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Discussion Groups | Matlab DSP | cut off frequency

Technical discussion about Matlab and issues related to Digital Signal Processing.

  

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cut off frequency - vani chezhiyan - Mar 25 9:36:00 2004

hi all,

i'm doing a project in preprocesing biosignals.

if i'm given with a signal,how will i find out the cut off frequency?

is it possible only by looking into the power spectrum.is there any formula(given only the sampling frequency)?

kindly help.

 

thanx in advance

 




_____________________________
 Free pdf download: Complex Digital Signal Processing in Telecommunications.




RE: cut off frequency - Jeff Winter - Mar 25 13:55:00 2004

Hi Vani,
 
Most biosignals tend to be low frequency in nature, making them an interesting challenge to process.  Because they tend to be low frequency, they can very easily be corrupted by unwanted interference e.g. mains supply or other biosignals.  As in most things, you must have a good idea of what you are trying to achieve.  Preprocess a signal, for what purpose?
 
I suggest you use the SPTOOL feature of Matlab to get started with, as this requires little knowledge of Matlab.  This will allow you to view your data, look at the spectrum and apply some filtering.    One point to remember you must know the sampling frequency of your data acquisition, as this will determine all the initial design parameters for your signal processing.
 
As for cut-off frequency, if this is in relation to a filter you want to design, you probably need to look at the unprocessed spectrum first to see where the activity is present.
 
As was suggested in a previous posting to this group, the more information that's provided, the better the response.
 
Best regards,
 
Jeff
 
======================
Jeff Winter
Snr Design Engineer
Aeroflex
www.aeroflex.com
 
 -----Original Message-----
From: vani chezhiyan [mailto:v...@yahoo.com]
Sent: Thursday, March 25, 2004 9:36 AM
To: m...@yahoogroups.com
Subject: [matlab] cut off frequency

hi all,

i'm doing a project in preprocesing biosignals.

if i'm given with a signal,how will i find out the cut off frequency?

is it possible only by looking into the power spectrum.is there any formula(given only the sampling frequency)?

kindly help.

 

thanx in advance

 



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_____________________________
 Free pdf download: Digital Signal Processor Fundamentals and System Design.