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Diffstat (limited to 'help/en_US/ellipord.xml')
| -rw-r--r-- | help/en_US/ellipord.xml | 37 |
1 files changed, 20 insertions, 17 deletions
diff --git a/help/en_US/ellipord.xml b/help/en_US/ellipord.xml index 0f562c8..2a3dbe2 100644 --- a/help/en_US/ellipord.xml +++ b/help/en_US/ellipord.xml @@ -17,14 +17,14 @@ <refnamediv> <refname>ellipord</refname> - <refpurpose>This function computes the minimum filter order of an elliptic filter with the desired response characteristics.</refpurpose> + <refpurpose>Minimum filter order of a digital elliptic/Cauer filter with the desired response characteristics. </refpurpose> </refnamediv> <refsynopsisdiv> <title>Calling Sequence</title> <synopsis> - [n] = ellipord(Wp, Ws, Rp, Rs) + n = ellipord(Wp, Ws, Rp, Rs) [n, Wp] = ellipord(Wp, Ws, Rp, Rs) </synopsis> </refsynopsisdiv> @@ -33,36 +33,39 @@ <title>Parameters</title> <variablelist> <varlistentry><term>Wp:</term> - <listitem><para> scalar or vector of length 2, all elements must be in the range [0,1]</para></listitem></varlistentry> + <listitem><para> scalar or vector of length 2 (passband edge(s)), all elements must be in the range [0,1]</para></listitem></varlistentry> <varlistentry><term>Ws:</term> - <listitem><para> scalar or vector of length 2, all elements must be in the range [0,1]</para></listitem></varlistentry> + <listitem><para> scalar or vector of length 2 (stopband edge(s)), all 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 order of filter satisfying given specs.</para></listitem></varlistentry> </variablelist> </refsection> <refsection> <title>Description</title> <para> -This is an Octave function. -This function computes the minimum filter order of an elliptic filter with the desired response characteristics. -Stopband frequency ws and passband frequency wp specify the the filter frequency band edges. -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 measured in decibels and is the minimum attenuation in the stop band. -If ws>wp then the filter is a low pass filter. If wp>ws, then the filter is a high pass filter. -If wp and ws are vectors of length 2, then the passband interval is defined by wp and 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 an elliptic filter with the desired response characteristics.</para> +<para>Stopband frequency ws and passband frequency wp specify the the filter frequency band edges.</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 measured in decibels and is the minimum attenuation in the stop band.</para> +<para>If ws>wp then the filter is a low pass filter. If wp>ws, then 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 and 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[ -[a,b]=ellipord(0.2, 0.5, 0.7, 0.4) -a = 1 -b = 0.20000 + Wp = [60 200]/500; + Ws = [50 250]/500; + Rp = 3; + Rs = 40; + [n,Wp] = ellipord(Wp,Ws,Rp,Rs) ]]></programlisting> </refsection> </refentry> |