I have been using the PXIe-4463 to generate a sine wave for vibration testing, as well as to generate a stepped-sine voltage. After tuning the amplifier gain, I found that a 10-Hz sine wave was acceptably free of harmonics, despite the data sheet giving 20 Hz as a minimum frequency.
When I ran a stepped-sine output (10, 20, 30, 40, 50 Hz) with the same amplifier gain, the 10-Hz output was severely distorted while the distortion disappeared at 30 Hz and above. Why did the device behave differently at 10 Hz in these tests? After reviewing the code, the amplitude is definitely set to a constant for all sine steps.
