In a message dated 2007/06/26, Paulc@........ writes:


> The preamp board I have from Larry Cochrane is set to 10 HZ -3db point low 
> pass filter. This means that a minimum sample rate of at least 2x should be 
> used, I think according to Mr Nyquist.
>  
> My Amaseis is set to sample at 6 SPS.  This should lead to some interesting 
> aliasing results.

Hi Paul,

       It is only the AS1 electronics box which is set to 6.15 SPS. The AS1 
has a resonance at 0.67 Hz, so the output falls off sharply above about 2 - 3 
Hz

       If you are using a Dataq ADC for instance, you can set the sample rate 
to any rate that the board offers, by altering the config file value..

>  In the config file I changed the sample rate to 20 SPS and now the 
> Winquake FFT window shows out to 10 Hz.

       This should be OK, if the ADC can provide it.
       
       Regards,

       Chris Chapman   
In a me=
ssage dated 2007/06/26, Paulc@........ writes:





The preamp board I have from L=
arry Cochrane is set to 10 HZ -3db point low pass filter. This means that a=20=
minimum sample rate of at least 2x should be used, I think according to Mr N=
yquist.

 

My Amaseis is set to sample at 6 SPS.  This should lead to some intere=
sting aliasing results.




Hi Paul,



       It is only the AS1 electronics box whic=
h is set to 6.15 SPS. The AS1 has a resonance at 0.67 Hz, so the output fall=
s off sharply above about 2 - 3 Hz



       If you are using a Dataq ADC for instan=
ce, you can set the sample rate to any rate that the board offers, by alteri=
ng the config file value..



 In the config file I changed=20=
the sample rate to 20 SPS and now the Winquake FFT window shows out to 10 Hz=
..




       This should be OK, if the ADC can provi=
de it.

       

       Regards,



       Chris Chapman