MR8740、MR8741_user_manual_eng_20191016H.pdf - 第273页

12.3 Setting FFT Analysis Conditio ns 261 11 Chapter 12 FFT Function 12 3 When [Parameter] set ting content s are displaye d Set the p arameter . Move the flashing cursor to the [Parameter] column of the Anal- ysis No. t…

12.3 Setting FFT Analysis Conditions

260

Select the type of FFT analysis, channel(s), waveform display color and x and y axes.

12.3.9 Analysis Mode Settings

Select the FFT analysis mode.

Move the flashing cursor to the [Analyze] column of the Analysis No.

to se

Select

(When [List] is selected, a list of calculation types appears.)

Select whether to display the waveform, and its color.

Move the flashing cursor to the [Wave] column.

Select whether the waveform is to be displayed (On) or not, and its

color if displayed.

Analysis No.

Settings can be made from the

dialogs, or copied from another

Analysis No. (p.160)

Analysis

Type

Analysis Setting

Contents

Channel for

Analysis

34 5

Display

Color

X/Y Axes

Display

Parameter

Off No analysis.

(default setting)

Storage Waveform (p.275)

Histgram (p.275)

Linear Spectrum (p.276)

RMS Spectrum (p.277)

Powre Spectrum (p.279)

Powre Spectrum

density*

(p.280)

LPC (density)* (p.281)

Transfer Function (p.282)

Cross Power Spectrum (p.283)

Impulse Response (p.284)

Coherance Function (p.285)

Phase Spectrum (p.286)

Auto-Correlation (p.287)

Cross-correlation (p.288)

1/1 Octave* (p.288)

1/3 Octave* (p.288)

*Not available with external sampling enabled.

See: "12.8.2 Analysis Mode Functions" (p.293)

Procedure

To open the screen: Right-click and select [STATUS]  [Status] sheet

See: To set from the Waveform screen (p.265)

12.3 Setting FFT Analysis Conditions

261

Chapter 12 FFT Function

When [Parameter] setting contents are displayed

Set the parameter.

Move the flashing cursor to the

[Parameter] column of the Anal-

ysis No. to set.

Select

Select the channel for analysis.

Move the flashing cursor to the [Ch1] item.

Select which channel number to use. However, the channel of

MR8990 Digital Voltmeter Unit cannot be set.

Set the horizontal and vertical axes displaying the calcu-

lation results.

Move the flashing cursor to the

[X Axis] or [Y Axis].

Set the contents of the calculation results to be displayed on

the horizontal and vertical axes.

(Selectable display contents vary by analysis mode.)

See: "Analysis Modes and X/Y Axis Display" (p.262)

Y-axis display

X-axis display

Analyze Parameter Setting Contents

1/1 Octave,

1/3 Octave

Filter: Normal

nables the octave filter.

See: "Octave Filter Setting" (p.262)

Filter: Sharp

Phase Spectrum

1ch FFT Calculates the phase of [Ch1].

2ch FFT Calculates the phase difference between [Ch1] and

[Ch2].

LPC (dencity)

Order :2 to 64 Larger numerical values make finer spectrum compo-

nents visible.

Lin-Mag Analysis results are displayed as amplitude values.

Log-Mag Analysis results are displayed as dB values.

The dB reference is 1 eu. (As a voltage example, 1 V is

0 dB.)

Lin-Real The real-number component of analysis results are dis-

played.

Lin-Imag The imaginary component of analysis results are dis-

played.

Linear Frequency-axis is displayed linearly.

Log Frequency-axis is displayed logarithmically.

This is convenient when the data of interest is at the lower end

of the frequency range, such as for sound and vibration.

Analysis channel setting

For any of the following analysis modes,

set both channels 1 and 2.

Transfer Function, Impulse Response,

Cross-correlation Function, Cross Power

Spectrum, Coherence Function, Phase

Spectrum (2ch FFT)

To analyze using external sampling

The horizontal axis ( x-axis) displays the

number of data points.

How do I copy settings to other calculation No.?

See: "7.8 Copying settings to other channels (calculation No.) (Copy function)" (p.160)

12.3 Setting FFT Analysis Conditions

262

 Octave Filter Setting

Filter features are based on JIS C1513-2002 class 1, class 2 (IEC61260).

After determining the entire power spectrum, the instrument performs octave analysis defined by the

above filter characteristics.

See:"Octave Filter Characteristics" (p.A25)

 Analysis Modes and X/Y Axis Display

Normal

Filter characteristics approximate those

of an analog filter.

Sharp

Only those spectral component within the

octave band are used for analysis. Spec-

tral components outside of the octave

band are totally ignored.

: Settable, ×: Unsettable

Analysis Mode

X axis Y axis

Nyquist

display

Linear Log Lin-Mag Log-Mag Lin-Real Lin-Imag

OFF

×××××× ×

Storage Waveform



××× ×

Histogram



××× ×

Linear Spectrum

 

RMS Spectrum



Power Spectrum



×× ×

Power Spectrum Density



×× ×

LPC analysis (Power Spectrum

Density)



×× ×

Transfer Function

 

Cross Power Spectrum

 

Impulse Response



××× ×

Coherence Function



××× ×

Phase Spectrum



××× ×

Auto-correlation Function



××× ×

Cross-correlation Function



××× ×

1/1 Octave



×× ×

1/3 Octave



×× ×

The x/y axes cannot be set when Nyquist Display is selected.