YOKOGAWA DL 1540 User Manual

8-18
IM 701510-01E
8.6 Displaying the Power Spectrum (Performing
FFT Computation)
1. Press the SHIFT + MATH (FFT) key to display the FFT computation
setting menu.
2. Press the “FFT” soft key and select “ON”.
Selecting the waveform of measurement
3. Press the “Trace” soft key to display the trace selection menu.
4. Press the soft key corresponding to the trace you want to measure.
For DL1520DL1520L, menus such as “1”, “2” and “MATH” are
displayed instead of the trace selection menu shown below.
Selecting the time window
3. After step 2 has been completed, press the “RECT” or the
“HANNING” soft key to select the time window.
Selecting the display format
3. After step 2 has been completed, press the “VT&FFT” or the “FFT”
soft key to select the display format.
Explanation
Waveforms on which FFT computation can be performed
FFT computation can be performed on any one trace selectable from trace 1 to trace 4 (for
DL1520/DL1520L, 1/2/MATH).
Selecting the time window
The time window can be selected from the following window types.
RECT (rectangular window)
Useful for transient signals which attenuate completely within the time
window
HANNING Useful for signals which are continuous and not periodical
FFT frequency band
Maximum 50 MHz
Display format
The display format depends on the expansion settings. Refer to page 7-5 for more details.
Points to note relating to displaying the power spectrum
• FFT computation is not possible in repetitive sampling mode or when the acquisition
mode is envelope mode.
• FFT computation is not possible when the Waveform’s Horizontal Position set except to
0div.
• The unit of the voltage axis is [dBV].
• In case the waveform is expanded, FFT computation will be carried out on the expanded
range.
Keys and Procedure
MATH(FFT) key
Soft keys
SHIFT key
Upper
-limit
value
Lower
-limit
value
The upper and lower limits of
the power spectrum display
take on fixed values depending

on the vertical sensitivity
(V/div) as shown in the figure
below. They are not displayed

on the screen.

V/div


5000 V
2000 V
1000 V
500 V
200 V
100 V
50 V
20 V
10 V
5 V
2 V
1 V
500 mV
200 mV
100 mV
50 mV
20 mV
10 mV
5 mV
2 mV
1 mV
Upper
-limit
value
(dBV)
100
90
80
80
70
60
60
50
40
40
30
20
20
10
0
0
ｰ10
ｰ20
ｰ20
ｰ30
ｰ40
Lower
-limit
value
(dBV)
20
10
0
0
ｰ10
ｰ20
ｰ20
ｰ30
ｰ40
ｰ40
ｰ50
ｰ60
ｰ60
ｰ70
ｰ80
ｰ80
ｰ90
ｰ100
ｰ100
ｰ110
ｰ120

YOKOGAWA DL 1540 Specifications

General

Brand	YOKOGAWA
Model	DL 1540
Category	Test Equipment
Language	English