MR8740、MR8741_user_manual_eng_20191016H.pdf - 第277页

12.3 Setting FFT Analysis Conditio ns 265 11 Chapter 12 FFT Function 12 The following settings can be ma de on the Waveform screen. Changes to the displayed analysis results b eco me effective when the setting s are chan…

12.3 Setting FFT Analysis Conditions

264

The display range of the vertical (y) axis can be set to automatically suit analysis results, and can be freely

expanded and compressed.

12.3.10Setting the Display Range of the Vertical Axis

(Scaling)

Select automatic or manual scaling of the y-axis display.

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

to set.

Select

When [Manu] is selected

Set the upper and lower limits to display.

Move the flashing cursor to the

[Lower] or [Upper] item.

Set the upper and lower limits to display the analysis results.

Setting range: -9.9999E+29 to +9.9999E+29

(with exponent from E-29 to E+29)

See: "7.1.3 Alphanumeric Input" (p.141)

Auto Scaling of the vertical (y) axis is automatically set according to

analysis results. (default setting)

Manu-

Scaling of the vertical (y) axis can be set as desired, to suit the pur-

pose of the measurement.

This is useful for magnifying or reducing the displayed amplitude,

and for shifting the displayed waveform up or down.

Procedure

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

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

265

Chapter 12 FFT Function

The following settings can be made on the Waveform screen.

Changes to the displayed analysis results become effective when the settings are changed.

• Available settings are frequency range, number of analysis points, type of win-

dow function, trigger mode and pre-triggering

• Available settings are analysis number, analysis mode, waveform color, analy-

sis channel and x/y axis display type

• Trigger settings (p.192)

(Note: If [Reference] is [From Memory], triggers cannot be set.)

12.3.11Setting and Changing Analysis Conditions on

the Waveform Screen

Trigger mode and Pre-trigger

Select the trigger mode and pre-triggering (same as fo

the Memory function).

Trigger Mode: Single, Repeat, Auto

Pre-trigger: Select from list

See: "8.2 Setting the Trigger Mode" (p.191)

"8.9 Pre-Trigger Settings" (p.204)

Number of Analysis Points

(p.251)

(1000, 2000, 5000, 10000)

Frequency Resolution (dur-

ing acquisition)

Select the frequency range (133

mHz to 8 MHz). (p.251)

FFT Window Function Type

(p.254)

Setting method

Use the mouse to move the flashing cursor

to each item, and select a setting from the

GUI displayed on the bottom right of the

screen.

Analysis

Numbe*(p.260)

Analysis Channel

Analysis

Mode

*Coupled with the [Analy-

sis] list at the [Status]

sheet of the Status screen.

Display types of X-axis (horizontal

axis) and Y-axis (vertical axis)

Setting details

To open the screen: Right-click and select [DISP]  Waveform screen

Waveform Color

12.4 Selecting Channels

266

Channel selection is the same for all functions.

For the setting method, refer to "3.5 Input Channel Setting" (p.73) and "7.9 Setting Details of Mod-

ules" (p.161).

 Scaling

The scaling setting allows values displayed on this instrument to match the actual values read directly on

a sound level meter or vibration meter.

Setting example: To display measurement data on this instrument so that it corresponds

to that on a sound level meter.

In a case where a sound level meter displays 93.5 dB and the overall value displayed on the Wave-

form screen of this instrument is -6-51 dB.

12.4 Selecting Channels

Without Scaling

With Scaling

Sound Level Meter

93.5

1 Select [Num].

2 Select [Ratio].

3 Move the flashing cursor to [Ratio], and

click [dB Scaling].

The dB Scaling dialog appears.

4 Enter the (overall) value “-6.51” displayed

on the instrument.

5 Enter the value "93.5" (from the sound

level meter) that you want to read

directly.

6 Click [Confirm] to perform scaling.

Scaling is performed automatically and the con-

version value is set in the conversion rate column.

See: "Overall Value" (p.A19)

0 dB reference differs depends on the physical quantity.

As an example for sound pressure, 20 Pa is 0 dB.

In dB scaling, the dB value can be directly read; howev-

er, it may not be possible to directly read instantaneous

values.

Read the written standards and other materials regard-

ing 0 dB references.

93.5

Overall:

-6.51dB