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Agilent E4404B - Changing number of Measurement points - labview

I have a Labview VI that uses the Agilent ESA PSA series vis to configure and save a trace from an Agilent E4404B spectrum analyzer connected to my PC through a GPIB cable. I know this is an outdated piece of hardware, but was hoping someone knew of a way to set the number of measurement points on the trace remotely. I hope I am not just glossing over it in the VI tree, but I cannot seem to find anything that does this job. Or am I missing something - and are the resolution BW, the sweep time and the number of points related? I know the first two are...

 

Thanks!

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Yes, the number of points depends on the Start Freq., Stop Freq, VBW, RBW and the sweep time.  No way to set # of pts.  Especially if you have "auto VBW/RBW" or "auto span/RBW" enabled. 

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Thanks for clearing that up! I have a certain span I want to look at. So I can't mess with that, but what is the relationship between the videoBW, the resolutionBW, the sweep time and the # of points? I do have auto VBW/RBW enabled right now, but I can set them manually if I know what I want.

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I'm not sure there's an easy answer to that.  Spectrum analysers change a lot of settings without really telling you depending on the frequency range,  RBW, etc..  Each seems to do it a bit differently.  I'd consult the manual to see what the model you're using says.

 

I'd leave auto enabled, otherwise you might run into problems.

 

Why do you need # of pits?

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I'm not familiar with the E4404, but I do have an E4440 PSA. On that SpecAn you can change the number of points. Look in your manual to see if this command is available on your model.

 

p.s. Those PSAs may be old but they are a reliable workhorse in my lab

 

Num_Points.JPG

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This is great! I had never used SCPI commands before - was working with Labview, but SCPI with Matlab works so much better now. But, I am having some trouble in collecting data. When I do this:

 

[data_temp] = query(h, ':TRAC:DATA? TRACE1') ;

 

The data is saved as a character string of only 512 characters. Regardless of the number of points in the trace, it saves the first 512 characters (not points in the trace - so if the first point reads -54.0012, that is 8 characters). Is there some way to change this? Or some other command to collect data that I am missing? I'm sorry, this is not related to the original question, but would appreciate an answer!

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