filtering signal

Thread Starter

Aagash

Joined Jun 7, 2017
43
Hi,

I have a waveform of 1.2Hz and with the spike constituting of almost 1/10th of the single wave , how to eliminate just the spike without destroying the signal.Do I have to design any filter or by any other mean?

given the signal . thanks in advance !Capture.PNG
 

AnalogKid

Joined Aug 1, 2013
8,143
Doing it with just a filter will be difficult, because although the frequency of the signal is 1.2 Hz, it has significant energy at much higher frequencies. For example, notice that the inflection in the signal as it crosses the lower right portion of the red oval is gone in the filtered image on the right. Either a clipper or a slew-rate limiter probably will give better performance. A more complex option is to build an analog gate that switches to a steady DC voltage during the spike period.

ak
 

AnalogKid

Joined Aug 1, 2013
8,143
Something like that. The signal has a unambiguous negative tip that could be used to trigger a delay followed by a key pulse to freeze a T&H or analog switch to a DC level. Similar to a burst gate in NTSC video.

ak
 

crutschow

Joined Mar 14, 2008
23,520
omething like that. The signal has a unambiguous negative tip that could be used to trigger a delay followed by a key pulse to freeze a T&H or analog switch to a DC level.
But what DC level would you use?
It would seem that you want to just hold the signal at the level just before the spike rather than some arbitrary DC level, which would put a large step in the signal.
 

AnalogKid

Joined Aug 1, 2013
8,143
Knowing so little about the signal and its use, or what is causing the spike, I just threw out the clamp idea as one of several possible solutions, not necessarily preferred. Again channeling old video circuits, the clamp wouldn't have to be a true analog switch; it could be a diode switch or simply a saturated transistor.

ak
 
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