connect RFSA output as input to RFSG

[wonder31]

Hi! I'm using NI PXIe-5601 (RF Downconverter) and NI PXIe-5611(I/Q Vector Modulator). Both are working fine; the 5601 can display external input signals and I can read the 5611 output from an external program.

Question is, can the 5601 output become the signal "generated" by 5611 because I want an external program to generate a signal then pass through the 5601 and 5611 (as channel) then receive it by the same program.

THANKS! Sorry for such a basic question. 🙂

[I.B.Hating]

Hi,

Are you using the 5601 as part of the 5663E and the 5611 as part of the 5673E?

Are you looking to pass the signal going into the VSA straight into the VSG without going through software? For example, take IF Out from the downconverter and put it directly into the I/Q Vector modulator? If so then your answer is no. This is because the signal coming out of the IF Out port is going to be a complex waveform while going into the I/Q modulator you have to put your I and Q signals. So you will have to split that in software before you can put the signal into the 5611.

Getting the signal using your VSA, bringing it into software, and then outputting it on your VSG is definitely a possibility.

[wonder31]

Hi! Thanks for answering!

I directly put my signal into the 5601 with the 5652 (RF Signal Generator) and 5622 (16-Bit IF Digitizer) then I'm directly reading 5611's output with the 5450 (400 MS/s I/Q SIgnal Generator) and the 5652 (RF Signal Generator).

I do want to pass the signal inside LabVIew software because it will act as a channel (which I can vary the SNR and such). How can I do that? Are there available VI's for getting the 5601 output then put it (directly or indirectly) as 5611's input.

Again thank you for giving time to reply! 🙂

[I.B.Hating]

Does it need to happen immediately? Or can you run, save the data, and then load it into another VI?

The easiest thing to do would be to simply acquire the data with a RFSA example, compile the data, and then pass it into a RFSG example. So, you could use the Acquire Continuous IQ example, save the data, and then use something like RFSG Write Waveform from File to output the data. There is no example for this, unfortunately, but you can definitely stitch together two examples to make this.

If you need to output the data immediately then the programming gets more complex. Now you will have to figure out a way to stream to the VSG rather than writing a waveform to the buffer which may be supported in the IDL. I would look into this tutorial for more information:

http://www.ni.com/tutorial/14647/en/

[wonder31]

Hi! Thanks for the reply!

I found VI called niRFSA Read IQ which "initiates an acquisition and fetches a single I/Q data record". Can I use this together with the example RSFG Arbitrary Waveform Generation (which takes in the I/Q output from the Read IQ VI)? The data types are different as Read IQ outputs a complex cluster while the RSFG example takes in the double data type? How can I get the appropriate data from the complex cluster?

THANKS AGAIN!

PS. Would want to try this first (would totally appreciate the answer to the questions above) then I'll do the data pass method after if this won't work.

[I.B.Hating]

Hi,

So the issue with Arbitrary Waveform Generation is that it requires an IQ array before generation begins. Meaning that you must have already acquired all of your data before you begin to generate a waveform.

Now the example RFSG Arbitrary Wavform Streaming is more like what you want to look at. This example looks at chunks of data from a file and then wrties that to the VSG. So here what you would need to do is make sure you have enough data points from the VSA to write to your VSG. So the VSA will have to start some amount of time before generation then your generation cannot run faster than the acquisition otherwise the VSG will just start repeating data or holding the last data point depending on how you've configured it. Of course the Waveform Streaming Example will not work out of the box, you will have to modify it so that you are not using a file but rather you are putting your acquired data directly into a queue to write to the VSG.

Next, for the VSA, I would recommend looking at the Acquire Continuous IQ example. You will need to continuously acquire the IQ data so that you can then continuously output it.