In a message dated 02/02/2006, jonfr500@......... writes:

Hi  all
I have started digital filtering my gif files online. With a  lowpass
filter cutoff of 10Hz. Any suggestion on that move is welcomed by  me,
since i am still learning on this.



Hi Jon, 
 
    Your amplifier Low Pass Filter is actually set to  20 Hz, so there should 
be very little data above about 22 Hz. This should be  well suited to you 
local quakes.
    Sorry that I got it wrong, but I was reading the  characteristics from 
the psn website.
    
    Regards,
 
    Chris Chapman
 
   
In a message dated 28/01/2006, lcochrane@.............. writes:

Chris  wrote:
> The low pass filter on your amplifier board should  be 10  Hz and have 8 
> poles. In practice, a signal at 13.4 Hz will be reduced  to  1/10 and one 
at 18 
> Hz to 1/100.
>      The amplifier has a high pass filter set at 0.05 Hz  = 20 sec., which 
is  
> well below the lowest response of your geophones.

Actually  Jon's Amp/Filter board has a 20 Hz 7 pole low pass filter. I 
usually set the  
filter to 20 Hz instead of the 10 Hz if I know that the filter board will  be 
used 
with a geophone to record local events.

Regards,
Larry  Cochrane







In a message dated 02/02/2006, jonfr500@......... writes:
<=
FONT=20
  style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size=
=3D2>Hi=20
  all
I have started digital filtering my gif files online. With a=20
  lowpass
filter cutoff of 10Hz. Any suggestion on that move is welcomed=20=
by=20
  me,
since i am still learning on this.


Hi Jon, 
 
    Your amplifier Low Pass Filter is actually set=20=
to=20
20 Hz, so there should be very little data above about 22 Hz. This should be=
=20
well suited to you local quakes.
    Sorry that I got it wrong, but I was reading th=
e=20
characteristics from the psn website.
    
    Regards,
 
    Chris Chapman
 
 =20
In a message dated 28/01/2006, lcochrane@.............. writes:
<=
FONT=20
  style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size=
=3D2>Chris=20
  wrote:
> The low pass filter on your amplifier board should  be=
 10=20
  Hz and have 8 
> poles. In practice, a signal at 13.4 Hz will be red=
uced=20
  to  1/10 and one at 18 
> Hz to 1/100.
>   &nbs=
p;=20
  The amplifier has a high pass filter set at 0.05 Hz  =3D 20 sec., whi=
ch is=20
  
> well below the lowest response of your geophones.

Actually=
=20
  Jon's Amp/Filter board has a 20 Hz 7 pole low pass filter. I usually set t=
he=20
  
filter to 20 Hz instead of the 10 Hz if I know that the filter board w=
ill=20
  be used 
with a geophone to record local events.

Regards,
Lar=
ry=20
  Cochrane