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Satellite TV receivers & systems support forums
DISH SETUP: Single sat, Multi-Sat & Motorised
Satellite Meters and Installation Equipment
Using the "138MHz-4.4GHz USB SMA Source/Signal Generator/Simple Spectrum Analyzer" for TV/CATV/SAT
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<blockquote data-quote="vma" data-source="post: 995231" data-attributes="member: 256592"><p>Hi,</p><p></p><p>I think you are looking at a <strong>double sideband</strong> amplitude modulation (<strong>DSB-AM</strong>) (see <a href="https://en.wikipedia.org/wiki/Sideband" target="_blank">Sideband - Wikipedia</a>).</p><p></p><p>The SMA device has quite a high resolution, mind you!</p><p></p><p>Most field meters will not allow user selectable RBW (Resolution Bandwidth). The only exception I know is the Deviser S7000 and Deviser S7200 field meters, better known as TV Analyzer (great devices, btw., with full TS analyzer on board).</p><p></p><p>The SPAN has nothing to do with RBW: it just selects the start and end frequencies being rendered in the spectrum.</p><p></p><p>Your Promax will then internally adjust to whatever RBW the engineers implemented, which certainly has a lower resolution than what you are seeing in my software. This causes the signal to be averaged out. See this picture:</p><p></p><p><img src="http://www.ni.com/cms/images/devzone/tut/a/d7986ce2186.gif" alt="" class="fr-fic fr-dii fr-draggable " style="" /> </p><p></p><p>Source: <a href="http://www.ni.com/white-paper/3983/en/" target="_blank">Resolution Bandwidth (RBW) - National Instruments</a></p><p></p><p>Try to render the same signal in my software with less samples: start with 500 samples then go to 250 samples, 200 samples and finally 100 samples. At a given point you should see the same signal as on your Promax.</p><p></p><p>My point is: while the spectrum on my software has a lower refresh rate than your Promax HD Ranger+, it will show the spectrum at higher resolution (read: lower RBW). Try to set the samples at 1000 in my software!</p><p></p><p>As opposed to normal spectrum analysers, you cannot directly select the RBW in my software, because the SMA device itself works by specification of the number os samples. So I did it the other way around: you specify the samples and the software displays the relevant RBW.</p><p></p><p>Regards,</p><p>vma</p></blockquote><p></p>
[QUOTE="vma, post: 995231, member: 256592"] Hi, I think you are looking at a [B]double sideband[/B] amplitude modulation ([B]DSB-AM[/B]) (see [URL="https://en.wikipedia.org/wiki/Sideband"]Sideband - Wikipedia[/URL]). The SMA device has quite a high resolution, mind you! Most field meters will not allow user selectable RBW (Resolution Bandwidth). The only exception I know is the Deviser S7000 and Deviser S7200 field meters, better known as TV Analyzer (great devices, btw., with full TS analyzer on board). The SPAN has nothing to do with RBW: it just selects the start and end frequencies being rendered in the spectrum. Your Promax will then internally adjust to whatever RBW the engineers implemented, which certainly has a lower resolution than what you are seeing in my software. This causes the signal to be averaged out. See this picture: [IMG]http://www.ni.com/cms/images/devzone/tut/a/d7986ce2186.gif[/IMG] Source: [URL="http://www.ni.com/white-paper/3983/en/"]Resolution Bandwidth (RBW) - National Instruments[/URL] Try to render the same signal in my software with less samples: start with 500 samples then go to 250 samples, 200 samples and finally 100 samples. At a given point you should see the same signal as on your Promax. My point is: while the spectrum on my software has a lower refresh rate than your Promax HD Ranger+, it will show the spectrum at higher resolution (read: lower RBW). Try to set the samples at 1000 in my software! As opposed to normal spectrum analysers, you cannot directly select the RBW in my software, because the SMA device itself works by specification of the number os samples. So I did it the other way around: you specify the samples and the software displays the relevant RBW. Regards, vma [/QUOTE]
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Satellite TV receivers & systems support forums
DISH SETUP: Single sat, Multi-Sat & Motorised
Satellite Meters and Installation Equipment
Using the "138MHz-4.4GHz USB SMA Source/Signal Generator/Simple Spectrum Analyzer" for TV/CATV/SAT
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