SAA7710T データシートの表示（PDF） - Philips Electronics

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SAA7710T

Dolby* Pro Logic Surround; Incredible Sound

Philips Electronics 

Philips Semiconductors

Dolby* Pro Logic Surround;

Incredible Sound

Product specification

SAA7710T

FUNCTIONAL DESCRIPTION

Figure 1 shows the block diagram of the SAA7710T.

The SAA7710T consists of a Dolby Pro Logic decoder

together with equalizer or tone control. The Dolby Pro

Logic part of the IC may be used to decode audio

soundtracks (Dolby surround movies or Dolby surround

video productions) from for example, a video recorder

(VCR) or a CD laser disc into four channels Left, Centre,

Right and Surround (L, C, R and S).

If desired, post-processing with either an equalizer or a

tone control section is possible. In addition to this, a Sub

Woofer (SW) channel, digital volume control and a

user-programmable variable output matrix are

implemented.

Hall/matrix surround sound functions are implemented for

material not encoded using Dolby Surround. These

features can be used as an alternative to Dolby Pro Logic

and can also be combined with the equalizer or tone

control sections.

Incredible sound is a Philips patented technology which

substantially improves the stereo effect of a television or

audio system. Using advanced signal processing,

speakers that are positioned close together can imitate the

sound produced by speakers that are far apart.

Functional modes

The device thus supports three main modes, Dolby Pro

Logic/Dolby 3 stereo or hall/matrix surround or Incredible

sound mode. All modes can be combined with equalizing

(3-band or 5-band) or tone control depending on fs and

available cycle budget.

THE DOLBY PRO LOGIC MODE

In Dolby Pro Logic mode, several blocks must be initialized

and controlled during operation:

• Noise generator and noise sequencer

• Centre channel mode(1) (normal, phantom, wide, off)

• Combining network coefficients

• 7 kHz low-pass filter in surround channel(1)

• Surround channel delay time(1)

• Modified Dolby B noise reduction must be on.

Possible post-processing modes for Dolby Pro Logic are:

• Volume control only

(1) The coefficient set used to initialize and control the operation

of the Dolby Pro Logic mode depends upon the selected

sampling frequency fs = 32, 44.1 or 48 kHz.

• Equalizer (3- or 5-band on L, C and R) or tone control

(L, C, R and S); fixed output matrix(1); volume control

• Equalizer (5-band on L, C and R); variable output

matrix(1); volume control

• Extra sub woofer(1).

THE DOLBY 3 STEREO MODE

In Dolby 3 stereo mode, several blocks must be initialized

and controlled during operation:

• Noise generator and noise sequencer

• Centre channel mode(1) (normal, phantom, wide and off)

• Combining network coefficients

• Incredible Sound widening of the stereo base on two

speakers

• Effect is user adjustable.

THE HALL/MATRIX SURROUND MODE

In hall/matrix surround mode, the blocks listed below must

be initialized and controlled during operation:

• Input balance control

• Hall or matrix surround Mode setting

• All-pass and filter transfer characteristics(1)

• 7 kHz low-pass filter in surround channel(1)

• Surround channel delay(1).

Possible post-processing modes for hall/matrix surround

are as above:

• Volume control only

• Equalizer (5-band on L, C and R) or tone control

(L, C, R and S); fixed output matrix(1); volume control

• Equalizer (5-band on L,C,R); variable output matrix(1);

volume control

• Extra sub woofer(1).

THE INCREDIBLE SOUND MODE

In the Incredible sound mode the blocks listed below must

be initialized and controlled during operation:

• Incredible sound coefficients

• Combining network coefficients.

Possible post-processing modes for incredible sound are

as follows:

• Volume control only

• Equalizer (5-band on L and R) or tone control (L and R);

variable output matrix(1), volume control

• Extra sub-woofer(1).

1998 Mar 13

5

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