VST installation WLAN 802.11ac

[DaveMu]

My company recently purchased a PXIe-5644R VST Instrument without purchasing any software or licenses!

I've figured out with some help from NI support AE's what I think the requirements are for making some 802.11ac measurements with the VST.

LabVIEW 2012 Development Suite

Spectral Measurements Toolkit

Modulation Toolkit

WLAN Measurement Suite V4.0

I expect to have all the software and licenses I need in a few days.

I have a number of questions remaining on installation and configuration related to this 802.11ac measurement solution that I really hope to get help with from NI folks or any other folks that have gone through this already.

1. Do I also need a FlexRIO module like PXIe-7965R for basic 802.11ac Generation and Analysis or is this card only required if I need to do channel modeling or other custom tasks?  I do actually have this hardware already but don't know if its required and it is not entirely clear to me exactly when I need to use it.

2. Is there a process I should follow [or can anyone suggest one] to ensure I can get all this hardware and software to work together without too much wheel spinning?

3. Are there any LabVIEW examples for making an ACPR measurement with the VST?  Have not found any.

4. How do I setup the trigger routing between the FlexRIO module and the VST?  Had some trouble getting some of the basic VST LabVIEW examples to work and didn't understand the explanation. The error message summary said "the example uses PXI trigger lines for FPGA I/O, that these lines need to be routed to the VST"  It went on to say that this routing can be done in MAX.  I messed around with the routing but couldn't get the error message to disappear. 

Thanks for any help or guidance you can provide,

Dave M

[Nathan-P]

DaveMu,

Thanks for purchasing a VST, and hopefully you'll be able to be up and running soon!

1. You don't need a FlexRIO module for doing custom processing because the PXIe-5644R VST includes a FPGA in its hardware.  The VST is the only hardware needed for 802.11ac generation and analysis, and the onboard FPGA allows you the flexability to do any custom processing/filtering you need.

WLAN Measurements with the VST:

http://www.ni.com/white-paper/14058/en

2. I'm not 100% sure of what your asking, but you will want to be sure to install LabVIEW before any of the toolkits.  The VST has a getting started guide that discusses how to install all the hardware and software.  I would also reccomend checking out the VST Help file in the VST Manuals link below:

http://digital.ni.com/manuals.nsf/websearch/A9B21276CB1BA32F86257A41004698D2

VST Manuals

3. I also have been unable to find any examples that have been written for ACPR measurements.  I have found a good tutorial for using a PXIe-5665 VSA, which could be used as a reference for implementing the code for the VST.

4. The VST includes an FPGA so it sounds like you don't need to use an external FlexRIO module.  Which VST LabVIEW examples are you having a hard time with?  To help troubleshoot the error your getting, could you explain all the steps you took before the error occured?  Could you please include the error number for the error you recieved?

Thanks,

Nathan

[Nathan-P]

DaveMu,
I also found the following resources that might help you get up and running sooner with your WLAN measurements:
https://decibel.ni.com/content/docs/DOC-26431

Here is a list of several more VST example programs, foryour reference:

https://decibel.ni.com/content/docs/DOC-26212

Also, I forgot to mention that if you want to customize the FPGA built in the VST, you would need the LabVIEW FPGA module:
http://sine.ni.com/nips/cds/view/p/lang/en/nid/11834

That being said, you do not need to have LabVIEW FPGA to run the WLAN examples from the first link in this post, you will just not have access to the otherwise available LabVIEW FPGA code in the VST.

Hope this helps!

[DaveMu]

Hi Nathan,

I leveraged the RFSA ACP example you mentioned and substituted in VST Reciever commands. 

I set up an external VSG to play an LTE 5MHz - FDD waveform into the VST Rx and I can see the spectrum.

However, I cannot make a valid power measurement of my main channel or my upper/lower adjacent channels.

The VST Rx acquires the signal OK and outputs a Power Spectrum (dBm). In the LabVIEW program I route this signal to the 

SMT Filter Spectrum.vi , the SMT Spectrum Units.vi and the SMT Adjacent Channel Power.vi as they are used in the RFSA example.

Although I can capture the VST acquisition spectrum, I cannot do this with the Measurement Conversion Units and Power Spectrum Type settings  I expect to have to use?

When I use the settings I think I should be using I get an error.  I expect to use Conversion Units [dBm], Spectrum Type [V^2] [dB]. 

Even if I have this wrong, I cant get the Spectrum measurment to return valid power measurments regardless of the combination of Units / Types used.

My vi is attached, as is an image of the acquired spectrum, and finally an image including one of the main errors I see.

I'm hoping you can look at what I've done and work out why I can't measure power.

Thanks very much for your help on this,

Dave

[Nathan-P]

Dave,

I've only had enough time today to browse your code, but it seems that your error might be caused by the coersion dots on the VI's.  It seems that the datatypes might not be matching up, so I would reccomend taking a look at that.  

Tomorrow I'll have a bit more time to dig into your code a bit more and I'll provide some more feedback then.

Thanks,

Nathan

[DaveMu]

Hi Nathan,

Thanks for the update. I did see the coersion dot on the SMT Filter Spectrum vi and SMT Spectrum Unit vi but I currently don't have a valid license for the SMT so I can't see the block diagram vi's in order to debug.  I leveraged this example from the RFSA and it has the same coersion dot.  I'll check to make sure I have all the latest application updates installed.

Thanks,

Dave

[DaveMu]

Nathan,

I see that the SMT ACO (Simulated ) example is quite different from leveraged RFSA ACP  example. I'll play around with this. 

This example works OK but does also have coersion dots on the SMT Spectral units vi and the SMT Adjacent Channel vi.

Thanks,

Dave

[Nathan-P]

You mentioned that I pointed you to the  RFSA ACP example, where was that?  I'm having a hard time finding that particular example since I pointed you to several places all at once...

[DaveMu]

Nathan,

Ni RFSA example attached.

I've been communicating with Ni Apps Eng, Peter Williams by email too.

Have attached the outlook email thread of our discussions.

There is a newer version of the example program in this email as an attachment [don't use this version, has files missing; instead use the VST ACP program folder mentioned below ].

I've added a zip folder with this new VST ACP program folder [and dependant custom vi's].

The instructions for use and the issue details are in the email thread.

Thanks,

Dave

[DaveMu]

Nathan,

The instability I'm seeing when playing a waveform in the VST w/ VSG / VSA in loopback is not present when I feed an external signal into the Receiver.

So either I'm causing the problem when I load the waveform or the VST source is not configured correctly for the waveform samples I'm playing back. Or some other source setup criteria I'm not aware of.

The instability I'm seeing looks like additional spectral content. I'll check to make sure its not self inflicted.

Maybe the VST waveform sample size needs to be divisible by 4, 8 or 16, something like that?

Thanks

Dave