Sony DVP S9000ES Bedienungsanleitung PDF herunterladen (Seite 15)

DVD Technical Notes

Audio

Organizing the data into left and right pulse streams is the job of

the DSD decoder. A Sony-built LSI, the DSD decoder first reads

the invisible watermark — a key anti-piracy feature — and then

decodes the incoming data. Data on the disc originate as

alternating bursts of left-channel and right-channel information.

Buffer memory and master clock sync enable the bursts to be

output as two

continuous,

simultaneous

streams. The DSD

decoder also reads

sub code data,

including text and

Table of Contents

information such

as track number

and playing time.

To preserve the maximum accuracy of the DSD pulses, our

design program identified two basic goals:

• Amplitude axis precision

• Time axis precision

Sony’s Accurate Complementary Pulse Density Modulation (ACP)

system and Current Pulse D/A Converter meet the first goal.

Sony’s new pulse generator in VC24 achieve the second goal.

The Megahertz switching speeds of DSD decoding have an

unfortunate byproduct, switching glitches, rough irregularities in

the DSD pulse train. Sony’s Accurate Complementary Pulse

Density Modulation (ACP) overcomes this by converting the

DSD pulses. Instead of encoding 1 as a pulse and 0 as the

absence of a pulse, ACP represents each digital 1 as wide 1

followed by a narrow 0. And ACP represents each digital 0 as a

narrow 1 followed by a wide 0. In this way, ACP effectively

converts the data from pulse height (sensitive to glitches) to

pulse width (insensitive to glitches). So glitches are not passed

along to subsequent circuitry.

Conventional D/A converters generate pulse height from the voltage

power supply — a method that can expose the signal to subtle

power supply voltage fluctuations. The Current Pulse Converter

overcomes this limitation. The design changes the incoming train of

voltage pulses to a train of current pulses. Because the circuit

incorporates an extremely clean “constant current” source, the

pulses emerge with the desired flat tops, flat bottoms and identical

height. You get audio output of extraordinarily low distortion. The

Current Pulse D/A converter operates for SACD, CD and DVD-

Video sound tracks alike. The system supports the highest sound

quality in DVD-Video: 96 kHz/24-bit recording.

A conventional digital filter has a fixed filtering coefficient with

no user controls. Sony’s Variable Coefficient digital filter is a

dramatic departure. The VC digital filter actually offers different

settings, representing different filter coefficients, different

filtering methods and different objectives in reproduced sound.

After current-to-voltage conversion, a simple low-pass filter is

all that’s required to produce an analog output. Unlike CD, the

SACD cutoff frequency is largely determined by the characteris-

tics of the player’s low-pass filter. The DVP-S9000ES low-pass

filter has aresponse

curve that slowly

falls in the vicinity

of 50 kHz,

enabling usable

response out to

100 kHz, some

five times higher

than previous

home audio

sources.

As an audio/video player, the DVP-S9000ES needs to generate

master clock frequencies for audio and video simultaneously.

Typical practice deploys a Phase Locked Loop (PLL) circuit to

subdivide the video master clock for audio use. However, this

exposes the audio signal to unwanted jitter, which can generate

audible distortion. That’s why the DVP-S9000ES subdivides

audio master clock for video use. The SACD and CD master

clock runs at 44.1 kHz x 1024 = 45 MHz. The DVD-Video sound

track master clock runs at 48 kHz x 1024 = 49 MHz. And the

DVD-Video clock for pictures downconverts this via PLL to

DSD Decorder

Photo 3: The heart to SACD reproduction, Sony’s DSD

decoding LSI.

ACP System

Fig.17: Thanks to Pulse Density Modulation, the ACP system

disregards amplitude distortions and switching glitches.

96 kHz / 24-bit capable Current Pulse

D/A Converter ( for all discs )

VC 24 Plus Digital Filter ( for DVD-Video and CD )

Fig. 18:

The Low Pass Filter of the DVP-S9000ES enables

usable frequency response to 100 kHz, some five times higher

than previous home audio sources.

Two Audio Master Clocks ( for all discs )

Separate Low-Pass Filters ( for all discs )

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