Using NI RFSG Playback Library for Generating an NR Waveform

This article provides general information about the NI RFSG Playback Library and includes step-by-step instructions for loading a waveform file (TDMS format) and generating that waveform using an NI Vector Signal Transceiver.

Requirements:

• NI-RFSG driver

• NI-RFSA driver

• RFmx

The NI RFSG Playback Library is included in the installation of the NI RFSG driver. Currently, it supports I/Q rate, PAPR, Runtime Scaling, Signal Bandwidth, Burst Locations, RF Blanking Enabled, and RF Blanking Marker Source as waveform properties. It reads and downloads the waveforms present in the TDMS file to the NI-RFSG vector signal generator memory and stores the waveform properties in the database. The NI-RFSG Playback Library automatically sets the appropriate NI-RFSG properties corresponding to waveforms in the generated script.
We will use LabVIEW as the programming language for the purpose of this Knowledge Base article, but all the features and functionalities of the drivers and APIs can map to other languages like C and C# and the programming flow will be similar.
Note:  This article applies to NI RFSG driver version 2022 Q3 and previous.

Next will be described the programming flow that you will find in the RFSG Playback Library examples, which you can find in the following location of your computer: C:\Users\Public\Documents\National Instruments\NI-RFSG Playback Library\Examples

• The niRFSG Initialize. vi opens a session to the NI RFSG Resource specified.

• Then use the niRFSG Configure RF.vi to configure the center frequency and output power level which will be the average power (this can also be configured using a Property Node).

• After configuring that session, the niRFSGPlayback Read and Download Waveform From File. vi reads the waveform stored in the TDMS file specified and downloads it to the NI VST using the file path that you specified in the File Path Control on the Front Panel.

• Then with the niRFSGPlayback Set Script to Generate.vi, you will configure the NI-RFSG driver to generate the waveforms specified in the script.

• After configuring the session and the script, the niRFSG Initiate.vi will start the generation according to programmed settings. Even though it is in script mode, there is no need to set the Peak Power mode, there is also no need to select the mode of the generator, it is taken care of underneath the hood of the Playback Library itself.

• Then the niRFSG Check Generation Status. vi will check for any error that may occur during the signal generation or if the device has finished generating.

• Once the generation is finished, the niRFSG Abort will make sure to stop the signal generation, and the niRFSGPlayback Clear Waveform.vi will delete the waveform from the NI-RFSG device memory and removes all the related waveform properties.

• Lastly, the niRFSG Close. vi will end the session of the NI-RFSG driver when the one the generation is done.

When running this code, the first that needs to be configured is the resource name to make sure it matches the actual name for the NI RFSG device on NI MAX. In this case, we are using a PXIe-5644 VST with the name PXI1Slot8.
Then the center frequency and power level need to be configured, for which we will use the values of 3.5 GHz and -10 dBm respectively.
Lastly, we select the New Radio waveform that was created on the Creating and Generating Signals Using NI RFmx Waveform Creator article the code will read and download the waveform to the NI RFSG device selected resource.

For this example, we are using the VST connected in loopback so we will use the RFmx Soft Front Panel to display the waveform being generated using the RFSG Playback Library.
Note: As per version 2022 Q3 and moving forward the RFmx Soft Front Panel will be integrated within the Instrument Studio application, the RFmx SFP button in NI MAX now will appear as an Instrument Studio button for the particular device and will open the RFmx SFP as an Instrument Studio layout.
To display the waveform properly we need to configure the NR personality as it is explained in the Creating and Generating Signals Using NI RFmx Waveform Creator article so the ModAcc and ACP measurements for that generated waveform will look like the following image:

Next Steps

To get more information about other functionalities the RFSG Playback Library has available feel free to check the instructor training lesson called Introduction to Generating Waveforms with RFSG and RFmx Waveform Playback Library which is part of the Introduction to RF Signal Generation Acquisition and Analysis with NI RF Technologies online training.