes. Automatic processes

handle standard detection and identification without

controller

interaction.

The

key

features

the

MSP 34x7G demodulator blocks are

Standard Selection: The controlling of the demodula-

tor is minimized: All parameters, such as tuning fre-

quencies or filter bandwidth, are adjusted automati-

cally

transmitting

one

single

value

the

STANDARD SELECT register. For all standards, spe-

cific MSP standard codes are defined.

Automatic Standard Detection: If the TV sound stan-

dard is unknown, the MSP 34x7G can automatically

detect the actual standard, switch to that standard, and

respond the actual MSP standard code.

Automatic Carrier Mute: To prevent noise effects or

FM identification problems in the absence of an FM

carrier, the MSP 34x7G offers a configurable carrier

mute feature, which is activated automatically if the TV

sound standard is selected by means of the STAN-

DARD SELECT register. If no FM carrier is detected at

one of the two MSP demodulator channels, the corre-

sponding demodulator output is muted. This is indi-

cated in the STATUS register.

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