How to make a Delta measurement with Agilent N9030A PXA Signal Analyzer

[LoquitoPollo]

I'm using the Agilent N9030A PXA Signal Analyzer, LabVIEW 8.6.1, and Windows XP.

I can't seem to take a delta measurement.

By hand, I set the center frequency and span, then the delta marker, adjust the input signal (coming from a Signal Generator for now) to some different dBm level, and I see the delta measurement (~20dBm in my case).

When I use the example "Agilent MXA Series Configure and Query Marker.vi" in the "Agilent MXA Series" driver, I get a Marker Amplitude of 0 every time. I've tried adding in a One Button Dialog VI (to pause while I change the Signal Generator's output) and a second Query Marker to see if it just needed an initial measurement as reference, but I always read 0 dBm.

I need help with setting up the VI to take a delta measurement on the same marker after I change the SigGen's output (which is the SpecAn's input).

Thanks!

[Jake_G]

Hey LoquitoPollo,

Is there a way you can post a VI or an image of your block diagram to take a look at?

Hopefully we can get a better look at what exactly is going on.

Also, you could try to probe to see if you are getting these values specifically on the wires instead of trying to do One Button Dialogs.

[Charles.Tac]

Dear LoquitoPollo,

I got a N9020A model (firmware ver. A.03.08) in my site. I run the "Agilent MXA Series Configure and Query Marker.vi" with the following settings (see fig 1) and seems everything went on well. The marker amplitude indicates the delta value in the instrument (see fig 2).

Noticed that you have setting the marker position by hand. To keep your manual setting when running this example, please remove the VI "Configure Marker Peak Search.vi " (see fig 3) .

If the above didn't work for you. Would you please go to the Block Diagram and click the "Highlight Execution" button in toolbar? Then try to run the example to see if there are any error messages appeared during exectuion.

Fig 1

Fig 2

Fig 3

Yours,

Charles

[LoquitoPollo]

Thanks for the response, Charles.

I got back to this after working on something else for a bit. Now whenever I run the example with all the default settings (except my correct instrument), I get:

"Error -1074003950 occurred at Extended Noise User Data.vi

Reference Not Found: (xBFFC0012) Cannot retrieve user data for the given resource name as there was not data associated with the resource name. Before you can read data, you need to write the user data using the Write Data action of this User Data VI."

(Sorry for not including the screenshot, but we can't post pictures from work.)

My coworker thinks that this is referencing an option on the SpecAn that we don't have installed and thus throws the error. The "solution" was to delete Configure Sweep Coupling.vi that was calling Extended Noise User Data.vi.

I recall getting this error before and may have solved it the same way, but don't recall. (I'm documenting this now in my modified VI.) I'm not sure what happened before, but it seems to work fine now.

Thanks!

[LoquitoPollo]

Charles (or anyone else),

When I say "working fine", I mean that the VI runs. The question I had still remains. How did you get a delta measurement in relation to marker 12? Specifically, how do you tell the SpecAn to move marker 12 somewhere other than the center frequency? I've changed the VI to a center/span configuration and am (for testing the VI) setting the frequency of my SigGen to 2 GHz and match the SpecAn with a 2 GHz center frequency and a 2 MHz span. Since it's right in the middle of the span, I get both markers (1 and 12) to be the same, thus resulting in a 0dBm delta measurement.

Any ideas on how to get marker 12 somewhere in the noise floor for a good delta measurement?

[Charles.Tac]

Hi LoquitoPollo

Before run the example, please try to change the Marker Type to Delta, then it should return the delta value.

[LoquitoPollo]

The way I finally got my delta measurement is by doing three things:

1) Run the Agilent MXA Series Configure and Query Marker VI with the Marker Type as Delta and the Marker Search subVI (second to last) removed, as it errored out with a delta measurement.  (I was doing this all along.),

2) Lower the signal's power, and

3) Run a Query Marker subVI (I wrapped this in a separate VI to run separately) with the Active Marker set to 1. This now returns the difference in signal.

Reflecting on my stupidity it makes sense that some change in signal level needs to take place before a delta measurement can happen. But that's also why the first VI won't work all on its own: it lacks a time to wait for a change. But once I set it up as a starting power, change the power, then read the delta, it works.

I hope that helps anybody stuck in the future.