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13. Super Audio Cd
LEVEL
(dB)
0
-100
-200
20
100
1k
10k
100k
FREQUENCY (Hz)
(ANALYSIS
LIMIT:
-200dB)
FIGURE 13-8 - DELTA SIGMA MODULATOR NOISE FLOOR SIMULATION
1/21/02
13.9A124 1399
Figure 13-9 illustrates the difference in outcome when a 10kHz square waveform is converted with the DSD
format compared to the PCM format. A square waveform is made up of a fundamental waveform and multiple
sine waves. That is, the square wave contains many odd-number harmonic waves. With CD’s PCM format, the
wave cannot be reproduced beyond the second harmonic wave, resulting in a sine wave output that cannot
exceed 20kHz. In contrast, the DSD format is able to reproduce harmonic waves up to a high order, achieving
output that is extremely similar to the original square waveform. This example demonstrates how the DSD
format can achieve faithful sound conversion, resulting in sound output almost identical to the original source.
DSD signal processing has a more detailed sound image, and therefore the potential to record instrumental
harmonic components, the calls of animals and all of the sounds that exist in the natural world. In addition, it is
able to express the ambience of a live performance, often expressed as being able to feel the “air”. The DSD
system used in Super Audio CD is able to express the artistic quality of a performance like never before,
communicating the liveliness of the performer and the vividness of the hall.
Disc Features and Watermark Technology
New Large-Capacity Disc
Thanks to the DSD format used by Super Audio CD, data capacity was increased to four times that of a conventional
CD using PCM. Even with more capacity, a Super Audio CD disc features the exact same dimensions as a
current CD disc: a 12cm diameter and a 1.2mm thickness. The most elementary Super Audio CD disc (single-
layer) features about six times the capacity over a CD disc, or 4.7Cbytes. For 2-channel stereo, this translates
into over 100 minutes of recording capacity. Actual recording time depends on the content of each title.
Table 13-1 – Comparison of Super Audio CD and Conventional CD Format
Items
Super Audio CD (Single Layer)
CD
Disc diameter
12cm
12cm
Disc thickness
1.2mm
1.2mm
Playback side
One
One
Coding system
1-bit DSD
16-bit linear PCM
Sampling frequency
2.8224 MHz
44.1kHz
Disc data capacity
4,700MB
780MB
Disc minimum bit length
0.40µm
0.83µm
Disc track space
0.74µm
1.6µm
Laser wavelength
650nm
780nm
Lens aperture
0.60
0.46
Playback frequency range*
DC – over 100kHz
DC – 20kHz
Dynamic range*
More than 120dB (audible range)
96dB
Maximum recording time
Approx. 110 min. (2-channel)
74 min.
Additional functions
Text, graphics, video
Text
Содержание STR-DE845
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