Yes, Im using an n=1 LPF
below the resonance.

But, I do not understand why that
would cause a dead area in the noise.

If i want to equalize the noise
I must use the BPF at resonance
N=2 then the dead spot goes away.

But, none of this makes any sense to me.

Unless something else is happening.



On 3/5/2012 12:36 PM, chrisatupw@....... wrote:
> 
> From: Geoffrey gmvoeth@.........
> Subject: Just Sitting on my couch thinking.
> 
> 
> Hello PSN;
> I was sitting on my couch thinking about why
> here seems to be a signal dead spot at resonance in my geophone.
> 
> i Geoff, 
>     There SHOULDN'T be a dead spot at the resonance of a 1Hz 
> gepophone. What amplifier / filter circuits are you using ? 
> You aren't by any chance trying use 2nd order filters to try 
> to increase the period range, do you ? These can produce a 
> dead spot at the resonant frequency. 
> .
>     Regards, 
> .
>     Chris
> 
> 
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