Agilent Technologies 54657A Guía de usuario descargar pdf (Pagina 28)

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

1 2 ... 23 24 25 26 27 28 29 30 31 32 33 ... 88 89

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Agilent Technologies 54657A Guía de usuario Pagina 28