Iwatsu DS-8814, Operation Manual

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F-7
FFT Menu Operation
OFFSET Sets the vertical position of the waveform. (Units: dBm)
The same operation can be performed by using either the CH1/CH2 or
CH3/CH4 knobs. Pressing the knob causes a shift of 1div in the direction
of the last movement.
VOLT/DIV Sets the sensitivity of the waveform’s vertical axis to 1, 2, 5, 10, or
20dBm/div.
The same operation can be performed by using either the CH1/CH2 or
CH3/CH4 knobs. Enlarges or reduces the display waveform based on
the screen center.
DELAY Sets the horizontal position of the waveform. (Units: Hz)
The frequency of the screen center is always displayed at the top of the
screen. Pressing the knob causes a shift of 1div in the direction of the last
movement.
TIME/DIV The zoom rate along the waveform’s horizontal axis can be selected as
×1, ×2, ×5, or ×10. The set value is also reflected in the value of the
horizontal axis sensitivity (units: Hz/div) and is displayed based on the
center of the screen. Pressing the knob will alternately switch the FFT
and YT/XY screens.
ZERO DELAY Initializes the position along the waveform’s horizontal axis.
F Source
FUNCTION
Selects the waveform of CH1, CH2, CH3 or CH4 for computation. FFT
results are displayed regardless of the On/Off setting of Trace of the
selected waveform.
Data points for FFT (F Points)
The number of data points for the FFT is selected as 1024 or 4096.
Length F Points Data points for FFT
Short 1024 All of the waveform data (1024 points) of the specified source are
used for FET.
Long 1024 From the waveform data (100000 points) of the specified source,
with the center as the boundary, the data for the FFT is every 80th
data point, 512 points to the left and to the right.
Long 4096 From the waveform data (100000 points) of the specified source,
with the center as the boundary, the data for the FFT is every 20th
data point, 2048 points to the left and to the right.
Channels for FFT (F Source)
A channel (CH1 to 4) for the FFT is selected. CH2 and CH4 cannot be selected in the
interleave mode.