Owon TAO3000 Dual-Channel Series, Руководство пользователя

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4.Advanced User Guidebook
90
Notes for using FFT

Use the default dB scale for details of multiple frequencies, even if they
have very different amplitudes. Use the Vrms scale to compare
frequencies.

DC component or offset can cause incorrect magnitude values of FFT
waveform. To minimize the DC component, choose AC Coupling on the
source signal.

To reduce random noise and aliased components in repetitive or
single-shot events, set the oscilloscope acquisition mode to average.
What is Nyquist frequency?
The Nyquist frequency is the highest frequency that any real-time digitizing
oscilloscope can acquire without aliasing. This frequency is half of the sample
rate. Frequencies above the Nyquist frequency will be under sampled, which
causes aliasing. So, pay more attention to the relation between the frequency
being sampled and measured.
Use XY Format
Click to call up the menu panel. Click the XY softkey on panel to switch to
the ON or OFF state.
The XY menu:
This format is only applicable to Channel 1 and Channel 2. After the XY display
format is selected, Channel 1 is displayed in the horizontal axis and Channel 2
in the vertical axis; the oscilloscope is set in the un-triggered sample mode: the
data are displayed as bright spots.
The operations of all control knobs are as follows:

When the HOR button is lit, the upper and lower knobs are used to set the
horizontal scale and position.

When one of the channel buttons is lit, the upper and lower knobs are used
to set the vertical scale and position.
The following functions cannot work in the XY Format:

Reference or digital wave form

Cursor
Function
Menu
Setting Description
Full Screen
ON
OFF
Turn on/off the full screen view in XY mode