User manual

23
UNI-T
®
UT4000 User Manual
Definition :
FTT recognition rate : It means the quotient of the sampling and math points. When
math point value is fixed, the sampling rate should be as low as possible relative to the
FFT recognition rate.
Nyquist frequency : To rebuild the original waveform, at least 2f sampling rate should be
used for waveform with a maximum frequency of f. This is known as Nyquist stability
criterion, where f is the Nyquist frequency and 2f is the Nyquist sampling rate.
Digital Filtering Function
Function Menu Setup Explanatory Note
Type Digital filtering Digital filtering
Signal source CH1
CH2
REF A
REF B
Set CH1 as filter target.
Set CH2 as filter target.
Set REF A as filter target.
Set REF B as filter target.
Filtering Type Low-pass
High-pass
Band-pass
Set the filter to low-pass filtering.
Set the filter to high-pass filtering.
Set the filter to band-pass filtering.
Minimum
Frequency
⎯
Set the minimum frequency with the multifunction
control knob.
Maximum
Frequency
⎯
Set the maximum frequency with the multifunction
control knob.
II. Reference Waveform
Display of the saved reference waveforms can be set on or off in the [REF] menu. The
waveforms are saved in the non volatile memory of the oscilloscope or an external USB
device and are identified with the following names : RefA, RefB. To display (recall) or
hide (off) the reference waveforms, take the following steps :
1. Press the [REF] menu button on the front panel.
2. Press [CALL BACK]. Select the signal source by turning the multifunction control
knob on the upper part of the front panel. You can choose from 1 to 10. After
selecting a numeral for saved waveform, e.g. 1, press [SELECT] to recall the
waveform which was originally stored in that position. For instructions on storing or
recalling reference waveforms on the USB device, read “Storage and Recall”.
3. Press RefB (RefB reference option). Select the second signal source for the math
function by repeating step 2.
In actual application, when using your UT4000 to measure and observe such
waveforms, you can compare the current waveform with the reference waveform for
analysis. Press [REF] to display the reference waveform menu. For setup please
refer to Table 2-5.
4. To close the reference waveform, press [OFF] in the vertical zone.
Note : When [AUTO] is pressed after a reference waveform is recalled, that waveform
will remain.