Creating and Generating Signals Using NI RFmx Waveform Creator

This article provides some general information about the RFmx Waveform Creator and includes step-by-step instructions for creating and generating a waveform using an NI Vector Signal Transceiver.
Requirements:

• • NI-RFSG driver
  • NI-RFSA driver
  • RFmx

The NI RFmx Waveform Creator is included with the installation or the RFmx but you can also download it standalone using the RFmx Waveform Creator download page.

NI RFmx Waveform Creator is application software you can use to create general-purpose and standards-based waveforms for design, validation, and production test applications. With this software, you can generate waveforms interactively with signal generators or save them to a TDMS (Technical Data Management Streaming) file and use it in the future for test automation purposes or other signal processing that you may want to perform on it. 

Those TDMS files created with NI RFmx Waveform Creator can be used along with the NI-RFSG Playback Library which allows users to generate waveforms saved in this format using the NI-RFSG instrument driver.

The supported standards are Bluetooth, 5G NR, LTE/LTE-Advanced, W-CDMA/HSPA+, GSM/EDGE+, TD-SCDMA, CDMA2k, EV-DO, including more general-purpose modulation formats such as FSK, PSK, QAM, and Tones.

Note: If you don’t see the specific standard format you were expecting or if you see it but it is gray-out, open NI License Manager and check that it is installed and activated since each personality requires activation, only the general purpose formats don't require a license.

As a general overview, the RFmx Waveform Creator has the following buttons:

• File: Here you can create a new file or open an already existing one.
• Modulation: In this button, will be listed all the available and supported standards as well as the general-purpose modulation formats.
• Save Waveform File: This button gives you the ability to save the waveform into a TDMS file.
• Instrument: With this button, you will be able to generate the created waveform. If multiple waveform windows are opened, the last window where you clicked will be generated using this Instrument button.
• Tools: In this option, you will be able to launch any Registered Plugin.
• Window: If no waveform windows are opened this button will show grey-out, but once you open a new waveform window this button will be used for managing those windows.
• Help: Here you can launch the RFmx Waveform Creator Help.

The steps for creating a single-tone waveform are the following: 
1. Open the RFmx Waveform Creator and click on Modulation>Tones: 2. Then click in Add… to configure the parameters for the tones you want to add: 3. It will pop up a window where you can configure the number of tones and the settings for those. If you only want to generate a CW leave the Number of Tones as 1 or use a number greater than 1 for a multi-tone signal. Take into account that in this window the Frequency represents the Offset Frequency from the center frequency you select later on. For this example we will set the Frequency to 0 for a single tone: 4. After configuring the tone click OK and you will see the tone that you just configured listed in the table, as it is shown in the following screenshot:  

Once you added the tone, go to the Graphics tab where we will select FFT to display the spectrum for the CW signal that we just created, which we can see by clicking the Plot button, and will look as follows:

1. Open the RFmx Waveform creator and click Modulation>NR: 2. It will prompt a New Settings File window, let’s select the Example setting and choose the NR_FR1_DL_FDD_SISO_BW-100MHz_CC-1_SCS-30kHz_Mod-256QAM-OFDM-SSBCasB.rfws as a starting point and hit OK: 3. The example file will open in another window where we can configure the settings for that waveform, so let’s change the Link direction to Uplink: 4. Then click on the Carrier Definition 0 where we will set the Channel Bandwidth to 10 MHz: 5. After that, move to the BWP 0 tab where we will set the Subcarrier Spacing to 15 kHz: 6. Then move to the PUSCH 0 tab and select the Modulation Type as QAM256: 7. Lastly for the configuration part, move to the Multi-Carrier tab where you can configure multiple NR carrier parameters and click in Edit to prompt the Edit Carrier Properties window, set 2 component carriers by setting the Number Of CCs to 2. When this value is increased, the new carriers added are preconfigured with the configuration for the last carrier set: 8. After clicking OK in the previous window, the 2 carrier components will be listed in the Carriers table, and then move to the Graphics tab to plot the waveform that was just created: 9. Once in the Graphics tab, click on Regenerate Plot to visualize the created waveform:  10. Once the created waveform is already displayed correctly you can save this waveform by clicking the Save Waveform File>Current Settings… where it will prompt you to select the location where you want to save the waveform in a form or a TDMS along with the description you would like to add.
11. Alternatively, you can generate this waveform using a VST by clicking Instruments>Download & Play to prompt the window where you can configure the instrument and settings for generating this waveform. Here you will select your device from the Device Name drop-down menu, set the desired Center Frequency (use 3.5 GHz for this example) then click the Create & Play button, once it starts generating the waveform it will display a status message as shown below:  12. For this example, we are using a PXIe-5644 connected in loopback (RF OUT connected to RF IN) so we will launch the RFmx Soft Front Panel for the instrument by clicking the Instrument Studio button in the device window in NI MAX. Once the RFmx Soft Front Panel opens we will configure the center frequency to 3.5 GHz and the bandwidth to 30 MHz: 13. Then we will use the NR personality in the RFmx Soft Front Panel (SFP) to confirm that the waveform is being generated correctly by clicking on Personalities and selecting the NR one: 14. Once you prepared the layout, you will need to configure the settings in the RFmx SFP to properly match the signal you have connected to the RF IN port as follows:
a. First, change the Bandwidth and Subcarrier Spacing to match the settings you configured for the waveform you just created using the RFmx Waveform Creator: b. Then click in the 3 dots (…) next to the NR section header to launch the New Radio settings and click in the Subblock to increase the Number of Component Carriers accordingly: c. Once you added the second Component Carrier, scroll down and select it to set the Bandwidth to the right value (10 MHz for this example): d. And then select the Bandwidth Part for that new Component Carrier and select the correct Subcarrier Spacing (15 kHz in this case): e. Now that all the settings have been configured correctly, you can see the Modulation Accuracy measurement for the signal that you just created:

Next Steps

You can find the instructor video for the RFmx Waveform creator on the Introduction to Creating and Modifying Waveforms Using RFmx Waveform Creator lesson from the Introduction to RF Signal Generation Acquisition and Analysis with NI RF Technologies online training.