Siglent SDS-5000X-FG User Manual

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SDS5000X Series Digital Oscilloscope User Manual

 FFT sample rate (Sa): FFT operation results present the first Nyquist zone

(DC ~ Sa/2) of the frequency spectrum. Be aware that the FFT sample rate

may be inconsistent with the sample rate in the time domain. Assuming the

max points is set to 2 Mpts:

 When the number of points in time domain, N, is less than 2 Mpts, the

FFT takes the number which is an integer power of 2 closest to N. In

this case, FFT sample rate = sample rate in time domain.

 When N is greater than 2 Mpts, FFT first decimates N by D, and then

takes the first 2 Mpts for the calculation. In this case, FFT sample rate

= sample rate in time domain/D.

For example, in the case of sample rate in time domain is 5 GSa/s and

the number of samples is 5 Mpts, the FFT first decimates the samples

by 2, to 2.5 Mpts, and then takes the first 2 Mpts to calculate the

spectrum. In this example, FFT sample rate = 5 GSa/s ÷ 2 = 2.5 GSa/s.

 FFT points (Curr): The current FFT points, which is an integer power of 2.

The SDS5000X supports up to 2 M points (2097152, to be exact).

 Frequency interval (

△f): The frequency interval between two adjacent

points in the FFT sequence, which is proportional to the frequency

resolution.

 Average count of FFT (Avg): Displayed only when the FFT mode is set to

"Average", indicating the completed average count.

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Siglent SDS-5000X-FG Waveform Generator Software