49
13. Super Audio Cd
Delta
Sigma
Modu
-lator
∆ Σ
Delta
Sigma
Modu
-lator
∆ Σ
Decimation
Digital
Filter
Super
Audio
CD
CD
Interpol
-ation
Digital
Filter
Delta
Sigma
Modu
-lator
∆ Σ
Analog.
Low -
Pass
Filter
Analog.
Low -
Pass
Filter
Input
Signal
Input
Signal
Output
Signal
Output
Signal
RECORDING PROCESS
RECORDING PROCESS
PLAYBACK PROCESS
PLAYBACK PROCESS
(Noise
Shaping)
(Noise Shaping)
64fs
1 bit
fs
16 bit
8fs
24 bit
64fs
1 bit
(Noise
Shaping)
fs
16 bit
64fs
1 bit
64fs
1 bit
SUPER AUDIO CD
CONVENTIONAL CD
Note fs: 44.1kHz
FIGURE 13-2 - DIFFERENCES IN RECORDING -TO- PLAYBACK PROCESSES FOR
SUPER AUDIO CD AND CONVENTIONAL CD
11/27/01
13.2A124 1393
BASE
LEVEL
BASE
LEVEL
ONE
SAMPLING
INTERVAL
ONE SAMPLING
INTERVAL
BASE LEVEL
SAMPLING RATE
SAMPLING RATE
ONE
SAMPLING
INTERVAL
COMPARISON OF
INPUT & OUTPUT
INPUT SINE WAVE
1 BIT QUANTIZER OUTPUT WAVE
QUANTIZATION NOISE
1
0
FIGURE13-4 - OUTPUT FROM 1-BIT QUANTISER
1/21/02
13.3A124 1393
Delta Signal (
∆Σ)
Modulation and A/D Converter
As shown in 13-3, the 1-bit quantiser decimates incoming analogue signals at a standard level and outputs these
signals as one of two values, “0” or “1” (1 bit). Suppose that we input sine waves into this 1-bit converter. As
shown in Figure 13-4, the portion above the base level is output as “1”, while the portion below the base level is
output as “0”. The result is a square wave output.
Содержание STR-DE845
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