How To Generate Pure Tone Using The NI PXIe-4467/ 4468

NI PXIe-4467/ 4468 comes with the Pure Tone Generator. This new mode produces sine waves with distortion, previously only achievable by larger, boxed instruments and enables the testing of demanding parameters like data converter linearity and amplifier distortion. This article provides a brief overview of how to use the Pure Tone Generator on NI PXIe-4468 and its performance benefits.

Performance Benefits
Many signal generators use widely available digital to analog converters (DACs) to create the user’s desired waveforms. Noise and distortion performance is these types of generators is then limited by the performance of commercially available parts. The NI Pure Tone sine wave generator uses novel DSP techniques to enable distortion performance far beyond the capabilities of conventional digital to analog converters to produce previously unachievable residual THD and THD+N.

1. Install NI-DAQmx 2022 Q3 (22.8) or above version.

2. Generate pure tone like below code.
To generate sine waves using the Pure Tone generator, the DAQmx Function Generation channel type is used (“AO FuncGen”). This not only enables the Pure Tone generator, but it also provides a streamlined interface to generate sine waveforms when compared to generating each sample individually and streaming to the device. Only sine wave generation is supported.

The LabVIEW 2020 example (code snippet) below shows the configuration of a Pure Tone generation using the “AO FuncGen” DAQmx channel type.


Note: The Pure Tone generator requires a specific amount of time to stabilize after the task is started to achieve the specified performance. Refer to your device specifications for the duration of this settling time.