MR8740、MR8741_user_manual_eng_20191016H.pdf - 第422页

Appendix 4 FFT Definitions A 26 Linear Predictive Coding (L PC) ______________ _____________________ In the following figure , linear predictive coding is implemen ted by passing a sam- ple of the input signal thr ough t…

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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)
Appendix 4 FFT Definitions
A26
Linear Predictive Coding (LPC)___________________________________
In the following figure, linear predictive coding is implemented by passing a sam-
ple of the input signal through the prediction filter while altering the filter so as to
minimize errors in the original signal.
Given a time-discrete signal {x
t
} (t is an integer) where the input signal is sam-
pled at interval T, LPC analysis presumes the following relationship between
current sample value x
t
and the value of previous sample p.
However, is an uncorrelated random variable with average value 0 and the
dispersion .
Expression (16) shows how current sample value x
t
can be “linearly predicted”
from previous sample values. If the predicted value of x
t
is actually , expres-
sion (16) can be transformed as follows.
Here,
i
is called the linear predictor coefficient.
For LPC analysis, this coefficient is calculated using the Levinson-Durbin algo-
rithm, and a spectrum is obtained. In this instrument, the order of the coefficient
can be set from 2 to 64. Larger orders reveal fine spectral components, while
small orders reveal the overall spectrum shape.
予測フィルタ
入力信号
予測信号
誤差信号
Error Signal
Prediction Signal
Input Signal
Prediction Filter
(16)
tptpttt
xxxx
2211
}{
t
2
t
x
(17)
t
p
i
itit
t
t
xxx
1
Index
1
Index
Numerics
100BASE-TX .....................................................318
2-Point ...............................................................149
9333 LAN Communicator ..................................334
A
A.A.F .................................................................174
A/B cursors .......................................................120
Acquisition interval ............................................252
Aliasing ............................................................ A16
Analog Trigger ..................................................192
Analysis Modes .........................................262, 293
Analysis modes .................................257, 262, 293
Analysis Starting Point ......................................273
Anti-aliasing filter .............................................. A17
Area ..................................................................224
Attenuation rate .................................................254
Auto correlation function ...................................287
Auto Print ..........................................................111
Auto Save ...........................................................87
Average .............................................................223
Averaging ................................................. 256, A19
B
Beep Sound ......................................................310
Blackman ......................................................... A23
Blackman Harris ............................................... A23
Blackman Harris Window ..................................254
Blackman Window ............................................254
Blank Panel .........................................................36
Blocks in use .....................................................136
C
Calculation No. ..................................................260
Captured Screen Image ......................................85
Change Media .....................................................84
Clamp ..................................................................45
Coherence function ...........................................285
Comment
Print (Channel marker) ..................................113
Communications ...............................................313
Access ..........................................................328
Command Communications ..........................332
Delimiter ....................................................333
Header ......................................................333
Command Port (Port number) ...................... 332
Deleting and Renaming Files ....................... 330
Delimiter ....................................................... 332
Downloading ................................................ 330
Gateway ....................................................... 315
Header ......................................................... 332
Host Name ................................................... 315
IP Address .................................................... 315
Network ........................................................ 314
Subnet Mask ................................................ 315
Connection
Current Measurement .................................... 45
Frequency, number of rotations,
and count Measurement ................................ 41
Temperature Measurement ............................ 42
Voltage Measurement .................................... 39
Connection cord ................................................. 41
Connection Cords .............................................. 39
Conversion Ratio .............................................. 148
Coupling ............................................................. 76
Cross power spectrum ..................................... 283
Cross-correlation function ................................ 288
Cursor Value .................................................... 120
XY Synthetic Waveform ............................... 123
D
Damage ............................................................ 372
Delete ............................................................... 106
Display color
Calculation waveforms ................................. 235
Display Types and Split-Screen Settings ......... 268
Disposing
Lithium Battery ............................................. 384
Downloading .................................................... 330
Duty Ratio ........................................................ 225
E
Entering Numerals ........................................... 144
Entering Text .................................................... 141
Event Count ..................................................... 195
Exponential ...................................................... A23
Exponential averaging ...................................... A19
Exponential window ......................................... 254
external .............................................................. 67
External Control ............................................... 335
External Sampling ............................................ 340
External sampling ............................................... 67
Index