IRA/ira_spectrum.html at master · patchvonbraun/IRA · GitHub

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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
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	<META NAME="AUTHOR" CONTENT="Marcus Leech">
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<P STYLE="margin-top: 0.17in; page-break-after: avoid"><FONT FACE="Albany, sans-serif"><FONT SIZE=4>The
IRA Spectrum Window</FONT></FONT></P>
<P>This window shows a conventional spectral display, such as one
might expect to see on a laboratory RF spectrum analyzer.</P>
<P><IMG SRC="ira_spectrum.png" NAME="graphics1" ALIGN=LEFT WIDTH=950 HEIGHT=472 BORDER=0><BR CLEAR=LEFT><BR><BR>
</P>
<P STYLE="margin-top: 0.17in; page-break-after: avoid"><FONT FACE="Albany, sans-serif"><FONT SIZE=4><I>The
Spectral Maximum Control</I></FONT></FONT></P>
<P STYLE="font-style: normal">This control determines the maximum
value to be shown in the display, it is a slider control, which
ranges from -10 to 120, and is calibrated in dB.</P>
<P STYLE="margin-top: 0.17in; page-break-after: avoid"><FONT FACE="Albany, sans-serif"><FONT SIZE=4><I>The
Compression Method Control</I></FONT></FONT></P>
<P STYLE="font-style: normal">This selects the method used to
compress the SETI spectrum (usually several million bins) into the
smaller conventional spectral display. The usual method is <I>Average</I>,
but both <I>Max</I> and <I>Median </I>are also available.</P>
<P STYLE="margin-top: 0.17in; page-break-after: avoid"><FONT FACE="Albany, sans-serif"><FONT SIZE=4><I>The
Flatten Control</I></FONT></FONT></P>
<P>This control allows you to “flatten” the spectrum, using a
function that inverts the roll-off effects of the CIC filtering in
the USRP FPGA.</P>
<P STYLE="margin-top: 0.17in; page-break-after: avoid"><FONT FACE="Albany, sans-serif"><FONT SIZE=4><I>The
Create Postscript Control</I></FONT></FONT></P>
<P STYLE="font-style: normal">This control allows you to create a
postscript file of the spectral plot. It will pop-up a file browser
to allow you to choose a directory and filename for the resulting
<I>PostScript </I>file.</P>
<P STYLE="margin-top: 0.17in; page-break-after: avoid"><FONT FACE="Albany, sans-serif"><FONT SIZE=4><I>The
Spectral Span Control</I></FONT></FONT></P>
<P>This slider control controls the total span of the spectral
display, in dB. Smaller values give higher resolution in the Y axis,
while larger values reduce the resolution in the Y axis.</P>
<P STYLE="margin-top: 0.17in; page-break-after: avoid"><FONT FACE="Albany, sans-serif"><FONT SIZE=4><I>The
Notch Filter Length Control</I></FONT></FONT></P>
<P STYLE="font-style: normal">This control determines the length of
the notch filter. Individual notches can be set using the <B>RIGHT</B>
mouse button at a point on the spectral display.</P>
<P STYLE="margin-top: 0.17in; page-break-after: avoid"><FONT FACE="Albany, sans-serif"><FONT SIZE=4><I>The
Clear Notches Control</I></FONT></FONT></P>
<P STYLE="font-style: normal">This control clears any notch filter
points that have been set.</P>
<P><I>DISMISS</I></P>
<P>This control causes the IRA Spectral Window to close, but spectral
data are still updated while the window is closed.</P>
<P>Using the <B>LEFT</B> mouse button causes a small display to pop
up with the corresponding frequency, relative power (dB), and the
Doppler velocity (km/s).</P>
<P><BR><BR>
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