Reference Waveform; Term Explanation; Nyquist Frequency - UNI-T UTD2025C Operating Manual

Term explanation:

FFT resolution: It is defined as factor of sampling
and calculation point. FFT resolution increases
when sampling rate decreases for fixed calculation
point quantity.

Nyquist frequency:

Original waveform can not be
reset until using sampling rate of at least 2f for
waveform with the maximum frequency of "f". It is
also called as Nyquist guideline. "f" refers to Nyquist
frequency and "2f" refers to Nyquist sampling rate.

Reference waveform

Please refer to waveform stored in nonvolatile
memory (NVM) of digital storage oscillograph or
peripheral U disk with name of RefA and RefB as
follows. Please operate according to following
steps to call out or close reference waveform.
5. Please press REF menu key on the front panel
for 5.7-screen oscillograph
Please press [STORAGE]key and enter into the
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Operating Manual for UTD2000/3000
second page to select call-out for 7-inch
oscillograph (namely, UTD2000L/2000EX series).
2. Please press [RefA] (RefA reference option) and
select information source then select its position by
rotating multi-purpose knob in upper part of front
panel. 1 10 (or 1 20) can be selected for the
position. Press "call-out" to call out waveform
which is stored inthe position originally after
selecting a certain position such as "1". Please
plug in U disk if waveform is stored in the U disk.
There are 2 options for magnetic disk as follows:
DSO/USB; Please press [F2] key and select USB.
(The menu can not be activated until plugging in U
disk.) Called out waveform is displayed on the
screen for waveform called out and stored from U
disk. Please press cancel key (F5) Return to
previous menu after waveform call-out.
3. To press [RefB] (RefB reference option) and
select