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	<updated>2026-09-18T12:48:04Z</updated>
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		<title>130.126.255.92: /* Fundamental Matrix in Linear Systems */</title>
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		<summary type="html">&lt;p&gt;&lt;span class=&quot;autocomment&quot;&gt;Fundamental Matrix in Linear Systems&lt;/span&gt;&lt;/p&gt;
&lt;p&gt;&lt;b&gt;New page&lt;/b&gt;&lt;/p&gt;&lt;div&gt;{{Orphan|date=September 2008}}&lt;br /&gt;
A &amp;#039;&amp;#039;&amp;#039;Fraser Filter&amp;#039;&amp;#039;&amp;#039; is typically used in [[geophysics]] when displaying [[Very Low Frequency|VLF]] data. It is effectively the [[first derivative]] of the data.&lt;br /&gt;
&lt;br /&gt;
If &amp;lt;math&amp;gt;f(i) = f_i&amp;lt;/math&amp;gt; represents the collected data then &amp;lt;math&amp;gt;average_{12}=\frac{f_1 + f_2}{2}&amp;lt;/math&amp;gt; is the average of two values. Consider this value to be plotted between point 1 and point 2 and do the same with points 3 and 4: &amp;lt;math&amp;gt;average_{34}=\frac{f_3 + f_4}{2}&amp;lt;/math&amp;gt;&lt;br /&gt;
&lt;br /&gt;
If &amp;lt;math&amp;gt;\Delta x&amp;lt;/math&amp;gt; represents the space between each station along the line then&lt;br /&gt;
&amp;lt;math&amp;gt;\frac{average_{12}-average_{34}}{2 \Delta x}=\frac{(f_1 + f_2)-(f_3 + f_4)}{4 \Delta x}&amp;lt;/math&amp;gt; is the Fraser Filter of those four values.&lt;br /&gt;
&lt;br /&gt;
Since &amp;lt;math&amp;gt;4 \Delta x&amp;lt;/math&amp;gt; is constant, it can be ignored and the Fraser Filter considered to be&lt;br /&gt;
&amp;lt;math&amp;gt;(f_1 + f_2)-(f_3 + f_4)&amp;lt;/math&amp;gt;.&lt;br /&gt;
&lt;br /&gt;
==References==&lt;br /&gt;
{{cite book |title=Applied Geophyisics |last=Telford |first=W.M.|coauthors=L.P. Geldart, R.E. Sheriff |pages=p480+ |edition=2nd}}&lt;br /&gt;
&lt;br /&gt;
{{Geophysics-stub}}&lt;br /&gt;
{{Signal-processing-stub}}&lt;br /&gt;
&lt;br /&gt;
[[Category:Geophysics]]&lt;br /&gt;
[[Category:Linear filters]]&lt;/div&gt;</summary>
		<author><name>130.126.255.92</name></author>
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