Re: Slow varying inputs

On Thu, Mar 03, 2005 at 09:36:42AM +0000, Bernd Porr wrote:
> You can use the program 
> http://www.linux-usb-daq.co.uk/software2/comedi-record/
> to sample quite slowly. It internally always samples at 1kHz and then 
> averages on the fly to get a lower rate. It also has a 50Hz notch filter 
> (sorry, American colleagues). However, the filter frequency can be 
> changed in the program. I used it also with thermocouple sensors.

Bernd,

Thanks for the pointer, this is very close to exactly what I was
looking for. From looking closer at your filter characteristics in the
code I see that you are creating a pretty sharp notch filter. From the
description above I take it that the purpose of this notch filter was
to only take care of the 50Hz noise ? Is there a specific reason why
you decide to do a notch filter instead of a low-pass filter in your
application ? Is the notch filter applied before the averaging
function ?

Thanks
-- 
Daniel Nilsson

Received on 2005-03-04Z01:44:45