You need to test, we're here to help.

You need to test, we're here to help.

22 February 2019

About Data Truncation in Fast Fourier Transforms

The first precondition of using the Fourier transform is a repetitive signal
Figure 1: The first precondition of using the Fourier transform
is a repetitive signal
Our last post discussed how time-domain signals acquired by an oscilloscope might be translated into the frequency domain using the discrete Fourier transform. We noted that using the Fourier transform only works if our signal is repetitive (Figure 1), and that it allows us to identify only harmonics of the first harmonic frequency, which is 1/acquisition window. Moreover, the discrete Fourier transform, if used on a large number of data points, is relatively slow to calculate.

30 January 2019

Getting From the Time Domain to the Frequency Domain

A fundamental underlying assumption of a discrete Fourier transform is a repetitive waveform
Figure 1: A fundamental underlying assumption of a discrete
Fourier transform is a repetitive waveform
Fundamentally, oscilloscopes are time-domain instruments: We use them to acquire signals from our circuitry or device under test, and the instrument displays them in the time domain. We see the voltage of the signal in the vertical axis, and we see how that voltage changes over time in the horizontal axis.