MR8740、MR8741_user_manual_eng_20191016H.pdf - 第420页

Appendix 4 FFT Definitions A 24 The following example shows input sine waves of 1050 and 115 0 Hz analyzed with different win dow functions. Becaus e the frequencies in this example a re close to one another, a re ctangu…

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Appendix 4 FFT Definitions
A23
Appendix
Exponential window
Time-Domain Waveform Spectrum
Hamming window
Time-Domain Waveform Spectrum
Blackman window
Time-Domain Waveform Spectrum
Blackman-Harris window
Time-Domain Waveform Spectrum
N-10
Amplitude
0
0.1%
50%
99.9%
Gain [dB]
0 2 4 6 8 10
-80
-60
-40
-20
0
Frequency (1/W)
0.1%
50%
99.9%
N-10
Amplitude
0
0 2 4 6 8 10
-80
-60
-40
-20
0
Frequency (1/W)
Gain [dB]
N-10
Amplitude
0
0 2 4 6 8 10
-80
-60
-40
-20
0
Frequency (1/W)
Gain [dB]
N-10
Amplitude
0
0 2 4 6 8 10
-80
-60
-40
-20
0
Frequency (1/W)
Gain [dB]
Appendix 4 FFT Definitions
A24
The following example shows input sine waves of 1050 and 1150 Hz analyzed
with different window functions. Because the frequencies in this example are
close to one another, a rectangular window with a narrow main lobe is able to
separate and display both frequencies, but a Hann window with a wide main lobe
displays the two as a single spectral component.
Flat top window
Time-Domain Waveform Spectrum
Analysis Using a Rectangular Window Analysis Using a Hann Window
N-10
Amplitude
0
0 2 4 6 8 10
-80
-60
-40
-20
0
Frequency (1/W)
Gain [dB]
100 500 1000 5000 10000
-100
-50
0
Frequency [Hz]
Amplitude [dB]
100 500 1000 5000 10000
-100
-50
0
Frequency [Hz]
Amplitude [dB]
Appendix 4 FFT Definitions
A25
Appendix
Octave Filter Characteristics _____________________________________
Octave filter characteristics are determined according to IEC61260 standards.
The figures below show these standards and the filter characteristics of this
instrument.
1/1 Octave Filter Characteristic
1/3 Octave Filter Characteristic
1 2 3 4 5 6 7 8 9 10
-80
-60
-40
-20
0
クラス１( 上限)
クラス２ (上限）
ノーマルフィルタ
規格化周波数 f/fm
ゲイン[dB]
クラス１, ２ (下限)
シャープフィルタ
Gain [dB]
1 1.5 2
-10
-5
0
クラス１ (上限)
クラス２ (上限）
ノーマルフィルタ
規格化周波数 f/fm
ゲイン[dB]
クラス１ (下限)
シャープフィルタ
クラス２ （下限）
Normalized Frequency f/fm
Normalized Frequency f/fm
Gain [dB]
Sharp
filter
Normal filter
Normal filter
Class 1 and 2 (lower limit)
Sharp filter
Class 2
(upper limit)
Class 1
(upper limit)
Class 2 (lower
limit)
Class 1
(lower limit)
Class 2
(upper limit)
Class 1
(upper limit)
1 1.5
-20
-10
0
クラス１ (上限)
クラス２ (上限）
ノーマルフィルタ
規格化周波数 f/fm
ゲイン[dB]
クラス１ (下限)
シャープフィルタ
クラス２ (下限）
1 2 3 4 5 6 7 8 9 10
-100
-80
-60
-40
-20
0
クラス１ (上限)
クラス２ (上限）
ノーマルフィルタ
規格化周波数 f/fm
ゲイン[dB]
クラス１, ２ (下限)
シャープフィルタ
Gain [dB]
Normalized Frequency f/fm
Class 1 and 2 (lower limit)
Normalized Frequency f/fm
Gain [dB]
Class 2
(upper limit)
Class 1 (upper limit)
Class 1
(lower
limit)
Class 2
(lower
limit)
Sharp filter
Normal filter
Sharp filter
Normal filter
Class 1 (upper limit)
Class 2 (upper limit)