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very low frequency high pass filter

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reyge

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Hello!
Is there anyway I could discriminate a 0 Hz signal from a 1 Hz signal? I was thinking of a dc blocking capacitor but I think the capacitor values will be too large. Any suggestions? I could really use some help. Thanks!
 

to get such a rejection for 1Hz difference would make the design too complex...
 

yeah, that's what I thought.. But how would you do it? How complex will the design be if we are going to implement such an almost perfect filter?
 

A simple RC filter will do this, remember if you place a zero at 0 Hz and a pole at 1 Hz you have infinite decades of distance between the two (logarithmic scale) and a single pole filter will slope at 20 db per decade.

To have a pole at 1 Hz is not unheard of for a simple RC filter:

w = 1/rc = 2*pi*f

For example c = 10uF and r = 16k will make a practical, simple filter.

-jonathan
 

0Hz means that the signal is constant , so if you have to discriminate 0Hz from any other frequency you can use some type of logic edge detector
 

reyge,
A commutating filter behaves as a bandpass filter. Depending on the number of stages, it can achieve extremely high Q's. This might work for your application.
Regards.
Kral
 

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