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Re: Multiple digitizers with one downconverter

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samantham

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Jul 17, 2008, 7:10:11 PM7/17/08
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Hello,
 
The first concern would be making sure the output of the 5600 is properly split by using a 6 dB splitter.  This way the SNR and thus the demodulation is not negatively influenced.  Second, I am curious which digitizer will be used for displaying the spectrum and which one for the demodulation and recording.  Please give me some feedback and I will make sure there is nothing else to consider.

samantham

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Jul 28, 2008, 11:10:14 AM7/28/08
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Hello,

What type of audio demodulation are you referring to ? Amplitude or Frequency Modulation (AM or FM)?  My concern is that the 5122 does not have the On-Board Signal Processing (OSP) to take the IF signal to IQ Baseband in hardware.  The 5142 has OSP and would reduce the processor time and RAM needed to do the Digital Downconverting.  Plus, the 5124 is supported by the NI-RFSA driver and the 5122 is not. 

Please consider reversing the cards, where the 5122 is displaying the spectrum and the 5124 as part of the 5661 is demodulating the audio signal.  This would involve using NI-RFSA for the 5661 and NI-Scope for the 5122.  The way originally noted will use NI-Tuner for the 5600 and two sessions of NI-Scope for each individual digitizer.  This sounds like a bit more work.  Please give me some feedback or insight on some reasons that I might not be aware of that might make audio demodulation on the 5122 better for this specific application. 

I noted that you have that Spectral Meausurement Toolkit.  Do you have the Demodulation Toolkit?

 

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