Basic Operation
DSO1000B Series HandHeld Oscilloscope User Manual 23
Limit option to Limited.
Filter the signal input from outside and limit the bandwidth of the source waveform to lower
than the Nyquist frequency.
Identify and ignore the aliased frequencies.
Use zoom controls and cursors to magnify and measure the FFT spectrum.
5.3.1.6
Magnifying and Positioning FFT Spectrum
You may scale the FFT spectrum and use cursors to measure it through the FFT Zoom option
which enables the horizontal magnification. To vertically magnify the spectrum, use the vertical
controls.
Horizontal Zoom and Position
You can use the FFT Zoom option to magnify the FFT spectrum horizontally without changing the
sample rate. The available zoom factors are X1(default), X2, X5 and X10. When the zoom factor is
set to X1 and the waveform is located at the center graticule, the left graticule line is at 0Hz and
the right is at the Nyquist frequency.
You magnifies the FFT spectrum to the center graticule line when you change the zoom factor.
That is, the axis for horizontal magnification is the center graticule line. Click the Horizontal
Position Key to move the FFT spectrum to the right.
Vertical Zoom and Position
When the FFT spectrum is being displayed, the channel vertical keys become the zoom and
position controls corresponding to their respective channels. The VOLTS key provides the
following zoom factors: X1(default), X2, X5 and X10. The FFT spectrum is magnified vertically to
the marker M (math waveform reference point on the left edge of the screen). Click
the Vertical
Position key to move up the spectrum.
5.3.1.7
Using Cursors to Measure FFT Spectrum
You may use cursors to take two measurements on the FFT spectrum: amplitude (in dB) and
frequency (in Hz). Amplitude is referenced to 0db that equals 1VRMS here. You may use cursors
to measure at any zoom factor.
Push the CURSOR button, choose the Source option and then select Math. Press the Type option
button to select between Amplitude and Frequency. Click the SELECT CURSOR option to choose
a cursor. Then move Cursor S and Cursor E. Use the horizontal cursor to measure the amplitude
and the vertical cursor to measure the frequency. Now the display at the DELTA menu is just the
measured value, and the values at Cursor S and Cursor E.
Delta is the absolute value of Cursor S minus Cursor E.
