SV: [scilab-Users] lowpassfilter

[Stefan Du Rietz]

Hi Anders,
everything is OK. At the cut-off frequency the amplitude of the filter 
output (your red curve) should be 1/sqrt(2) (- 3 dB), i.e. around 0.7, 
and it actually is.

Regards
Stefan


On 2010-04-15 07:14, Anders Sneckenborg wrote:
--------------------
> Hi again
> 
>  
> 
> I edited the code (removed dead code) and here it is again. It will 
> execute exactly as before but without the disturbing dead code.
> 
>  
> 
> //---------------------------
> 
> f1 = 0.1;      //Hz
> 
> tSamp = 0.01;  //s
> 
> tMax = 200;
> 
>  
> 
> t = 0:tSamp:tMax;
> 
> y = sin(2*%pi*f1*t);
> 
>  
> 
> Order = 1;
> 
> Fcutoff = 0.1;
> 
> Fs = 1/tSamp;
> 
> hz = iir(Order,'lp','butt',[Fcutoff/Fs 0],[0 0]);
> 
> sl = tf2ss(hz);
> 
> yf = flts(y,sl);
> 
>  
> 
> plot(t,y,'-b');
> 
> plot(t,yf,'-r');
> 
> //---------------------------
> 
>  
> 
> /Anders
> 
>  
> 
>  
> 
> *Från:* Julio Gonzalez-Saenz [mailto:julio.gonzalez at ymail.com]
> *Skickat:* den 14 april 2010 22:42
> *Till:* users at lists.scilab.org
> *Ämne:* Re: [scilab-Users] lowpassfilter
> 
>  
> 
> Hi Anders,
> 
> Can you please double check the semicolon on the function y definition? 
> You also have a f1 and f2 but only f1 is defined..
> 
> Regards,
> 
> 
> Julio Gonzalez-Saenz
> www.part-time-scientists.com
> www.neex-technologies.com
> 
>  
> 
>  
> 
> ------------------------------------------------------------------------
> 
> *From:* Anders Sneckenborg <anders at simbalsyd.se>
> *To:* "users at lists.scilab.org" <users at lists.scilab.org>
> *Sent:* Wed, 14 April, 2010 22:19:29
> *Subject:* [scilab-Users] lowpassfilter
> 
> Hi
> 
>  
> 
> When running the following script I expected the filtered signal to have 
> an amplitude of 0.5.
> 
> My intention was to lowpassfilter a signal with the same frequency as 
> the cutoff frequency.  Am I doing something wrong?
> 
>  
> 
> //---------------------------
> 
> f1 = 0.1;      //Hz
> 
> tSamp = 0.01;  //s
> 
> tMax = 200;
> 
>  
> 
> t = 0:tSamp:tMax;
> 
> y = 1*sin(2*%pi*f1*t);  + 0.5*sin(2*%pi*f2*t);
> 
>  
> 
> Order = 1;
> 
> Fcutoff = 0.1;
> 
> Fs = 1/tSamp;
> 
> hz = iir(Order,'lp','butt',[Fcutoff/Fs 0],[0 0]);
> 
> sl = tf2ss(hz);
> 
> yf = flts(y,sl);
> 
>  
> 
> plot(t,y,'-b');
> 
> plot(t,yf,'-r');
> 
> //---------------------------
> 
>  
> 
> Best regards
> 
> Anders
> 
>  
> 
>  
>