Gain

A gain measurement measures the amplification between the amplitude of the identified tone in the input signal and the reference amplitude.

The accuracy of gain measurement depends on the absolute amplitude accuracies of the output channel and the input channel. For example, when you generate and acquire the signal with an NI PXI-4461, the expected measurement uncertainty is less than 0.3 dB.

A gain distortion occurs when the output amplitude is not a linear function of the input amplitude at an identified frequency. You must identify the expected fundamental frequency and the amplitude of the stimulus tone regardless of whether you are using the output of the acquisition device or an external source.