Although I'm really not that young, I seem to be having a Junior Moment.
I had a circuit which produced a sine wave which had a peak positive voltage of, say, 1V. The peak negative voltage was a tad greater, say
-1.1V. But, the average was zero over a full cycle. I have no way to measure the distortion nor the spectrum.
Can someone give me a qualitative idea of what picture that wave might produce on a SA and what its harmonic distribution might look like?
Accuracy not required. Just an idea so I can get a "feeling" for that sort of thing.
Thanks, John
--------------- Measure about 16 amplitude points on the waveform from the same point on adjacent cycles (one exact cycle) and then find some fast Fourier transform software and plug in the values.
As posted by others a flat bottom waveform is indicative of some 2nd harmonic but other harmonics are involved to keep the top of the waveform looking rounded.
One fallacy that people will tell you is that Nth harmonics will make the wave look like this and that. This only applies when the harmonic is in phase with the fundamental at zero crossings. Third harmonics can flatten the peak of a sine wave or increase the amplitude. This can be simulated in Excel with it's charting abilities. We needed this to analyze some waveforms on a job and a co-worker produced one with variable harmonics and variable phase lag in about half an hour. It was really cool to play with the figures and see what happens in different condition of noise.
mike