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Diffstat (limited to 'help/en_US/buttord.xml')
| -rw-r--r-- | help/en_US/buttord.xml | 45 |
1 files changed, 27 insertions, 18 deletions
diff --git a/help/en_US/buttord.xml b/help/en_US/buttord.xml index da92712..32b7f21 100644 --- a/help/en_US/buttord.xml +++ b/help/en_US/buttord.xml @@ -17,7 +17,7 @@ <refnamediv> <refname>buttord</refname> - <refpurpose>/This function computes the minimum filter order of a Butterworth filter with the desired response characteristics.</refpurpose> + <refpurpose>Minimum filter order and 3dB cutoff frequency of a digital Butterworth filter with the desired response characteristics. </refpurpose> </refnamediv> @@ -33,38 +33,47 @@ <title>Parameters</title> <variablelist> <varlistentry><term>Wp:</term> - <listitem><para> scalar or vector of length 2</para></listitem></varlistentry> + <listitem><para> scalar or vector of length 2 (passband edge(s)), elements must be in the range [0,1]</para></listitem></varlistentry> <varlistentry><term>Ws:</term> - <listitem><para> scalar or vector of length 2, elements must be in the range [0,1]</para></listitem></varlistentry> + <listitem><para> scalar or vector of length 2 (stopband edge(s)), elements must be in the range [0,1]</para></listitem></varlistentry> <varlistentry><term>Rp:</term> - <listitem><para> real or complex value</para></listitem></varlistentry> + <listitem><para> passband ripple in dB.</para></listitem></varlistentry> <varlistentry><term>Rs:</term> - <listitem><para> real or complex value</para></listitem></varlistentry> + <listitem><para> stopband attenuation in dB.</para></listitem></varlistentry> + <varlistentry><term>n:</term> + <listitem><para> Minimum filter order satisfying specs.</para></listitem></varlistentry> + <varlistentry><term>Wc:</term> + <listitem><para> 3dB cutoff frequency/frequencies.</para></listitem></varlistentry> </variablelist> </refsection> <refsection> <title>Description</title> <para> -This is an Octave function. -This function computes the minimum filter order of a Butterworth filter with the desired response characteristics. -The filter frequency band edges are specified by the passband frequency wp and stopband frequency ws. -Frequencies are normalized to the Nyquist frequency in the range [0,1]. -Rp is measured in decibels and is the allowable passband ripple, and Rs is also in decibels and is the minimum attenuation in the stop band. -If ws>wp, the filter is a low pass filter. If wp>ws, the filter is a high pass filter. -If wp and ws are vectors of length 2, then the passband interval is defined by wp the stopband interval is defined by ws. -If wp is contained within the lower and upper limits of ws, the filter is a band-pass filter. If ws is contained within the lower and upper limits of wp the filter is a band-stop or band-reject filter. +This function computes the minimum filter order of a Butterworth filter with the desired response characteristics. </para> +<para>The filter frequency band edges are specified by the passband frequency wp and stopband frequency ws.</para> +<para>Frequencies are normalized to the Nyquist frequency in the range [0,1]. </para> +<para>Rp is measured in decibels and is the allowable passband ripple, and Rs is also in decibels and is the minimum attenuation in the stop band.</para> +<para>If ws>wp, the filter is a low pass filter. If wp>ws, the filter is a high pass filter.</para> +<para>If wp and ws are vectors of length 2, then the passband interval is defined by wp the stopband interval is defined by ws. </para> +<para>If wp is contained within the lower and upper limits of ws, the filter is a band-pass filter. If ws is contained within the lower and upper limits of wp the filter is a band-stop or band-reject filter. </para> </refsection> <refsection> <title>Examples</title> <programlisting role="example"><![CDATA[ -Wp = 40/500 -Ws = 150/500 -[n, Wn] = buttord(Wp, Ws, 3, 60) -n = 5 -Wn = 0.080038 + Wp = 40/500 ; + Ws = 150/500 ; + [n, Wc] = buttord(Wp, Ws, 3, 60) ]]></programlisting> </refsection> + +<refsection> +<title>Modified by :</title> +<simplelist type="vert"> +<member>Sonu Sharma, RGIT Mumbai (fellow at FOSSEE, IIT Bombay)</member> + </simplelist> +</refsection> + </refentry> |