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How to access Cal Sets remotely using FieldFox N9923A

Question asked by jdjdo92 on Jan 4, 2019
Latest reply on Jan 17, 2019 by wstark

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Trying to use Visual Studio to use the N9923A remotely. I need to take measurements at different frequencies and want to do the calibrations for each frequency all at once. Ideally, I would like to save the calibrations for each frequency and then access them again when taking measurements.

I saw online that this is capable for other Keysight analyzers using User Cal Sets. Is it possible for the N9923A? I tried following the code from the links listed below. I kept getting an error on the VNA that said the headers I was using for the Cal Sets were undefined.

Using Cal Sets

Calibrating the Analyzer Using SCPI

CorrCset SCPI

Sense Correction SCPI

If anyone has any insight on this issue, please let me know!

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wstark Jan 7, 2019 11:05 AM
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FieldFox (including N9923A) saves one network analyzer calset per saved state. This calset applies to NA type modes, including VVM and CAT modes.

Therefore, the method for achieving what you want is to perform instrument setup (including frequencies) and calibration, then save the instrument state. Then repeat the process for your other frequency ranges. Save each state to a different filename.
Then you can recall each state (which will recall the calset along with it) and make measurements at the frequency range corresponding to that saved state.

Note: The setup+cal and also the state recall processes may be performed via the GUI as well as SCPI.

Also Note: The saved states contain information for each analyzer mode (e.g. CAT, NA, ...) that has been activated/selected since instrument power-on. If you are creating a lot of states and are concerned about the size of the states, consider avoiding changing modes after power on when doing your state creation+cal process.
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- jdjdo92 @ wstark on Jan 17, 2019 8:57 AM
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  Thank you for your response. I tried doing this and the line of code I am trying to use is MMEM: STOR: STAT "FileName.sta" however, I keep getting Error -113, undefined error. Would there be any reason why the above code would not work to save the instrument state?
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  - wstark @ jdjdo92 on Jan 17, 2019 9:24 AM
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    The SCPI command:
    MMEM:STOR:STAT "FileName.sta"
    
    should work. I note you have spaces after the ":" characters, which will cause an error but not the one you describe (you get -110).
    
    Here some sample SCPI that demonstrate the error and also correct usage.
    
    IC 141.121.151.55> MMEM: STOR: STAT "FileName.sta"
    IC 141.121.151.55> syst:err?
    -110,"Command header error;Missing program mnemonic"
    IC 141.121.151.55> MMEM:STOR:STAT "FileName.sta"
    IC 141.121.151.55> syst:err?
    0,"No error"
    IC 141.121.151.55> MMEM:CAT?
    315351040,3975405568,"FileName.sta,,26838","[Keywords],,","[calkits],,","[EventLog],,"
    IC 141.121.151.55> MMEM:DEL "FileName.sta"
    IC 141.121.151.55> syst:err?
    0,"No error"
    IC 141.121.151.55>
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am95405 Jan 7, 2019 1:50 PM
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I am not exactly sure of your measurement requirements, but doing a wideband (wide frequency range), lots of points calibration may be sufficient for your needs. So you'd set up your start/stop such that it covers all your bands, set # of points to a high value (1601 or higher), do a cal, and then during the measurement recall this one cal and reduce the frequency range to the subset needed, and depend on cal interpolation.

This wouldn't work for example for a # of waveguide cals, but for coax, it may be good enough.
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- wstark @ am95405 on Jan 7, 2019 2:13 PM
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  FieldFox will interpolate calibrated data points across frequency. This means that if a measured frequency point does not line up exactly with an available calibrated frequency point, FieldFox creates a calibration for that point using adjacent (in frequency) calibration points.
  Interpolation has limits, in particular if the calibrated point(s) are "far enough" from the measured point the calibration may not provide a good result. For example, with an electrically long device, it can be possible to have many phase wraps even when the frequency difference is small. Trying to interpolate across wraps of phase generally will not work.
  
  That said, depending on what you frequency ranges are, you might be able to choose a state to calibrate (start freq, stop freq, # of points) that calibrates all or many of your desired points for your frequency ranges. E.g. if you had 2 ranges, 1-2GHz and 3-4GHz, than you could calibrate 1-4GHz with 3x your point count and save that state. Then recall the state, set 1-2GHz (or 3-4GHz), and measure. You can repeat changing between 1-2GHz and 3-4GHz and measuring without recalling a new state, as the FieldFox will re-interpolate from the original calibration data each time.
  
  Note that the frequency of the ith data point (i starting at 1) from startF to stopF for N points is: startF + (stopF-startF)*(i-1)
  
  So the first point is startF, and the Nth point is stopF.
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How to access Cal Sets remotely using FieldFox N9923A

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