Random noise in Spectrum display in Waveforms demo

[Phil_D]

Hi,

I am using the Waveforms demo, version 3.7.5.

I downloaded a time domain waveform from my Tektronix o-scope, and uploaded it into the Wavegen in Waveforms. When I go to the Spectrum view, the noise is dynamic, even though the data I uploaded is static. Why is the noise changing? If I were to take an FFT of the same Tek o-scope data in Excel, the noise would not be moving. I guess I'd like to know what is going on to make the noise move in the Waveforms spectrum display.

Thanks!

-Phil

[attila]

Hi @Phil_D

When generating a signal with a real device the digital data is transformed to analog then the scope converts it back to digital data. During conversion and in analog stage the signals can pick up noise.
The demo mode adds a little noise (random) to simulate such real word behaviour. 

[Phil_D]

Thanks! We suspected this, but wanted to make sure.