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2009SE283

8kHz

[1]

3.2

Windows Media Player

LPF

Low-Pass Filter
[1]

bit

[1]

4 = 22

1/2

2bit
8 = 23

3bit

1/2

[1]

3.2.1

A-D

A-D

CD

Analog-to-Digital

[1]

A-DdB

A-D

[1]

dB = 20 log10A-D21!

16bit

CD

3.1

 16 2∼
20 log10= 96dB
11CD

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CD

sfs

60dB

ts

[1]

CD

ts = 1/fs

100dB
CD

CD

44.1kHzDVDDVD

1/2

20Hz

20kHz

[1]

24bit
144dB

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4.1

s1 (n)

s0 (n)

gain[1]

2

sinsin 1
s1 (n) =gain ∗ s0 (n) −1(gain ∗ s0 (n) ≥ 1)(−1 < gain ∗ s0 (n) < 1)(gain ∗ s0 (n) ≤ −1)1|s1 | ≤ 1

level



 levels1 (n) =level ∗ gain ∗ s0 (n) −level

220Hz

2i

440Hz 3

(gain ∗ s0 (n) ≥ 1)(−1 < gain ∗ s0 (n) < 1)(gain ∗ s0 (n) ≤ −1)

660Hz...

hif0

A-D

hi = if0(i ≥ 2)

1/2

[1]

LPF

sin[1]

sins(n) = A sin

2πf0 nfs

(gain)

100 level0.5A
2πh3 n2πf0 n+ sins(n) =A sin
fs3fs


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A
2πh5 nA
2πhi n+ sin+ · · · sin
5
fsifs


[1]

[1]

C–

2008.

[2] FFT
http://www.aandd.co.jp/adhome/products/nvh_
analysis/fft/fft01.html