niVNA 5632 missing functions compared to Soft Front Panel

[Erickey]

Its pretty disappointing to find the LabVIEW driver for the niVNA platform is missing several functions the soft front panel has. Even using the property node I cant find certain functions.

Lets start with basics: Sweep averaging and Averaging Restart. With the soft front panel I can enable sweep averaging. You can issue a trigger but to get a new measurement you need to Restart Averaging. This functions similar to Agilent VNAs.

Questions:

1.Does anyone have sample code they can share that shows how the proper use of averaging is done?(LV 2013 please). Not a single sample program has this ability. I can set averaging count, type, but LV is missing the Average Restart function. Maybe there is another way to accomplish this

2. to NI: The VNA platform has been out for years.....when will 100% of the functions of the Soft Front panel be programmable within LV?

[ericthemantis]

What you described with setting the Averaging Type and Averaging Count sounds like the correct steps to be taking to do an averaged measurement. To get a new measurement, like the "Averaging Restart", would be to just call niVNA Initiate.vi again - this starts a new measurement. The niVNA_PowerSweep.vi is a good example of this.

If you want to replicate the functionality of the SFP exactly, I would recommend running NI I/O Trace while performing your measurements in the SFP, then replicate the instrument calls listed on the Trace in LabVIEW (I don't have a VNA available or I would post an example of this).

I attached the PowerSweep example with a trigger and averaging controls added. Again, I haven't tested this since I don't have a VNA, but should do what you were describing.

[Erickey]

Eric thanks for your reply.

#1. NI Trace is not capturing commands from the VNA SFP. It does capture from NI DMM SFP

#2. When setting up Sweep averaging and Average count of 2, do I need 1 initiate and 2 triggers,2 initiates and 1 trigger?? I can't seem to get sweep averaging to work.

[ericthemantis]

#1 - that is unfortunate. did a little investigating and NI-VNA does not have IO Trace support.

#2 - My understanding is, for sweep averaging - 1 initiate, 1 trigger. The VNA will perform the specified number of sweeps off of the 1 trigger and return the averaged sweep. If a more iterative averaging is desired like in the SFP, don't set averaging in the API, but instead perform the iterative averaging in LabVIEW, perhaps with an array where once the specified number of sweeps have been acquired through each Initiate-Trigger pair, new sweeps overwite previous sweeps instead of being appended to the array. A "Restart Averaging" function could be created to clear out all sweeps from the array and begin the iterative averaging process over again.

Does this provide some direction into getting the functionality you are looking for in LabVIEW?

[Erickey]

Hi Eric, 

thanks for the response. I still have a noise issue but I think its related to how the Dual Source works. When using an Agilent and taking an S11 and S22 measurement, both ports are not active at the same time. It appears that the NI 5632 has both ports active all the time. While I can set ports to "inactive" I still believe the inactive port is in the path. I have an active ticket with support.....

I am trying to see if there is a way to make the NI instrument function like an Agilent.