Agilent Technologies 54657A, User Manual

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The following FFT spectrum was obtained by connecting the front panel
probe adjustment signal to input 1. Set Time/Div to 500 s/div, Volts/Div to
100 mV/div, Units/div to 10.00 dB, Ref Level to –10.00 dBV, Center Freq to
6.055 kHz, Freq Span to 12.21 kHz, and window to Hanning.
FFT Measurements
FFT Measurement Hints
It is easiest to view FFT’s with Vectors set to On. The Vector display mode is set
in the Display menu. Note that on the 54615/54616, when Vectors is set from Off
to On, the frequency span is halved, and when Vectors is set from On to Off, the
frequency span is doubled.
The number of points acquired for the FFT record is normally 1024 (see FFT
"Operating Characteristics" in Chapter 3 for specifics,) and when frequency span
is at maximum, all points are displayed. Once the FFT spectrum is displayed, the
frequency span and center frequency controls are used much like the controls
of a spectrum analyzer to examine the frequency of interest in greater detail.
Place the desired part of the waveform at the center of the screen and decrease
frequency span to increase the display resolution. As frequency span is
decreased, the number of points shown is reduced, and the display is magnified.
f1(F2) = 1.221kHz f2(F2) = 3.662kHz f(F2) = 2.441kHz
Cent Freq Freq Span Move 0Hz Autoscale Window Previous
6.055kHz 12.21kHz To Left FFT Hanning Menu
fft(1) 6.05kHz 12.2kHz 1 STOP
Figure 2– 3
Operating the Measurement/Storage Module
FFT Measurement
2–12