I analyzed a signal I got from a sensor reading a periodic signal. The waveform looks pretty periodic to me. It froma pump that pumped once every few seconds. However, in the frequency analysis, the dominant frequency seems to be 0 or very close to zero. Is ther any reason why this would happen? The wave form is clearly periodic to me just by looking at it.
2006-10-22 16:33:51 · 3 answers · asked by abcdefghijk 4 in Science & Mathematics ➔ Engineering
The zero frequency component is your DC component. If the pump has a net flow then thats going to be accounted for in the DC component. Its a pump, not just an oscillator, so there is net flow in one direction, an the DC component should be large.
If you are interested in the oscillatory behavior, artificially set the DC component magnitude to zero. Any scaling after that should reveal dominant harmonics.
2006-10-22 16:57:35 · answer #1 · answered by Curly 6 · 0⤊ 0⤋
The waveform may look periodic, but is it equally distributed over negative and positive values? If more positive than negative values occur, there is a net DC (frequency zero) component. The DC component is the average value of the wave's amplitude over several cycles.
2006-10-23 02:03:13 · answer #2 · answered by gp4rts 7 · 0⤊ 0⤋
how are you getting this frequency analysis? Do you have sufficient sampling to get the actual frequency? A few seconds, say 3, would be a 0.33 Hz signal, which is pretty close to zero frequency under poor sampling conditions.
2006-10-22 23:48:25 · answer #3 · answered by arbiter007 6 · 0⤊ 0⤋