MSP3400CPP View Datasheet(PDF) - Micronas

Part Name

Description

Manufacturer

MSP3400CPP

Multistandard Sound Processor

Micronas 

PRELIMINARY DATA SHEET

MSP 3400C

7.1.21. Equalizer Loudspeaker Channel

Band 1 (below 120 Hz)

Band 2 (Center: 500 Hz)

Band 3 (Center: 1.5 kHz)

Band 4 (Center: 5 kHz)

Band 5 (above 10kHz)

+12 dB

+11 dB

+1 dB

+1/8 dB

0 dB

–1/8 dB

–1 dB

–11dB

–12 dB

0021hex

0022hex

0023hex

0024hex

0025hex

0110 0000

0101 1000

0000 1000

0000 0001

0000 0000

RESET

1111 1111

1111 1000

1010 1000

1010 0000

H

H

H

H

H

60hex

58hex

08hex

01hex

00hex

FFhex

F8hex

A8hex

A0hex

With positive equalizer settings, internal overflow may

occur even with overall volume less than 0 dB. This will

lead to a clipped output signal. Therefore, it is not recom-

mended to set equalizer bands to a value that, in con-

junction with volume, would result in an overall positive

gain.

Equalizer must not be used simultaneously with Bass

and Treble (Mode Tone Control must be set to FF to use

the Equalizer).

7.1.22. Automatic Volume Correction (AVC)

AVC on/off

AVC off and Reset

of int. variables

AVC on

AVC Decay Time

8 sec (long)

4 sec (middle)

2 sec (short)

20 ms (very short)

0029hex

0000

RESET

1000

0029hex

1000

0100

0010

0001

[15:12]

0hex

8hex

[11:8]

8hex

4hex

2hex

1hex

Different sound sources (e.g. Terrestrial channels, SAT

channels or SCART) fairly often don’t have the same

volume level. Advertisement during movies as well has

mostly a different (higher) volume level, than the movie

itself. The Automatic Volume Correction (AVC) solves

this problem and equalizes the volume levels.

The absolute value of the incoming signal is fed into a

filter with 16ms attack time and selectable decay time.

The decay time must be adjusted as shown in the table

above. This attack/decay filter block works similar to a

peak hold function. The volume correction value with it’s

quasi continuous step width is calculated using the at-

tack/decay filter output.

The Automatic Volume Correction works with an internal

reference level of –18 dBFS. This means, input signals

with a volume level of –18 dBFS will not be affected by

the AVC. If the input signals vary in a range of –24 dB to

0 dB the AVC compensates this.

Example: A static input signal of 1 kHz on Scart has an

output level as shown in the table below.

Scart Input

0dbr = 2 Vrms

Volume

Correc-

tion

Main Output

0dBr = 1.4 Vrms

0 dBr

–18 dB

–18 dBr

–6 dBr

–12 dB

–18 dBr

–12 dBr

–6 dB

–18 dBr

–18 dBr

–0 dB

–18 dBr

–24 dBr

+ 6 dB

–18 dBr

–30 dBr

+ 6 dB

–24 dBr

Loudspeaker Volume = 73h = 0 dBFS

Scart Prescale = 20h i.e. 2.0 Vrms = 0dBFS

To reset the internal variables, the AVC should be

switched off and on during any channel or source

change. For standard applications, the recommended

decay time is 4sec.

Note: AVC should not be used in any Dolby Prologic

modes, except PANORAMA, where no other than the

loudspeaker output is active.

Micronas

39

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