AnsweredAssumed Answered

Select I/Q Waveform mode on MXA using GPIB

Question asked by steveh on Jan 7, 2009
Latest reply on Jan 9, 2009 by steveh

Like • Show 0 Likes0
Comment • 5

I want to select I/Q waveform mode on on MXA (N9020A) using GPIB commands.

Using buttons on the MXA, I would do the following: Mode button-> IQ Analyzer (Basic), View/Display button -> I/Q Waveform.

These GPIB commands get me part way there:

SYST:PRES
INST:SEL BASIC

But I end up looking at the RF Envelope instead of the I/Q waveform. How I do I select the I/Q waveform?

Thanks!

No one else has this question

Outcomes

5 Replies

raphael Jan 7, 2009 5:34 PM
Mark Correct
Correct Answer
I believe the problem is that you haven't setup the IQ analyzer to be in IQ waveform measurement mode. By default, it's in complex spectrum.

Try the following:
SYST:PRES
INST:SEL BASIC
CONFIGURE:WAV
DISP:WAV:VIEW IQ

Regards,
Raphael
Like • Show 0 Likes0
Actions
steveh Jan 8, 2009 9:21 AM
Mark Correct
Correct Answer
Thanks, that did the trick. I actually figured it out myself late last night because I finally found a different MXA programming guide that covers I/Q waveform mode.

I've made more progress, but... now I'm stuck again. I want to read data out, so I used
FETCH:WAV0?

Then I try to read the data with this Matlab command:
data = fread(mxa_object, num_of_bytes/4, 'float32')

That always gives an error:
"
Warning: GPIB: NI: An I/O operation has been canceled mostly likely due to a timeout.
"

Any ideas what I'm doing wrong? Is FETCH the right command? Maybe I need READ or MEASURE?
Like • Show 0 Likes0
Actions
steveh Jan 8, 2009 4:23 PM
Mark Correct
Correct Answer
I figured out what I was doing wrong. The MXA was set up to use a trigger, but there was no trigger input. That seemed to prevent me from reading data out.
Like • Show 0 Likes0
Actions
raphael Jan 8, 2009 5:03 PM
Mark Correct
Correct Answer
I just tried this with a free running trigger and I couldn't get valid data to be returned using "FETCH:WAV0?" but seeing as how you have it working now, maybe something else is wrong.

FETCH:WAV1? AND FETCH:WAV2? did return what was described in the manual though. I'm looking at document N9060-90023.pdf.
Like • Show 0 Likes0
Actions
steveh Jan 9, 2009 9:07 AM
Mark Correct
Correct Answer
I believe I am getting valid data with a free running trigger and "FETCH:WAV0?". I'm looking at the same document.
Like • Show 0 Likes0
Actions

Select I/Q Waveform mode on MXA using GPIB

Outcomes

Related Content

Recommended Content